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The Respiratory system consists of seven main parts; nose, mouth, pharynx, larynx, trachea, bronchi, and bronchioles which carries air between the lungs and the body's exterior. HELPS YOU BREATHE!

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Respiration

Respiration is the act of breathing:

Respiratory system

The respiratory system is made up of the organs included in the exchange of oxygen and carbon dioxide. The respiratory system is divided into two areas: the upper respiratory tract and the lower respiratory tract.

The upper respiratory tract is made up of the:

The lower respiratory tract is made up of the:

Lungs

The lungs take in oxygen. Your body's cells need oxygen to live and carry out their normal functions. The lungs also get rid of carbon dioxide, a waste product of the cells.

The lungs are a pair of cone-shaped organs made up of spongy, pinkish-gray tissue. They take up most of the space in the chest (thorax).

The lungs are surrounded by a membrane (pleura).

The lungs are separated from each other by the mediastinum, an area that contains the:

The right lung has three sections, called lobes. The left lung has two lobes. When you breathe in:

Air enters your body through your nose or mouth.

Air then travels down the throat through the larynx and trachea.

Air goes into the lungs through tubes called main-stem bronchi.

One main-stem bronchus leads to the right lung and one to the left lung:

In the lungs, the main-stem bronchi divide into smaller bronchi.

The smaller bronchi divide into even smaller tubes (bronchioles).

Bronchioles end in tiny air sacs (alveoli) where the exchange of oxygen and carbon dioxide occurs.

You then breathe out carbon dioxide.
Medical Reviewers:

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Respiration is the act of breathing: The respiratory system is made up of the organs included in the exchange of oxygen and carbon dioxide. The respiratory system is divided into two areas: the upper respiratory tract and the lower respiratory tract.

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The human digestive system consists of seven steps. ingestion, propulsion, mechanical digestion, chemical digestion, absorption, and defecation. The digestive system breaks down food into nutrients such as carbohydrates, fats and proteins.

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Key facts

The digestive system breaks down food and absorbs nutrients for energy and growth.

It is a long tube starting from your mouth, going all the way to your anus.

Common digestive health conditions are gastro-oesophageal reflux disease (GORD), diverticulitis, stomach ulcers, and haemorrhoids.

What is the digestive system?

The digestive system is made up of the digestive tract (the gut) and other organs like the liver, pancreas and gall bladder. It is where your body breaks down food and absorbs nutrients. The digestive system is a long, twisting tube that starts at the mouth and goes through the oesophagus, stomach, small intestine, large intestine and ends at the anus.

The digestive system breaks down food into simple nutrients such as carbohydrates, fats and proteins. These can then be absorbed into your blood, so your body can use them for energy, growth and repair. Anything that isn't used is waste, and leaves the body as faeces (poo).

How does my digestive system work?

Each organ of your digestive system has an important role in digestion.

Mouth

When you eat, your teeth chew food into small pieces. Glands in your cheeks and under your tongue make saliva that coats the food. This makes it easier to chew and swallow. Saliva also contains enzymes that start to digest the carbohydrates in food.

Oesophagus

Your oesophagus is a tube that carries food from the mouth to the stomach, after it is swallowed. A ring of muscle at the end of the oesophagus lets food into your stomach and stops stomach contents from going back up to the oesophagus.

Stomach

Your stomach breaks down food with liquid (gastric acids) to help with digestion and absorption of vitamins and minerals.

Small intestine

The small intestine of an adult is around 5 metres long and made up of many bends and folds. The large surface area helps proteins, fatty acids, sugars, vitamins and minerals pass through its wall into the blood. Most of the chemical digestion of proteins, fats and carbohydrates, happens in the small intestine.

Large intestine, rectum and anus

Your large intestine absorbs water, minerals and vitamins. Undigested fibre is mixed with mucus and bacteria, which breaks down some of the fibre to keep the large intestine healthy. Solid bowel motions (faeces, or poo) are formed and stay in the last part of the large intestine (the rectum) before leaving the body through the anus as a bowel movement.

Illustration showing some of main organs that form the digestive system.

What are common health conditions of the digestive system?

Gastro-oesophageal reflux

Gastro-oesophageal reflux disease (GORD) is when stomach content moves from the stomach back up the oesophagus. Because it is acidic, it causes a burning sensation in the chest or throat.

Diverticulitis and diverticulosis

Diverticulosis is the formation of abnormal pouches in the lower part of the large intestine, and diverticulitis is when these pouches become inflamed or infected. Diverticulosis is common from the age of 40 years and above. Around one in every 2 people over the age of 70 years have the condition.

Stomach ulcers

Stomach ulcers or peptic ulcers can be found in the stomach or the upper part of the small intestine. Helicobacter pylori (H. pylori) bacterium causes most stomach ulcers.

Haemorrhoids

Haemorrhoids are itchy or painful lumps of swollen veins in and around the anus. Haemorrhoids can cause bleeding and pain. You might notice bright red blood on the toilet paper or in the toilet. Haemorrhoids are diagnosed by a doctor examining the anus and anal canal.

When should I see my doctor?

You should speak to your doctor if you have any concerns, pain of discomfort with your digestion. See your doctor immediately if you:

have chest pain

continue to vomit or are vomiting blood

symptoms stop you from eating, drinking or sleeping

are losing weight without trying

How do I prevent digestive system problems?

You can help prevent digestive system problems by leading a healthy lifestyle. This might include the following:

Resources and support

Speak with your doctor about any concerns when it comes to your health.

Visit the Gastroenterological Society of Australia (GESA) website for resources on digestive health and disease.

You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available 24 hours a day, 7 days a week.

Last reviewed: August 2023

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Your digestive system breaks down the foods you eat so they can be absorbed into the body and used for energy and nutrients. Discover how it works.

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The Reproductive system explains the genitalia of a male/ female and their functions in order to reproduce. The female reproductive organs are the vagina, womb (uterus), fallopian tubes and ovaries. The male reproductive organs are the penis, the testicles, the epididymis, the vas deferens and the prostate gland.

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(Image credit: <a href="http://www.shutterstock.com/gallery-380674p1.html"> Jezper</a>, <a href="http://www.shutterstock.com/index-in.mhtml">Shutterstock</a>)

The reproductive system is a collection of internal and external organs - in both males and females - that work together for the purpose of procreating, according to the Cleveland Clinic. Due to its vital role in the survival of the species, many scientists argue that the reproductive system is among the most important systems in the entire body.

How reproductive systems work

The male reproductive system consists of two major parts: the testes, where sperm are produced, and the penis, according to Merck Manuals. The penis and urethra belong to both the urinary and reproductive systems in males. The testes are carried in an external pouch known as the scrotum, where they normally remain slightly cooler than body temperature to facilitate sperm production.

The external structures of the female reproductive system include the clitoris, labia minora, labia majora and Bartholin's glands, according to the Cleveland Clinic. The major internal organs of the female reproductive system include the vagina and uterus - which act as the receptacle for semen - and the ovaries, which produce the female's ova. The vagina is attached to the uterus through the cervix, while the fallopian tubes connect the uterus to the ovaries. In response to hormonal changes, one ovum, or egg - or more in the case of multiple births - is released and sent down the fallopian tube during ovulation. If not fertilized, this egg is eliminated during menstruation.

(Image credit: National Institute of Health)

Fertilization occurs if a sperm enters the fallopian tube and burrows into the egg. While the fertilization usually occurs in the oviducts, it can also happen in the uterus itself. The egg then becomes implanted in the lining of the uterus, where it begins the processes of embryogenesis (in which the embryo forms) and morphogenesis (in which the fetus begins to take shape). When the fetus is mature enough to survive outside of the womb, the cervix dilates, and contractions of the uterus propel it through the birth canal.

Variations in the reproductive system

Around 49.5 percent of the world's population is female, so there are slightly more men on the planet than women, according to World Bank. A person's sex is determined by what reproductive system the person has, but it isn't always so simple. Some humans are born with parts of both male and female reproductive systems or incomplete reproductive organs of one sex or the other. Those with both male and female reproductive parts are considered intersex. Sometimes children are labeled as male or female, depending on how complete or functional one sexual reproductive system is over the other. Then, the other organs are removed.

Today, many parents are opting to leave both sets of reproductive organs intact with the intent of letting the child decide to keep or remove the various parts when they are older. A baby is born atypical genitalia in one in about 1,500 to 2,000 births, according to Intersex Society of North America.

Females that are born without all of their reproductive system are labeled as having Mayer Rokitansky Kuster Hauser Syndrome. This occurs in one in 5,000 female births, according to the Center for Young Women's Health.

Diseases of the female reproductive system

Many parts of the male and female reproductive systems can be affected by cancer. In females, cancer can attack the uterus, ovaries, breast and cervix, among other organs, according to the American Cancer Society.

Many experts have seen what they refer to as the "Angelina Jolie" effect, where women are taking proactive measures by having breasts and internal reproductive organs removed if they have a family history of cancer before there are signs of the disease. "With better genetic testing and screening, we have seen a number of women who are being more proactive about their reproductive health," said Dr. Shana Wingo, who specializes on gynecologic oncology at Arizona Oncology.

Ovarian cancer tends to have a poorer outcome than other gynecological cancers, Ross noted, because it is not typically diagnosed until it has progressed significantly. "There is no standard screening available for ovarian cancer, so it is very difficult to identify it early."

Tests to detect ovarian cancer, as well as cancer of the fallopian tube, and primary peritoneal cancer are currently being studied, according to the National Cancer Institute.

There are two tests used to screen for cervical cancer. The Pap test screens for cellular changes in the cervix called cytology, while the genital human papillomavirus (HPV) test identifies the presence of infection with high-risk HPV, the strains that are linked to cervical cancer, according to Dr. Charles Dubin, an OB/GYN in Santa Monica, Calif.

A recent study published by Cancer Cytopathology, found that HPV-only screening misses more cervical cancer in women than Pap-only or co-testing, based on approximately 8.6 million women ages 30 to 65. There is approximately a three-fold improvement in the cancer detection rate of co-testing compared to HPV only.

Current guidelines recommend that women first start getting the Pap test alone when they turn 21 and repeat every three years if the test is normal until age 30. A Pap-plus-HPV test, or co-testing, is recommended for women ages 30 to 65, and if both are negative repeated every five years, regardless of whether they have received HPV vaccination. "However, there is compelling scientific evidence that co-testing every three years misses less cases of cancer and pre-cancer than every five-year co-testing," Dubin noted.

While genital HPV is typically associated with females, it is the most common sexually transmitted infection. The majority of sexually active people in the United States - male and female - will have HPV at some time in their lives, but most will not experience any symptoms. In a small portion of women, it can result in cervical cancer and genital warts; in men, it can cause penile and anal cancer and genital warts, according to the NIH.

Both genders can develop sexually transmitted diseases, including genital herpes, gonorrhea and syphilis, according to the National Institutes of Health (NIH). HIV/AIDS, a disease of the immune system, is not exclusively transmitted through sexual contact; sexual activity is one of the ways that the HIV virus is spread.

For females, severe menstrual cramping, or dysmenorrheal, is the most common disease of the reproductive system occurs with a woman's monthly menstrual period, according to Dr. Sheryl Ross, OB/GYN and Women's Health Specialist at Providence Saint John's Health Center.

"Severe pain before or during your period can last anywhere from one to seven days and disrupt your normal day-to-day routines at school, work and socially," Ross noted. Diagnosis is made by the patient's medical history and a pelvic exam. The best treatment includes medications that block the effects of prostaglandins and include ibuprofen and naproxen. The birth control pill also works well in treating dysmenorrhea by decreasing the blood flow, Ross noted.

Another common disorder of the female reproductive system is a vaginal yeast infection, which is caused by a yeast fungus in the vagina. Most can be successfully treated with over-the-counter medications, according to WebMD.

Endometriosis is a condition where that normally lines the inside of your uterus - the endometrium - ends up outside of uterus, most commonly in the ovaries, bowel or the tissue lining your pelvis. The endometrial tissue becomes trapped, causing pain, according to the Mayo Clinic.

Pelvic inflammatory disease can involve an infection of any of the female reproductive organs, including the uterus and ovaries. Sexually transmitted diseases, such as gonorrhea and chlamydia, are typical causes of pelvic inflammatory disease, according to the NIH. "Any of these STIs can cause serious and potentially long term reproductive problems that include chronic pelvic pain and infertility," Ross said.

(Image credit: National Institute of Health)

Diseases of the male reproductive system

Of male-specific diseases of the reproductive system, prostate cancer is the most common, but men can also suffer from testicular and penile cancer, according to the American Cancer Society.

Treatment for prostate cancer depends on the age, severity of the disease and other health conditions of the patient. The usual treatments for prostate cancer are surgery, radiation therapy, watchful waiting, and hormonal treatment, according to the Cleveland Clinic.

Erectile dysfunction is a common condition that affects about one in 10 males on a long-term basis, the Cleveland Clinic noted. It can be linked to vascular disease, neurological disorders such as Multiple Sclerosis, trauma and psychological episodes.

Prostatitis typically involves swelling or inflammation of the prostate gland, according to the Mayo Clinic, and can cause painful or difficult urination and ejaculation. Nearly half of all men experience symptoms of prostatitis at some point during their lives.

Defining and treating infertility

Infertility is defined as a couple's inability to conceive after one year of unprotected intercourse. It can be caused by a condition in one partner or a combination of circumstances, according to the Mayo Clinic.

In males, infertility is a condition in which they produce no sperm cells (azoospermia) or too few sperm cells (oligospermia), or their sperm cells are abnormal or die before they can reach the egg. Causes range from chromosomal defects to hormonal imbalance to tumors. Lifestyle factors, such as drug and alcohol use, can also play role. In rare cases, infertility in men is caused by an inherited condition, such as cystic fibrosis, according to the Mayo Clinic.

In women, infertility is defined as a disorder of the reproductive system that hinders the body's ability to ovulate, conceive, or carry an infant to term.

Reproductive conditions are treated by a variety of specialists. In women, many issues are treated by obstetricians/gynecologists and for males, urologists handle many disorders of their reproductive systems. There are also infertility experts that treat couples who are unable to conceive and endocrinologists who treat hormonal disorders.
Additional reporting by Alina Bradford, Live Science contributor.
Editor's Note: If you'd like more information on this topic, we recommend the following book:

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Systems of the human body

Circulatory System: Facts, Function & Diseases

Digestive System: Facts, Function & Diseases

Endocrine System: Facts, Functions and Diseases

Immune System: Diseases, Disorders & Function

Lymphatic System: Facts, Functions & Diseases

Muscular System: Facts, Functions & Diseases

Nervous System: Facts, Function & Diseases

Respiratory System: Facts, Function & Diseases

Skeletal System: Facts, Function & Diseases

Skin: Facts, Diseases & Conditions

Urinary System: Facts, Functions & Diseases

Parts of the human body

Bladder: Facts, Function & Disease

Human Brain: Facts, Anatomy & Mapping Project

Colon (Large Intestine): Facts, Function & Diseases

Ears: Facts, Function & Disease

Esophagus: Facts, Function & Diseases

How the Human Eye Works

Gallbladder: Function, Problems & Healthy Diet

Human Heart: Anatomy, Function & Facts

Kidneys: Facts, Function & Diseases

Liver: Function, Failure & Disease

Lungs: Facts, Function & Diseases

Nose: Facts, Function & Diseases

Pancreas: Function, Location & Diseases

Small Intestine: Function, Length & Problems

Spleen: Function, Location & Problems

Stomach: Facts, Function & Diseases

The Tongue: Facts, Function & Diseases

Additional resources

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Reproductive System: Facts, Functions & Diseases

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(Image credit: Jezper , Shutterstock ) The reproductive system is a collection of internal and external organs - in both males and females - that work together for the purpose of procreating, according to the Cleveland Clinic.

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The Urinary system is to filter blood and create urine as a waste by-product. The organs of the urinary system include the kidneys, renal pelvis, ureters, bladder and urethra. The body takes nutrients from food and converts them to energy.

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How does the urinary system work?

The urinary system's function is to filter blood and create urine as a waste by-product. The organs of the urinary system include the kidneys, renal pelvis, ureters, bladder and urethra.

The body takes nutrients from food and converts them to energy. After the body has taken the food components that it needs, waste products are left behind in the bowel and in the blood.

The kidney and urinary systems help the body to eliminate liquid waste called urea, and to keep chemicals, such as potassium and sodium, and water in balance. Urea is produced when foods containing protein, such as meat, poultry, and certain vegetables, are broken down in the body. Urea is carried in the bloodstream to the kidneys, where it is removed along with water and other wastes in the form of urine.

Other important functions of the kidneys include blood pressure regulation and the production of erythropoietin, which controls red blood cell production in the bone marrow. Kidneys also regulate the acid-base balance and conserve fluids.

Kidney and urinary system parts and their functions

The kidneys remove urea from the blood through tiny filtering units called nephrons. Each nephron consists of a ball formed of small blood capillaries, called a glomerulus, and a small tube called a renal tubule. Urea, together with water and other waste substances, forms the urine as it passes through the nephrons and down the renal tubules of the kidney.

Two ureters. These narrow tubes carry urine from the kidneys to the bladder. Muscles in the ureter walls continually tighten and relax forcing urine downward, away from the kidneys. If urine backs up, or is allowed to stand still, a kidney infection can develop. About every 10 to 15 seconds, small amounts of urine are emptied into the bladder from the ureters.

Bladder. This triangle-shaped, hollow organ is located in the lower abdomen. It is held in place by ligaments that are attached to other organs and the pelvic bones. The bladder's walls relax and expand to store urine, and contract and flatten to empty urine through the urethra. The typical healthy adult bladder can store up to two cups of urine for two to five hours.

Upon examination, specific "landmarks" are used to describe the location of any irregularities in the bladder. These are:

Trigone: a triangle-shaped region near the junction of the urethra and the bladder

Right and left lateral walls: walls on either side of the trigone

Posterior wall: back wall

Dome: roof of the bladder

Two sphincter muscles. These circular muscles help keep urine from leaking by closing tightly like a rubber band around the opening of the bladder.

Nerves in the bladder. The nerves alert a person when it is time to urinate, or empty the bladder.

Urethra. This tube allows urine to pass outside the body. The brain signals the bladder muscles to tighten, which squeezes urine out of the bladder. At the same time, the brain signals the sphincter muscles to relax to let urine exit the bladder through the urethra. When all the signals occur in the correct order, normal urination occurs.

Facts about urine

Normal, healthy urine is a pale straw or transparent yellow color.

Darker yellow or honey colored urine means you need more water.

A darker, brownish color may indicate a liver problem or severe dehydration.

Pinkish or red urine may mean blood in the urine.

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The urinary system's function is to filter blood and create urine as a waste by-product. The organs of the urinary system include the kidneys, renal pelvis, ureters, bladder and urethra. The body takes nutrients from food and converts them to energy.

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The Lymphatic system maintains fluid levels in our body tissues by removing all fluids that leak out of our blood vessels. It is important for the optimal functioning of our general and specific immune responses. It drains fluid (called lymph) that has leaked from the blood vessels into the tissues and empties it back into the bloodstream via the lymph nodes.

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The lymphatic system is an extensive network of vessels, nodes, and ducts that pass through almost all bodily tissues. It allows the circulation of a fluid called lymph through the body in a similar way to blood.

The lymphatic system is essential for fluid balance, absorption of fatty acids in the stomach, and immune system regulation.

This article details the lymphatic system, its role in the body, and what conditions can impair its function.

The lymphatic system is a network of vessels, nodes, and ducts that collect and circulate excess fluid in the body.

There are lymph nodes throughout the body. These nodes swell in response to infection due to a buildup of lymph fluid, bacteria, or other organisms and immune system cells.

The lymphatic system is part of the immune system. It also maintains fluid balance and plays a role in absorbing fats and fat-soluble nutrients.

The lymph system has three main functions.

Fluid balance

The lymphatic system returns excess fluid and proteins from the tissues that cannot return through the blood vessels. The fluid often collects in the tiny spaces surrounding cells, known as the interstitial spaces. Small lymph capillaries connect these spaces to the lymphatic system.

of the plasma that reaches tissues from the arterial blood capillaries returns through the venous capillaries and veins. The remaining 10% travels through the lymphatic system.

A disruption of fluid processing in localized swelling, known as lymphedema.

Absorption

The lymphatic system plays a in intestinal function. It assists in transporting fat, fighting infections, and removing excess fluid.

Part of the gut membrane in the small intestine contains tiny finger-like protrusions called villi. Each villus contains tiny lymph capillaries, known as lacteals. These absorb fats and fat-soluble vitamins to form a milky white fluid called chyle.

This fluid contains lymph and emulsified fats, or free fatty acids. It delivers nutrients indirectly when it reaches the venous blood circulation. Blood capillaries take up other nutrients directly.

The immune system

The third function of lymph nodes is to defend the body from exposure to potentially hazardous microorganisms, such as infections.

The body's first line of defense involves:

physical barriers, such as the skin

toxic barriers, such as the acidic contents of the stomach

"friendly" bacteria in the body

However, pathogens often do succeed in entering the body despite these defenses. In this case, the lymphatic system enables the immune system to respond appropriately.
Learn more about how the immune system works here.
How does the lymphatic system fight infection?

The lymphatic system produces white blood cells called lymphocytes. There are two types of lymphocytes: T cells and B cells. They both travel through the lymphatic system.

As they reach the lymph nodes, they come into contact with viruses, bacteria, and foreign particles in the lymph fluid.

Following contact, lymphocytes form antibodies and start to defend the body. They can also produce antibodies from memory if they have already encountered the specific pathogen in the past.

The lymphatic system and the action of lymphocytes form part of the body's adaptive immune response. These are highly specific and long lasting responses to particular pathogens.
Learn more about antibodies and their role in the body here.
The lymphatic system consists of lymph vessels, ducts, nodes, and other tissues throughout the body.

Lymphatic vessels collect interstitial fluid and transport it to lymph nodes. These nodes filter out damaged cells, bacteria, and other foreign bodies.

Once this fluid passes out of the lymph nodes, it travels to larger vessels and eventually lymph ducts, which converge in the thoracic duct at the base of the neck.

The thoracic duct returns filtered lymph into the bloodstream.

Other lymphatic tissues

Lymph nodes are not the only lymphatic tissues in the body. The tonsils, spleen, and thymus glands are also lymphatic tissues.

Thymus gland: The thymus gland is a lymphatic organ and an endocrine gland behind the sternum. It secretes hormones and is crucial to the production, maturation, and differentiation of immune T cells.

Tonsils: The tonsils produce lymphocytes and antibodies. They can help protect against inhaled and swallowed foreign bodies.

Spleen: The spleen is not part of the connected lymphatic system, but it is lymphoid tissue. It produces white blood cells and filters the blood to remove microbes as well as old and damaged red blood cells and platelets.

Bone marrow: Bone marrow is not lymphatic tissue but is part of the lymphatic system because it is here that the B cell lymphocytes of the immune system mature.

Below is a 3D model of the lymphatic system, which is fully interactive.

Lymph nodes can swell for two common reasons: a reaction to an infection and direct infection of the lymph nodes.

In the former, the lymph nodes react when coming into contact with foreign materials from infected tissue.

Direct infection can cause lymphadenitis. In this, infection causes inflammation in the lymph nodes, and a person will require antibiotic treatment.

Most people who have swollen glands with a cold or flu do not need to contact a doctor.

However, a person should seek medical advice if:

lymph nodes stay swollen for longer than 2 weeks

a swollen lymph node feels hard or fixed in place

swelling accompanies a fever, night sweats, or unexplained weight loss

Swollen lymph nodes can be a symptom of numerous conditions:

Glandular fever: Also known as infectious mononucleosis, or mono, this is a viral infection that can cause long lasting swelling, a sore throat, and fatigue.

Tonsillitis: This is more common in children than in adults. It occurs when the lymph nodes at the back of the mouth are fighting an infection, usually viral but sometimes bacterial.

Pharyngitis: Some people refer to this infection as "strep throat." It results from a Streptococcus bacterial infection, and it can cause lymph nodes to swell.

Cancer that starts in the lymphatic system is known as lymphoma. It is the most serious lymphatic disease.

Hodgkin lymphoma affects B lymphocytes, a type of white blood cell.

People with Hodgkin lymphoma will have a certain type of lymphocyte present in their blood called Reed-Sternberg cells. Non-Hodgkin lymphoma refers to types that do not involve these cells.

Hodgkin lymphoma can occur across the lymphatic system. However, it most commonly affects lymph nodes in the upper part of the body, such as the neck, chest, and under the arms.

Non-Hodgkin lymphoma can arise from B or T lymphocytes but is most common in B lymphocytes. There are many types of non-Hodgkin lymphomas. These can vary in their location and how aggressive their growth is.
Visit our dedicated cancer hub here.
If the lymphatic system does not work properly, fluid may not drain effectively. As the fluid builds up, this can lead to swelling in an arm or leg. This is lymphedema.

The skin may feel tight and hard, and skin problems may occur. In some cases, fluid may leak through the skin.

Obstruction can result from:

surgery

radiation therapy

injury

a condition known as lymphatic filariasis

a congenital disorder

The lymphatic system drains excess fluid that accumulates in bodily tissue, filters out foreign bodies, and transports it back into the bloodstream.

The lymphatic system is a collection of vessels, nodes, and ducts that span most of the body.

Failures of the lymphatic system can cause swelling, venous dysfunction, and life threatening complications.

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Lymphatic system: Definition, anatomy, function, and diseases

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The lymphatic system is an extensive network of vessels, nodes, and ducts that pass through almost all bodily tissues. It allows the circulation of a fluid called lymph through the body in a similar way to blood. The lymphatic system is essential for fluid balance, absorption of fatty acids in the stomach, and immune system regulation.

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The Skeletal system consists of bones, cartilage, ligaments and tendons and accounts for about 20 percent of the body weight. Did you know there are a total of 206 bones in the fully grown human body?

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Humans are vertebrates, animals having a vertabral column or backbone. They rely on a sturdy internal frame that is centered on a prominent spine. The human skeletal system consists of bones, cartilage, ligaments and tendons and accounts for about 20 percent of the body weight.

The living bones in our bodies use oxygen and give off waste products in metabolism. They contain active tissues that consume nutrients, require a blood supply and change shape or remodel in response to variations in mechanical stress.

Bones provide a rigid framework, known as the skeleton, that support and protect the soft organs of the body.

The skeleton supports the body against the pull of gravity. The large bones of the lower limbs support the trunk when standing.

The skeleton also protects the soft body parts. The fused bones of the cranium surround the brain to make it less vulnerable to injury. Vertebrae surround and protect the spinal cord and bones of the rib cage help protect the heart and lungs of the thorax.

Bones work together with muscles as simple mechanical lever systems to produce body movement.

Bones contain more calcium than any other organ. The intercellular matrix of bone contains large amounts of calcium salts, the most important being calcium phosphate.

When blood calcium levels decrease below normal, calcium is released from the bones so that there will be an adequate supply for metabolic needs. When blood calcium levels are increased, the excess calcium is stored in the bone matrix. The dynamic process of releasing and storing calcium goes on almost continuously.

Hematopoiesis, the formation of blood cells, mostly takes place in the red marrow of the bones.

In infants, red marrow is found in the bone cavities. With age, it is largely replaced by yellow marrow for fat storage. In adults, red marrow is limited to the spongy bone in the skull, ribs, sternum, clavicles, vertebrae and pelvis. Red marrow functions in the formation of red blood cells, white blood cells and blood platelets.

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Humans are vertebrates, animals having a vertabral column or backbone. They rely on a sturdy internal frame that is centered on a prominent spine. The human skeletal system consists of bones, cartilage, ligaments and tendons and accounts for about 20 percent of the body weight.

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The Muscular system is muscles attached to bones or internal organs and blood vessels, are responsible for movement. Nearly all movement in the body is the result of muscle contraction. There are about 600 muscles in the human body. The three main types of muscle include skeletal, smooth and cardiac.

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Without muscle, humans could not live. The primary job of muscle is to move the bones of the skeleton, but muscles also enable the heart to beat and constitute the walls of other important hollow organs.

There are three types of muscle tissue:

Skeletal muscle: This type of muscle creates movement in the body. There are more than 600 skeletal muscles, and they makes up about 40 percent of a person's body weight. When the nervous system signals the muscle to contract, groups of muscles work together to move the skeleton. These signals and movements are nearly involuntary, yet they do require conscious effort. However, humans do not need to concentrate on individual muscles when moving.

Cardiac muscle: Cardiac muscle is involuntary muscle. This type makes up the walls of the heart and creates the steady, rhythmic pulsing that pumps blood through the body from signals from the brain. This muscle type also creates the electrical impulses that produce the heart's contractions, but hormones and stimuli from the nervous system can also affect these impulses, such as when your heart rate increases when you're scared.

Smooth muscle: Smooth muscle makes up the walls of hollow organs, respiratory passageways, and blood vessels. Its wavelike movements propel things through the bodily system, such as food through your stomach or urine through your bladder. Like cardiac muscle, smooth muscle is involuntary and also contracts in response to stimuli and nerve impulses.

Muscle movement happens when neurological signals produce electrical changes in muscle cells. During this process, calcium is released into the cells and brings about a short muscle twitch. Problems with the junction between the cells - called a synapse - can lead to neuromuscular diseases.

Muscle pain is a common issue that can signal numerous problems, even if it's something as simple as overuse. Some muscular disorders and conditions that affect muscles include:

Muscle pain

Sprains and strains

Bruising

Cramping

Myopathy

Muscular dystrophy

Parkinson's disease

Fibromyalgia

Multiple sclerosis

Proper nutrition and exercise is important to keeping all muscles healthy, whether they are cardiac, smooth, or skeletal.

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Muscular System Anatomy, Diagram & Function | Healthline

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Without muscle, humans could not live. The primary job of muscle is to move the bones of the skeleton, but muscles also enable the heart to beat and constitute the walls of other important hollow organs. There are three types of muscle tissue: Skeletal muscle: This type of muscle creates movement in the body.

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The Endocrine system is made up of several organs called glands. Hormones are chemicals that coordinate different functions in your body by carrying messages through your blood to your organs, skin, muscles and other tissues. These signals tell your body what to do and when to do it.

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What are the endocrine system organs?

Your endocrine system consists of three types of tissues:

Endocrine glands.

Organs.

Endocrine-related tissues.

Endocrine system glands

Glands are special tissues in your body that create and release substances. Endocrine glands make and release hormones directly into your bloodstream. The endocrine glands in your body from head to toe include:

Pineal gland: This is a tiny gland in your brain that's beneath the back part of your corpus callosum. It makes and releases the hormone melatonin.

Pituitary gland: This is a small, pea-sized gland at the base of your brain below your hypothalamus. It releases eight hormones, some of which trigger other endocrine glands to release hormones.

Thyroid gland: This is a small, butterfly-shaped gland at the front of your neck under your skin. It releases hormones that help control your metabolism.

Parathyroid glands: These are four pea-sized glands that are typically behind your thyroid. Sometimes they exist along your esophagus or in your chest (ectopic parathyroid glands). They release parathyroid hormone (PTH), which controls the level of calcium in your blood.

Adrenal glands: These are small, triangle-shaped glands on top of each of your two kidneys. They release several hormones that manage bodily processes, like metabolism, blood pressure and your stress response.

You have other glands in your body that aren't endocrine glands, such as sweat glands (a type of exocrine gland).

Endocrine system organs

Certain organs in your body also make and release hormones. An organ is a group of tissues that form a structure that performs specific important functions in your body. The organs that are part of your endocrine system include:

Hypothalamus: This is a structure deep within your brain (which is an organ). It's the main link between your endocrine system and your nervous system. It makes two hormones that your pituitary gland stores and releases (oxytocin and vasopressin) and makes and releases two hormones (dopamine and somatostatin).

Pancreas: This organ is in the back of your abdomen (belly). It's both an organ and a gland and is also part of your digestive system. It releases two hormones that are essential to maintaining healthy blood sugar levels: insulin and glucagon.

Adipose tissue (body fat): This is a connective tissue that extends throughout your body. It's found under your skin (subcutaneous fat), between your internal organs (visceral fat) and in the inner cavities of bones (bone marrow adipose tissue). Adipose tissue releases many different hormones, including leptin, angiotensin and adiponectin.

Ovaries: These are small, oval-shaped glands located on either side of your uterus. They produce and store your eggs (also called ova) and make sex hormones that control your menstrual cycle and pregnancy.

Testicles (testes): These are small, round organs underneath your penis in your scrotum. They make sperm and sex hormones, particularly testosterone.

Other tissues that release hormones

Other tissues in your body release hormones. But we don't typically think of them as endocrine system tissues because they have other, more significant functions or roles. They include:

Digestive tract (stomach and small intestine): Your digestive tract is the largest endocrine-related organ system. It makes and releases several hormones that play a role in your metabolism. Examples include gastrin and ghrelin.

Kidneys: Your kidneys are two bean-shaped organs that filter your blood. They're part of your urinary system, but they also produce hormones, like erythropoietin and renin.

Liver: Your liver is part of your digestive system, but it also produces hormones, including insulin-like growth factor 1 (IGF-1) and angiotensinogen.

Heart: When your blood pressure rises, your heart releases two hormones called A-type natriuretic peptide and B-type natriuretic peptide.

Placenta: The placenta is a temporary endocrine organ that forms during pregnancy. It produces hormones that are important for maintaining a healthy pregnancy and preparing your body for labor and breastfeeding (chestfeeding).

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Your endocrine system consists of the tissues (mainly glands) that create and release hormones. Endocrine tissues include your pituitary gland, thyroid and others.

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The Cardiovascular system is the system responsible for delivering blood to different parts of the body. The following organs & tissues include; the heart, arteries, veins, and capillaries. There are two blood circulatory systems in the body. First, the systemic circulatory system that transports blood to the organs, tissues, and cells throughout the body. Second, the pulmonary circulatory system that moves blood between the heart and lungs. It is where oxygen enters the blood and carbon dioxide leaves the blood.

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The cardiovascular system consists of the heart, blood vessels, and blood. Its primary function is to transport nutrients and oxygen-rich blood to all parts of the body and to carry deoxygenated blood back to the lungs.

Abnormalities or injuries to any or all parts of the cardiovascular system can result in serious health complications. Common conditions that can affect the cardiovascular system include coronary artery disease, heart attack, high blood pressure, and stroke.

This article explores the cardiovascular system, including its components and their functions. We also outline some common cardiovascular system diseases and their associated treatments.

The cardiovascular system is the system responsible for delivering blood to different parts of the body. It consists of the following organs and tissues:

The heart: A muscular pump that forces blood around the body.

A closed system of blood vessels: These vessels include:
Arteries: Vessels that carry blood away from the heart.

Veins: Vessels that bring blood back to the heart.

Capillaries: Tiny vessels that branch off from arteries to deliver blood to all body tissues.

There are two blood circulatory systems in the body. The first is the systemic circulatory system. This is the main blood circulatory system that transports blood to the organs, tissues, and cells throughout the body.

The second is the pulmonary circulatory system. This circulatory system moves blood between the heart and lungs. It is where oxygen enters the blood and carbon dioxide leaves the blood.

Click on the BodyMap above to interact with a 3D model of the circulatory system.

The heart consists of four distinct chambers: two upper chambers called "atria" and two lower chambers called "ventricles." A wall or "septum" separates the atria and ventricles. Valves control the flow of blood within the different chambers.

Blood follows the following path through the heart:

1. Blood lacking oxygen returns from the body and enters the right atrium (upper right chamber) via the inferior vena cava and superior vena cava veins.

2. Blood flows through the tricuspid valve and enters the right ventricle (lower right chamber).

3. The right ventricle pumps blood through the pulmonary valve and out of the heart via the main pulmonary artery.

4. The blood then flows through the left and right pulmonary arteries into the lungs. Here, the process of breathing draws oxygen into the blood and removes carbon dioxide. As a result, the blood is now rich in oxygen.

5. The blood returns to the heart and flows into the left atrium (upper left chamber) via four pulmonary veins.

6. Blood flows through the mitral valve and enters the left ventricle (lower left chamber).

7. The left ventricle pumps the blood through the aortic valve into a large artery called the "aorta." This artery delivers blood to the rest of the body.

The heart pumps blood through closed vessels to every tissue within the body. The blood itself then nutrients and oxygen to all cells in the body. Without blood, the cells and tissues would not function at their total capacity and would begin to malfunction and die.

The cardiac cycle consists of two phases.

The first phase is diastole, in which the ventricles fill with blood. It begins when the aortic or pulmonary valve closes and ends when the mitral or tricuspid valve closes. During diastole, blood vessels return blood to the heart in preparation for the next contraction of the ventricles.

The second phase is systole, in which the ventricles contract and eject blood. It begins when the mitral or tricuspid valve closes and ends when the aortic or pulmonary valve closes. The pressure inside the ventricles becomes greater than the pressure inside adjacent blood vessels, thereby forcing the blood from the ventricles to the vessels.

Cardiovascular diseases can be severe and potentially life threatening. Understanding conditions that can affect the cardiovascular system may help people seek appropriate and timely medical advice.

Overviews of some common cardiovascular diseases are below.

Heart attack

A heart attack happens when a part of the heart muscle does not receive enough blood. This can occur due to a blockage, a tear in an artery around the heart, or if the heart requires more oxygen than is available.

Symptoms of a heart attack :

chest pain or discomfort

feeling lightheaded

pain or discomfort in the jaw, neck, or back

pain or discomfort in one or both arms or shoulders

shortness of breath

Three of the main risk factors of a heart attack are:

People who have had a heart attack can lower their chances of future cardiovascular problems by engaging in the following:

Stroke

A stroke is a medical condition in which the blood supply to a part of the brain becomes cut off. This lack of blood supply triggers the death of brain cells.

There are two types of stroke. Ischemic stroke occurs as a result of a blood clot blocking blood flow to the brain. Hemorrhagic stroke occurs as a result of a bleed in or around the brain.

Some significant risk factors of a stroke include:

high blood pressure

heart disease

smoking

personal or family history of stroke

older age

being of African American heritage

Symptoms of a stroke begin suddenly and may include:

one-sided weakness or numbness of the leg, arm, or face

vision problems in one or both eyes

difficulty speaking or understanding speech

confusion

dizziness, loss of balance, or difficulty walking

severe headache

The treatment for stroke will depend on the type. A person who experiences ischemic stroke may receive medications to help break up the blood clot and restore blood flow to their brain. A person who experiences a hemorrhagic stroke may require surgery to fix the blood vessel that is bleeding out.

Follow-up treatments for stroke may include:

antiplatelet or anticoagulant medications to help prevent the formation of new blood clots

medications to lower blood pressure

medications called statins to reduce levels of cholesterol in the blood

physical therapy

rehabilitation therapy

speech therapy

Heart failure

Heart failure occurs when the heart is unable to pump enough blood to satisfy the body's needs.

Some symptoms of heart failure :

Risk factors of heart failure include:

There is no cure for heart failure. But treatments can help to slow the progression of the disease and alleviate symptoms. Examples :

lifestyle changes, such as dietary and exercise changes

devices and surgical procedures

medications to manage blood pressure or cholesterol levels

diuretics to reduce swelling, or edema

Arrhythmia

An arrhythmia is an abnormal heart rhythm. It may present as a heartbeat that is too quick, too slow, or has a distinctive pattern. Symptoms may include:

The risk factors of arrhythmia include:

heart disease

congenital heart defect

high blood pressure

high cholesterol

older age

alcohol use

untreated sleep apnea

For dangerous arrhythmias, doctors a device called a pacemaker to restore a regular heart rate.

As a person ages, their heart begins to work less effectively than it used to. For example, it beat as fast during physical activity, although the resting heart rate remains steady. Arrhythmias can also develop as the heart ages.

Another common condition of aging is more stiffness in the large arteries and stiffness of the heart muscle. This stiffness can cause high blood pressure, increasing the risk of heart attacks, stroke, and heart failure. Stiffness of the heart can also cause congestive heart failure.

The cardiovascular system consists of the heart, veins, arteries, and capillaries. These components make up two circulatory systems: the systemic and pulmonary circulatory systems. The cardiac cycle consists of two phases: systole (relaxation) and diastole (contraction).

Some conditions that can affect the heart include heart attack, stroke, heart failure, and arrhythmia.

As the body ages, the heart functions less effectively, especially during periods of high physical activity. The arteries also have a higher likelihood of becoming stiff with age, which increases the possibility of high blood pressure and associated cardiovascular issues.

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Cardiovascular system: Function, organs, diseases, and more

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The cardiovascular system consists of the heart, blood vessels, and blood. Its primary function is to transport nutrients and oxygen-rich blood to all parts of the body and to carry deoxygenated blood back to the lungs. Abnormalities or injuries to any or all parts of the cardiovascular system can result in serious health complications.

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The Nervous system includes the brain, spinal cord, and a complex network of nerves. This system sends messages back and forth between the brain and the body. The brain is what controls all the body's functions. The spinal cord runs from the brain down through the back.

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The nervous system has two main parts:

The central nervous system is made up of the brain and spinal cord.

The peripheral nervous system is made up of nerves that branch off from the spinal cord and extend to all parts of the body.

The nervous system transmits signals between the brain and the rest of the body, including internal organs. In this way, the nervous system's activity controls the ability to move, breathe, see, think, and more.

The basic unit of the nervous system is a nerve cell, or neuron. The human brain contains about 100 billion neurons. A neuron has a cell body, which includes the cell nucleus, and special extensions called axons (pronounced AK-sonz) and dendrites (pronounced DEN-drahytz). Bundles of axons, called nerves, are found throughout the body. Axons and dendrites allow neurons to communicate, even across long distances.

Different types of neurons control or perform different activities. For instance, motor neurons transmit messages from the brain to the muscles to generate movement. Sensory neurons detect light, sound, odor, taste, pressure, and heat and send messages about those things to the brain. Other parts of the nervous system control involuntary processes. These include keeping a regular heartbeat, releasing hormones like adrenaline, opening the pupil in response to light, and regulating the digestive system.

When a neuron sends a message to another neuron, it sends an electrical signal down the length of its axon. At the end of the axon, the electrical signal changes to a chemical signal. The axon then releases the chemical signal with chemical messengers called neurotransmitters (pronounced noor-oh-TRANS-mit-erz) into the synapse (pronounced SIN-aps)-the space between the end of an axon and the tip of a dendrite from another neuron. The neurotransmitters move the signal through the synapse to the neighboring dendrite, which converts the chemical signal back into an electrical signal. The electrical signal then travels through the neuron and goes through the same conversion processes as it moves to neighboring neurons.

The nervous system also includes non-neuron cells, called glia (pronounced GLEE-uh). Glia perform many important functions that keep the nervous system working properly. For example, glia:

Help support and hold neurons in place

Protect neurons

Create insulation called myelin, which helps move nerve impulses

Repair neurons and help restore neuron function

Trim out dead neurons

Regulate neurotransmitters

The brain is made up of many networks of communicating neurons and glia. These networks allow different parts of the brain to "talk" to each other and work together to control body functions, emotions, thinking, behavior, and other activities.

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What are the parts of the nervous system?

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The nervous system has two main parts: The central nervous system is made up of the brain and spinal cord. The peripheral nervous system is made up of nerves that branch off from the spinal cord and extend to all parts of the body.