https://www.niddk.nih.gov/health-information/digestive-diseases/digestive-system-how-it-works

Last Reviewed December 2017

This content is provided as a service of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), part of the National Institutes of Health. NIDDK translates and disseminates research findings to increase knowledge and understanding about health and disease among patients, health professionals, and the public. Content produced by NIDDK is carefully reviewed by NIDDK scientists and other experts.

Circulatory System Diagram Pictures, Images, and Stock Photos.

https://www.istockphoto.com/photos/circulatory-system-diagram

An illustration of the lungs is below. The trachea, or windpipe, leads to the bronchioles. The lungs are further divided into the alveoli.

Biologydictionary.net Editors. "Respiratory System Fun Facts." Biology Dictionary, Biologydictionary.net, 24 Apr. 2019, https://biologydictionary.net/respiratory-system-fun-facts/.

The endocrine system comprises several distinct glands and tissues, which are made up of specialised cells that synthesise, store, and secrete hormones. Hormones are chemical messengers that can act on nearby cells via interstitial fluid (paracrine effect), on the cell of origin (autocrine effect), at a distant site (endocrine or exocrine effects), or as neurotransmitters (Knight, 2021). Neurotransmitters across synapses contribute to the rapid actions of the nervous system. In contrast, endocrine effects tend to be slow to develop and result in prolonged responses potentially lasting weeks, as hormones travel in the bloodstream from an endocrine gland to another organ. Hormones control a wide range of physiological processes, including growth, metabolism, sleep, immune system response, ‘fight or flight’, reproduction, mood, and behaviour (Kumar and Clark, 2017). They also assist in maintaining homeostasis (a state of physiological equilibrium) by regulating the body's internal environment in response to changes in the external environment. The human body produces more than 100 hormones to carry out these processes, and research is continuing to further our understanding of their functions and interactions as well as identifying more hormones (Knight, 2021).

Al Halteet S, Abdel-Hadi A, Hassan M, Awad M. Prevalence and antifungal susceptibility profile of clinically relevant Candida Species in postmenopausal women with diabetes. Biomed Res Int. 2020; 2020 https://doi.org/10.1155/2020/7042490

Body movements are generated through the contraction and relaxation of specific muscles. Some muscles, like those in the arms and legs, bring about such voluntary movements as raising a hand or flexing the foot. Other muscles are involuntary and function without conscious effort. Voluntary muscles include the skeletal muscles, of which there are about 650 in the human body. Skeletal muscles are controlled by the somatic nervous system; whereas the autonomic nervous system controls the involuntary muscles, including those that line the internal organs and blood vessels. These smooth muscles are called visceral and vascular smooth muscles, and they perform tasks not generally associated with voluntary activity. Smooth muscles control several automatic physiological responses such as pupil constriction, which occurs when the muscles of the iris contract in bright light. Another example is the dilation of blood vessels that occurs when the smooth muscles surrounding the vessels relax or lengthen. In addition to the categories of skeletal (voluntary) and smooth (involuntary) muscle, there is a third category, cardiac muscle, which is neither voluntary nor involuntary. Cardiac muscle is not under conscious control, and it can also function without regulation from the external nervous system.

Katch, Victor L., William D. McArdle, and Frank I. Katch. Essentials of Exercise Physiology, 5th ed. Philadelphia: Wolters Kluwer/Lippincott Williams & Wilkins Health, 2016.

Manocchia, Pat. Anatomy of Exercise: A Trainer's Inside Guide to Your Workout. Richmond Hill: Firefly Books, 2009.

A Guide to the Psychological Functions of the Muscular System. Berkeley: North Atlantic Books, 2010.

Murphy, Wendy. Weight and Health. Minneapolis: Twenty-First Century Books, 2008.

Prentice, William. Get Fit, Stay Fit, 7th ed. Boston: McGraw-Hill College, 2015.

Rizzo, Donald C. Introduction to Anatomy and Physiology. Clifton Park: Delmar, 2011.

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.¹

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.

1. MedlinePlus. (2016). Neurosciences. Retrieved June 16, 2017, from https://medlineplus.gov/ency/article/007456.htm

2. Society for Neuroscience. (2012). Brain facts. Washington, DC. Retrieved January 17, 2018, from http://www.brainfacts.org/The-Brain-Facts-Book

3. National Institute of Neurological Disorders and Stroke. (2018). Brain basics: Know your brain. Retrieved August 9, 2018, from https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Know-Your-Brain

05 Dec
2020

Mozibur Laskar

0

Health

Our Immune System

The immune system and microbial infection

The immune system keeps a record of every microbe it has ever defeated, in types of white blood cells (B- and T-lymphocytes) known as memory cells. This means it can recognise and destroy the microbe quickly if it enters the body again, before it can multiply and make you feel sick.

Some infections such as flu and the common cold, have to be fought many times because so many different viruses or strains of the same type of virus can cause these illnesses. Catching a cold or flu from one virus does not give you immunity against the others. 

Parts of the immune system

The main parts of the immune system are:

• white blood cells

• complement system

• antibodies

• lymphatic system

• bone marrow

• spleen

• Thymus.

By Mozibur Laskar / Doctor, quickobook on Dec 5th, 2020

Reproductive health refers to the condition of male and female reproductive systems during all life stages. These systems are made of organs and hormone-producing glands, including the pituitary gland in the brain. Ovaries in females and testicles in males are reproductive organs, or gonads, that maintain health of their respective systems. They also function as glands because they produce and release hormones.

Reproductive disorders affect millions of Americans each year.

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Female disorders include:

• Early or delayed puberty.

• Endometriosis, a condition where the tissue that normally lines the inside of the womb, known as the endometrium, grows outside of it.

• Inadequate breastmilk supply.

• Infertility or reduced fertility (difficulty getting pregnant).

• Menstrual problems including heavy or irregular bleeding.

• Polycystic ovary syndrome, ovaries produce more male hormones than normal.

• Problems during pregnancy.

• Uterine fibroids, noncancerous growths in a woman’s uterus or womb.

Male disorders include:

• Impotence or erectile dysfunction.

• Low sperm count.

• Article title

  Reproductive Health

  URL

  https://www.niehs.nih.gov/health/topics/conditions/repro-health

  Website title

  National Institute of Environmental Health Sciences

  Date accessed

  December 5, 2024