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Haemoglobin is a protein that can be found in red blood cells. This protein is responsible for the delivery of oxygen to the tissues.
- Each red blood cell has between 200-300million of haemoglobin proteins.
- Each protein is made up of 4 different protein that are folded in a Certain way. Each of the 4 proteins contain an ion of iron which is way the oxygen is bound to the haemoglobin protein.

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System Connection: The respiratory System

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System Connection: The respiratory System

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The respiratory system and cardiovascular system work together in the transport of blood cells, in particular haemoglobin to deliver oxygen to the body and remove carbon dioxide in the form of bicarbonate acid within pulmonary and systemic circulation.

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- Platelets are small, cell-like fragments of larger cells called megakaryocytes.

- They play a pivotal role in blood clotting (hemostasis) by aggregating at the injury site to stop the bleeding.

- Platelets release chemicals that help in the clotting process.

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- White blood cells are part of the body's immune system and are responsible for defending against infections and foreign cells.

- There are various types of white blood cells including lymphocytes, neutrophils, eosinophils, monocytes, and basophils each has different and specific functions in immune response.

- White blood cells can move out of the bloodstream to reach infected tissues and cells as well as engage pathogens.

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Red blood cells are the most common blood cells, covering approximately 40-45% of total blood volume.

- They are specific cells that contain the protein hemoglobin, hemoglobin binds to oxygen and carbon dioxide throughout the body.

- Red blood cells transport oxygen from the lungs to tissues throughout the body and carry carbon dioxide from tissues back to the lungs during exhalation.

- Red blood cells have a biconcave shape of red blood cells which provides a larger surface area that creates efficient gas exchange.

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- Plasma makes up approximately 55% of total blood volume it is also the liquid component of the blood

- Plasma is a straw-coloured fluid that appears translucent and yellow.

- Plasma is mainly composed of water (around 90%), however, it contains multiple solutes, such as proteins, electrolytes (such as sodium, potassium, calcium, and chloride), waste products, gases, and hormones.

- The three major proteins in plasma are fibrinogen, globulins (including antibodies), and albumin.

- The various roles of plasma are that it helps maintain blood pressure, transport nutrients, hormones, and waste products and it plays a pivotal role in maintaining the blood's pH level.

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Blood is a vital bodily fluid that inhabits a crucial role in many physiological functions of the body, these include oxygen transport, delivery of nutrients, immune defence, the removal of waste, and temperature regulation.

The composition of blood includes 4 specific components, each with their own unique functions. The primary components of blood are:

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A Heart Murmur is the sound of abnormal blood flow travelling through the heart. It normally has humming or rasping sounds between each heartbeat.

Most heart murmur are mild and don’t require treatment however in more serious cases it can be controlled by antibiotics or surgery (Services, n.d.).

Symptoms can include:

Cyanosis

Chest pain

Heart palpitations

Breathlessness

Fatigue

Accelerated heart rate

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Angina is a temporary pain or discomfort in the chest. It is generally an underlying symptom of more serious complications of the heart. It is caused when your heart does not receive enough blood or oxygen (Heart Foundation, 2023).

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u3271898 Clinical connection: heart failure 

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u3271898 Clinical connection: heart failure 

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Heart failure is a chronic medical condition where the heart is unable to pump blood effectively. This can happen when the hearts muscles are weakened or if there are troubles with the heart valves. This leads to a reduction in the hearts ability to pump blood adequately through the body. Heart failure is separated into two groups one being systolic heart failure where the hearts ability to pump blood is negatively affected. The other is diastolic heart failure where the heart becomes stiff and can’t fill up with blood.

Symptoms of heart failure may include shortness of breath, fatigue, swelling (edema) in the legs and ankles, and fluid retention.

Treatments for heart failure include medications that lower the strain on the heart and lower blood pressure. Some medications include ACE inhibitors and angiotensin II receptor blockers (ARBs). (Healthdirect Australia, 2020)

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It is important to know patients’ blood types and what antigen their blood has before giving a blood transfusion. If patient’s are given incompatible blood for example given A blood when they have B antigens, the immune system will attack the new blood as it is foreign. If the immune system attacks the blood transfusion it can have major complication on your body such as blood clotting, shock, circulatory collapse etc (Dean,2005).

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Clinical Connection: Hypotension and Hypertension 

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Clinical Connection: Hypotension and Hypertension 

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Hypertension (High Blood Pressure):

- Hypertension is defined as constantly elevated blood pressure.

- It is often categorised into two stages:
- Stage 1 Hypertension: Systolic BP is 130-139 mm Hg, and/or diastolic BP is 80-89 mm Hg.

- Stage 2 Hypertension: Systolic BP is 140 mm Hg or higher, and/or diastolic BP is 90 mm Hg or higher.

- Hypertension is a common risk factor for strokes and heart disease.

Hypotension (Low Blood Pressure):

- Hypotension is defined as blood pressure that is lower than normal.

- symptoms linked with hypotension include dizziness, fainting, and fatigue.

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u3271898 Clinical connection: Heart attack

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u3271898 Clinical connection: Heart attack

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A heart attack, also known as a myocardial infarction happens when blood supply to a section of the heart muscle is rapidly and severely reduced or completely blocked.

Some of the Symptoms of a heart attack include chest pain, discomfort shortness of breath, nausea or vomiting, dizziness or lightheadedness, Indigestion, or heartburn.

Treatments for heart attack include medications such as Aspirin, aspirin helps decrease the clotting of blood and assist the blood flow through narrow arteries. (Mayo Clinic, 2018)

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- Coagulation is the final and most complex phase of hemostasis, involving a cascade of enzymatic reactions.

- coagulation results in the formation of fibrin clots, which strengthens the platelet plug to create a more steady barrier at the injury site.

- The coagulation cascade involves several factors of clotting, including prothrombin, and fibrinogen.

- The cascade ends in the conversion of soluble fibrinogen into insoluble strands of fibrin, which will form a mesh-like structure around the platelet plug.

- Fibrin strands can trap blood cells; this creates a solid clot that aids in stopping bleeding.

- The formation of the fibrin clot is tightly controlled to avoid excessive clotting (thrombosis) throughout the body.

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Platelet Plug Formation:
After vasoconstriction occurs, the next process in hemostasis is the formation of a platelet plug.

- Platelets are small, cell-like fragments in the blood.

- When a blood vessel is injured, the exposed collagen fibres in the vessel wall activate platelets to stick to the site of injury.

- Once attached, platelets will release chemicals, including ADP and thromboxane, which further activate nearby platelets.

- The activation leads to platelet aggregation, where platelets bind together to form a plug at the site of injury that temporarily plugs the damaged area.

- The platelet plug is not stable or a permanent solution, but its purpose is to serve as an initial barrier to prevent excessive bleeding.

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The first response to a blood vessel being injured is vascular spasm or vasoconstriction. It is an immediate, automatic constriction of blood vessel walls in order to reduce blood flow to the damaged vessel.

Vasoconstriction assists to minimise blood loss and allows time for the subsequent phases of hemostasis to occur. Things such as injury, pain, and reflexes can trigger a vascular spasm.

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The autonomic Nervous System regulates the bodys automatic and involuntary functions.

It unconciously controls cardiac muslce of the internal organs and inhibits dual innervation between the sympatheric and parasympathetic system.

Some involuntary controls of the heart that are effected are:
- Blood Pressure
- Heart Rate
- Heart Contraction
- Cardiac Output

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The Cardiomyocyte contains large amounts of mitochondria which function to generate ATP or energy.

Cells like cardiomyocytes which require a lot of energy, need a large abundance of mitochondria for the cardiac muscle.

Cardiac Muscle is one of 3 types of muscle and features striated and branched structures in the muscle cell to support in the overall function of heart contraction.

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(Frontiers in Cell and Developmental Biology, 2020)

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Cardiomyocytes are found within the myocardium layer of the heart wall and are responsible for providing a large abundance of ATP from mitochondria to maintain contractual force in the heart.

Specialised Cardiomyocytes are the baseline of the heart's electrical conduction system to support a healthy rhythmic beating (Woodcock & Matkovich, 2005).

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Myocarditis is the inflammation of the myocardium and in severe cases weakens the myocardial muscle. Myocarditis can be triggered by autoimmune diseases and viral infections. The diagnosis can be confirmed with blood tests and ECG's (Myocarditis Foundation, 2017).

Symptoms of Myocarditis include:
- Weakness
- Fatigue
- Chest pain
- Swelling in Legs
- Shortness of Breath

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An ECG is an important instrument used in healthcare. We use this to see the rhythm and rate of the heart. This is important as it can be used to diagnosis most heart conditions such as sinus tachycardia or bradycardia.

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Clinical Connection:                                      Atresia Heart Valve Disease

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Clinical Connection:                                      Atresia Heart Valve Disease

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Atresia is a heart condition the occurs when a heart valve is failing to open. Instead of opening, tissue forms between the chambers of the heart restricting blood flow.

There are two main types of atresia:

-       Pulmonary Atresia – this effects the pulmonary valve when you have this condition blood is unable to flow from the heart to the lungs via the pulmonary artery.

-       Tricuspid Atresia – this effects the tricuspid valve when you have this type of atresia blood is unable to flow from the right atrium to the right ventricle (Heart Valve Diseases – Types / NHLBI, NIH, 2022).

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Clinical Connection:                                    Ventricular Septal Defect (VSD)

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Clinical Connection:                                    Ventricular Septal Defect (VSD)

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Ventricular Septal Defect (VSD) is a hole located in the wall that separates the left and right ventricles. When the hole does not close before birth it allows the oxygenated blood to mix with the deoxygenated blood, due to the heart and lungs needing to work harder the lungs can become congested which can cause reduced oxygen to the heart or higher pressure in the heart.

When an infant is very ill a temporary operation known as Pulmonary artery banding can be done. This is when they narrow the pulmonary artery which results in reduced blood flow to the lungs. When the child Is older an operation will be performed to remove the banding an complete open heart surgery to correct the hole (American Heart Association, 2019)

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Clincial Connection:                Coronary Heart Disease   

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Clincial Connection:                Coronary Heart Disease   

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Coronary heart disease is a build-up of plaque within the blood vessels. This can reduce the blood flow and oxygen to your heart which can eventually result in a heart attack.

Coronary heart disease needs to be diagnosed by a medical professional and can normally be managed by lifestyle changes and medications, however in more severe cases it may require surgery (Heart Foundation, n.d.).

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Vasodilation is defined as the widening or relaxation of blood vessels, increasing their diameter. This process is also controlled by the relaxation of smooth muscle cells in the vessel walls. When blood vessels dilate, their lumen becomes larger, resulting in reduced resistance to blood flow.

Vasodilation is a response to various factors, including increased levels of certain chemicals (e.g., nitric oxide), decreased sympathetic nervous system activity, and local metabolic demands (e.g., during exercise or in response to tissue injury).

Its role is to increase blood flow to specific areas, helping to transport more oxygen and nutrients to tissues and remove waste products.

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Vasoconstriction is defined as the constricting of blood vessels, reducing their diameter. This process is controlled by the contraction of smooth muscle cells in the walls of blood vessels. When blood vessels constrict, their lumen reduces its size, which leads to an increase in resistance to blood flow.

Vasoconstriction is a natural response to various stimuli, including cold temperatures, the release of certain hormones (e.g., epinephrine and norepinephrine), and sympathetic nervous system activation (the fight-or-flight response).

It helps to redirect blood flow away from less critical areas and increase blood pressure, ensuring an adequate supply of oxygen and nutrients to vital organs and tissues during times of stress or need.

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Blood pressure is a fundamental physiological measurement that assesses the pressure of blood against the walls of the arteries as the heart contracts. Blood pressure is conveyed as a numerical value in millimeters of mercury (mm Hg).

1. Systolic Blood Pressure (SBP):

- Systolic blood pressure is the top number in a blood pressure reading. It signifies the highest pressure within the arteries when the heart contracts and pumps blood into the arteries.

- Systolic blood pressure is the result of the pressure during the heart's systole phase.

2. Diastolic Blood Pressure (DBP):

-DBP is the bottom number in a blood pressure reading. It conveys the lowest pressure within the arteries when the heart is at rest between beats or in the diastole phase.

- Diastolic blood pressure is the baseline pressure within the arteries.

A typical blood pressure reading is presented as systolic over diastolic, with normal values often reading as 120/80 mm Hg. In this example:

- Normal Blood Pressure: Generally considered to be around or below 120/80 mm Hg.

- It indicates that blood pressure is within a healthy and normal range, and reduces the risk of cardiovascular problems.

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u3271898                            Capillaries 

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u3271898                            Capillaries 

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- Capillaries are the smallest and most frequent blood vessels in the body, connecting arterioles to venules.

- They have extremely thin walls, consisting of a single layer of endothelial cells, this allows for the exchange of gases (oxygen and carbon dioxide), nutrients, and waste products between the blood and tissues.

- Capillaries take the role of delivery of oxygen and nutrients to cells and the removal of metabolic waste products.

- The extensive network of capillaries makes certain that nearly every cell in the body is near a capillary bed.

- Blood flow in capillaries is quite slow, enabling efficient exchange.

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- Veins are blood vessels that transport deoxygenated blood from the body's tissues back to the heart.

- veins have much thinner walls than arteries and have less muscular tissue because they operate at lower pressure.

- Veins commonly appear bluish in color due to the deoxygenated blood they carry.

- Valves are present in lots of veins, specifically in the limbs, to stop the backflow of blood and assist in the return of blood to the heart.

- The largest veins in the body are the superior and inferior vena cava, which carry deoxygenated blood back to the right atrium of the heart.

- Smaller veins join into larger ones, eventually leading to the vena cava.

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- Arteries are the blood vessels that carry oxygenated blood away from the heart to different tissues and organs throughout the body.

- arteries have thick, muscular walls, which allows them to endure the high pressure generated by the heart's pumping action.

- The biggest and main artery in the body is the aorta, the aorta carries oxygenated blood from the left ventricle of the heart and transports it into smaller arteries across the body.

- Arteries usually have a pulsatile flow of blood due to the rhythmic contractions of the heart, leading to a strong, sporadic surge of blood.

- Arteries branch into smaller arterioles, which further branch into tiny capillaries to enable the exchange of oxygen, nutrients, and waste products.

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u3271898                                                    Haemostasis                     

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u3271898                                                    Haemostasis                     

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Hemostasis is the physiological process that facilitates the control of bleeding and maintaining the circulatory system in the event of blood vessels being injured. It involves a complex series of events that end in the formation of a blood clot to close off the damaged blood vessel. Hemostasis is divided into three primary phases: platelet plug formation, vascular spasm, and coagulation (blood clotting).

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Clinical Connection: Chronic Kidney Disease

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Clinical Connection: Chronic Kidney Disease

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Chronic Kidney disease of CKD involves the loss of function in the Kidneys for over 3 months. The kidneys can no longer optimally remove wastes, filter blood and support the heart in maintaining homeostasis.

Individuals with CKD have an increased risk of heart disease due to the abnormal pressures it places on a patient's heart as they can no longer filter the blood of ions needed and waste to be excreted(National Kidney Foundation, 2019).

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Sympathetic stimulation is an autonomous process, supplied by sympathetic fibres in the kidneys that release norepinephrine.

Norepinephrine function causes vasoconstriction of the afferent arteriole and causes a reduction in the Glomerular filtration rate.

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The primary function of the Urinary system involves elements of regulation of Ion levels in blood, blood pressure, blood volume and the excretion of waste.

Nephrons are the functional unity of the kidney that functions to filter the blood of wastes in the form of urine with the support of the glomerular filtration membrane.

Both systems work together to maintain homeostasis for waste elimination, maintaining BP and the delivery of important nutrients to the body.

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General structure of blood vessels:
Tunica Interna – smooth lining that encounters the blood. It is smooth the reduce the friction of flowing blood.

Tunica Media – this is the middle layer of the blood vessel it contains smooth muscle, and its function is to control the size of the lumen.

Tunica Externa – contains the vessels and nerves used to feed and stimulate the vessels. It also anchors the vessels to surrounding tissues.

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blood groups are based on antigens.

Type A – when you only have A antigen on the surface of your red blood cells.

Type B – when you only have B antigen on the surface of your red blood cells.

Type AB – when you have both A and B antigens on the surface of your red blood cells.

Type O – when you have neither A or B antigens on the surface of your red blood cells.

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CO is the amount of blood that is pumped out of the ventricles each minute.

SV is the volume of blood pumped from each ventricle during each contraction.

HR is the number of heart beats per minute.

It is important that we keep measure of cardiac output as if it is too low it means that the bodies vital organs aren’t receiving enough oxygen.

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When an action potential travels through the hearts conduction system they produce electrical currents which we can detect on the surface of the skin. An ECG is a recording of these electrical signals.
Electrical events:

Atrial Depolarisation – is the movement of an action potential through the atria.

Ventricle Depolarisation – the movement of an action potential through the ventricle.

Ventricle Repolarisation – recharging of ventricles after an action potential.

Atrial Repolarisation – occurs as the same time as ventricle depolarisation, therefore is hidden on the ECG under the QRS Complex.

Waves of an ECG:
P Wave = Atrial Depolarisation

QRS Complex = Ventricle Depolarisation

T Wave = Ventricle Repolarisation

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The heart has four valves. It has two atrioventricular valves and two semilunar valves. The AV valves prevent the back flow of blood into the atria when the ventricles contract and the SL valves prevent the back flow of blood into the ventricles.

both AV valves are located between the atriums and ventricles.

Bicuspid Valves

Tricuspid Valves

Structures of the Av valves:

-       Cusps

-       Papillary muscles

-       Chordae tendineae

SL valves

Aortic Valve – located between the left ventricle and aorta.

Pulmonary Valve – located between the right ventricle and pulmonary trunk.

Structures of SL valves:

-       Cusps reinforced by connective tissue.

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The heart has four chambers.

Right Atrium – receives deoxygenated blood from the body via the superior and inferior vena cava. It contracts pumping blood to right the right ventricle.

Right Ventricle – receives blood from the right atrium and pumps the blood to the pulmonary trunk to be oxygenated via the lungs.

Left Atrium – receives oxygenated blood from the lungs via the pulmonary vein and then pumps the blood to the left ventricle.

Left Ventricle – receives the oxygenated blood from the eft atrium and pumps it back into the body via the aorta.

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When the SA Node isn't working at its optimal pace and rapidly directing a fast heartbeat conduction, it generates an arrhythmia. This causes poor movement of blood between the atria and ventricle as the atria contract rapidly.

Symptoms may include angina, fatigue and dizziness.

Treatment for Atrial fibrillation may include medications such as warfarin and having a pacemaker to maintain a normal heart rate (NHS Choices, 2019).

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American Heart association. (2019). Ventricular Septal Defect (VSD).

https://www.heart.org/en/health-topics/congenital-heart-defects/about-congenital-heart-defects/ventricular-septal-defect-vsd

Dean, l. (2005). Blood Transfusions and the immune system. Nih.gov; National Center for Biotechnology Information (US).

https://www.ncbi.nlm.nih.gov/books/NBK2265/

Frontiers in Cell and Developmental Biology. (2020). Mechanotranduction Pathways in the Regulation of Mitochondrial Homeostasis in Cardiomyocytes (X. Tang, Ed.) [Review of Mechanotranduction Pathways in the Regulation of Mitochondrial Homeostasis in Cardiomyocytes]. https://www.frontiersin.org/articles/10.3389/fcell.2020.625089/full

Healthdirect Australia. (2020, September 15). Heart failure. Www.healthdirect.gov.au. https://www.healthdirect.gov.au/heart-failure

Heart Foundation. (2023). What is angina | Heart Foundation. Heartfoundation-Prod.azurewebsites.net. https://www.heartfoundation.org.au/bundles/your-heart/angina

Heart Foundation. (n.d.). Coronary heart disease / Heart Foundation.

https://www.heartfoundation.org.au/bundles/your-heart/coronary-heart-disease

Heart Valve Diseases – Types / NHLBI, NIH. (2022, March 24). Nih.gov.

https://www.nhlbi.nih.gov/health/heart-valve-diseases/types

Mayo Clinic. (2018). Heart attack - Diagnosis and treatment - Mayo Clinic. Mayoclinic.org. https://www.mayoclinic.org/diseases-conditions/heart-attack/diagnosis-treatment/drc-20373112

Myocarditis Foundation. (2017). Understanding Myocarditis – Myocarditis Foundation. Myocarditis Foundation. https://www.myocarditisfoundation.org/about-myocarditis/

National Kidney Foundation. (2019, May 8). The Heart and Kidney Connection. National Kidney Foundation. https://www.kidney.org/atoz/content/heart-and-kidney-connection

NHS Choices. (2019). Treatment - Atrial fibrillation. NHS. https://www.nhs.uk/conditions/atrial-fibrillation/treatment/

Services, D.of H. & H. (n.d.) Heart murmur.

https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/heart-murmur#symptoms

Troughton, Asher, C. R., & Klein, A. L. (2004). Pericarditis. The Lancet (British Edition), 363(9410), 717–727. https://doi.org/10.1016/S0140-6736(04)15648-1

Woodcock, E. A., & Matkovich, S. J. (2005). Cardiomyocytes structure, function and associated pathologies. The International Journal of Biochemistry & Cell Biology, 37(9), 1746–1751. https://doi.org/10.1016/j.biocel.2005.04.011

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Pericarditis is an inflammation of the pericardium and can be:

Acute- sudden onset of symptoms of pericarditis
Chronic-  Longer time period of pericarditis of 3 months and above.
Constrictive-  The pericardium develops scar tissue, stiffens, and interferes with normal heart function.
Idiopathic- Unknown cause of pericarditis

Varying pericarditis is caused by non-infectious and infectious.

Most individuals who suffer pericarditis only require rest and medication. However, individuals who suffer from constrictive pericarditis may require surgery (Troughton et al., 2004).

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Blood is oxygenated via pulmonary circulation within the cardiovascular system.

The respiratory zone within the respiratory system's primary function is a passageway for external air (O2 and CO2), within the process of external inspiration. The alveoli within the respiratory zone are the primary site for gas exchange with their simple endothelial layers to exchange oxygen within the blood for systemic capillaries and the tissue cells.

The respiratory zone receives external air from the conducting zone of the respiratory system. The respiratory zone functions and structures, such as the alveoli, allow gas exchange between the external air and blood with their simple endothelial layers to move oxygen and carbon dioxide.

Within external inspiration, the alveoli oxygenates blood within pulmonary circulation for the pulmonary capillaries and veins.

The transport of oxygen is supported by red blood cells which transport oxygen and carbon dioxide with their unique cell structure. RBCs are shaped in a biconcave disk with no nucleus and contain haemoglobin. This increases surface area and flexibility for the transport of oxygen within systemic circulation.

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Dub is also referred to as S2.

Blood hits the semilunar valves (pulmonary and aortic valves) as they close. This marks the end of ventricular systole and causes the 'dub' sound.

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Lub is also referred to as S1

Blood is hitting the AV Valves as the tricuspid and bicuspid valves close. This marks the beginning of ventricular systole and causes the 'lub' sound

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Heart Sounds (Auscultation sounds of Lubb Dubb)

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Heart Sounds (Auscultation sounds of Lubb Dubb)

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Ventricular systole lasts 0.3 seconds.

The ventricles receive impulses from the fibre branches of the conduction system of the heart, causing the Ventricles to contract and simultaneously, the Semilunar valves open to transport blood for pulmonary or systemic circulation.

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The atria contracts and forces blood into the ventricles via the response of the SA node which triggers the AV valves (tricuspid and bicuspid valves) to open.

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The relaxation period lasts 0.4 seconds when all 4 heart chambers are in diastole.

This is when blood flows into the atria.

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Function of the Purkinje Fibres allows AP to rapidly conduct for the ventricles to contract which require energy as the chambers are pushing blood at a high pressure.

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The AV bundle is a passageway for action potential in the ventricular septum between the ventricles and the atria.

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The bundle branches connect the AV bundle to the Purkinje Fibres and act as a transport passageway for Action potential to reach the Apex of the heart.

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The AV node slows the pace of Action potential from the SA Node, allowing time for blood to be ejected into chambers and out of the heart.

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The SA node's function is to kickstart Action Potential conduction via the autorhythmic fibres at a high pace.

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Electrical Conduction System of the Heart

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Electrical Conduction System of the Heart

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When the Left Ventricle contracts, oxygenated blood is pumped through the Aortic valve and into the Aorta, which distributes the blood to the body via its three major branches. Systemic Circulation occurs.

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Oxygenated blood enters back into the heart via pulmonary veins and into the Left Atrium. The pathway of blood continues when the Left atrium contracts and blood moves through the mitral valve and enters the Left Ventricle

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Gas exchange occurs within pulmonary circulation, providing oxygen-rich blood to the Left Atrium.

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The pulmonary trunk divides into the left and right pulmonary arteries and delivers deoxygenated blood for gas exchange to the respective lungs. Pulmonary circulation occurs.

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The Right Ventricle receives the de-oxygenated blood and exits via the pulmonary valve to enter the pulmonary trunk.

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The right atrium receives de-oxygenated blood from the superior vena cava (upper body) and the inferior vena cava (lower body). Blood exits the Right Atrium via the tricuspid valve and into the Right Ventricle.

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Cardiac muscle which enables heart contractions. Contains cardiomyocytes which is rich in mitochondria to generate energy.

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Composed of a smooth endothelial layer to make a non-stick surface, preventing blood clots from forming in the heart.

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Serous pericardium produces pericardial fluid that lubricates your heart to avoid friction and pressure with external tissues.

It is made of two layers:
Parietal Layer - firmly attached with fibrous Pericardium.
Visceral Layer - Directly covers the heart
Pericardial Cavity - A space between 2 layers which stores pericardial fluid.

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Fibrous Pericardium holds the heart within the mediastinum. It a protective membrane that allows heart movement (contractions) but its tough compromise allows the heart to not fill with too much blood from over-expanding.

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Pericardium is a protective membrane that surrounds and protects the heart and contains 2 structures

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The Heart is a part of the cardiovascular system and is located medially between the lungs within the thoracic cavity or the mediastinum.