Cardiovascular System

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Questions and Answers

What separates the right atrium from the right ventricle?

Interatrial septum

Atrioventricular valve (correct)

Aortic arch

Interventricular septum

During which phase of the cardiac cycle does the heart fill with blood?

Atrial contraction

Ventricular relaxation

Systole

Diastole (correct)

What role does the tricuspid valve serve during systole?

Closes to prevent blood from leaving the heart

Facilitates blood flow to the lungs

Prevents backflow of blood into the atrium (correct)

Allows blood to flow from the atrium to the ventricle

What is the function of the interventricular septum?

Separates the left ventricle from the right ventricle Signup and view all the answers

What structures supply blood to the heart wall?

Coronary arteries Signup and view all the answers

What is the primary function of the right side of the heart?

To pump blood to the lungs Signup and view all the answers

Which layer of the heart is the thickest and primarily responsible for its pumping action?

Myocardium Signup and view all the answers

Where is the heart primarily located in the human body?

In the thoracic cavity between the lungs Signup and view all the answers

What component of the heart ensures smooth and coordinated contractions?

Intercalated discs Signup and view all the answers

Which heart chamber receives deoxygenated blood from the body?

Right atrium Signup and view all the answers

What is the purpose of pericardial fluid?

To lubricate the heart and reduce friction Signup and view all the answers

Which statement about cardiac muscle is true?

It is controlled by the autonomic nervous system. Signup and view all the answers

Which chamber of the heart is primarily responsible for pumping oxygenated blood to the body?

Left ventricle Signup and view all the answers

What is the general size of the heart compared to a common reference?

The size of a clenched fist Signup and view all the answers

What anatomical position does the apex of the heart point towards?

Downwards Signup and view all the answers

What is the primary function of the mitral valve during systole?

It prevents backflow of blood into the left atrium. Signup and view all the answers

Which structure initiates the electrical impulse for a heartbeat?

Sinoatrial node Signup and view all the answers

What does the first heart sound (S1) commonly referred to as 'Lub' indicate?

Closure of the mitral and tricuspid valves Signup and view all the answers

During which phase does the left ventricle fill with blood?

Diastole Signup and view all the answers

How does an ECG provide information about the heart?

By recording electrical activity during contraction Signup and view all the answers

What is the role of the atrioventricular (AV) node in the heart's conduction system?

To delay impulses allowing full emptying of the atria Signup and view all the answers

Which part of the heart wall is primarily responsible for contractions?

Myocardium Signup and view all the answers

What is a common consequence of problems with heart valves detected through heart sounds?

Heart murmurs Signup and view all the answers

What structure separates the left and right atria?

Interatrial septum Signup and view all the answers

What significant phase follows atrial systole in the cardiac cycle?

Ventricular systole Signup and view all the answers

Which type of circulation is responsible for transporting blood from the right ventricle to the lungs?

Pulmonary circulation Signup and view all the answers

What is the primary function of the coronary circulation?

To deliver oxygenated blood to the heart muscle Signup and view all the answers

What role does the foramen ovale play in foetal circulation?

Allows blood to flow from the right atrium to the left atrium Signup and view all the answers

Which type of blood vessel has the thinnest walls and allows for the exchange of nutrients and gases?

Capillaries Signup and view all the answers

What is the primary difference between arteries and veins in terms of blood flow?

Arteries carry oxygenated blood away from the heart, while veins carry deoxygenated blood back to the heart Signup and view all the answers

What is the primary protective function of the blood-brain barrier?

To prevent foreign substances from entering the brain Signup and view all the answers

What do the pulmonary veins do?

Return oxygenated blood from the lungs to the left atrium Signup and view all the answers

Which component of arteries is responsible for maintaining high blood pressure?

Tunica media Signup and view all the answers

What is the purpose of valves in veins?

To prevent backflow of blood Signup and view all the answers

Study Notes

Heart

The heart is a hollow muscular organ with four chambers.
It is located in the mediastinum, behind the sternum, mostly left of the midline.
The heart is protected by the parietal pericardium, or pericardial sac, that isolates the heart from other thoracic organs, containing pericardial fluid.
The heart wall has three distinct layers:
- Epicardium: outer layer
- Myocardium: thick, middle layer made up of cardiac muscle
- Endocardium: smooth, inner layer lining the heart and its internal structures
Cardiac muscle cells are connected by intercalated discs that consist of fascia adherens, gap junctions, and desmosomes, allowing coordinated contractions.
The heart has four chambers:
- Right atrium: receives blood from the superior and inferior vena cava.
- Right ventricle: pumps blood to the lungs through the pulmonary valve.
- Left atrium: receives oxygenated blood from the lungs through the pulmonary veins.
- Left ventricle: pumps oxygenated blood to the body through the aortic valve.
The heart beats around 100,000 times a day, acting as two separate pumps:
- Right heart: pumps deoxygenated blood to the lungs.
- Left heart: pumps oxygenated blood to the body.

Conduction System of the Heart

The heart’s natural pacemaker is the sinoatrial (SA) node.
The SA node spontaneously depolarizes, generating the pacemaker potential, initiating each heartbeat.
The wave of depolarization spreads across the atria, causing atrial systole. It converges at the atrioventricular (AV) node.
The AV node delays the impulse, allowing time for the atria to fully empty into the ventricles.
The Bundle of His conducts the impulse to the Purkinje fibers of the ventricles.

Electrocardiogram (ECG)

ECG measures the electrical activity generated by heart contractions.
It records a trace consisting of the P wave, QRS complex, and T wave.
ECG can detect abnormalities in heart rate, rhythm, and structure, such as arrhythmias, enlarged heart due to hypertension, and myocardial infarction.

Circulatory system

The circulatory system, also known as the cardiovascular system, circulates blood, transporting nutrients, oxygen, hormones, and removing waste products.
It plays a crucial role in maintaining homeostasis.
The system includes the pulmonary and systemic circulations:
- Pulmonary circulation: transports blood from the right ventricle to the lungs and then to the left atrium.
- Systemic circulation: comprises all blood vessels outside the pulmonary system.

Coronary Circulation

The heart has its own circulation system known as the coronary circulation.
The right and left coronary arteries deliver oxygenated blood to the heart.
Blood from the myocardium capillaries enters the cardiac veins and then flows into the right atrium.

Fetal Circulation

During fetal development, the pulmonary circulation is inactive because the fetus receives oxygen from the placenta.
The umbilical cord connects the fetus to the placenta.
Blood from the right atrium is diverted through the foramen ovale to the left atrium, bypassing the pulmonary circulation.
Blood from the left ventricle flows through the ductus arteriosus, directly to the aorta.

Blood Vessels

Blood vessels transport blood throughout the body:
- Arteries: Carry oxygenated blood away from the heart (except for the pulmonary artery). Arteries have thick, elastic, muscular walls, and blood flow under high pressure. They are composed of three layers: tunica externa, tunica media, and tunica intima.
- Arterioles: Smaller branches from arteries that regulate blood flow into capillaries.
- Capillaries: Smallest and most abundant blood vessels, facilitating rapid exchange of oxygen, nutrients, and waste between blood and tissues. There are three types: continuous, fenestrated, and discontinuous (sinusoidal).
- Venules: Small veins that collect blood from capillaries.
- Veins: Carry deoxygenated blood back to the heart. They have valves to prevent backflow and act as a reservoir of blood. Veins also have three layers, but are less muscular and elastic than arteries, relying on the skeletal muscle pump and respiratory pump for blood flow.

Blood-Brain Barrier

The blood-brain barrier acts as a boundary between circulating blood and the brain and spinal cord.
It is highly selective, protecting the brain from foreign substances and maintaining a constant environment for the brain.
Brain capillaries are not fenestrated and have tightly packed endothelial cells, preventing large molecules, immune cells, bacteria, and viruses from entering the central nervous system.

Major Blood Vessels – The Great Vessels

Arteries:
- Pulmonary artery: Carries deoxygenated blood from the right ventricle to the lungs for oxygenation.
- Aorta: The largest artery in the body; originates from the left ventricle as the ascending aorta, forms the aortic arch, and continues down the body as the descending aorta.
Veins:
- Pulmonary vein: Returns oxygenated blood from the lungs to the left atrium.
- Superior vena cava: Receives deoxygenated blood from the upper body.
- Inferior vena cava: Receives deoxygenated blood from the lower body.

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