The Heart

Question 1

What are the 3 types of valves in the heart, and where are they located?

Answer 1

• Tricuspid - between the Right Atrium and Right Ventricle
• Semi-Lunar - one where the Aorta leaves the heart; one where the Pulmonary Artery leaves the heart
• Bicuspid - between the Left Atrium and Left Ventricle

Question 2

What is meant by “double-circulatory” system?

Answer 2

There are 2 separate circuits pumping blood around the body - Pulmonary Circuit (heart-lungs) and the Systemic Circuit (heart-other organs).

Question 3

What is meant by “myogenic”?

Answer 3

The heart doesn’t have to rely on the brain to signal its contractions, it does it by its own accord.

Question 4

What phases make up the cardiac cycle?

Answer 4

• Diastole
• Atrial Systole
• Ventricular Systole

Question 5

How does blood flow through the heart?

Answer 5

Blood enters the Right Atrium via the Vena Cava; It gets forced through the Tricuspid Valves, into the Right Ventricle; Passes through the Semi-Lunar Valves into the Pulmonary Artery towards the Lungs; After being oxygenated at the Lungs, the blood is passed through the Pulmonary Vein, to the Left Atrium; Passes through the Bicuspid Valve to the Left Ventricle; Forced through the Semi-Lunar Valves into the Aorta, to the organs and tissues.

Question 6

What happens in Diastole?

Answer 6

The heart is relaxed, and fills with blood.

Question 7

What happens in Atrial Systole?

Answer 7

The Atria contract, forcing blood into the Ventricles.

Question 8

What happens in Ventricular Systole?

Answer 8

The Ventricles contract, forcing blood out of the vessels.

Question 9

What are the 2 nodes in the heart?

Answer 9

• Sino-Atrial
• Atrioventricular

Question 10

What does the Sino-Atrial Node do, and where is it located?

Answer 10

• Located at the top of the Right Atrium
• Behaves as a pacemaker.
• The myocytes contract, becoming less negative, sending electrical current across the atrium, causing contraction.

Question 11

What does the Atrioventricular Node do, and where is it located?

Answer 11

• Located on the “floor” of the Atrium, where the Ventricle starts.
• Known as the gatekeeper.
• Helps to slow the current, shutting the Tricuspid Valves, allowing the Ventricle to fill.
• Conduction causes the Purkeyne Fibres to squeeze the Ventricles, forcing the blood out.

Question 12

What is an ECG, and what does it do?

Answer 12

• Electrocardiogram
• Monitors heart activity using electrodes that are attached to the chest.

Question 13

What do the P; QRS; T waves represent?

Answer 13

• P - Atrial Contraction
• QRS - Ventricular Contraction (Atrial Relaxation)
• T - Ventricular Relaxation

Question 14

How is Tissue Fluid formed?

Answer 14

• Blood leaves left side of heart via Aorta, under high pressure.
• Arteries branch off into Capillaries.
• Plasma forced out of leaky Capillaries due to hydrostatic pressure.
• Tissue fluid bathes the surrounding cells, which absorbs the O2 and nutrients.
• 90% of the water reabsorbed by osmosis at the venule end of the Capillaries.
• 10% drains into lymphatic system.