Unit 2 Lecture 1: Basic Heart Structure & Function

Question 1

What does the circulatory system do?

Answer 1

1. Transport
2. Regulates temperature

O2 and Co2, Substrates, Hormones, Immunological agents

Question 2

What are the different systems of the heart involved in transporting blood?

Answer 2

• Venous system - low pressure
• Arterial system - high pressure
• Pulmonary system - low pressure

Question 3

Which part of the circulation contains the most pressure and why?

Answer 3

Systemic circulation (arteries) because it needs to pump blood to the majority of tissues and the entire body

Question 4

Why is pulmonary circulation low in pressure?

Answer 4

Anatomically the blood vessels are small but expansive because they are required to have good SA for gas exchange

Question 5

Partial pressure of oxygen differs between these two systems…?

Answer 5

Pulmonary circulation arteries (40mmHg) & systemic circulation arteries (100mmHg)

Question 6

What is the heart made of and what does it contain?

Answer 6

• Walls are made of myocardium (cardiac muscle)
• 4 chambers (2 atria and 2 ventricles)
• Valves

Question 7

Through what process does blood move from one chamber to another?

Answer 7

Pressure gradient

• When contraction occurs, volume decreases but pressure increases to cause the blood to flow from one chamber to the next

Question 8

What is the purpose of the valves in the heart?

Answer 8

To prevent backflow of blood into the heart

Question 9

What do the valves contain to help with their function?

Answer 9

Chordae Tendinae which is attached to the heart and to the valve to keep the valve closed

Note: ONLY in AV VALVES

Question 10

What muscle do the AV valves have to prevent collapse? What are the names of the AV valves?

Answer 10

• Papilary muscle prevents collapse
• Tricuspid and Bicuspid

Question 11

Semilunar valves are connected to what? Which valves are more stronger and why?

Answer 11

• Semilunar valves connect to major arteries
• Semilunar valves are stronger as the AV valves are like leaflets compared to structurally sound valves

Note: You can tell what the valve is based on cusps (3 tricuspid and 1 bicuspid)

Question 12

Why is the Left AV valve bicuspid?

Answer 12

More prone to handling high pressures to come from the end of systolic pressure

Question 13

What is cardiac muscle and what does it do?

Answer 13

• Forms sheets to make the walls of the heart
• They cause contraction to make the heart smaller and increase pressure within the 4 chambers
• Cells are joined by intercalated discs

Innervated by sympathetic and parasympathetic nerves along with the fact that they have gap junctions which can move molecules like Na+, K+ and so forth.