7.4 The structure of the heart

Question 1

What is the heart made of?

Answer 1

Cardiac muscle (thick muscular layer)

Question 2

What properties does cardiac muscle hold?

Answer 2

1. its myogenic
   - it can relax and contract without nervous or hormonal stimulation
2. it ever fatigues
   - as long as it have a supply of oxygen and glucose

Question 3

What is the function and sight of coronary arteries (which surround the heart)?

Answer 3

• supply the cardiac muscle with oxygenated blood (to make sure they never fatigue)
• branches off the aorta so all the cardiac muscle is supplied with oxygenated blood

Question 4

What causes myocardial infarction (heart attack)?

Answer 4

Coronary arteries get blocked and cardiac muscle won’t receive oxygen, therefore will not be able to respire and the cells will die.

Question 5

Describe the structure of the atria

Answer 5

-thinner muscular walls

( do not need to contract as hard as not pumping blood far (only to ventricles))

Elastic walls to stretch when blood enters

Question 6

Describe the structure of ventricles

Answer 6

Thicker muscular walls to enable bigger contraction

This creates higher blood pressure to enable blood to flow longer distances (to the lungs and rest of body)

Question 7

Why does the right ventricle have thinner walls than the left ventricle?

Answer 7

The right ventricle pumps blood to the lungs and high pressure of blood to the lungs isn’t wanted as :

1. it could damage capillaries in the lungs
2. reduce time needed for gas exchange

Question 8

Why does the left ventricle have thicker walls than right ventricle?

Answer 8

It needs to contract at the highest force to pump blood out at the highest pressure as blood leaving the left ventricle goes to the rest of the body

Question 9

What do veins do? What are the 2 veins connected to the heart?

Answer 9

Bring blood into the heart

1. vena cava
   - carries deoxygenated blood from the body into the right atrium
2. pulmonary vein
   - carries oxygenated blood from the lungs to the left atrium

Question 10

What do arteries do? What are the 2 arteries connected to heart?

Answer 10

Carry blood away from the heart.

1. pulmonary artery
   - carries deoxygenated blood from the right ventricle to the lungs to become oxygenated
2. aorta
   - carries oxygenated blood from the left ventricle to the rest of the body

Question 11

What are the 2 mains sets of valves and where are they found?

Answer 11

1. semi-lunar valves
   - in the AORTA and PULMONARY artery
   (between the ventricles and arteries)
2. atrioventricular valves
   - found between the ATRIA and VENTRICLES

they may also be called Bicuspid (on left side of heart)
Tricuspid (on right side of heart) (Bi & Tri represent the number of flaps that make up the valve)

Question 12

What is the function of valves?

Answer 12

Makes sure blood flows in one direction

Question 13

How do valves ensure blood flows in only one direction?

Answer 13

They OPEN when pressure is higher BEHIND the valve

They CLOSE when the pressure is higher in FRONT of the valve.

This process prevents back flow of blood.

Question 14

What is the septum?

Answer 14

A piece of cardiac muscle that runs all the way down the middle separating the left and right side of the heart.

Separates the deoxygenated and oxygenated blood.

Question 15

Why is it important for the septum to be there?

Answer 15

Ensures that oxygenated blood isnt being diluted by deoxygenated blood.

Maintains high concentration of oxygen in oxygenated blood to maintain concentration gradient to enable diffusion at respiring cells.