HES 111 Week 1

Question 1

How many chambers does the heart have? and what are they called

Answer 1

4 chambers, 2 atria and 2 ventricles

Question 2

Where do the atria receive blood from

Answer 2

Receive blood from veins and pump blood into ventricles via one way valves.

Question 3

Where do ventricles eject blood into

Answer 3

eject blood into the arteries and carry blood either through the systemic or pulmonary circuit

Question 4

Describe the pulmonary circuit (3 steps)

Answer 4

1. deoxygenated blood pumped to the lungs by the right side of the heart
2. Gas exchange occurs between air in the alveoli and blood in the pulmonary capillaries
3. oxygenated blood is returned to the left side of the heart

Question 5

Describe the systemic circuit (3 steps)

Answer 5

1.Oxygenated blood is pumped to the body by the left side of the heart

2. Gas exchange occurs between the tissues and blood in systemic circuits
3. Deoxygenated blood is returned to the right side of the heart

Question 6

Are the ventricles or atria larger and have thicker walls?

Answer 6

Ventricles are larger and have thicker walls

Question 7

What atrium is larger and which atria has thicker walls

Answer 7

Right atrium is larger and thinner walled and left atrium is smaller and thicker walled

Question 8

What are the valves called between the atria and ventricles

Answer 8

Av Valves

Question 9

Where is the tricuspid valve located and how many cusps does it contain

Answer 9

between right atrium and right ventricle and contains 3 cusps

Question 10

Where is the bicuspid valve located and how many cusps does it have

Answer 10

between left atrium and left ventricle and contains only 2 cusps.

Question 11

What are the valves called between the ventricles and pulmonary artery and aorta called

Answer 11

semilunar valves

Question 12

Where is the pulmonary valve locted

Answer 12

between right ventricle and pulmonary trunk

Question 13

Where is aortic valve located

Answer 13

between left ventricle and aorta

Question 14

What happens when there is high pressure in the ventricles

Answer 14

causes blood flow that pushes the aortic valve open

Question 15

When high pressure in the ventricle pushes the blood up to the bicuspid valve what does it do

Answer 15

close

Question 16

What happens when there is pressure from the blood flowing backwards in aorta

Answer 16

aortic valve closes

Question 17

What happens when there is pressure from the blood in left atrium

Answer 17

bicuspid valve opens, allowing blood in the left atrium to drain into the relaxed ventricle

Question 18

What are myocytes? what do they generate

Answer 18

99% of the cells are packemaker cells. They are striated muscle fibers who generate AP when membrane is depolarized to threshold

Question 19

What are pacemaker cells and what do they generate

Answer 19

pacemaker cells account for 1% of cells. They generate spontaneous rythmic action potentials and are the signal for myocyte contraction.

Question 20

Describe the cardiac conduction system (3 steps)

Answer 20

1. SA node generates AP which spreads to the atrial cells and and AV node.
2. After the AV node delay, AP is conducted to the AV bundle an then to the right and left bundle branches
3. The AP spreads from bundle branches along purkinje fibres to the contractile cells of the ventricles

Question 21

What is the AV node delay?

Answer 21

It allows the atria to fully depolarize (and contract) before the ventricles which gives the ventricles time to fill with blood.

Question 22

What does the P wave deflect

Answer 22

Atrial depolarization and reflects depolarization of all the myocytes of the left and right atria

Question 23

What does the QRS complex reflect

Answer 23

Ventricular depolarization. It reflects depolarization of all the myocytes of the left and right ventricles

Question 24

What does the T wave reflect

Answer 24

Ventricular repolarization of all the myocytes if the left and right ventricles.

Question 25

Describe each phase of the cardiac cycle (step 1)

Answer 25

1. ventricular filling phase
   STEP 1

Ventricles fill with blood and are in diastole. AV valves are open. Atrial systole occurs and semilunar valves are closed.

Question 26

Describe each phase of the cardiac cycle (step 2)

Answer 26

2. Isovolumetric contraction

STEP 2
Ventricular systole begins. AV and semilunar valves close when enough pressure builds in the ventricles and atrial diastole begins

Question 27

Describe each phase of the cardiac cycle (step 3)

Answer 27

ventricular systole continues
AV valves are still closed
Atrial diastole continues
Pressure opens SL valves and blood is ejected into pulmonary artery and aorta

Question 28

Describe each phase of the cardiac cycle (step 4)

Answer 28

ventricular diastole begins
AV valves still closed
Atrial diastole continues
SL valves closed