Gross And Cellular Structure Of The Heart

Question 0

What is the positioning of the heart in the body ?

Answer 0

Behind the sternum for protection
Extends from 2nd to 5th rib
Angled in the chest cavity

Question 1

What are the roles of cardiac muscle ?

Answer 1

1- supply oxygenated blood containing nutrients to major organs
2- remove waste products formed during metabolism

Question 2

Describe the pulmonary circulation ?

Answer 2

Pulmonary artery which carries deoxygenated blood to the lungs
Pulmonary veins which carries oxygenated blood to the heart
Important for taking blood to the lungs for re-oxygenation

Question 3

Describe the coronary circulation ?

Answer 3

Is provides oxygenated blood to the heart
Coronary arteries branch from the base of the aorta
Left coronary artery splits into the the anterior inter ventricular artery and supplies mainly the wall of left ventricle
Right splits into marginal artery and supplies the free right ventricular wall and goes around to the posterior aspect of the heart
The venous blood drains into the coronary sinus

Question 4

What mirrors the marginal artery in the coronary vessels ?

Answer 4

Small cardiac vein

Question 5

What vessel mirrors then terror interventricular artery ?

Answer 5

Great cardiac vein

Question 6

Describe the systemic circulation ?

Answer 6

Provides oxygenated blood to the organs and tissues of the body
Served by the left side of the heart

Question 7

What arteries of the systemic circulation supply the head and brain ?

Answer 7

Vertebral and carotid arteries

Question 8

What the 1st vessel to branch from the aorta ?

Answer 8

brachiocephalic trunk

Question 9

What arteries of the systemic circulation supply blood to the arms ?

Answer 9

Subclavian arteries, they run under the clavicles

Question 10

What artery supplies blood to the upper part of the digestive tract ?

Answer 10

Superior mesenteric

Question 11

Which artery supplies the lower part of the digestive tract?

Answer 11

Inferior mesenteric

Question 12

What arteries supply blood to the pelvis and legs ?

Answer 12

The common iliac and internal iliac feed into the external iliac and deep femoral

Question 13

What is the outer layer of the heart called ?

Answer 13

Fibrous pericardium

• protects the heart
• anchors the heart to adjacent structures
• it’s indistensible so it prevents overfilling

Question 14

What is the inner layer of the heart called ?

Answer 14

Serous pericardium

- secretes fluid into the pericardial cavity to aid the twisting of the heart during pumping

Question 15

What is the epicardium?

Answer 15

It surrounds the outside of the muscular surface of the heart

Question 16

What is the endocardium ?

Answer 16

It surrounds the inner face of the heart

Question 17

What is pericarditis ?

Answer 17

It is the inflammation of the pericardial membranes

• causes sharp chest pains
• with a stethoscope you can hear the membrane rubbing against one another

Question 18

What is the right AV valves called ?

Answer 18

Tricuspid valve cos it has 3 cusps

Question 19

What is the right AV valve called ?

Answer 19

It’s the biscuspid valve or mitral valve with 2 cusps

Question 20

How many cusps do the semi-lunar valves have ?

Answer 20

3

Question 21

Why do valves open and close ?

Answer 21

It is a passive movement based upon the pressure gradients across them

Question 22

When do valves open ?

Answer 22

They open when the pressure gradient is greater behind the valves

Question 23

When are valves shut ?

Answer 23

They are shut when the pressure gradient is greater in front of the valves

Question 24

What is the role of the papillary muscles ?

Answer 24

They are used to close the AV valves
When the ventricles contract the pressure is greater in the ventricles than in the atria so the valves shut. This occurs because the papillary muscles also contract when the ventricles contract and they pull on chordae tendinae to prevent the valves eventing into the atria

Question 25

What are the dimensions of muscles cells of the ventricles ?

Answer 25

120 micrometers long

30 micrometers wide

Question 26

How do cardiac muscle cells join together ?

Answer 26

They are joined together by intercalated discs which tend to join end to end

Question 27

What are the 2 roles of the intercalated discs ?

Answer 27

1- they act by firmly binding together the adjacent cells allowing mechanically coupling
2- this also enables electrical coupling

Question 28

What are gap junctions ?

Answer 28

They are proteins made up of connexins which create ion channels so small ions can pass between cells
Allow electrical coupling so aps can pass between cells easily and quickly
Enables heart to function as functional syncytium

Question 29

What is the flow of arteries for the upper chest and arms ?

Answer 29

Subclavian - axialllary - brachial arteries

Question 30

Where does venous blood from the coronary circulation drain into ?

Answer 30

Coronary sinus then into right atrium.

Question 31

What is the double walled sac of the heart called ?

Answer 31

Pericardium

Question 32

When do valves open ?

Answer 32

When pressure behind them is greater

Question 33

When do valves close ?

Answer 33

When pressure is greater in front of them

Question 34

What size of the gap between adjacent cardiac cells ?

Answer 34

0.02 micrometers - filled with connective tissue

Question 35

What causes the membranes of adjacent cardiac cells to be joined together more strongly at certain points ?

Answer 35

Desmosomes