Anatomy of the Heart 2

Question 1

What are the four chambers of the heart?

Answer 1

Atrioventricular (one on each side): valve between the atrium and ventricle

Semilunar (one on each side): valve which controls flow from ventricular layers to outflow artery (on this side aorta)

Question 2

What is the function of the atrioventricular valves?

Answer 2

Prevents blood returning to atria during ventricular contraction
When ventricle contracts pressure goes up in chamber, if nothing was there the blood would be pushed back in the opposite direction, blood can only go from atrium to ventricle

Question 3

What are the AV valves on the left and right side?

Answer 3

Tricuspid valve : three distinct flaps forming valve on right side

Bicuspid valve : two distinct flaps forming valve on left side

Question 4

What happens when the AV valves are open?

Answer 4

Blood moves from vena cavas into chamber via AV valve - diastole phase of cycle
Diastole : Filling phase of cycle, fills chambers of blood so it is ready to pump blood around body

Question 5

What happens when the AV valves are closed?

Answer 5

Blood can’t move back into atrium - systole phase
Systole : contractile phase, AV valve is pushed shut by raised pressure from chamber

Question 6

What is the function of the semilunar valves?

Answer 6

Prevent blood returning into ventricle when the heart relaxes (stops contracting). Right semilunar valve opens into pulmonary circulation to go to the lungs. Valves pushed open when pressure in ventricles is significant and overcomes the pressure in the arteries

Question 7

What is the papillary muscle?

Answer 7

Papillary muscle is attached to fine tendon strands - chordae tendineae, close leaflets gently

Question 8

What is the chordae tendineae ?

Answer 8

Extremely strong tenuous strands attached to ends of AV valve leaflet
AV valve leaflet would fold back if they were not attached to anything hence chordae tendineae are essential

Question 9

Why do semilunar valves not need chordae tendineae?

Answer 9

Semilunar do not need chordae tendineae as leaflets are not exposed to same amount of pressure and support each other when they’re closed

Question 10

What is the function of the right coronary artery?

Answer 10

Runs from an aortic branch (ascending aorta) over the surface of the epicardium in a groove between the right atrium and right ventricle around to the posterior of the heart, most of the blood supply goes to the ventricular wall as there is more muscle there, provides oxygenated blood to the heart

Question 11

What is the function of the left coronary artery?

Answer 11

Comes off aorta, runs along a stem and branches in a groove between left atrium and left ventricle and over the anterior surface of the heart. Branches to form the anterior interventricular artery and circumflex artery, provides oxygenated blood to the heart

Question 12

What is the function of the anterior inter-ventricular artery?

Answer 12

Branches off the left coronary artery and found on the anterior surface of the heart and runs over the interventricular section- muscle layer that partitions the left and right ventricle

Question 13

What is the function of the circumflex artery?

Answer 13

Branches off the left coronary artery and runs around and circumflexes around to the left lateral margin

Question 14

What is the function of the small cardiac vein?

Answer 14

Drains territory supplied by right coronary artery, draining from the anterior surface running around the right margin around to the posterior of the heart draining the blood back to the back of the heart

Question 15

What is the function of the great cardiac vein?

Answer 15

Drains all territory supplied by anterior inter ventricular artery and circumflex artery, left coronary supply

Question 16

What is the function of the coronary sinus?

Answer 16

Where small and great cardiac vein drain to, receiving chamber for cardiac veins, found at the posterior of the heart, allows blood to drain into the right atrium where it will drain into the pulmonary circuit for reoxygenation

Question 17

What is cardiac muscles appearance (LS)?

Answer 17

Striated muscle when looking at longitudinal profile
Orange blobs are red blood cells traveling down thin tubes to supply the cardiac muscle with nutrients
Nucleus of epithelial cell forms wall of capillary

Question 18

What is the function and structure of cardiac muscle?

Answer 18

Beating of the heart
Striated, short branched cell, one nuclei per cell, central nucleus, cytoplasmic organelles packed at the poles of nucleus, interconnected with neighbouring cells via intercalated disks (ICDs)

Question 19

How can you identify cardiac muscle in transverse section (TS)?

Answer 19

In transverse section you don’t see striations however can identify as you can see nuclei (centrally located) which you can’t do in skeletal muscle (they have peripheral nuclei)

Question 20

Why does cardiac muscle have a lot of mitochondria?

Answer 20

Cardiac muscle has a lot of mitochondria as mitochondria tells you about oxygen dependent aerobic metabolism, cardiac muscle relies on oxygenated blood supply allowing it to burn any fuel source hence lots of oxygen required hence lots of mitochondria present

Question 21

What are cardiomyocytes?

Answer 21

Found at the end of the cardiac muscle cell and are thicker bands, rich in network of intracellular junctions

Question 22

What are intercalated disks?

Answer 22

Intracellular junctions that cross over one cardiac muscle cell to another
Darker stained areas are called intercalated disks which contains two (adhesion belts and desmosomes) intracellular junctions

Question 23

What are adhesion belts?

Answer 23

Adhesion belts link actin of one cell to actin of a neighbouring cell, actin transmits first into neighbouring cell when cell contracts

Question 24

What are desmosomes?

Answer 24

Desmosomes link cytokeratin of one cell to cytokeratin to a neighbouring cell, cytokeratin are the cells internal cytoskeletal proteins, buttons cells together

Question 25

What are gap junctions?

Answer 25

Gap junctions allow electrochemical communication between cells which releases calcium stores - which stimulate contraction electrochemically

Question 26

What does the conduction system of the heart do? (BRAIN DUMP)

Answer 26

Controls functions of heart valves, makes sure papillary muscles attach to chordae tendineae and make sure they are the first parts of the ventricular chamber to contract to make sure chordae tendineae are pretensioned for contraction
Sympathetic and parasympathetic nerves will increase and decrease the rate of firing of conduction pathways, if we are excited sympathetic tone increases and our heart beats faster, if we are relaxed parasympathetic tone increases and our heart slows

Question 27

What are the three things conduction systems of the heart do?

Answer 27

Its actions greatly increase the efficiency of heart pumping
This system is responsible for the co-ordination of heart contraction and of atrioventricular valve action
Autonomic nerves alter the rate of conduction impulse

Question 28

What are conduction cells?

Answer 28

Conduction cells have peripheral myofibrils, a central nucleus, mitochondria, glycogen, lots of gap junctions, some desmosomes and few adhesion belts