The Heart

Question 1

What are the key functions of the heart?

Answer 1

• transport of oxygen
• transport of nutrients
• removal of waste products
• immune system
• paracrine system

Question 2

Describe the structure of the heart

Answer 2

the heart is a dual pump driving 2 parallel circulatory systems –> pulmonary circulation & systemic circulation

Question 3

Describe the function of the Vena Cava

Answer 3

• carries deoxygenated blood from the heart
• superior vena cava carries blood from the head & upper body
• inferior vena cava carries blood from the lower body

Question 4

Describe the function of the pulmonary veins

Answer 4

carries oxygenated blood from the lungs to the heart

Question 5

Describe the function of the aorta

Answer 5

carries oxygenated blood from the heart to the body

Question 6

Describe the function of the pulmonary artery

Answer 6

carries deoxygenated blood from the heart to the lungs

Question 7

Describe the atria

Answer 7

• receives incoming blood from veins
• contraction of atria pushes blood into ventricles
• thin walls
• valves prevent blood from ventricles going back into atria

Question 8

Describe the ventricles

Answer 8

• responsible for pumping blood through arteries
• thick muscular walls
• left ventricle has thicker wall as it does more work
• two ventricles are separated by a muscular septum

Question 9

What are the 2 kinds of semilunar valves ?

Answer 9

• pulmonary valve
• aortic valve

Question 10

Describe the pulmonary valve

Answer 10

regulates blood flow from the right ventricle into the pulmonary artery

Question 11

Describe the aortic valve

Answer 11

regulates the blood flow from the left ventricle into the aorta

Question 12

What are the 2 types of atrioventricular valves ?

Answer 12

• mitral valve
• tricuspid valve

Question 13

Describe the mitral valve

Answer 13

• regulates blood flow from the left atrium into the left ventricle
• 2 leaflets = bicuspid

Question 14

Describe the tricuspid valve

Answer 14

• regulates blood flow from the right atrium
• 3 leaflets = tricuspid

Question 15

How are the atrioventricular valves connected to the ventricle wall ?

Answer 15

via chordae tendineae and regulated by papillary muscles

Question 16

Describe the coronary vasculature

Answer 16

• supplies oxygenated blood to the heart muscle
• coronary arteries branch off from the aorta

Question 17

What are the 5 components of the heart wall ?

Answer 17

1. Pericardium
2. Pericardial cavity
3. Epicardium
4. Myocardium
5. Endocardium

Question 18

Describe the pericardium

Answer 18

outer layer of connective tissue

Question 19

Describe the epicardium

Answer 19

role in homeostasis & regeneration

Question 20

Describe the myocardium

Answer 20

• the contractile part of the heart
• made up of cardiomyocytes, fibroblasts, vascular endothelium & monocytes/macrophages

Question 21

Describe cardiomyocytes

Answer 21

• contractile heart muscle
• striated muscle cells containing filaments of contractile proteins
• 30% of all heart cells
• 70-80% by volume
• linked via gap junctions

Question 22

Describe Fibroblasts

Answer 22

• function to maintain structure and in homeostasis
• forms scar tissue
• 13% of all heart cells
• 1-2% by volume

Question 23

Describe vascular endothelium

Answer 23

• forms the walls of vasculature supplying blood to heart muscle
• 55% of all heart cells
• 3-5% by volume

Question 24

Describe monocytes/macrophages

Answer 24

• involved in the immune system
• 4% of all heart cells

Question 25

Define systole

Answer 25

squeezing

Question 26

Define diastole

Answer 26

dilation

Question 27

Define traverse tubule

Answer 27

extension of plasma membrane into cell permitting fast transmission of action potential

Question 28

What are the key components of the conduction system ?

Answer 28

- Sino-atrial node - atrio-ventricular node - right bundle of His - purkinje fibres - left bundle of his

Question 29

Describe the function of the Sino-atrial node

Answer 29

- located in the right atrium - specialised cardiomyocytes with the ability to generate action potentials - these impulses are then transmitted to the atria myocardium & to the atrio-ventricular node

Question 30

Describe the function of the atrioventricular node

Answer 30

- located at the base of the right atrium at the atria-ventricular junction - atria are electrically isolated from ventricles --> AV node is the pathway between them - function is to delay transmission of impulse till atria are fully contracted

Question 31

Describe the function of the Bundle of His

Answer 31

- transmits the impulse to the apex of the heart without depolarising cardiomyocytes en route - important that contraction of the ventricles begins at the apex, forcing blood towards the aorta & pulmonary artery

Question 32

How does the neural input influence the SA node & regulate heart rate ?

Answer 32

- heart rate is controlled by the cardiovascular centre of the hindbrain - 2 nerves connect the hindbrain to the SA node - the vagus nerve releases acetylcholine onto the SA node which reduces heart rate - accelerens nerve releases norepinephrine onto the SA node which increases heart rate

Question 33

What is a heart attack?

Answer 33

- blockage of one of the arteries which supplies the heart itself with oxygenated blood - leads to the death of a region of heart muscle

Question 34

What causes a heart attack ?

Answer 34

- atherosclerosis = build up of fatty plagues within artery walls, constricting blood flow - rupture of plaque leads to formation of a blood clot which can dislodge & cause acute disease

Question 35

Describe congenital heart disease

Answer 35

- malformations which are present at birth - affects 1 in 100 newborns - causes by an error during embryonic development

Question 36

Blockage of which vessel causes a heart attack ?

Answer 36

coronary artery