Section 1: The Heart part 1

Question 1

where is the heart located?

Answer 1

in between the 2nd and 5th intercostal space which is the same as in between the 3rd costal cartilage and 6th costal cartilage, near the midclavicular line

Question 2

how many layers does the heart have

Answer 2

3
pericardium
myocardium
endocardium

Question 3

describe the fibrous pericardium

Answer 3

outer sac
made of fibrous tissue
fibrous, inelastic, protects and prevents over-distension of the heart

Question 4

describe the serous pericardium

Answer 4

inner layer
continuous double layer of serous membrane
single layer of endothelial cells, folded in on itself
forming a double membrane around the heart with an enclosed space between the layers

Question 5

describe the layers of the serous pericardium

Answer 5

parietal pericardium, outer layer, lines the fibrous pericardium
visceral pericardium (epicardium), inner layer, firmly attached to the myocardium

Question 6

describe the myocardium

Answer 6

specialised cardiac muscle, striated but not under voluntary control
each fibre/cell has a nucleus and one or more branches and is rich in mitochondria
sheet arrangement enables contraction of heart to be coordinated

Question 7

describe the endocardium

Answer 7

thin membrane lines chambers and valves
single layer of flattened epithelial cells
is continuous
endothelium lines the blood vessels
smooth to minimise friction

Question 8

name the right side of the heart

Answer 8

superior vena cava, branches of right pulmonary artery, right pulmonary veins, pulmonary valve, right atrium, right atrioventricular valve (tricuspid valve), right ventricle, inferior vena cava, thoracic aorta

Question 9

name the left side of the heart

Answer 9

arch of aorta, branches of left pulmonary artery, branches of left pulmonary veins, left atrium, aortic valve, left atrioventricular valve (bicuspid/mitral), left ventricle, chordae tendineae, papillary muscle, interventricular septum

Question 10

describe the chordae tendineae

Answer 10

prevents backflow by preventing the valves opening upwards

Question 11

describe the papillary muscles

Answer 11

anchor the chordae tendineae to the ventricular wall

Question 12

Describe the role of the sinoatrial node

Answer 12

Depolarises, initiating a new heartbeat
Impulse spreads through atrial muscle triggering atrial contraction then reaching the AVN

Question 13

Describe the role of the AVN

Answer 13

Transmits the electrical signals from the atria into the ventricles
There is a delay to allow atria to finish contracting before ventricles start

Question 14

Describe the role of the av bundle or bundle of his

Answer 14

Within the ventricular myocardium the branches break up into Purkinje fibres.
With those it transmits electrical impulses from the AV node throughout the ventricular myocardium triggering ventricular contractions

Question 15

How is heart rate/force decreased

Answer 15

Vagus nerve (parasympathetic) supplies the SA and AV nodes and atrial muscle. Stimulation of vagus nerve reduces the rate of SA nod firing, decreasing the rate and force of heartbeat

Question 16

Describe how heart rate/force is increased

Answer 16

Sympathetic nerves (accelerator) supply the SA and AV nodes and the myocardium, stimulation increases the rate and force of the heartbeat

Question 17

Where is the rate and force of contraction controlled

Answer 17

Cardiovascular centre in medulla oblongata

Question 18

Describe atrial systole

Answer 18

SA node triggers wave of contraction that spreads over atria myocardium, emptying atria and filling ventricles. Delay of AV transmission as impulse reaches AV node so atria can finish emptying before ventricles contract

Question 19

Describe ventricular systole

Answer 19

Av node triggers own electrical impulse spreads to ventricular muscle via av bundle, bundle branches and purkinje fibres,ware of contraction moves to apex and ventricular walls pumping blood into the pulmonary artery and aorta

Question 20

How does pressure change in atrial systole

Answer 20

Pressure rises in atria, theatriovertricular valves open, blood flows into ventricles and gravity helps if thorax is upright

Question 21

How does pressure change in ventricular systole

Answer 21

High pressure generated during ventricular contraction forces the atrioventricularvalves to close, preventing backflow of blood into the atria as it exceeds atrial pressure

Question 22

Describe complete cardiac diastole

Answer 22

Rest period between beats the myocardium in atria and ventricles is completely relaxed.

Question 23

how is blood pressure controlled (short-term)

Answer 23

baroreceptor reflex and chemoreceptors

Question 24

describe the baroreceptor reflex in high blood pressure

Answer 24

aortic and carotid baroreceptors stimulated, so increased input to CVC. decreased cardiac output occurs by parasympathetic activity to heart and sympathetic activity inhibited to the heart. sympathetic activity inhibited to blood vessels causes vasodilation of blood vessels. blood pressure falls

Question 25

describe the baroreceptor reflex with low blood pressure

Answer 25

aortic and carotid baroreceptors inhibited so decreased input to CVC. increased cardiac output occurs by parasympathetic activity to heart and sympathetic activity increased to heart. sympathetic activity increased to blood vessels causing vasoconstriction of blood vessels

Question 26

describe how chemoreceptors control blood pressure when pO2 fall and pCO2 and pH rise

Answer 26

carotid and aortic chemoreceptors detect change so send signals to CVC to increase sympathetic activity to heart and blood vessels so stroke volume and heart rate increases and vasoconstriction of blood vessels so blood pressure rises

Question 27

describe how chemoreceptors control blood pressure when pH and pCO2 falls and pO2 rises

Answer 27

carotid and aortic chemoreceptors detect change and send signal to CVC to decreases sympathetic activity to heart and blood vessels causing stroke volume and heart rate to decrease and vasodilation of blood vessels so blood pressure decreases

Question 28

describe he renin-angiotensin mechanism (RAAS) and how it controls blood pressure

Answer 28

kidneys respond to a reduction in BP and kidney blood flow by reducing excretion
excrete renin and renin activates angiotensinogen into angiotensin 1 which is then converted to angiotensin 2 by ACE
it is a powerful vasoconstrictor and triggers the release of aldesterone cause sodium retention and increased excretion of K so water reabsorption is increased therefore the body’s fluid load and circulating blood volume so BP is increased

Question 29

describe how atrial natriuretic peptide (ANP) controls blood pressure

Answer 29

a hormone released by the heart causing sodium and water loss from the kidney and reduces BP