Week 9 - Control of the CV System

Question 1

When the aortic valve become calcified, what can happen to the heart

Answer 1

Left ventricular hypertrophy leading to heart failure

Question 2

What are korotkoff sounds

Answer 2

Sounds heard under the distal half of the sphygmomanometer cuff when between diastole and systole i.e when blood starts to flow into artery after being cut off

Question 3

Stroke volume

Answer 3

Volume of blood ejected from the ventricle each beat

Question 4

What is the stroke volume normally

Answer 4

Around 5L/min on both sides!

Question 5

Describe the structure of purkinje fibres in the heart

Answer 5

They interdigitate with myocytes to spread the impulse across the ventricles

Question 6

Tachycardia

Answer 6

Heart beats too fast

Question 7

Bradycardia

Answer 7

Heart beats too slow

Question 8

atrial/ventricular fibrillation

Answer 8

aberrant heartbeat due to problems with conduction of impulse across the heart

Question 9

What does ECG measure

Answer 9

Changes in potential difference between two electrodes

Question 10

Where are two electrodes on the heart

Answer 10

Heart surface

On limbs

Question 11

Arrhythmias

Answer 11

Irregular heartbeat

Question 12

What is P wave

Answer 12

Atrial depolarisation

Question 13

What is QRS

Answer 13

Ventricular depolarisation

Question 14

T wave

Answer 14

Ventricular repolarisation

Question 15

P-R interval

Answer 15

Delay through the AV node

Question 16

Which ion enters the SA node upon its depolarisation

Answer 16

Calcium

Question 17

Which ion leave the SAN during repolarisation

Answer 17

Potassium

Question 18

Drugs that increase heart rate affect SAN permeability in which way

Answer 18

Increased Ca permeability

Question 19

Drugs that decrease heart rate affect SAN permeability in which way

Answer 19

Increased K permeability

Question 20

How can drugs be used to treat heart failure

Answer 20

They increase intracellular calcium and/or increase myofilament sensitivity hence increasing contraction and input from failing heart

Question 21

What does digoxin do and how does it work

Answer 21

slows the heart down and improves the filling of ventricles

It increases the intracellular calcium concentration

Question 22

What is the main receptor type found on heart nodal tissue, conducting system and myocardium.

Answer 22

Adrenoreceptor B1

Question 23

Effects of adrenoreceptor activation on heart

Answer 23

Positive intropy (strengthen the force of heartbeat)

Positive chronotropy (increase heart beat)

Positive lusitropy (causes heart to relax more quickly hence shortening heartbeat- greater efficiency)

Positive dromotropy (increases conduction through the AV node)

Question 24

What are used as short-term support following cariogenic shock

Answer 24

Beta-agonists

Question 25

Left vagus nerve terminates on which heart structure

Answer 25

AV node

Question 26

Right vagus nerve terminates on which heart structure

Answer 26

SAN

Question 27

How does acetylcholine reduce hr

Answer 27

Activates M2 receptors which increase k permeability

Question 28

How does atropine (vagolytic drug) increase heart rate in bradycardic patients

Answer 28

Inhibits muscaranic receptor

Question 29

Role of endothelial cells

Answer 29

Lines all vessels and inside heart chambers Controls local blood pressure Prevents platelet aggregation and blood clot formation Releases nitric oxide Angiogenesis and vessel remodelling Permeability barrier for nutrients/fluid between plasma and interstitial fluid

Question 30

Name of constrictor that endothelial cell can release

Answer 30

Thromboxane

Question 31

Name of dilator that endothelial cells can release

Answer 31

Nitric oxide

Question 32

How can endothelial cells affect LDL

Answer 32

Can release free radicals which oxidise LDL

Question 33

Which vessels have vessels have vascular smooth muscle

Answer 33

All vessels apart from small capillaries

Question 34

Why is compliance important in blood vessels

Answer 34

Prevents the pressure going to 0 as blood leaves the arteries

Question 35

What happens to arterial compliance as we age

Answer 35

Compliance decreases

Question 36

How does arterial calcification occur

Answer 36

Healing response to the presence of dead cells which reduces the elasticity of the vessels

Question 37

How do we calculate mean arterial pressure

Answer 37

Diastolic BP + 1/3 pulse pressure (PP) OR CO x TPR

Question 38

What is mean arterial pressure

Answer 38

The average pressuring pushing blood round the system

Question 39

What type of artery is the carotid artery

Answer 39

Elastic artery

Question 40

What structure dissipates the blood pressure from the arteries

Answer 40

The arterioles

Question 41

Which structure contains most of the blood at low pressure (70%)

Answer 41

The venules, veins and vena cavae

Question 42

What percentage of blood is help in the capillaries

Answer 42

5%

Question 43

What happens to the colloid (osmotic pressure exerted by larger molecules) pressure between the arterial and venous end of the capillary

Answer 43

It stays the same

Question 44

What happens to the hydrostatic pressure between the arterial and venous end of the capillary

Answer 44

It decreases as fluid is moves out

Question 45

What is exceptional about pulmonary hydrostatic pressuress

Answer 45

Pulmonary hydrostatic pressures are much lower than systemic pressure which prevents pulmonary oedema

Question 46

What can the result of capillary hydrostatic pressure increase be

Answer 46

Pitting oedema Pulmonary oedema Jugular vein distension

Question 47

TPR (total peripheral resistance)/SVR (systemic vascular resistance)

Answer 47

Force exerted onto blood by vasculature of the body

Question 48

Examples of alpha-1 selective adrenoceptor antagonists

Answer 48

prazosin doxazosin

Question 49

Examples of non-selective adrenoreceptor antagonists

Answer 49

Phentolamine

Question 50

How do nasal decongestants work

Answer 50

Vasoconstrict the mucosal blood vessels

Question 51

3 local controls of blood vessel tone

Answer 51

Active hyperaemia - changes in o2, co2, cellular metabolites can dilate arterioles causing this Reactive hyperaemia - blockage of blood flow induces this

Question 52

Factors which affect blood flow

Answer 52

Length of blood vessel Viscosity of liquid flowing in the tube Pressure gradient across the tube

Question 53

Problems with the 'French equation'

Answer 53

It assumes that: flow is laminar, non-pulsatile and flows through a uniform, straight pipe.

Question 54

Ways to reduce risk of viscous blood

Answer 54

Movement to encourage venous return Hydration and reduce alcohol Compression socks - create a pressure gradient which promotes flow

Question 55

What is resistance proportional to

Answer 55

Diameter

Question 56

What happens to resistance down the arterial tree

Answer 56

It increases and decreases flow

Question 57

What percentage of total blood volume is contained in the veins

Answer 57

70%

Question 58

What is the relative cross sectional area of veins

Answer 58

Large but pressure differential is small

Question 59

What is return to the right ventricle called

Answer 59

Preload

Question 60

What can increased preload cause

Answer 60

Heart failure Angina

Question 61

What drug can be used to decrease preload

Answer 61

Nitroglycerin causing venodilation

Question 62

Which structures detect blood pressure

Answer 62

Aortic arch baroreceptor Carotid sinus

Question 63

Which baroreceptor is more important

Answer 63

Carotid sinus since more sensitive

Question 64

Where does baroreceptor connect to

Answer 64

NTS (nucleus tractus solitarius) in brain

Question 65

What can the peripheral effect be of arterial baroreceptors firing in response to low arterial pressure

Answer 65

Increase in sympathetic outflow to heart/arterioles and veins and decrease in parasympathetic outflow to the heart

Question 66

Peripheral vs central control of BP

Answer 66

Peripheral - active/reactive/NO etc Central - in the brain

Question 67

Example of central control of high BP

Answer 67

NTS activates the parasympathetic nervous parasympathetic nervous system and inhibits the sympathetic nervous system AND VICE VERSA

Question 68

How does clonidine work

Answer 68

Alpha 2 agonist Activates presynaptic receptors in brain to lower sympathetic output.