Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

1st Year Med > Heart Physiology > Flashcards

Heart Physiology Flashcards

1
Q

what is the definition of the circulatory system?

A

oxygen system transporting O2, CO2, nutrients etc.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what are the characteristics of pulmonary circulation?

A

O2 depleted blood, passes from heart to lungs, returns oxygenated blood to heart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what are the characteristics of systemic circulation?

A

O2 rich blood, passes from heart to rest of body, returns deoxygenated blood to heart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what blood does the superior vena cava carry?

A

deoxygenated blood from head, neck and upper limbs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what blood does the inferior vena cava carry?

A

deoxygenated blood from below level of heart (abdomen, pelvis, lower limbs)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what blood does the coronary sinus contain?

A

venous blood from the heart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what septal defects can occur in the heart?

A

atrial, ventricular or atrioventricular (hole in the heart)
interventricular or interatrial

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what conditions/diseases can result in end arterial coronary arteries?

A

coronary artery disease
ischaemia
angina pectoris
infarction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is a coronary artery bypass graft?

A

redirecting blood supply if coronary arteries are blocked

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what vessels can be used in a coronary artery bypass graft (CABG)?

A

saphenous vein
internal mammary artery
internal thoracic artery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what are the main functions of the cardiovascular system?

A

transport - nutrients, O2, waste, heat, hormones
buffers body pH
assists in infection response and urine filtration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is each heart sound caused by?

A

first - AV valves closing
second - pulmonary/aortic valves closing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is the formula for cardiac output?

A

stroke volume x heart rate
(per min)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what makes the heart contract?

A

SA node impulses spread across atria then ventricles
L/R sides contract at same time, resulting in a rise and fall of blood pressure in atria then ventricles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

how does each node influence HR?

A

SA - determines HR (pacemaker)
AV - slows HR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

how does K+ permeability affect HR?

A

increased permeability - longer time to threshold, fewer BPM, lower HR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

how does Ca+ permeability affect HR?

A

increased permeability - shorter threshold time, more BPM, higher HR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what does Ca entry do to the cardiac muscle?

A

depolarisation then contraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

where is the vagal nerve and how does it influence HR?

A

terminates on nodal tissue (L = AV node, R = SA node)

releases ACl activating M2 receptors reducing HR and increasing K+ permeability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what is the cause of the atria-ventricular delay?

A

the annulus fibrosis acting as electrical insulator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what can carotid sinus syndrome be caused by?

A

vagus nerve overactivity
causes syncope/fainting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

briefly explain the mechanisms of the cardiac cycle

A

a systole contraction then a diastole relaxation of the atria then the ventricles

blood flow controlled by valves and the diastole-systole sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what are the stages of the cardiac cycle?

A

atrial systole
atrial diastole
ventricular systole (1st phase)
ventricular systole (2nd phase)
ventricular diastole (early)
ventricular diastole (late)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what occurs during atrial systole?

A

atrial contraction forces blood into relaxed ventricles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

what is the name of the contraction occuring during atrial diastole?

A

isovolumetric contractions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

what occurs during ventricular systole? (1st phase)

A

ventricular contraction pushes AV valves closed
not enough pressure to open semilunar valves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what occurs during ventricular systole? (2nd phase)

A

ventricular pressure rises and exceeds arterial pressure, opening semilunar valves and ejecting blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

what occurs during ventricular diastole? (early)

A

ventricles relax
ventricular pressure drops
blood flows against cusps of semilunar valves forcing them closed
blood flows into relaxed atria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

what type of relaxation occurs in ventricular diastole?

A

isovolumetric relaxation

30
Q

what occurs during ventricular diastole? (late)

A

all chambers are relaxed
ventricles fill passively

31
Q

what changes in the cases of a positive or negative inotropy?

A

preload of the heart

32
Q

what is the hearts membrane potential determined by?

A

ion concentration outside vs inside the cell

33
Q

explain the changes to the membrane potential when Na, K and Ca currents affect the heart cells

A

Na and Ca: positive inwards (depolarising)
K: positive outwards (repolarising)

34
Q

what occurs at phase 0 of the action potential?

A

upstroke: voltage gated Na channels open allowing Na in and depolarisation

35
Q

what occurs at phase 1 of the action potential?

A

notch: voltage dependant inactivation of Na
activation of outwards K causing repolarisation

36
Q

what occurs at phase 2 of the action potential?

A

plateau: balance of inwards Ca and outwards K

37
Q

what occurs at phase 3 of the action potential?

A

repolarisation: inwards currents are inactivated and outwards K channels repolarise cell

38
Q

explain the process of an excitation-contraction coupling

A

after excitation, the increase in Ca due to AP causes myofilaments to contract
(Ca channels in high concentration in t-tubules)

39
Q

what is the sarcoplasmic reticulum and what is its release mediated by?

A

an intracellular Ca store

mediated by ryanodine receptor

40
Q

explain the process of ventricular filling in diastole

A

driven by venous pressure
walls expand as they fill
atria contract adding 10-20% extra
end diastolic volume is ~120ml
once ventricular pressure exceeds atrial, AV valves shut

41
Q

name the brain and spinal nerves associated with CVS regulation and whether they are sympathetic or parasympathetic

A

glossopharyngeal (P)
vagus (P)
vasomotor (S)
cardiac accelerator (S)

42
Q

what structure does the sympathetic and parasympathetic nervous activity impact in the heart?

A

SA node

43
Q

explain the sympathetic response to HR regulation

A

nerve terminals release noradrenaline as response to stimulation
downstream effects mediated by messenger system involving cAMP production

44
Q

explain the parasympathetic response to HR regulation

A

nerve terminals release ACl in response to stimulation
downstream effects mediated by ACl-regulated K channels coupled to muscarinic receptors (ACl binds to these)

45
Q

why is ACl rapidly decayed in the parasympathetic HR response?

A

SA and AV nodes contain cholinesterase (hydrolyses ACl)

46
Q

what is resting HR regulated by?

A

parasympathetic response (stronger than sympathetic)

47
Q

what is stroke volume determined by?

A

contractility

48
Q

in what ways is stroke volume regulated?

A

sympathetic - increases stroke volume, magnitude and force rate generated

parasympathetic - decreases stroke volume and weakens contractions

49
Q

where are baroreceptors found and what do they detect?

A

found in carotid sinus and aortic arch

detect stretch and pressure changes

50
Q

what does stretch in arterial baroreceptors do?

A

increases receptor firing
inhibits sympathetic outflow from pressure origin

51
Q

explain the result of excitatory and inhibitory post-synaptic potentials

A

excitatory (EPSP) - depolarises target neuron
inhibitory (IPSP) - hyperpolarises target neuron

52
Q

what is a convergence neuron?

A

a neuron influenced by many other neurons

53
Q

what is a divergence neuron?

A

many neurons influenced by 1 neuron

54
Q

what nerves affect HR?

A

vagus (P) - decreases HR
cardiac accelerator (S) - increases HR and contractility

55
Q

which parts of the brain control CVS input?

A

higher brain centres
proprioreceptors
baroreceptors
chemoreceptors

56
Q

explain the input function of each relevant part of the brain

A

higher brain centre - cerebral cortex, limbic system and hypothalamus

proprioreceptors - joint movements

baroreceptors - BP

chemoreceptors - blood acidity

57
Q

what changes are seen in the heart during exercise?

A

increase:
cardiac output (25l/min)
HR (140bpm)
stroke volume (180ml)

decrease:
filling time (33%)

58
Q

compare the ECG times of a resting HR and an exercised HR

A

resting:
AV systole - 0.48s
diastole - 0.32s

exercised:
AV systole - 0.3s
diastole - 0.1s

59
Q

how is BP controlled during exercise?

A

when CO increases, skeletal muscle vascular beds dilate reducing PR

60
Q

what does TPR depend on and what is it controlled by?

A

depends on arteriole diameter

controlled by local metabolic factors
low O2 and high CO2 levels act on smooth muscle to relax/dilate

61
Q

why does BP increase during static exercise?

A

increase in SV with no change in TPR

62
Q

where do the parasympathetic nerves regulating HR originate from and where do they act?

A

vagal motor nuclei in brainstem (medulla)
left side acts on AV node
right side acts on SA node

63
Q

describe the course of the sympathetic nerves affecting HR and where they supply

A

cardiac sympathetic fibres exit spinal cord at T1-5
long nerve fibres run along great vessels
left side supplies ventricles
right side supplies atria

64
Q

what is the sympathetic neurotransmitter increasing HR and what does it do?

A

noradrenaline - binds to a1 adrenoreceptors

increases AV conduction, decreases myocyte AP length, increases SV and increases relaxation rate

65
Q

what is the parasympathetic neurotransmitter decreasing HR?

A

ACl - activates M2 muscarinic receptor hyperpolarising SA node and reducing AP’s generated

66
Q

what is the SA node firing rate affected by?

A

changes in autonomic nerve activity
circulating hormones (hyper/hypothyroidism)
serum ion concentration (hyper/hypokalaemia)
cellular hypoxia
drugs

67
Q

explain the bruce protocol

A

fitness test involving different stages of exercise in 3 minute intervals
speed/gradient are gradually increased to measure cardiac work and identify areas of poorly perfused myocardium

68
Q

explain how hypoxia from exercise can appear on an ECG

A

O2 consumption increases with exercise, O2 delivery cant keep up
ST segment on ECG shows electrophysiological changes in O2 delivery

69
Q

how do nitrates work in reducing cardiac work?

A

venodilation
reduces venous pressure and preload

70
Q

what can be the problem of an increased preload? (venous return to RV)

A

heart has to work harder to pump blood out
can result in heart failure, coronary artery disease and angina

1st Year Med (52 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions