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CARDIO > PHYSIOLOGY > Flashcards

PHYSIOLOGY Flashcards

1
Q

Define the function of the cardiovascular system

A

bulk flow system. transporting oxygen and CO2, nutrients, metabolites, hormones and heat to supply the organs of the body in order for them to do their jobs

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2
Q

significance of pressure in the cvs system

A

blood flows from high pressure to low pressure

in practice, this means blood flows from arterial end of vessel to venous end - pressure gradient created by pumping action of the heart

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3
Q

significance of resistance in cvs system

A

resistance is the force that opposed the flow of blood

different blood vessels throughout the body have varying levels of resistance to blood flow

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4
Q

what law determines resistance

A

Poiseuilles’ Law

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5
Q

what 3 factors is resistance dependant upon?

A

radius
viscosity
vessel length

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6
Q

expand on the 3 factors that resistance is dependant upon

A

radius : smaller radius, larger resistance
viscosity : relatively constant , not a significant impact on blood flow
vessel length : directly proportional to resistance, longer the vessel, the higher its resistance , greater resistance, higher BP, lower blood flow

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7
Q

how to calculate flow

A

flow (cm3/s) = CSA (cm2) x Velocity (cm/s)

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8
Q

define velocity

A

measures rate at which fluid particles move

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9
Q

define flow

A

measures volume of fluid moving

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10
Q

parallel arrangement of vascular beds

A

most vascular beds are in parallel
all tissues get oxygenated blood
allows regional direction of blood

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11
Q

serial vascular bed arrangement

A

two sides of the heart are plumbed in serial

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12
Q

elastic arteries function

A

arterial elasticity gives rise to Windkessel effect, which through passive contraction after expansion helps to maintain a relatively constant pressure in the arteries despite the pulsating nature of the blood flow from the heart

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13
Q

muscular arteries function

A

contain layers of smooth muscle allowing for involuntary control of vessel caliber and thus control of blood flow

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14
Q

capacitance vessels

A

low resistance conduit & reservoir
allows fractional distribution of blood between veins and rest of circulation

maintains venous pressure and venous return

veins

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15
Q

resistance vessels

A

small diameter blood vessel in microcirculation that contributes significantly to creation of resistance to flow and regulation of blood flow

small arteries, arterioles, and precapillary sphincters

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16
Q

explain the terminology of excitation-contraction coupling

A

excitation - activation of a nerve, specifically a motor nerve
contraction - interaction that takes place between the actin and myosin filaments of the sarcomere
coupling - lead to muscle action

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17
Q

excitation-contraction coupling process

A

at the beginning of this process, starts in a resting position - not much overlap of the filaments
neuromuscular junction has to occur

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18
Q

basis of action potential in non-pacemaker tissue

A

resting membrane potential - high resting PK+
initial depolarisation - increase in PNa+
plateau - increase in PCa2+ (L-type) and decrease in PK+
repolarisation - decrease in PCa2+ and increase in PK+

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19
Q

basis of action potential in pacemaker tissue

A 
action potential - increase in PCa2+ (l-type)
pacemaker potential (=pre-potential)
- gradual decrease in PK+
- early increase in PNa+ (=PF)
- late increase in PCa2+ (T-type)
explains autorhythmicity
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20
Q

what are the 5 components of the conduction system

A
  1. sinoatrial node (SA node)
  2. atrioventricular node (AV node)
  3. atrioventricular bundle (of His)
  4. right and left branches of bundle of His
  5. subendocardial Purkinje fibres
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21
Q

location of the SA and AV nodes

A

SA node = upper part of RA, below opening of SVC

AV node = lower part of RA, above attachment of septal cusps of tricuspid valve or opening of coronary sinus

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22
Q

bundle of His

A

begins at AV node, crosses the AV ring and runs along the inferior part of the membranous part of the interventricular septum where it divides into left and right branches

only means of conducting impulses from atria to ventricles

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23
Q

explain different parts of ECG

A

P wave - atrial depolarisation
QRS complex - ventricular depolarisation & atrial repolarisation
T wave - ventricular repolarisation

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24
Q

sequence of changes in pressure and volume in chambers of heart throughout cardiac cycle

A
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25
Q

explain generation of heart sounds

A

created from blood flowing through heart chambers as the cardiac valves open and close during cardiac cycle
vibrations of structures from blood flow create audible sounds - more turbulent blood flow, more vibrations created

S1 and S2 high-pitched
S3 and S4 low pitched

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26
Q

S1

A

closing of atrioventricular valves

start of systolic contraction of ventricles

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27
Q

S2

A

closing of semilunar valves , once systolic contraction is complete

28
Q

S1 and S2 sounds

A

lub dub

29
Q

S3

A

rapid ventricular filling
chordae tendinae to pull to full length and ping

normal in young patients

30
Q

S4

A

always abnormal
rare to hear
stiff/hypertrophic ventricle
atria tries to force blood in - turbulent flow

31
Q

explain effects of SNS and PSNS on HR

A

SNS - releases hormones (catecholamines - adrenaline and noradrenaline) to increase HR

PSNS - releases hormone acetylcholine to decrease HR

32
Q

explain effects of SNS and PSNS on SV

A

SNS - acts via beta-1 adrenoreceptors and increases contractility

PSNS - acts via muscarinic receptors and decreases contractility

33
Q

explain effects of preload and afterload on SV

A

increase in preload - increase in SV

increased afterload - decreased SV

34
Q

afterload

A

amount of pressure that heart needs to exert to eject blood during ventricular contraction

35
Q

preload

A

stretch of myocardium or end-diastolic volume of ventricles (EDV)
refers to volume in a ventricle just before start of systole

36
Q

total peripheral resistance

A

amount of force exerted on circulating blood by vasculature of body

37
Q

end diastolic volume

A

amount of blood in LV at end of ventricular filling

avg = 120/130mL

38
Q

end systolic volume

A

amount of blood remaining in ventricle at end of systole, after heart has contracted

39
Q

systolic pressure

A

measures force of blood against artery walls while ventricles push blood to rest of body

40
Q

diastolic pressure

A

pressure in arteries when heart rests between beats

41
Q

pulse pressure

A

difference between upper and lower numbers of your BP

42
Q

origin of Korotkoff sounds and use

A

turbulent blood flow through vessels can be heard as soft ticking while measuring BP

first sound = systolic pressure
last sound = diastolic pressure

43
Q

changes in aortic pressure wave as it passes through vascular tree

A
44
Q

changes in blood velocity and total cross-sectional area of vessels through vasculature

A
45
Q

indicate factors affecting pressure and flow in veins

A 
cardiac output
compliance
blood volume
blood viscosity
length and diameter of vessels
46
Q

describe mechanisms preventing blood clotting in vessels

A

hemostasis - leads to cessation of bleeding from a blood vessel

47
Q

normal BP

A

120/80mmHg

48
Q

normal pulse

A

60-100 beats per min

49
Q

identify process involved in transport between capillaries and tissues

A

DIFFUSION

glucose and oxygen from blood - tissues
carbon dioxide from tissues into blood

50
Q

significance of blood brain barrier (BBB)

A

specialised system of brain microvascular endothelial cells
shields brain from toxic substances in blood, supplies brain tissues with nutrients, and filters harmful compounds from brain back to bloodstream

oedema - associated with extravasation of water and blood-borne proteins, known to exacerbate ischemic oedema

51
Q

significance of starling forces

A

govern passive exchange of water between capillary microcirculation and ISF

oedema - increased flow of fluid from vascular system into interstitium

52
Q

significance of lymphatic system in relation to oedema

A

not able to adequately drain lymph fluid, usually from arm or leg

53
Q

justify importance of Poiseuille’s law in relation to control of resistance and blood flow

A
54
Q

Poiseuille’s Law

A
55
Q

define active hyperaemia

A

associated with increased metabolic activity of organ or tissue

56
Q

define pressure autoregulation

A

intrinsic capacity of resistance vessels in end organs , to dilate and constrict in response to dynamic perfusion pressure changes, maintaining blood flow relatively constant

57
Q

define reactive hyperaemia

A

occurs following a transient occlusion of vessel

58
Q

explain basis of injury response

A
59
Q

identify various neural, hormonal and local factors affecting arteriolar tone

A

noradrenaline

60
Q

describe dominant factors controlling blood flow in cardiac, cerebral, pulmonary and renal vascular beds

A

vessel diameter(or radius)
vessel length
viscosity of blood

61
Q

define hyperaemia

A

increase in organ blood flow

62
Q

elastic arteries structure

A

large number of collagen and elastic filaments in the tunica media - giving them the ability to stretch in response to each pulse

63
Q

examples of elastic arteries

A

includes the large arteries eg aorta and pulmonary arteries

64
Q

muscular arteries structure

A

identified by the elastic lamina that lies between the tunica intima and media

65
Q

examples of muscular arteries

A

distributing arteries are medium-sized that draw blood from an elastic artery and branch into resistance vessels

CARDIO (12 decks)

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