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CARDIO > PHYSIOLOGY > Flashcards

PHYSIOLOGY Flashcards

(65 cards)

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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
explain generation of heart sounds
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
26
S1
closing of atrioventricular valves | start of systolic contraction of ventricles
27
S2
closing of semilunar valves , once systolic contraction is complete
28
S1 and S2 sounds
lub dub
29
S3
rapid ventricular filling chordae tendinae to pull to full length and ping normal in young patients
30
S4
always abnormal rare to hear stiff/hypertrophic ventricle atria tries to force blood in - turbulent flow
31
explain effects of SNS and PSNS on HR
SNS - releases hormones (catecholamines - adrenaline and noradrenaline) to increase HR PSNS - releases hormone acetylcholine to decrease HR
32
explain effects of SNS and PSNS on SV
SNS - acts via beta-1 adrenoreceptors and increases contractility PSNS - acts via muscarinic receptors and decreases contractility
33
explain effects of preload and afterload on SV
increase in preload - increase in SV | increased afterload - decreased SV
34
afterload
amount of pressure that heart needs to exert to eject blood during ventricular contraction
35
preload
stretch of myocardium or end-diastolic volume of ventricles (EDV) refers to volume in a ventricle just before start of systole
36
total peripheral resistance
amount of force exerted on circulating blood by vasculature of body
37
end diastolic volume
amount of blood in LV at end of ventricular filling | avg = 120/130mL
38
end systolic volume
amount of blood remaining in ventricle at end of systole, after heart has contracted
39
systolic pressure
measures force of blood against artery walls while ventricles push blood to rest of body
40
diastolic pressure
pressure in arteries when heart rests between beats
41
pulse pressure
difference between upper and lower numbers of your BP
42
origin of Korotkoff sounds and use
turbulent blood flow through vessels can be heard as soft ticking while measuring BP first sound = systolic pressure last sound = diastolic pressure
43
changes in aortic pressure wave as it passes through vascular tree
44
changes in blood velocity and total cross-sectional area of vessels through vasculature
45
indicate factors affecting pressure and flow in veins
``` cardiac output compliance blood volume blood viscosity length and diameter of vessels ```
46
describe mechanisms preventing blood clotting in vessels
hemostasis - leads to cessation of bleeding from a blood vessel
47
normal BP
120/80mmHg
48
normal pulse
60-100 beats per min
49
identify process involved in transport between capillaries and tissues
DIFFUSION glucose and oxygen from blood - tissues carbon dioxide from tissues into blood
50
significance of blood brain barrier (BBB)
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
significance of starling forces
govern passive exchange of water between capillary microcirculation and ISF oedema - increased flow of fluid from vascular system into interstitium
52
significance of lymphatic system in relation to oedema
not able to adequately drain lymph fluid, usually from arm or leg
53
justify importance of Poiseuille's law in relation to control of resistance and blood flow
54
Poiseuille's Law
55
define active hyperaemia
associated with increased metabolic activity of organ or tissue
56
define pressure autoregulation
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
define reactive hyperaemia
occurs following a transient occlusion of vessel
58
explain basis of injury response
59
identify various neural, hormonal and local factors affecting arteriolar tone
noradrenaline
60
describe dominant factors controlling blood flow in cardiac, cerebral, pulmonary and renal vascular beds
vessel diameter(or radius) vessel length viscosity of blood
61
define hyperaemia
increase in organ blood flow
62
elastic arteries structure
large number of collagen and elastic filaments in the tunica media - giving them the ability to stretch in response to each pulse
63
examples of elastic arteries
includes the large arteries eg aorta and pulmonary arteries
64
muscular arteries structure
identified by the elastic lamina that lies between the tunica intima and media
65
examples of muscular arteries
distributing arteries are medium-sized that draw blood from an elastic artery and branch into resistance vessels

CARDIO (12 decks)

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