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Systems Phys 2022 > Definitions: Cardiovascular System > Flashcards

Definitions: Cardiovascular System Flashcards

1
Q

Right heart

A

volume pump
delivers high volumes of blood at low pressures

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2
Q

Pulmonary vessels

A

function in blood - gas exchange an serve as volume reservoirs

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3
Q

left heart

A

pressure pump
the energy source for the circulatory system

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4
Q

Elastic arteries

A

their elastic behavior allows them to serve as a “surge pump”.
energy is stored in the elastic fibers during the contraction phase (systole) and is released during the relaxation phase (diastole)

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5
Q

Muscular arteries

A

function as low resistance conduits that rapidly deliver blood to the tissues

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6
Q

Arterioles

A

collectively termed “resistance vessels”
serve as variable resistors that regulate the flow of blood into capillary beds

range in diameter from 5-100um

give rise to capillaries directly or metarterioles

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7
Q

Capillaries

A

one cell layer separates blood from tissue space
site of nutrient and waste exchange

contain no connective tissue or smooth muscle

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8
Q

Venous vessels

A

serve as a volume reservoir
these vessels function in both the storage and mobilization of blood

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9
Q

Pulmonary circulation

A

blood flow through the lungs

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10
Q

Systemic circulation

A

blood flow through all organs of the body except the lungs

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11
Q

Cardiovascular circuit

A

pumps in series, resistance circuits in parallel
the CO of the right heart must equal the CO of the left heart

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12
Q

Phase 0

A

rapid upstroke, depolarization (QRS)

rapid depolarization due to increased gNa (fast Na channels open)

K+ conductance declines

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13
Q

Phase 1

A

initial rapid repolarization (QRS)

repolarization due to the “h” gates closing the fast Na channels

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14
Q

Phase 2

A

plateau (ST segment)

caused by slow Na+-Ca++ influx channel

K+ conductance continues to decrease

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15
Q

Phase 3

A

repolarization (T wave)

decline ini Na+-Ca++ slow channel and a restoration of the normal K+ efflux

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16
Q

Phase 4

A

resting membrane potential (RMP) isoelectric
NaO > Nai

CaO > Cai

KO > Ki

gNa+ and gCa++ are low - gK+ is high

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17
Q

refractory periods

A

periods of reduced excitability

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18
Q

Absolute refractory period (ARP)

A

interval from beginning of the AP to a point in phase 3 when the membrane potential reaches approximately -50 mV

no stimulus can elicit an AP

extends through the maximum tension development of the muscle

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19
Q

Tetanus

A

repetitive stimuli at increasing frequency

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20
Q

Relative Refractory Period (RRP)

A

AP can be elicited but would require a greater than normal stimulus

resultant AP would have lower than normal amplitude and a reduced rate of ride due to the fast Na+ channels not having been completely reset

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21
Q

Supernormal Period (SNP)

A

a stimulus of less than normal magnitude can bring the membrane to threshold and initiate AP

APs generated during this time propagate slowly

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22
Q

Sinoatrial (SA) node

A

ordinarily displays the highest order of rhythmicity

consists of a bundle of specialized neuromuscular tissue

cells here have unstable RMP (responsible for Pacemaker activity)

region with the most rapid rate of decay of K+ conductance

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23
Q

unstable resting membrane potential in SA nodal cells

A

prepotential

pacemaker potential

diastolic depolarization

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24
Q

Sympathetic

A

increases conduction velocity

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25
Q

Parasympathetic

A

decreases conduction velocity in AV node

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26
Q

Reentry

A

occurs when an excitation wave reexcites some region through which it has recently passed

reentry circuits can be either random or ordered

Must have: unidirectional block and the effective refractory period of the reentered region must be shorter than the propagation time around the loop

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27
Q

Ca++ induced Ca++ release

A

depolarization of the sarcolemma (SL) causes influx of Ca++ through voltage sensitive Ca++ channels → Ca++ entering the cell binds to the Ca++ release channel located in the membrane of the SR, thereby activating channel opening

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28
Q

Charge movement coupled Ca++ release

A

activation of the Ca++ channel by membrane depolarization is associated with concomitant activation of charge movement → this activation is transmitted via a spanning protein to the Ca++ release channel, thereby, initiating Ca++ release (the spanning protein could be a subunit of the Ca++ channel or an extrinsic protein)

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29
Q

Inositol triphosphate (IP3) induced Ca++ release

A

depolarization activates voltage sensitive phospholipase C (PLC) resulting in the conversion of PIP2 to IP3 → IP3 binds to the Ca++ release channel and activates channel opening

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30
Q

Preload

A

tension or stretch in the wall of the LV just before the onset of contraction

determined by EDV

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31
Q

Afterload

A

tension nor stretch in the wall of the LV just before the aortic valve opens

related to aortic pressure

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32
Q

Frank-Starling Relationship

A

relates changes in initial myocardial fiber length (i.e. preload) to force or pressure development by the ventricle

describes length dependent changes (i.e. preload) in cardiac performance

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33
Q

Contractility

A

the performance of the heart at a given preload and afterload

a length independent change in cardiac performance

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34
Q

Atrial Systole

A

first phase of the cardiac cycle

LV pressure begins to increase

Mitral valve closes at the end of phase

4th heart sound would be heard

P-Q

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35
Q

Isovolumic contraction

A

phase 2 of the cardiac cycle

Aortic valve opens at the end of phase

Aortic pressure begins to rise

1st heart sound is heard here

R-S

36
Q

Rapid ejection

A

3rd phase of cardiac cycle

Aortic pressure and LV pressure begin to peak

LA pressure starts to rise gradually
Aortic blood flow rises and peaks

Ventricular volume decreases

37
Q

Reduced ejection

A

4th phase of the cardiac cycle

Aortic valve closes at end

LV pressure and Aortic pressure decrease

LA pressure is increasing

aortic blood flow decreasing

T wave

38
Q

Isovolumic relaxation

A

5th phase of the cardiac cycle

Aortic valve closes at beginning

Aortic pressure somewhat plateaus

LV pressure significantly decreases

Mitral valve opens at end

LA pressure peaks

heart sound 2 is heard

39
Q

Rapid Ventricular Filling

A

Aortic presure decreases

LA and LV pressure begin to plateau

Aortic blood flow plateaus

ventricular volume increases

third heart sound heard

40
Q

Reduced ventricular filling - diastasis

A

Ventricular volume peaks

Aortic, LV, and LA pressure bottom out

aortic blood flow is 0

P wave starts at end

41
Q

Cardiac Cycle Loop

A

start at lower left hand corner

read to the right and around

42
Q

Cardiac Cycle: Mitral valve opens

A

dot at lower left hand corner

occurs when LV pressure drops below that of the left atrium

43
Q

Cardiac Cycle: rapid filling

A

dip between first and second point

blood rushes into the LV as it continues to relax → volume increases, however, the pressure decreases during this phase since the ventricle is actively relaxing

44
Q

Cardiac Cycle:third heart sound

A

recorded near the end of the rapid filling phase when the ventricle reaches its elastic limit

45
Q

Cardiac Cycle: slow (reduced) filling phase

A

ventricle continues to fill due to continuous venous return - the slow filling phase contributes ¼ to ⅓ of LVEDV → ventricular pressure rises slightly during this phase

46
Q

Cardiac Cycle: atrial contraction

A

final contribution of blood to LVEDV prior to isovolumic contraction

47
Q

Cardiac Cycle: mitral valve closes

A

as ventricular pressure begins to increase the mitral valve snaps closes, recording the first heart sound

lower right hand point

48
Q

Cardiac Cycle: isovolumic contraction

A

right vertical bar

steep rise in ventricular pressure → ventricular volume remains constant until ventricular pressure exceeds aortic pressure, forcing the aortic valve open → the opening of the aortic valve ends isovolumic contraction

49
Q

Cardiac Cycle: systolic ejection (rapid and reduced ejection)

A

top curve

during this phase ventricular and aortic pressures rise and fall together because the aortic valve provides an open communication between the two chambers

50
Q

Cardiac Cycle: aortic valve closes

A

near the end of systolic ejection both ventricular volume and pressure are decreasing → when ventricular pressure drops below aortic pressure the aortic valve closes creating the 2nd heart sound →The closure of the aortic valve marks the end of systole (end systolic pressure point)

51
Q

Cardiac Cycle: isovolumic relaxation

A

left vertical line

during this phase there is a steep drop in ventricular pressure with no change in ventricular volume

52
Q

Pressure

A

force in a fluid system

expressed as force/unit are → dynes/cm2 → mmHg in US

one of the principle determinants of the rate of flow

53
Q

Hydrostatic pressure

A

the pressure produced by the height of a column of a liquid

important when considering the effect of postural changes on the cardiovascular system

54
Q

Transmural pressure

A

pressure across the wall of a blood vessel

essentially equal in head, heart, and foot when lying down

when standing: decreases above heart, increases below heart

55
Q

Compliance

A

The pressure change which occurs in the organ with a given volume change is indicative of organ compliance

compliance of an organ or vessel can be altered by changing the mechanical properties of the walls (ΔV/ΔP)

reduced by aging and atherosclerosis

56
Q

Poiseuille’s Law

A

Flow is non-pulsatile

Flow is laminar

Fluid is a Newtonian Fluid

57
Q

Length

A

flow is inversely proportional to the length of the tube

58
Q

Radius

A

flow varies directly proportional to the fourth power of the radius

doubling the radius of a tube results in a 16-fold increases in flow (24)

59
Q

Viscosity

A

the ratio of sheer stress to shear rate of the fluid

the internal friction of a fluid which opposes the separation of its laminae → a force must be applied to overcome viscosity in order to move one layer of fluid past another (laminar flow)

60
Q

Laminar flow

A

as blood flows through the vasculature the fluid appears to flow in discrete cylindrical lamina

61
Q

Total peripheral resistance (TPR)

A

the resistance of the entire systemic circulatory circuit

62
Q

Autoregulation

A

intrinsic tendency of an organ to maintain a constant blood flow despite changes in arterial perfusion pressure

exists over limited range of pressures beyond which flow changes with perfusion pressure

63
Q

Active hyperemia

A

blood flow increases within seconds of the beginning of muscular exercise and returns to control values following completion of exercise

64
Q

Reactive Hyperemia

A

increased blood flow which occurs following the interruption of blood flow to a tissue

65
Q

Endothelium Relaxing Factor (EDRF)

A

NO

produced in endothelial cells

relaxes muscle cells

66
Q

Endothelial Sheer Stress (ESS)

A

flow induced modulation of blood vessel diameter

vessel diameter increases as flow is progressively increased in a vascular segment with intact endothelium

67
Q

Vasodilators

A

dilate vessels

arachidonic acid metabolites → PGI2, PGE2, PGD2

Atrial Natriuretic Factor (ANF)

Adenosine

Nitric Oxide (NO) → EDHF

Histamine

68
Q

Vasoconstrictors

A

constrict vessels

arachidonic acid metabolites → TxA2, PGF2a, LTC4, LTD4, LTE4

angiotensin II

arginine vasopressin

endothelin

adrenomedullary hormones (epinephrine, norepinephrine)

69
Q

Arachidonic acid (eicosanoids)

A

released from membrane phospholipids → metabolized by cyclooxygenase or lipoxygenase → form prostaglandins or leukotrienes → produces vasoconstrictors (TXA2, PGF2ac) and dilators (PGD2, PGE2, PGI2)

70
Q

Angiotensin II

A

Renin cleaves angiotensinogen → forms angiotensin I → Kininase II converts angiotensin I to angiotensin II (vasoconstrictor)→ binds cells in adrenal cortex and regulates release of aldosterone (promotes sodium reabsorption)

71
Q

Bradykinin

A

vasodilation and increased capillary permeability

involved in vascular responses to tissue injury and immune reactions

produced near sweat glands

72
Q

Atrial Natriuretic Factor (ANF)

A

aka atrial natriuretic peptide (ANP)

released when atria or ventricles are significantly stressed

promotes sodium excretion

vasodilator

73
Q

Adensosine

A

reduced oxygen tension causes hydrolysis of ATP to ADP and AMP → enzyme 5’- nucleotidase (is phosphorylated) catalyzes hydrolysis of AMP to adenosine → adenosine diffuses into the interstitial space → dilates arterioles → increases blood flow and oxygen delivery → adenosine reenters cell → rephosphorylated to AMP by adenosine kinase

74
Q

Vasopressin

A

released from posterior pituitary in responce to increased plasma osmolarity or decreasing blood volume/pressure

promotes water reabsorption

vasoconstrictor

infusions increas TPR

75
Q

Histamine

A

release is associated with antigen-antibody reaction in allergic and immune response

activated mast cells and circulating basophils release histamine → causes local vasodilation and increased vascular permeability

76
Q

Baroreceptor Reflex

A

keeps BP at a constant level

regulates pressure from a certain set point

only good at preventing abrupt changes in BP

77
Q

Metarterioles

A

branch from arterioles and give rise to capillaries

can serve as bypass channels to the venules

78
Q

Nutrient Flow

A

blood flows through the capillaries which provides for exchange of nutrients and metabolites

79
Q

Non-nutrient flow (shunt)

A

the blood flow bypasses the capillaries and passes directly from arterioles to venules

80
Q

Precapillary sphincters

A

regulate blood flow through the capillary

smooth muscle that constricts and dilates based on metabolic activity

81
Q

Flow limited diffusion

A

some substances aren’t allowed to leave the capillary, others are

concentration gradient in capillary limits how much of a certain substance can get to a cell

82
Q

Diffusion limited diffusion (transport)

A

diffusion is limited by the size of a molecule or the diffusion distance between the capillary and the parenchymal cell

83
Q

Ultrafiltration

A

fluid movement

84
Q

Hydrostatic Pressure

A

arteriolar blood pressure

principle force favoring filtering across the capillary wall

85
Q

Filtration

A

occurs wen the algebraic sum is positive

from capillary to interstitial space

86
Q

Reabsorption

A

occurs when the value is negative

movement of fluid from interstitial space to capillary

87
Q

Edema

A

abnormal increase in the volume of interstitial fluid in a tissue or organ

swelling

Systems Phys 2022 (25 decks)

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