Definitions: Cardiovascular System

Question 1

Right heart

Answer 1

volume pump
delivers high volumes of blood at low pressures

Question 2

Pulmonary vessels

Answer 2

function in blood - gas exchange an serve as volume reservoirs

Question 3

left heart

Answer 3

pressure pump
the energy source for the circulatory system

Question 4

Elastic arteries

Answer 4

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)

Question 5

Muscular arteries

Answer 5

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

Question 6

Arterioles

Answer 6

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

Question 7

Capillaries

Answer 7

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

contain no connective tissue or smooth muscle

Question 8

Venous vessels

Answer 8

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

Question 9

Pulmonary circulation

Answer 9

blood flow through the lungs

Question 10

Systemic circulation

Answer 10

blood flow through all organs of the body except the lungs

Question 11

Cardiovascular circuit

Answer 11

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

Question 12

Phase 0

Answer 12

rapid upstroke, depolarization (QRS)

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

K+ conductance declines

Question 13

Phase 1

Answer 13

initial rapid repolarization (QRS)

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

Question 14

Phase 2

Answer 14

plateau (ST segment)

caused by slow Na+-Ca++ influx channel

K+ conductance continues to decrease

Question 15

Phase 3

Answer 15

repolarization (T wave)

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

Question 16

Phase 4

Answer 16

resting membrane potential (RMP) isoelectric
Na_O > Na_i

Ca_O > Ca_i

K_O > K_i

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

Question 17

refractory periods

Answer 17

periods of reduced excitability

Question 18

Absolute refractory period (ARP)

Answer 18

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

Question 19

Tetanus

Answer 19

repetitive stimuli at increasing frequency

Question 20

Relative Refractory Period (RRP)

Answer 20

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

Question 21

Supernormal Period (SNP)

Answer 21

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

APs generated during this time propagate slowly

Question 22

Sinoatrial (SA) node

Answer 22

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

Question 23

unstable resting membrane potential in SA nodal cells

Answer 23

prepotential

pacemaker potential

diastolic depolarization

Question 24

Sympathetic

Answer 24

increases conduction velocity

Question 25

Parasympathetic

Answer 25

decreases conduction velocity in AV node

Question 26

Reentry

Answer 26

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

Question 27

Ca++ induced Ca++ release

Answer 27

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

Question 28

Charge movement coupled Ca++ release

Answer 28

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)

Question 29

Inositol triphosphate (IP₃) induced Ca++ release

Answer 29

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

Question 30

Preload

Answer 30

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

Question 31

Afterload

Answer 31

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

Question 32

Frank-Starling Relationship

Answer 32

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

Question 33

Contractility

Answer 33

the performance of the heart at a given preload and afterload a length independent change in cardiac performance

Question 34

Atrial Systole

Answer 34

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

Question 35

Isovolumic contraction

Answer 35

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

Question 36

Rapid ejection

Answer 36

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

Question 37

Reduced ejection

Answer 37

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

Question 38

Isovolumic relaxation

Answer 38

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

Question 39

Rapid Ventricular Filling

Answer 39

Aortic presure decreases LA and LV pressure begin to plateau Aortic blood flow plateaus ventricular volume increases third heart sound heard

Question 40

Reduced ventricular filling - diastasis

Answer 40

Ventricular volume peaks Aortic, LV, and LA pressure bottom out aortic blood flow is 0 P wave starts at end

Question 41

Cardiac Cycle Loop

Answer 41

start at lower left hand corner read to the right and around

Question 42

Cardiac Cycle: Mitral valve opens

Answer 42

dot at lower left hand corner occurs when LV pressure drops below that of the left atrium

Question 43

Cardiac Cycle: rapid filling

Answer 43

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

Question 44

Cardiac Cycle:third heart sound

Answer 44

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

Question 45

Cardiac Cycle: slow (reduced) filling phase

Answer 45

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

Question 46

Cardiac Cycle: atrial contraction

Answer 46

final contribution of blood to LVEDV prior to isovolumic contraction

Question 47

Cardiac Cycle: mitral valve closes

Answer 47

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

Question 48

Cardiac Cycle: isovolumic contraction

Answer 48

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

Question 49

Cardiac Cycle: systolic ejection (rapid and reduced ejection)

Answer 49

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

Question 50

Cardiac Cycle: aortic valve closes

Answer 50

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)

Question 51

Cardiac Cycle: isovolumic relaxation

Answer 51

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

Question 52

Pressure

Answer 52

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

Question 53

Hydrostatic pressure

Answer 53

the pressure produced by the height of a column of a liquid important when considering the effect of postural changes on the cardiovascular system

Question 54

Transmural pressure

Answer 54

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

Question 55

Compliance

Answer 55

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

Question 56

Poiseuille's Law

Answer 56

Flow is non-pulsatile Flow is laminar Fluid is a Newtonian Fluid

Question 57

Length

Answer 57

flow is inversely proportional to the length of the tube

Question 58

Radius

Answer 58

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)

Question 59

Viscosity

Answer 59

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)

Question 60

Laminar flow

Answer 60

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

Question 61

Total peripheral resistance (TPR)

Answer 61

the resistance of the entire systemic circulatory circuit

Question 62

Autoregulation

Answer 62

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

Question 63

Active hyperemia

Answer 63

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

Question 64

Reactive Hyperemia

Answer 64

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

Question 65

Endothelium Relaxing Factor (EDRF)

Answer 65

NO produced in endothelial cells relaxes muscle cells

Question 66

Endothelial Sheer Stress (ESS)

Answer 66

flow induced modulation of blood vessel diameter vessel diameter increases as flow is progressively increased in a vascular segment with intact endothelium

Question 67

Vasodilators

Answer 67

dilate vessels arachidonic acid metabolites → PGI₂, PGE₂, PGD₂ Atrial Natriuretic Factor (ANF) Adenosine Nitric Oxide (NO) → EDHF Histamine

Question 68

Vasoconstrictors

Answer 68

constrict vessels arachidonic acid metabolites → TxA₂, PGF_2a, LTC₄, LTD₄, LTE₄ angiotensin II arginine vasopressin endothelin adrenomedullary hormones (epinephrine, norepinephrine)

Question 69

Arachidonic acid (eicosanoids)

Answer 69

released from membrane phospholipids → metabolized by cyclooxygenase or lipoxygenase → form prostaglandins or leukotrienes → produces vasoconstrictors (TXA₂, PGF_2ac) and dilators (PGD₂, PGE₂, PGI₂)

Question 70

Angiotensin II

Answer 70

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)

Question 71

Bradykinin

Answer 71

vasodilation and increased capillary permeability involved in vascular responses to tissue injury and immune reactions produced near sweat glands

Question 72

Atrial Natriuretic Factor (ANF)

Answer 72

aka atrial natriuretic peptide (ANP) released when atria or ventricles are significantly stressed promotes sodium excretion vasodilator

Question 73

Adensosine

Answer 73

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

Question 74

Vasopressin

Answer 74

released from posterior pituitary in responce to increased plasma osmolarity or decreasing blood volume/pressure promotes water reabsorption vasoconstrictor infusions increas TPR

Question 75

Histamine

Answer 75

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

Question 76

Baroreceptor Reflex

Answer 76

keeps BP at a constant level regulates pressure from a certain set point only good at preventing abrupt changes in BP

Question 77

Metarterioles

Answer 77

branch from arterioles and give rise to capillaries can serve as bypass channels to the venules

Question 78

Nutrient Flow

Answer 78

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

Question 79

Non-nutrient flow (shunt)

Answer 79

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

Question 80

Precapillary sphincters

Answer 80

regulate blood flow through the capillary smooth muscle that constricts and dilates based on metabolic activity

Question 81

Flow limited diffusion

Answer 81

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

Question 82

Diffusion limited diffusion (transport)

Answer 82

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

Question 83

Ultrafiltration

Answer 83

fluid movement

Question 84

Hydrostatic Pressure

Answer 84

arteriolar blood pressure principle force favoring filtering across the capillary wall

Question 85

Filtration

Answer 85

occurs wen the algebraic sum is positive from capillary to interstitial space

Question 86

Reabsorption

Answer 86

occurs when the value is negative movement of fluid from interstitial space to capillary

Question 87

Edema

Answer 87

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