Physiology Exam 1

Front 1

As heart rate increases, what happens to contractilty and why

Back 1

contractility increases, b/c inc HR means more AP's, which means more Ca influx, and more contractions.

Front 2

Why must total systemic blood flow = cardiac output

Back 2

b/c once blood leaves ventricle (CO), the organ systems are in paralell

Front 3

Which blood vessels are under the highest pressure

Back 3

arteries (b/c they receive blood directly from the heart)

Front 4

Volume of Blood which moves through a vessel per unit of time

Back 4

Blood flow V/time

Front 5

Force per unit area of blood

Back 5

Blood pressure

Front 6

continuity equation

Back 6

Flow = velocity * area

Front 7

As you move distally away from the heart, what happens to cross sectional area of vessels and blodd velocity

Back 7

Since CA increases, velocity decreases (V=F/A)

Front 8

Why is blood flow in vessels the same

Back 8

because they are in series

Front 9

Where does Vmax occur

Back 9

at the center of the blood vessel

Front 10

Where is velocity O

Back 10

near the wall of the blood vessel

Front 11

What predicts whether flow will be laminar or turbulant

Back 11

Reynolds Number

Front 12

Laminar flow

Back 12

<2000

Front 13

Turbulant flow

Back 13

NR> 3000

Front 14

Reynolds Number

Back 14

R = ρ * v * D/η
n = viscosity
D = diameter
v = velocity of blood

Front 15

what does Pouseuille's eqn describe? what is it?

Back 15

Blood Flow
F = ∏ *r^4*∆P/8Lη
(pies r 4 p's)

Front 16

what is the pressure difference in the poseuille eqn attributed to

Back 16

pressure diff produced by the contraction of the heart

Front 17

According to Poseuille eqn, if delta P is zero, what is flow

Back 17

zero

Front 18

simplified Poseuille eqn

Back 18

F = delta P/R

Front 19

Mean Blood Pressure

Back 19

Right atrial pressure is close to 0, so we can use pressure in the proximal aorta. MBP = CO * TPR

Front 20

Organs are in paralell to each other...

Back 20

Pressure is the same
Flow & Resistance are not =

Front 21

Distensibility of a vessel, formula

Back 21

Compliance = Vol/P
Higher the compliance, the more volume it can hold

Front 22

If compliance decreases (stiffer), what happens if volume increases

Back 22

an increase in volume will produce a larger increase in pressure than it did before

Front 23

How much higher is outside [Ca] than inside

Back 23

10,000 higher outside

Front 24

Steps of Cardiac Muscle Contraction

Back 24

1) triggered by electrical signals
2)volted L type channels open
3)Ca that entered with L channels, bind to RYR receptors in the SR
4) Ca released from both bind to troponin
5)Crossbridge cycle
6) relaxation (channels close and Ca is pumped back out)

Front 25

Is relaxation of cardiac myocytes active or passive

Back 25

active, uses ATP

Front 26

How is Ca pumped back out of cell after contraction is done

Back 26

SERCA uses ATP to pump Ca back into SR

Front 27

What normally inhibits SERCA from pumping Ca out of cell and back into SR

Back 27

protein phospholamban

Front 28

what are 2 ways Ca can leave the cell after contraction

Back 28

Active transport with SERCA and the Na-Ca exchanger(NCX)that uses

Front 29

What are 2 ways to regulate force

Back 29

1) increase length
2) vary intracellular Ca via sympathetic NS

Front 30

Starlings Law

Back 30

Length Tension relationship (increase length, increase force)

Front 31

Calcium concentration is a major determinant of the force of cardiac contraction

Back 31

Force increases to maximum as [Ca] increases until 100% of max force is reached

Front 32

How is intracellular [Ca] regulated

Back 32

by sympathetic NS and the NT norepinephrine

Front 33

where does cardiac depolarization initiate

Back 33

SA node

Front 34

what is the order of depolarization through the heart

Back 34

SA node
Atria
AV node
His-Purkinje
Ventricle

Front 35

Which part of the heart has the longest refractory period (conducts AP slowest)

Back 35

AV node

Front 36

Pacemaker of the heart

Back 36

SA node

Front 37

Parasympathetic (ACh) effects on phase 4 of the AP

Back 37

Phase 4 is depolarization
ACh increases the duration of phase 4 depolarization and reduces heart rate.

Front 38

Sympathetic (norepinephrine) effects on phase 4 of the AP

Back 38

decreases the duration of phase 4 depolarization and increases heart rate

Front 39

Helps to ensure that the electrical activation of all portions of the ventricles are synchonrous

Back 39

His Purkinje (fastest conduction velocity in the heart)

Front 40

Occurs during the P wave

Back 40

Atrial depolarization
(right atrium at front of P wave and left atrium at hte end of P wave)

Front 41

Occurs during the PR interval

Back 41

Depolarization of Atrial, AV node, Bundle of His, and purkinje

Front 42

PR Interval

Back 42

time it takes for the AP to spread from the artia to the AV node

Front 43

QRS Complex

Back 43

depolarization of ventricles

Front 44

flat line after T line

Back 44

all cells of hte heart are resting

Front 45

Abnormalaity shown by a shakey area before QRS - no P wave

Back 45

Atrial fibrillation (complete loss of synchronous of excitation adn resting phases)

Front 46

Abnormality shown by a EKG that looks like a scribbled line

Back 46

ventricular fibrilation (ventricle quivers and heart needs shocked to reset to threshold)

Front 47

cycle length formula

Back 47

Cycle Length = 60/HR
Cycle length lasts from one AP to the next

Front 48

Systole

Back 48

contraction and ejection of blood

Front 49

Diastole

Back 49

resting and filling of blood

Front 50

shorter part of the cardiac cycle

Back 50

systole

Front 51

Why is blood flow through left and ride side equal

Back 51

they are in series with each other

Front 52

Side of the heart where pressure is higher

Back 52

left side is 4-5 time higher; so if there is a hole blood flows left to right

Front 53

Arrangement of systemic organs

Back 53

paralell: organs receive blood of identical composition

Front 54

The flow through systemic organs can be controlled independently of other organs because...

Back 54

all organs are in paralell

Front 55

Organs that have blood flow in excess of what they need for basic metabolism needs

Back 55

blood conditioning organs (skin, kidneys, lungs)

Front 56

they get blood solely for their metabolic needs (not excess)

Back 56

brain, heart and muscle (these dont tolerate blood fluctuations as well as blood conditioning organs)

Front 57

Cardiac output for adequate blood supply

Back 57

5L/min

Front 58

Flow equation

Back 58

F = Change in P/Resistance

Front 59

Only ways to change blood flow through an organ

Back 59

Pressure difference and vascular resistance(most common)
F = ΔP/R

Front 60

Why does blood flow through organs

Back 60

b/c the pressure difference exists between the arteries supplying it and the veins draining it

Front 61

Since change in pressure is the same in organs , how is cardiac output distributed amoung organs

Back 61

based on their resistances to flow

Front 62

is blood flow through organs passive or active

Back 62

passive (occurs only because venous pressure is kept lower then arterial pressure)

Front 63

Ventricle pressure drops below aorta pressure, why and what happens then?

Back 63

Ventricle contracts, inc pressue. Blood will be forced from high P to low P, out of ventricle through aorta.

Front 64

Ventricle pressure falls below atrium pressure, why and what happens then?

Back 64

ventricle relaxes, pressure falls. The Av valve can open and the ventricle can fill with blood from atrium.

Front 65

What is the purpose of gap junctions in the heart

Back 65

AP can conduct from one cell to the next via gap junctions that conecct all heart cells as one unit

Front 66

initites the AP and contains slow conducting cells

Back 66

SA node - pacemaker cell

Front 67

Assures all cells contract at the same time

Back 67

purkinje fibers

Front 68

what happens if cardiac filling increases

Back 68

volume ejected also increases (Starlings law: inc EDV inc SV)

Front 69

sympathetic nerve fibers effects (norepinephrine)

Back 69

inc HR
inc AP conduction rate
inc force of contraction
inc rate of contraction/relax

Front 70

parasympathetic nerve fibers effects (acetylcholine)

Back 70

interacts with muscarinic receptors to:
dec HR
dec AP conduction velocity
dec contraction of atrial cells

Front 71

what is an increase in parasymp activity usually coupled with

Back 71

sympathetic activity

Front 72

Main ions in cardiac cell membrane potential

Back 72

Ca, Na (high outside)
K (high inside)

Front 73

When mitral and aortic valves are closed

Back 73

Since volume is not changing, Isovolumic (IVC), pressure is rising though due to contraction

Front 74

SV equation

Back 74

SV = EDV - ESV

Front 75

EDV

Back 75

volume that fills the ventricle

Front 76

ESV

Back 76

Volume that is left after ejection

Front 77

Blood pressure eqn

Back 77

BP = CO * TPR

Front 78

Ejection fraction

Back 78

EF = SV/EDV

Front 79

final closing of valves is due to what

Back 79

small retrograde of blood flow

Front 80

S1 - what does it mark

Back 80

start of systole due to the closing of AV valve, which causes vibrations of cardiac structures

Front 81

S2 - what does it mark

Back 81

closure of aortic valve, end of systole

Front 82

ventricular preload

Back 82

(resting) end diastolic volume, because it is the resting length of hte cardiac muslce fibers

Front 83

Most important regulators of SA node

Back 83

para and sympa b/c they have immediate effects

Front 84

Tension - Muscle Length relationship

Back 84

As muslce length is increased, force created is increased

Front 85

Influences on Stroke Volume (5)

Back 85

1) HR
2) Preload - EDV
3) Afterload - total arterial pressure
4) Contractility
5) Diastolic ventricular compliance

Front 86

Compliance

Back 86

C = ΔV/ΔP
low compliance = stiff heart

Front 87

Force or pressure that the ventricle must overcome to eject the stroke volume

Back 87

afterload

Front 88

Relationship between HR and tme for ventricular filling

Back 88

If HR is increased(arrythimia), the ventricular filling can be reduced so much that SV, CO and blood pressure decrease

Front 89

which are more distensible, veins or arteries

Back 89

veins

Front 90

where is most blood of the body

Back 90

veins of hte systemic organs

Front 91

does gravity affect venous return

Back 91

yes, b/c CV system is composed of distensible vessels not rigid tubes

Front 92

Distention of veins due to gravity can cause:

Back 92

pooling of blood in the lebs, decrease n venous return to the heart

Front 93

What assist in venous return and overcome gravity

Back 93

closing of venous valves decreases weight of fluid column, contraction of muscle funcations as a pump

Front 94

Why does average venous return equal cardiac output

Back 94

b/c the CV system is a closed circuit

Front 95

what is the realtionship between CVP (central venous pressure) and CO (cardiac output)

Back 95

CO increases, CVP decreases
(as we increase CO, we are taking blood out of the veins)
CVP increases, CO increases

Front 96

what arises when a Starling curve and a vascualar fxn curve are plotted together?

Back 96

intersection point is an equillibrium point, the CVP

Front 97

what flows are equal at the intersection point of a cardiac adn vascular function curve

Back 97

total arterial flow, total venous flow, total system capillary flow

Front 98

List the arterial system in order of decreasing pressure

Back 98

heart pump, arteries, arterioles, capillaries, venules, veins

Front 99

Pulse pressure

Back 99

PP = Ps-Pd

Front 100

Mean Arterial(Blood) Pressure
Formula and definition

Back 100

pressure in the large arteries over a cardiac cycle
MBP = Pd + 1/3 (PP)

Front 101

How is BP controlled

Back 101

Baroreceptor reflex

Front 102

Effects of the baroreceptor reflex

Back 102

the increases in arterial pressure lead to an immediate decrease in sympathetic nerve activity and a simultaneous increase in parasympathetic nerve activity (vice versa)

Front 103

What initiates the baroreceptor reflex

Back 103

pressure sensing by stretch sensitive baroreceptor nerve endings in the walls of arteries

Front 104

After initiating pressure sensitive receptors what happesn

Back 104

neural centers in the brain adjust autonomic nerve activty in response to info received from baroreceptors

Front 105

Components of the baroreceptor reflex

Back 105

1) sensory receptors (arterial baroreceptor)
2) Afferent pathways (to CNS)
3) CNS - sends signals to para or sympa

Front 106

Where are the afferent pathways of hte baroreceptor reflex found

Back 106

walls of the aortic arch (aortic receptors)
carotid sinus (either side of the neck)

Front 107

what does increased stretch cause

Back 107

increased AP generation by arterial baroreceptors (sent to parasympathetic in this case; GABA inhibits the sending of AP to the sympathetic)

Front 108

What can pass through microvessels, what cant

Back 108

can: small molecules and water (K, Na, Cl); lipids
cant: proteins

Front 109

Why are microvessels efficient exchange sites

Back 109

thin walls and large surface area

Front 110

Name 4 mechanisms of blood flow

Back 110

neural, humoral, metabollic, myogenic

Front 111

Neural mechanism of blood flow

Back 111

sympathetic vasoconstrictor nerves release norepinephrine, which increases tone

Front 112

Humoral mechanism of blood flow

Back 112

histamine and bradykinin cause dilation of arterioles and constriction of venules

Front 113

Metabolic (local) blood flow control

Back 113

oxygen delivery to a tissue can be matched to oxygen consumption by altering the resistance of the arterioles, which in turn alters blood flow

Front 114

Myogenic mechanism of blood flow control

Back 114

when vascular smooth muscle is stretched, it contracts. So when arterial pressure is increased, the walls are stretched and then contract to maintain constant flow in teh face of increased pressure.

Front 115

Fluid Movement ini microvessels eqn

Back 115

FM = k[(Pc + ∏i)-(Pi + ∏p)]

Front 116

If Fluid movement in microvessel is 0

Back 116

no net flow

Front 117

Fluid movement is positive

Back 117

favors filtration

Front 118

Fluid movement is negative

Back 118

Favors absorption

Front 119

What is diffusion across microvessels calcualted by

Back 119

Ficks law
J = -P*A*(Cin-Cout)
P is the permeability

Front 120

What happens if large particles get into interstitial space

Back 120

filtration forces will exceed reabsorption (edema results)

Front 121

Function of plasma proteins (albumin)

Back 121

osmotic pressure rises b/c plasma has a higher protein concentration than does interstitial fluid

Front 122

why does the left coronary artery have higher flow

Back 122

left ventricle has more tissue mass

Front 123

Why is capillary density higher in the heart than skeletal muscle

Back 123

b/c cardiac cells are smaller in diameter (more room for capillaries)

Front 124

Why are myocardial capillaries more effective than skeletal muscle cells

Back 124

the distance hte molecules must diffuse is smaller

Front 125

Coronary Blood flow

Back 125

CBF = BP/CVR

Front 126

What determines coronary blood flow

Back 126

Blood pressure, CVR and mainly myocardial compression, metabolic control, mass

Front 127

metabolic control of coronary blood flow

Back 127

exercise and adenosine (product of metabolism that results in vasodilation and inc blood flow)

Front 128

Myocardial ischemia

Back 128

oxygen supply does not meet demand

Front 129

What does hypoxia increase the production of

Back 129

adenosine (vasodilator)

Front 130

what change does ischemia cause in the EKG

Back 130

change in ST segment

Front 131

Signs of ischemia

Back 131

change in ST segement and angina

Front 132

Treatment of ischemia

Back 132

to increase blood flow (thrombolytic agents, baloon angioplasty) or by decreasing myocardial energy consumption(dec HR, Dec work or inc efficiency)

Front 133

most imp vasodilator that controls cerebral vascular resistance

Back 133

CO2, adn inc in CO2 causes vasodilation of cerebral arteries, which results in inc blood flow to remove excess CO2

Front 134

Why dont many circulating vasoactive substances affect cerebral circulation

Back 134

b/c their large molecule size cant cross the blood brain barrier

Front 135

Cushing response

Back 135

-intercranial pressure inc
-compression of arteries
- CO2 inc b/s it is not adeequately removed
- medulla chemoreceptors respond and cause intense vasoconstriction (inc BP, dec HR)

Front 136

2 types of exercise

Back 136

dynamic (aerobic)
static (anerobic)

Front 137

why is it important to warm up

Back 137

to give CV and respiratory system to catch up to Oxygen demand (O2 debt)

Front 138

what is payback

Back 138

O2 consumption stays high until your body temp goes back down

Front 139

normal O2 consumption

Back 139

3.5 mL O2/min/kg