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GM Phys 3 > Exam 2 circulation > Flashcards

Exam 2 circulation Flashcards

1
Q

What are the main functions of systemic circulation?

A

1) Deliver adequate oxygen and nutrients to systemic tissues

2) remove CO2 and other waste products from systemic tissues

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2
Q

What serves as a conduit for transport of hormones, and other substances and allows these substances to
potentially act at a distant site from their production

A

Systemic circulation

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3
Q

What are systemic arteries functional role in systemic circulatory system

A

Carry blood under high pressure out to the tissue beds

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4
Q

What is the function of arterioles and precapillary sphincters in the circulatory system

A

Act as control valves to regulate local flow

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5
Q

What is the function of capillaries that are one cell layer thick

A

Exchange between tissue(cells) and blood

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6
Q

What is the function of venules in systemic circulation

A

Collect blood from capillaries

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7
Q

What is the function of systemic veins

A

Return blood to heart/dynamic storage

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8
Q

What is proportional to metabolic demand?

A

Blood flow

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9
Q

What is controlled by local tissue flow

A

Cardiac output

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10
Q

What control is independent of local flow or cardiac output

A

Arterial pressure

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11
Q

What makes up the components of blood vessels

A

Endothelium, elastic tissue, smooth muscle, fibrous tissue

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12
Q

What is the composition of the aorta, artery, vein, and capillary?
-Elastic tissue = (1)
– Smooth muscle =(2)
– Fibrous tissue = (3)

A

-Aorta = 1>3>2
-Artery= 2>1>3
-Vein 1=2=3
Capillary = endothelium only

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13
Q

What 4 things make up hemodynamics

A

1) flow = F
2) pressure gradient = change in pressure
3) resistance (R)
4) Ohm’s law

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14
Q

What is the equation for ohm’s law

A

V= IR (analogous to delta P = FR)

  • V = voltage
  • I = current flow
  • R = resistance
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15
Q

What is flow equal to?

A

F = velocity x cross sectional area

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16
Q

T/F = at a given flow, the velocity is inversely proportional to the total cross sectional area

A

T

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17
Q

T/F flow is directly proportional to delta P and inversely proportional to resistance (R)

A

True

F = change in pressure / R

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18
Q

What is the driving force of blood

A

Pressure gradient

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19
Q

Pressure gradient is proportional to what?

A

Proportional to flow (F)

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20
Q

At a given F the greater the drop in P a segment or compartment the greater the ____ to flow

A

Resistance

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21
Q

Where does the greatest resistance to flow occur?

A

Pre-capillary resistance vessels

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22
Q

What are pre-capillary resistance vessels

A

Arterioles, met-arterioles, pre-capillary sphincters

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23
Q

What do each of the abbreviations stand for in the resistance equation R= 8nl/ r4

A
  • n = viscosity
  • l = length of vessel
  • r = radius
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24
Q

In the parallel circuit what is the relationship of 1/Rt

A

1/Rt = 1/R1 + 1/R2 + 1/R3….

Rt< smallest individual R

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25
Q

What is the relationship of Rt in the series circuit?

A 
Rt = R1+ R2+R3....Rn
Rt= sum of individual R’s
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26
Q

What is systemic circulation primarily made of

A

Parallel circuit

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27
Q

What are some advantages of parallel circuitry?

A

1) independence of local flow control

2) minimizes total peripheral resistance (TPR)
3) oxygen rich blood supply to every tissue

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28
Q

What is the total vascular resistance (TVR) equal to

A

TVR = the sum of total pulmonic resistance + total peripheral resistance

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29
Q

What is viscosity

A

The internal friction of a fluid associate with intermolecular attraction

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30
Q

What is most viscosity in the blood due to?

A

RBC’s

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31
Q

With blood what is viscosity’s relationship with velocity

A

Viscosity is inversely proportional to velocity

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32
Q

What is the viscosity of blood, plasma, and water

A

3, 1.5, 1

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33
Q

When velocity decreases why does viscosity increase?

A

elements in blood sticking together more

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34
Q

Where can cells get stuck and what effect does it have?

A

They can get stuck at constriction points and increases apparent viscosity

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35
Q

What does fibrinogen do?

A

Increases flexibility of RBC’s

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36
Q

What happens in small vessels with regards to viscosity

A

In small vessels cells line up which decrease viscosity and offsets the viscosity at constriction points to some degree

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37
Q

What is the normal range of hematocrit

A

38-45%

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38
Q

What is hematocrit primarily made up of

A

RBC’s

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39
Q

What are the characteristics of laminar flow

A

Streamline, silent, most efficient, normal

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40
Q

What makes up turbulent flow

A

Cross mixing, vibrational noise, least efficient, frequently associated with vessel disease (bruit)

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41
Q

What is reynold’s number

A

Probability statement for turbulent flow, the greater the R# the greater the probability for turbulence

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42
Q

What do the abbreviations for reynolds number stand for?

V, D, p, n

A
  • v = velocity
  • D = tube diameter
  • p = density
  • n = viscosity
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43
Q

What does the R3 = if R#<2000, R#>3000

A
  • if R#<2000 = laminar flow

- if R#>3000 = turbulent flow

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44
Q

What is the purpose of a doppler ultrasonic flow-meter

A

Ultrasound to determine velocity of flow

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45
Q

How does a doppler ultrasonic flow-meter work

A

RBC’s move toward transmitter, compress sound waves, increase frequency of returning waves

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46
Q

Broad vs. narrow frequency bands

A
  • broad band is associated with turbulent flow

- narrow band is associated with laminar flow

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47
Q

What are the 2 things used for determination of cardiac output

A
  • fick principal

- indicator dilution

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48
Q

What can help determines vessel flow

A
  • venous occlusion plesthymography (momentary limb blood flow)
  • doppler ultrasonic flowmeter
  • vascular flow cuffs
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49
Q

What is the fick principal

A

Measures blood flow to tissue/organ

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50
Q

What are the 3 port systems of the fick principal

A
  • input blood concentration of x
  • output blood concentration of substance x
  • addition/removal of substance x from tissue
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51
Q

What is the fick principal equation

A

Flow= amount of substance per min / AV difference

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52
Q

PBF =

A

O2 uptake / AV O2 diff.

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53
Q

What is the indicator dilution based on

A

Conservation of mass

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54
Q

Distensibility vs. compliance

A
  • distensibility is the ability of vessel to stretch

- compliance is the ability of a vessel to stretch and hold volume

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55
Q

What is the equation for distensibility and compliance

A
  • D = change in volume/ (change in pressure x initial volume)
  • C = change in volume / change in pressure
  • C = distensibility x initial volume
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56
Q

What is the relationship of change in volume and change in pressure in systemic arteries and veins

A
  • Sys. Arteries a small change in volume = large change in pressure
  • veins = large change in volume = small change in pressure
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57
Q

What are 8x more distensible and ____ more compliant than systemic arteries

A

Veins/ 24x

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58
Q

Local blood flow is regulated in proportion to _______ in most tissues

A

Metabolic demand

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59
Q

Short term control of blood flow involves what?

A

Vasodilation, vasoconstriction of precapillary resistance vessels

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60
Q

Long term control of blood flow involves

A

Change in tissue vascularity

  • formation or dissolution of vessels
  • vascular endothelial growth factor and angiogenic
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61
Q

What is the role of arterioles in control of flow (3)

A
  • act as integrator of multiple input
  • richly innervated by SNS vasoconstrictor fibers and have alpha receptors
  • effected by local factors vasodilators, circulation substances
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62
Q

What constricts arterioles

A

SNS

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63
Q

What dilates arterioles

A

NO,CO, decreased O2, local vasodilators

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64
Q

Vasodilation equals what in R and F

A

Vasodilation = decrease in R and increase in F

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65
Q

Vasoconstriction has what effect of R and F

A

Increase R, decrease F

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66
Q

What is the local vasodilator theory

A

Active tissues release local vasodilator (metabolites) which relax vascular smooth muscle

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67
Q

Oxygen demand theory

A

As tissues use up oxygen, vascular smooth muscle cannot maintain constriction

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68
Q

What is autoregulation

A

The ability to keep blood flow constant in the face of a changing arterial BP

  • most tissues show this
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69
Q

In the kidney what two things are autoregulated

A

Renal flow and glomerular filtration rate (GFR)

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70
Q

Control flow (long term) changes tissue what?

A

Vascularity

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71
Q

Under which control of flow does angiogenesis takes place

A

Long term

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72
Q

What is ateriogenesis

A

Shear stress caused by enhanced blood flow velocity associated with partial occlusion

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73
Q

What are angiogenic factors

A
  • small peptides that stimulate growth (VEGF)

- first isolated from tumors (if blocked, they can’t grow)

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74
Q

What type of endothelium up regulates expression of monocyte chemoattractant protein 1 (MCP-1)

A

Stress activated endothelium

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75
Q

What does stress activated endothelium attract that invade arterioles

A

Monocytes

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76
Q

What is hypoxia’s affect on VEGF

A

It causes a release of VEGF

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77
Q

In response to hypoxia what enhances the production of VEGF

A

Partly mediated by adenosine

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78
Q

What does VEGF stimulate

A
  • Capillary proliferation

- development of collateral arterial vessels

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79
Q

What would the effect of hyperactive SNS be on tissue vascularity

A

May compromise blood flow by vasoconstriction

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80
Q

What is vasculogenesis

A

Mesenchymal cell differentiation into endothelial cells

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81
Q

What is angiogenesis and what is unique about it

A

Formation of new blood vessels by sprouting from pre existing small vessels usually lacking developed tunica media

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82
Q

What is arteriogenesis and what is unique about it

A

Rapid proliferation of pre-existing collateral vessels with fully developed tunica media

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83
Q

What are mechanical triggers for angiogenesis

A
  • hemodynamic

- shear stress

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84
Q

What chemically triggers angiogenesis

A

Hypoxia, NO

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85
Q

What molecularly triggers angiogenesis

A
  • decrease in glucose = increase in VEGF
  • inflammation
  • angiogenic growth factors (fibroblast, VEGF, PLGF, angiopoietin)
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86
Q

3 methods for therapeutic angiogenesis

A
  • protein therapy
  • gene therapy
  • cellular therapy
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87
Q

Vasoactive role of endothelium

A
  • release prostacyclin (PGI2)
  • releases nitric oxide (NO) (healthy endothelium)
  • releases endothelium (damaged endo)
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88
Q

What is prostacyclin (PGI2) role

A
  • inhibits platelet aggregation

- relaxes vascular smooth muscle

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89
Q

What does the release of NO do on endothelium

A
  • vasodilator

- stimulated by shear stress and ACh

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90
Q

How does endothelin affect endothelium

A
  • constricts vascular smooth muscle

- contribute to vasoconstriction when endo is damaged by hypertension

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91
Q

Where does the bulk of exchange take place

A

Microcirculation of capillaries

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92
Q

What are the mechanisms of exchange in microcirculation

A

Diffusion, ultrafiltration, vesicular transport

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93
Q

What is oxygen uptake/utilization

A

The product of flow (F) times the arterial venous oxygen difference

O2 uptake = (F)(A-VO2 difference)

94
Q

What is functional vs non functional flow

A
  • Functional/ nutritive flow (F) is associated with increased O2 uptake/utilization
  • O2 uptake must change to be functional/ nutritive
95
Q

What does non nutritive flow do

A

Increases are associated with shunting of blood through a bed

96
Q

How does passive diffusion take place in capillaries

A

Permeability and concentration gradient

97
Q

How does ultrafiltration take place in capillary exchange

A
  • Bulk flow through a filter (capillary wall)

- starling forces (hydrostatic or colloid osmotic P)

98
Q

How does vesicular transport take place in capillary exchange

A

Large MW nonlipid soluble substances

99
Q

Hydrostatic P gradient favors what kind of filtration

A

High (17mmHg) to low (interstitial avg = -3mmHg)

100
Q

Colloid osmotic P favors what type of flow

A

Low to high

  • capillary avg 28mmHg
  • interstitial avg 9mmHg
101
Q

What is the equation for net filtration

A

NFP = (CHP-IHP) - (CCOP-ICOP)

102
Q

What is a function of the protein concentration

A

Colloid osmotic pressure

103
Q

What is the discrepancy due to between calculated and actual colloid effect

A

Donnan effect

104
Q

What is the donnan effect

A
  • Increases the colloid osmotic effect

- large MW plasma proteins carry negative charge attracting positive ions increasing osmotic effect by 50%

105
Q

What does reflection coefficient express

A

It expresses how readily protein can cross the capillary wall ranging between 0 to 1

106
Q

How is reflection coefficient evaluated

A

0 to 1
0 = no colloid effect, proteins cross wall freely,
1= all colloid proteins reflected, none cross, full colloid effect

107
Q

No true lymphatic vessels found where

A
  • superficial skin
  • CNS
  • endomysium of muscle
  • bones
108
Q

What does the thoracic duct drain

A

Lower body, left side of head, arm, and part of chest

109
Q

What does right lymph duct drain

A

Right side of head, neck, right arm, part of chest

110
Q

What acts as a functional lymphatic system in the CNS

A

Plasma filtrate & escaped substances in
perivascular spaces returned to the vascular
system in the CSF via the arachnoid villi which
empties into Dural venous sinuses

111
Q

Where is most of the formation of lymph from?

A

2/3 of all lymph from liver and intestines

112
Q

What promotes lymph formation

A

Any factor that increases filtration and or decreases reabsorption will increase lymph formation

113
Q

What is the total lymph flow rate

A

120 ml/hr, 100 from thoracic duct, 20 from right duct

114
Q

What is the function of lymphatics

A
  • return lost protein to vascular system
  • drain excess plasma filtrate from ISF
  • carry absorbed substances/nutrients from GI tract
  • filter lymph at lymph nodes (defense)
115
Q

What are lymph noes sinuses lined with?

A

Tissue macrophages

116
Q

What is arterial blood pressure created by

A

Interaction of blood with vascular wall

117
Q

What is the equation for arterial bp

A

Art BP = CO (inflow) x TPR (outflow)

118
Q

Where is greater than 1/2 of TPR located

A

Systemic arterioles

119
Q

What happens during systole

A

Left ventricular output (SV) is greater than peripheral runoff = total blood volume rise = art. Bp increases

120
Q

The arteries are distended during systole T/F

A

True

121
Q

What happens during diastole

A
  • While left ventricle is filling arteries are recoiling, this maintains perfusion to tissue beds
  • total blood volume in arterial tree decreases causing art. Bp to fall to minimum value
122
Q

What is hydraulic filtering

A

Stretch (systole) and recoil (diastole) of arterial tree that normally occurs during the cardiac cycle

123
Q

What is hydraulic filterings effect?

A

This phenomenon converts an intermittent output by the heart to steady delivery at the tissue beds and saves the heart work

124
Q

As distensibility of the arterial tree decreases, what happens to hydraulic filtering

A

It is reduced therefore work load on the heart is increased

125
Q

What is the maximum pressure in the systemic arteries

A

Systolic bp

126
Q

When does pressure peak in systolic bp

A

As blood is ejected from left ventricle into aorta

127
Q

What happens faster, inflow volume of LV or peripheral runoff

A

Inflow volume from LV causing arterial P to increase

128
Q

What is the minimum pressure in systemic arteries

A

Diastolic bp

129
Q

How low the pressure falls in diastolic pressure is dependent on what 2 factors

A
  • cycle length inversely proportional to DBP

- total peripheral resistance (TPR) proportional to DBP

130
Q

What happens to DBP during exercise

A

DBP may not change much due to decrease CL is offset by decrease in TPR

131
Q

How is mean arterial bp configured

A

MAP = 1/3 pulse pressure + DBP (approx)

132
Q

What do most post ganglionic SNS terminals release

A

Norepinephrine

133
Q

What is the predominant receptor type of SNS

A

Alpha

134
Q

What is alpha receptors response in SNS

A
  • constriction of smooth muscle, raise art. Bp, increase venous return

About 1L of blood can be mobilized from splanchnic veins during exercise

135
Q

SNS causes widespread _____ causing _____ in blood flow with what 3 exceptions

A
  • vasoconstriction/ decrease

- brain, lung, heart

136
Q

What is critical closing pressure

A

As arterial pressure falls, there is critical pressure below which flow ceases due to closure of arterioles

137
Q

What is required to keep arterioles from closing completely

A

Critical luminal pressure

138
Q

Vascular tone is proportional to what?

A

Critical closing pressure

139
Q

If cardiac output is stopped what happens

A

Arterial pressure will fall and venous pressure will rise

140
Q

What is mean circulatory filling pressure

A

MCFP = equilibration pressure where arterial bp= venous bp

141
Q

What can prevent equilibration pressure

A

Closure of arterioles (critical closing pressure)

142
Q

What is mean circulatory filling pressure responsible for

A

For pressure gradient driving peripheral venous return

143
Q

As central venous pressure increases what happens to venous return

A

Decreases

144
Q

If MCPF = CVP what happens to venous return in the vascular function curve

A

Goes down to 0

145
Q

In the cardiac function curve what happens as central venous pressure increases

A

Cardiac output increases due to both intrinsic and extrinsic factors

146
Q

What is central venous pressure

A

The pressure in central veins (sup/inf vena cava) at entry to right atrium (CVP = right atrial pressure)

147
Q

What is the vasomotor center

A

Collection of neurons in medulla and pons

148
Q

What are the four main regions of the vasomotor center and what do they do

A
  • Pressor center = increases bp
  • depressor center = decreases bp
  • sensory area = mediates baroreceptor reflex
  • cardioinhibitory area = stimulates CN. X
149
Q

Where is the pressor center of VC located and what are its effects

A

Anterolateral portion of upper medulla has norepinephrine projections to intermediolateral horn cells for vasoconstriction and stimulation of cardiac activity

150
Q

What drives SNS outflow from IML

A

Tonically active pressor center

151
Q

What does the depressor center do

A
  • fibers project into/inhibit pressor center
  • ant. Lower MO
  • effects by inhibiting presser center to vasodilate and decreases cardiac activity
152
Q

What does the sensory area of the VC do

A
  • Postlat. Portions of pons and medulla in nucleus tractus solitarius
  • receive input from CN IX and X
  • outputs both on pressor and depressor centers
153
Q

What mediates baroreceptor reflex and how

A

Sensory area of VC by inhibiting pressor center, and lowers bp

154
Q

What does the carrdioinhibitory area do of the VC

A
  • Located medially next to dorsal motor nucleus of vagus

- transmits impulses to DMNV inhibiting heart activity

155
Q

What does sympathetic vasoconstrictor tone do

A
  • due to pressor center input
  • 1/2 to 2 IPS
  • maintains normal arterial bp
156
Q

Does short term or long term control involved in the nervous system effect on vascular smooth muscle

A

Rapid short term

157
Q

What is long terms control on bp

A

Dominated by the kidneys for renal body fluid balance

158
Q

What is contents vs containner

A

Control of bp is accomplished by either affecting vascular tone or blood volume

  • contents= blood volume
  • container=blood vessels
159
Q

Where are baroreceptors abundant

A

Carotid sinus, arch of aorta

160
Q

When are baroreceptors stimulated

A

When stretched, inhibits pressor center via CN IX,X and NTS

161
Q

What are baroreceptors effects

A

Vasodilation, decreased cardiac output

162
Q

What are baroreceptors more sensitive to

A

Changing P

163
Q

What is the buffer function of baroreceptors

A

Buffer change in bp to change in blood volume = during normal cardiac cycle / buffer change in bp due to. Change in body position

164
Q

Why does the barorecptor have to reset

A

Lack of long term control due to adaptation

165
Q

Where are low pressure baroreceptors and what do they do

A

Located in atrial walls and pulmonary arteries

- minimize arterial pressure changes in response to blood volume changes (mainly sense on low pressure side)

166
Q

What does the bainbridge reflex do

A

Increases heart rate from stretch on atrial wall

167
Q

What are the effects of releasing of atrial natriuretic peptide after stretch on atrial wall

A

Diuretic, natriuretic, vasodilator

168
Q

What is the barorecptors reflex after low pressure stretch on atrial walls

A

Decreased heart rate, increased urine production (decreases SNS and ADH)

169
Q

Increased ECF in _____ will cause AP to rise

A

Renal body fluid system

170
Q

What is renal body fluid system

A
  • arterial pressure control
  • increase ECF cause AP to rise
  • kidneys excrete ECF
171
Q

Determinants of long term arterial pressure

A
  • shift of renal output curve for water and salt
  • level of water/salt intake line
  • increased TPR will not create long term elevation of bp if fluid intake and renal function don’t change
172
Q

What supply the glomerular capillaries in the kidney

A

Afferent arterioles

173
Q

Where does filtration take place in kidney

A

Glomerular capillaries

174
Q

What do efferent arterioles do in the kidney

A

Drain the glomerular capillaries and give rise to perituubular capillaries where reabsorption takes place

175
Q

What are vasa recti in the kidney

A

Specialized peritubular capillaries associated with juxtamedullary nephrons

176
Q

What happens in renal control of bp

A

When ECF rises the AP rises, the kidney excretes more fluid and brings pressure to normal

177
Q

The higher the gain the more effective the ____

A

Control system

178
Q

What has chronic effect of AP

A

SNS, renin angiotensin system, aldosterone, ADH, ANP

179
Q

Hormones that decrease renal blood flow

A

Norepinephrine, epinephrine, angiotensin 2

180
Q

Hormones that increase renal blood flow

A

Prostaglandins (E and I)

181
Q

What is tobuloglomerular feedback

A

Monitors NaCl in the macula densa of the distal tubule

182
Q

What is increased renin has what effects on angiotensin 2 and efferent arteriole resistance

A

Increased renin increases angiotensin 2 and increases efferent arteriole resistance

183
Q

Decrease of NaCl does what in macula densa

A

Causes dilation of afferent arteriole

184
Q

What is the source of renin

A

Smooth muscle cells in afferent arteriole

185
Q

What is renin stimulated by

A
  • decrease in perfusion pressure
  • +SNS
  • decrease NaCl deliver to macula densa
  • hormonal stimulation (thyroid/growth hormone)
186
Q

What is renin

A

An enzyme the catalyses the formation of angiotensin 1 (10 amino acids) from angiotensinogen (liver)

187
Q

Where does angiotensin 1 turn to angiotensin 2

A

Occurs primarily in lung via angiotensin converting enzyme associated with pulmonary endothelium

188
Q

What are the functions of angiotensinn 2

A

Stimulate adrenal cortex to secrete aldosterone, release of ADH/vasopressin/kidney

189
Q

What stimulates thirst/drinking behavior at the level of hypothalamus

A

Angiotensin 2

190
Q

What is the role of breathing in BP control

A

Slow breathing (6/min) increases arterial baroreflex sensitivity

191
Q

What are the effects of antioxidants on BP

A
  • NO from endothelium relaxes smooth muscle
  • NO is rapidly inactivated by superoxide radicals
  • increasing antioxidants reduces free radicals allowing NO effect to last longer = lowering bp
192
Q

What is serotonins effect at CNS

A

May act at CNS to inhibit reflex SNS activation

193
Q

NO may act centrally to inhibit what?

A

Sympathetic nerve activity

194
Q

Nitric oxide may promote what in hypotension

A

Promote bradycardia and hypotension

195
Q

Where does gas exchange take place for a fetus

A

The placenta, pulmonary blood flow is minimal

196
Q

How does blood get to the placenta

A

It flows via umbilical arteries which is a branch off the anterior iliac arteries

197
Q

How does blood return to the fetus from the placenta

A

Umbilical veins

198
Q

What are the fetal shunts and their pathways

A
  • ductus arteriosis (DA) = SVC>RA>RV>pulm trunk>DA>aorta
  • foramen ovale (FO) = IVC>RA>FO>LA>LV>AORTA
  • ductus venosus(DV) = umbilical vein>DV>IVC, portal vein>DV>IVC
199
Q

What part of fetal shunts allow blood to bypass lungs

A

ductus arteriosis, and foramen ovale

200
Q

What is ductus venosus’ role in fetal shunts

A

DV allows umbilical and portal blood to bypass liver

201
Q

Oxygen saturation in fetal blood

A

Most in umbilical vein, then IVC, Then aorta

202
Q

What happens after increased blood flow through lungs and liver after birth

A

Pulmonary vascular resistance decreases = decreased RVP and pulmonary arterial bp

203
Q

What happens when there is a loss of blood flow through placenta

A

It doubles the systemic vascular resistance = increased LAP,LVP, and aortic bp

204
Q

What closes at birth

A

Foramen ovale, ductus arteriosis, ductus venosus

205
Q

How does the foramen ovale close

A

Due to reversal of pressure gradient between RA and LA, flap closes

206
Q

How does the ductus arteriosis close

A

Reversal of flow from aorta to artery and increased oxygen levels cause constriction of smooth muscle

207
Q

What happens when ductus venosus closes

A

Allows portal blood to perfuse liver sinuses

208
Q

Why is there low pressure in aorta of fetus

A

Due to low TPR because of placenta umbilical arteries

209
Q

How many shunts are there to bypass lungs in fetus

A

Two right to left shunts

210
Q

What shunts most of the blood returning to heart via IVC

A

Foramen ovale from IVC to left atrium

211
Q

What shunts most of blood returning to heart via SVC

A

Ductus arteriosis

212
Q

How much is CO increased during exercise

A

5-6 fold

213
Q

What are SNS effects after cerebral cortical activation

A
  • vasoconstriction of arterioles to decrease flow to non active tissues
  • vasoconstriction of veins to increase MCFP which increases venous return
  • stimulation of heart (increase HR,SV) increases CO
214
Q

What part of CV changes during exercise is not mediated by SNS

A

TPR decreases due to vasodilation in active muscle

215
Q

What is SNS stimulation during exercise due to

A

Cerebral cortex stimulation, reflex signals from joint proprioceptors, chemoreceptor signals originating in active muscle

216
Q

T/F SNS induces local metabolic vasodilation of the heart

A

True

217
Q

What SNS stimulation decreases blood flow

A

Stimulation of pre-capillary resistance vessels (organs/inactive muscle)

218
Q

How does venous return increase after SNS stimulation

A

SNS stimulation of veins cause constriction mobilizing blood out of veins redistributing blood volume

219
Q

What helps during SNS stimulation via vascular smooth muscle

A

Vascular smooth muscle in walls of arteries help maintain slightly increased bp during exercise

220
Q

What tissues escape SNS vasoconstriction

A

Heart, brain, lungs

221
Q

What is equation of pulse pressure and how does it change in exercise

A

PP=SBP - DBP

Increased PP (increaseSBP>increaseDBP)

222
Q

How does increased venous return help in exercise

A

Increase frequency and depth of respiration producing cyclic negative thoracic pressure

223
Q

How is increased blood flow to active muscle mediated

A

Not by SNS but local release of tissue metabolites in response to increase in metabolism ‘local vasodilators’

224
Q

Blood flow at rest and exercise

A

Rest CO = 5.9 L/min

Exercise = 24L/min

225
Q

Exercise increases all CV endpoints except ____

A

TPR

226
Q

What is oxygen debt

A

If energy needed in exercise can’t be met by oxidative phosphorylation, O2 debt occurs

227
Q

O2 debt equation

A

Energy consumed during exercise - E supplied by oxidative metabolism

228
Q

Respiration after exercise remains elevated, why?

A

To repay O2 debt of about 11.5 L restoring metabolite levels and lactate by glycolysis

229
Q

The phosphocreatine system in exercise

A

Uses ATP, creatine phosphate lasting 8-10 seconds

230
Q

The glycogen lactic acid system

A

1.3-1.6 min

Utilizing glycolysis

231
Q

The aerobic system during exercise

A

Utilizes oxidation of glucose, occurs in mitochondria with sufficient O2 - (this is unlimited with O2 and nutrition)

GM Phys 3 (3 decks)

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