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Blake_Physiology_Test 2 > Blake_Physio_10_Arterial Venous and Lymphatics > Flashcards

Blake_Physio_10_Arterial Venous and Lymphatics Flashcards

1
Q

Vascular Distensibility =

A

= increase in Volume/increase in Pressure*Original volume

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2
Q

Comparison of distensibility between arteries and veins: (3)

A
  1. Veins are about 8x more distensible
  2. Pulmonary vein distensibilities are about the same as for systemic veins
  3. Pulmonary artery distensibilities are about 6x that of systemic arteries
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3
Q

Vascular compliance (aka:______) =

Definition

A

Capacitance = Increase in voulume/increase in pressure

the total quantity of blood that can be stored in a given portion of the circulatory system

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4
Q

Capacitance describes WHAT about blood vessels?

In what way?

A
  • distensibility
  • Tells us the total quantity of blood (mL) that can be stored in a given portion of the circulation for each rise in pressure (mmHg)
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5
Q

How is capacitance related to elastance?

A

Capcitance is INVERSELY proportional to elastance.

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6
Q

What is the relationship of Compliance (capacitance) to Volume?

=> how can compliance be described using Volume, Distensibility and original volume?

A

Compliance = distensibility*volume

VD=Vinc/(Pinc*Vorig)

=>

VD*Vorig=Vinc/Pinc

[VD = vascular distensibility]

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7
Q

Vascular compliance and Elastance

Capacitance is __________ proportional to volume and __________ proportional to pressure

A

directly

inversely

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8
Q

Vascular Compliance and Elastance

Capacitance describes how volume changes in response to_______________

A

a change in pressure

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9
Q

Vascular Compliance and Elastance

Capacitance of veins vs arteries

A

Capacitance is much greater for veins

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10
Q

Vascular Compliance and Elastance

How does age affect vascular compliance?

A

Capactitance decreases with age

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11
Q

The greater the amount of elasic tissue in a blood vessel: (2)

A
  • the higher the elastance
  • the lower the compliance
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12
Q

Compliance is a measure of the ease with which a hollow viscus may be ______; i.e., the volume change resulting from the application of a unit ______ ________ between the inside and outside of the viscus; the ______ of elastance

A

distended

pressure differential

reciprocal

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13
Q

Vascular Elastance is a measure of the tendency of a hollow viscus to ______ towards its ______ _____ upon removal of a _______ or ______ force

A

recoil

original dimensions

distending or collapsing

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14
Q

A systematic vein is about 8x as distensible as its corresponding artery and has a volume of about 3x as great. How wold its compliance compare to that of its corresponding artery?

A

24x as compliant

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15
Q

Explain the following observation:

When the arterial system contains 700ml of blood, the mean arterial pressure is 100mmHg. But when the arterial system contains 400ml of blood, the mean arterial pressure is 0mmHg.

A

The decreased volume of blood is not enough to apply a distending force agains the wall of the vessel.

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16
Q

Explain the follosing observation:

The venous system contains a volume of blood ranging from 2000-3500ml. Removing several hundred mL from the normal venous volume only changes venous pressure 3 to 5mmHg.

A

The high elasticity of the venous system compensates for the loss of volume and maintains pressure.

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17
Q

Define: Pulse Pressure

A

~stroke volume/arterial compliance

also equal to the difference between systolic and diastolic pressures

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18
Q

Factors Affecting pulse pressure (2)

A
  • Stroke volume output of the heart
    • most important determinant of Pulse pressure
    • diastolic pressure remains unchanged during the ventricular systole; pulse pressure increases to the same extent as systolic pressure
  • Compliance of the arterial tree
    • decreases in compliance, i.e. aging, result in an increase in pulse pressure
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19
Q

Pulse Pressure:

COnditions causing abnormal contours of the pressure pulse wave:

A
  • Aortic Valve Stenosis
  • Atherosclerosis
  • Patent ductus ateriosus
  • Aortic regurgitation
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20
Q

Aortic Valve Stenosis

A
  • diameter of the aortic valve opening is reduced significanly, and the aortic pressure pulse is decreased significanly
  • Blood flow through aortic valve is diminished
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21
Q

Patent ductus arteriosus

A
  • half or more of the cardiac output flows back into the pulmonary artery and lung blood vessels
  • diastolic pressure falls very low before next heartbeat
22
Q

Aortic regurgitation

A
  • the aortic valve is absent or will not close completely
  • Aortic pressure may fall all the way to 0mmHg between heartbeats
23
Q

define “damping” of the pressure pulses

A

the progressive reduction of the pulsations in the periphery

24
Q

How does a blood pressure cuff work?

A
  • Pressure cuff cuts off flow to brachial artery
  • no sound is heard when there is no blood flow
  • Pressure cuff is gradually reduced
  • Sound is heard when tubulent blood flow begins to enter semirestricted artery
  • Pressure cuff is gradually reduced
  • No sound is heard when laminar flow is resumed
25
Q

Why is mean arterial pressure closer to the diastolic pressure?

A

Because 60% of the cardiac cycle is spent in the diastole

26
Q

Mean arterial pressure calculation

A

Mean Arterial Pressure=Diastolic pressure +1/3 pulse pressure

27
Q

Resistance and Cardiac Output

Pressure in the right atrium=

Factors that regulate right atrial pressure: (2)

A
  • = central venous pressure
  • Factors that regulate right atrial pressure:
    • Ability of the heart to pump blood out of the right atrium/ventrical
    • Tendency of blood to flow into the right atrium
28
Q

Factors that increase venous return (and increase right atrial pressure) (3)

A
  • Increased blood volume
  • Increased peripheral venous pressue due to large vessel tone
  • Dilation of the arterioles
29
Q

Large veins offer some resistance (2)

A
  • In a person lying down the pressure in peripheral veins is +4 to +6mmHg greater than the right atrial pressure
  • When intra-abdominal pressure increases, the venous pressure in the legs must increase above the abdominal pressure before blood can flow from the legs to the heart through the abdominal veins
30
Q

Compression points that collapse veins entering the thorax (5)

A
  • Atmospheric pressure colapse in neck
  • Rib collapse
  • Axillary collapse
  • Intrathoracic pressure =-4mmHg
  • Abdominal pressure collapse
31
Q

Effecto f gravitational pressure on venous pressures in standing position

A
  • Sagital sinus ~ -10mm
  • Cervical 0mm
  • Axial +6mm
  • Brachial +8
  • Celiac +22mm
  • Wrist +35
  • Femur +40
  • Feet +90mm
32
Q

How does changing blood volume alter blood pressure

A

In each case, delayed compliance compensates for additional volume

33
Q

Arterioles: (3)

A
  • Small arterioles control blood flow to each tissue
  • Local conditions in tissues control diameters of arterioles
  • Arterioles are highly muscular
    • continuous musclular coat is lost in metarterioles
34
Q

Capillaries

A
  • Smooth muscle fiber encercles capillary at point where it originates from a metarteriole (precapillary sphincter)
  • Capillary wall
    • unicellular layer of endothelial cells
    • thin basement membrane
    • Total wall thickness ~0.5µm
    • Internal capillary diameter ~4-9µm
35
Q

Capillaris: Special features

A
  • Slit pores
    • Intercellular clefts; 6-7nm
    • allow rapid diffusion
  • Plasmalemmal vesicles
    • formed from caveolins
    • play a role in endocytosis and transcytosis
  • Some capillaries have pores
    • ie: liver, GI tract, kidneys
36
Q

What is the most important factor regulating vasomotion?

A

Concentration of Oxygen in the tissues

37
Q

Diffusion is the most important means for the exchange of substances between the blood and the interstitial fluid: (3)

A
  • Lipid-soluble substances can diffuse readily through the capillary cell memranes (O2, CO2​)
  • Non-lipid-soluble substances diffuse through the intercellular pores/clefts
  • Rate of water diffusion through the capillary membrane is 80x faster than the flow of plasma within the capillary
38
Q

Rate of diffusion across capillaries is directly proportional to ________

A

the concentration differences of the diffusing substance

39
Q

Passage of substances through the interstitium is mostly via diffusion rather than flow: (2)

A
  • This is because of the large numbers of proteoglycan filaments found in the intersitium
  • Rivulets that allow fluid to flow through the intersitium do sometimes form
40
Q

Starling Forces

A

Starling Forces determine direction of diffusion into or out of a capillary

41
Q

Forces that determine Starling forces

A

Capilary pressure (out)

Interstitial fluid pressure (out)

Capillary plasma colloid osmotic pressure (in)

Interstitial fluid colloid osmotic pressure (out)

42
Q

Sum of the Starling forces =

A

Net Filtration Pressure

43
Q

Net Filtration pressure formula:

A

NFP= Pc - Pif - Πp + Πif

44
Q

Capillary filtration coefficient

A
  • Kf
  • Takes into consideration the number and size of pores
  • Filtration = Kf x NFP
45
Q

When fluid enters the lymphatics, the lymph vessel walls ____________

This causes_____________

A

contract momentarily and pump fluid into the blood circulation.

a slight negative pressure in the interstitial spaces

46
Q

Filtration at Arterial End of Capillary:

  • Forces moving Fluid outward: (3)
  • Total Outward Force = _____
  • Forces Moving Fluid inward (1)
  • Total Inward Force = _____
  • Net Outward Force = ______
A
  • Forces moving Fluid outward:
    • Capillary pressure 30mmHg
    • Negative interstitial free fluid pressure (3mmHg)
    • Interstitial fluid colloid osmotic pressure (8mmHg)
  • Total Outward Force = 41mmHg
  • Forces Moving Fluid inward
    • Plasma colloid osmotic pressure (28mmHg)
  • Total Inward Force = 28mmHg
  • Net Outward Force = 13mmHg
47
Q

Filtration at Venous End of Capillary

  • Forces moving fluid inward (1)
  • Total Inward Force = _____
  • Forces moving fluid outward (3)
  • Total Outward force = _______
  • Net Inward force = _______
    • also called ______
A
  • Forces moving fluid inward
    • Plasma colloid osmotic pressure (28mmHg)
  • Total Inward Force = 28mmHg​
  • Forces moving fluid outward
    • Capillary pressure (10mmHg)
    • Negative interstitial free fluid pressure (3mmHg)
    • Interstitial fluid colloid osmotic pressure (8mmHg)
  • Total Outward force = 21mmHg
  • Net Inward force = 7mmHg
    • also called Net Reabsorbtion Force
48
Q

Lymphatic Return

Special features of lymph vessels

A
  • Lymph Vessels posses 1-way valves
  • The edges of the vessels themselves act as 1-way valves
  • skeletal muscle pumps effect lymph flow
49
Q

Lymph flow reaches a maximum when_______

A

Interstitial pressure rises slightly above atmospheric pressure

50
Q

Factors that increas lymph flow (and also interstitial fluid pressure): (4)

A
  • Elevated capillary hydrostatic pressure
  • Decreased plasma colloid osmotic pressure
  • Increased interstitial fluid colloid osmotic pressure
  • Increase permeability of capillaries
51
Q

Rate of lymph flow =

A

interstitial fluid pressure * activity of lymphatic pump

52
Q

Why do lymph nodes swell during an infection?

A

Because lymphnodes contain masses of lymphocytes and macrophages which engulf foreign particles.

Blake_Physiology_Test 2 (6 decks)

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