Blake_Physio_10_Arterial Venous and Lymphatics

Question 1

Vascular Distensibility =

Answer 1

= increase in Volume/increase in Pressure*Original volume

Question 2

Comparison of distensibility between arteries and veins: (3)

Answer 2

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

Question 3

Vascular compliance (aka:______) =

Definition

Answer 3

Capacitance = Increase in voulume/increase in pressure

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

Question 4

Capacitance describes WHAT about blood vessels?

In what way?

Answer 4

• 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)

Question 5

How is capacitance related to elastance?

Answer 5

Capcitance is INVERSELY proportional to elastance.

Question 6

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

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

Answer 6

Compliance = distensibility*volume

VD=V_inc/(P_inc*V_orig)

=>

VD*V_orig=V_inc/P_inc

_{[VD = vascular distensibility]}

Question 7

Vascular compliance and Elastance

Capacitance is __________ proportional to volume and __________ proportional to pressure

Answer 7

directly

inversely

Question 8

Vascular Compliance and Elastance

Capacitance describes how volume changes in response to_______________

Answer 8

a change in pressure

Question 9

Vascular Compliance and Elastance

Capacitance of veins vs arteries

Answer 9

Capacitance is much greater for veins

Question 10

Vascular Compliance and Elastance

How does age affect vascular compliance?

Answer 10

Capactitance decreases with age

Question 11

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

Answer 11

• the higher the elastance
• the lower the compliance

Question 12

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

Answer 12

distended

pressure differential

reciprocal

Question 13

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

Answer 13

recoil

original dimensions

distending or collapsing

Question 14

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?

Answer 14

24x as compliant

Question 15

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.

Answer 15

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

Question 16

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.

Answer 16

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

Question 17

Define: Pulse Pressure

Answer 17

~stroke volume/arterial compliance

also equal to the difference between systolic and diastolic pressures

Question 18

Factors Affecting pulse pressure (2)

Answer 18

• 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

Question 19

Pulse Pressure:

COnditions causing abnormal contours of the pressure pulse wave:

Answer 19

• Aortic Valve Stenosis
• Atherosclerosis
• Patent ductus ateriosus
• Aortic regurgitation

Question 20

Aortic Valve Stenosis

Answer 20

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

Question 21

Patent ductus arteriosus

Answer 21

• 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

Question 22

Aortic regurgitation

Answer 22

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

Question 23

define “damping” of the pressure pulses

Answer 23

the progressive reduction of the pulsations in the periphery

Question 24

How does a blood pressure cuff work?

Answer 24

• 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

Question 25

Why is mean arterial pressure closer to the diastolic pressure?

Answer 25

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

Question 26

Mean arterial pressure calculation

Answer 26

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

Question 27

Resistance and Cardiac Output Pressure in the right atrium= Factors that regulate right atrial pressure: (2)

Answer 27

* = 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

Question 28

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

Answer 28

* Increased blood volume * Increased peripheral venous pressue due to large vessel tone * Dilation of the arterioles

Question 29

Large veins offer some resistance (2)

Answer 29

* 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

Question 30

Compression points that collapse veins entering the thorax (5)

Answer 30

* Atmospheric pressure colapse in neck * Rib collapse * Axillary collapse * Intrathoracic pressure =-4mmHg * Abdominal pressure collapse

Question 31

Effecto f gravitational pressure on venous pressures in standing position

Answer 31

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

Question 32

How does changing blood volume alter blood pressure

Answer 32

In each case, delayed compliance compensates for additional volume

Question 33

Arterioles: (3)

Answer 33

* 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

Question 34

Capillaries

Answer 34

* 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

Question 35

Capillaris: Special features

Answer 35

* 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

Question 36

What is the most important factor regulating vasomotion?

Answer 36

Concentration of Oxygen in the tissues

Question 37

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

Answer 37

* 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

Question 38

Rate of diffusion across capillaries is directly proportional to \_\_\_\_\_\_\_\_

Answer 38

the concentration differences of the diffusing substance

Question 39

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

Answer 39

* 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

Question 40

Starling Forces

Answer 40

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

Question 41

Forces that determine Starling forces

Answer 41

Capilary pressure (out) Interstitial fluid pressure (out) Capillary plasma colloid osmotic pressure (in) Interstitial fluid colloid osmotic pressure (out)

Question 42

Sum of the Starling forces =

Answer 42

Net Filtration Pressure

Question 43

Net Filtration pressure formula:

Answer 43

NFP= P_c - P_if - Π_p + Π_if

Question 44

Capillary filtration coefficient

Answer 44

* K_f * Takes into consideration the number and size of pores * Filtration = K_f x NFP

Question 45

When fluid enters the lymphatics, the lymph vessel walls \_\_\_\_\_\_\_\_\_\_\_\_ This causes\_\_\_\_\_\_\_\_\_\_\_\_\_

Answer 45

contract momentarily and pump fluid into the blood circulation. a slight negative pressure in the interstitial spaces

Question 46

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 = \_\_\_\_\_\_

Answer 46

* 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**

Question 47

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 \_\_\_\_\_\_

Answer 47

* 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**

Question 48

Lymphatic Return Special features of lymph vessels

Answer 48

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

Question 49

Lymph flow reaches a maximum when\_\_\_\_\_\_\_

Answer 49

Interstitial pressure rises slightly above atmospheric pressure

Question 50

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

Answer 50

* Elevated capillary hydrostatic pressure * Decreased plasma colloid osmotic pressure * Increased interstitial fluid colloid osmotic pressure * Increase permeability of capillaries

Question 51

Rate of lymph flow =

Answer 51

interstitial fluid pressure \* activity of lymphatic pump

Question 52

Why do lymph nodes swell during an infection?

Answer 52

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