Blood Vessels and Pressure

Question 1

blood flow rate through a vessel is:

Answer 1

proportional to the pressure gradient and inversley proportional to the vascular resistance

Question 2

Equation for flow rate

Answer 2

f = change P /R

Question 3

Pressure gradient (deltaP)

Answer 3

-difference in pressure between the beginning and end of a vessel
-contraction of the heart imparts pressure to the blood that drives bloodflow

Question 4

vascular resistance (R)

Answer 4

opposition to blood flow through a vessel due to friction between the fluid and the vessel wall

Question 5

map out the closed system of vessels

Answer 5

arteries -> arterioles -> capillaries -> venules -> veins

Question 6

Arteries

Answer 6

thick, highly elastic, large radii
transport blood from the heart to the organs

Question 7

Arterioles

Answer 7

highly muscular, well inervated walls, small radii
control the amount of blood that flows through each organ

Question 8

Capillaries

Answer 8

very thin walled, large total cross sectional area
vessels where materials are exchanged

Question 9

Venules

Answer 9

capillaries join to form venules

Question 10

Veins

Answer 10

thin walls compared to arteries, highly distensible, large radii
venules merge to form veins that return blood to the heart

Question 11

arterial pressure fluctuation numbers

Answer 11

systolic: 120 mm Hg
Diastolic: 80 mm Hg

Question 12

Arterial blood pressure

Answer 12

the force exerted by blood against the vessel wall

deltaP = change in blood volume (delta V)/ compliance

Question 13

how does a pressure cuff work (sphygmomanometer)

Answer 13

cuff inflation->pressure on brachial artery:

-cuff pressure > systolic pressure -> artery is pinched, no blood flow/no sound

-cuff pressure falls below the systolic pressure-> the artery partially opens, blood flow is turbulent, makes sound

-cuff pressure < diastolic pressure ->laminar flow, no sound

Question 14

Mean arterial pressure (MAP) equation

Answer 14

MAP = diastolic pressure + (1/3)pulse pressure

Question 15

Vasoconstriction

Answer 15

narrowing of a vessel due to smooth muscle contraction

Question 16

vasodilation

Answer 16

enlargement in circumfrence and radius of a vessel due to smooth muscle relaxation

Question 17

vascular tone

Answer 17

state of partial constriction of arteriolar smooth muscle which establishes a baseline of arteiolar resistance

Question 18

causes of vasoconstriction

Answer 18

-increased myogenic activity
-increased oxygen
-decreased co2
-increased endothelin
-increased sympathetic stimulation
-cold

Question 19

causes of vasodilation

Answer 19

-decreased myogenic activity
-decreased o2
-decreased co2
-increase nitric oxide
-decrease sympathetic stimulation
-heat

Question 20

what are differences in blood flow to various organs determined by

Answer 20

-differences in vascularization
-differences in resistance offered by arterioles supplying each organ (low resistance means large flow and vice versa)

Question 21

active hyperemia

Answer 21

increased blood flow in response to enhanced tissue activity

Question 22

local metabolic changes that cause vasorelaxation

Answer 22

decreased o2
increased adenosine release
increased co2, acid, k+, and osmolarity

Question 23

diffusion of substances across capillary walls

Answer 23

-depends on wall permeability to these substances
-endothelial cells are joined by narrow water-filled clefts (pores
-pores permit the passage of small water soluble substances

Question 24

why does reconditioning of blood occur

Answer 24

recoditioning blood occurs to make sure that the composition is constant despite the exchange of nutrients and wastes between blood and tissues

Question 25

whats the difference between blood flow through reconditioning organs vs. non reconditioning

Answer 25

organs that recondition (kidneys, liver, skin) recieve excess blood flow so that they can recondition blood for the rest of the bodies needs

Question 26

how do arteries serve as a pressure reservoir

Answer 26

the elastic arteries distend when the ventricles eject blood from the heart (the elasticity drive blood forward even when ventricles relax) - happens because more blood flows into the arteries than is drained off into the smaller arterioles.

Question 27

describe local controls that regulate arteriolar resistance

Answer 27

-local controls are changes within an organ that alter blood flow -they change diameter of the vessels running through them -ex: metabolic changes, histamine, application of heat or cold, chemical response to shear stress, myogenic response to stress

Question 28

describe the extrinsic controls that regulate the arteriolar resistance

Answer 28

-neural and hormonal factors that regulate vessel diameter -increasing sympathetic activity causes generalized vasoconstriction!!!!!

Question 29

what is the primary means individual solutes are exchanged across capillary walls

Answer 29

-lipid soluble substances pass directly through the endothelial cell wall -small water-soluble substances pass through pores between cells

Question 30

what forces produce bulk flow across capillary walls

Answer 30

-capillary pressure (pushes fluid out of the blood) -plasma colloid osmotic pressure (pulls fluid into blood) -interstitial fluid hydrostatic pressure (forces fluid into blood) -interstital fluid colloid osmotic pressure (tends to pull water out of the blood)

Question 31

how is a lymph formed

Answer 31

lymph is a fluid simmilar in composition to blood plasma. it is derived from blood plasma as fluids pass through capillary walls at the arterial end. as the interstitial fluid accumilates it is picked up and removed by tiny lymphatic vessels

Question 32

function of lymphatic system

Answer 32

-pick up excess fluid left in the interstitial fluid -plays a role in body defenses, transport absorbed fats, returns filtered proteins

Question 33

define edema

Answer 33

accumulation of excess interstitial fluid

Question 34

causes of edema

Answer 34

-reduced concentration of plasma proteins -increased permeability of capillary walls -increased venous pressure -blockage of the lymphatic system

Question 35

how do veins serve as a blood reservoir

Answer 35

-they are able to stretch and they hold onto a larger percentage of blood volume -they remain stretched without recoiling (unlike arteries which recoil and push blood forward)

Question 36

how much blood do veins contain under resting condition

Answer 36

more than 60% of blood volume

Question 37

compare effects of vasoconstriction on the rate of blood flow in arterioles v. veins

Answer 37

Arteriole: decreases blood flow through the vessel bc of increased resistance to blood flow Vein: increased blood flow because the narrowing of the vessel forces more blood out of it

Question 38

what is mean arterial pressure

Answer 38

the driving force that moves blood through the arterial system

Question 39

what is the mean arterial pressure driven by

Answer 39

cardiac output, total peripheral resistance, blood volume

Question 40

effect of parasympathetic stimulation on the cardiovascular system

Answer 40

-decreases heart rate through action of vagus nerve -decreases cardiac output and blood pressure

Question 41

effect of sympathetic stimulation on the cardiovascular system

Answer 41

-increases heart rate and contractile strength -increase blood pressure and cardiac output

Question 42

differentiate between secondary hypertension and primary hypertension

Answer 42

primary hypertension the cause is unknown and accounts for 90% of hypertension cases secondary hypertension the elevated blood pressure is secondary to a primary, known cause (renal disease/hormornal or neural issues)

Question 43

Potential consequences of hypertension

Answer 43

stress on both the heart and vessels heart has to work harder to pump against an increased resistance and the increased pressure can damage the blood vessels(leads to heart attack and stroke)

Question 44

define circulatory shock

Answer 44

when blood pressure drops so low that adequate blood flow to tissue cannot be maintained

Question 45

what are consequences of circulatory shock

Answer 45

decreased cardiac output and hypotension

Question 46

what are some compensations of circulatory shock

Answer 46

-increased sympathetic and decreased parasympathetic activity at heart and vessels which increase cardiac output to elevate blood pressure -urinary output is reduced and thirst sensations are enhanced to increase water retention for increased fluid volume

Question 47

what is irreversible shock

Answer 47

occurs when compensations are not enough and despite medical intervention blood flow to vital organs cannot be maintained

Question 48

blood vessel compliance

Answer 48

The ability of a blood vessel to stretch and accommodate changes in blood volume without a large increase in pressure