18-4: Capillary dynamics and blood diseases

Question 1

tissue perfusion

Answer 1

blood flow through tissues, depending on need at the time

Question 2

how do arterioles control tissue perfusion?

Answer 2

arterioles’ main function is to control peripheral resistance by changing diameter - this regulates blood flow to each organ

Question 3

autoregulation

Answer 3

organs regulate their own blood flow by varying the diameter (resistance) of their arterioles, based on their need at the time

Question 4

capillary dynamics

Answer 4

movement of fluid by bulk flow, while gas exchange is going on

Question 5

The velocity of blood flow is _ in the aorta and _ in the capillaries

Answer 5

fastest; slowest (to allow adequate time for exchange of material btwn blood and body tissue)

Question 6

How are materials (O2, CO2, nutrients) exchanged?

Answer 6

diffusion

Question 7

filtration

Answer 7

movement of fluid and solutes out of hte capillaries into the interstital fluid

Question 8

What 2 forces do capillary dynamics depend on?

Answer 8

hydrostatic pressure (water pushing) and osmotic pressure (solutes sucking)

Question 9

capillary hydrostatic pressure

Answer 9

HPc pressure of the water in blood pushing fluid out of vessels

Question 10

interstitial fluid osmotic pressure

Answer 10

OPif large proteins in the interstitial fluid draw water towrads them (sucking fluid out of capillaries and into tissues)

Question 11

reabsorption

Answer 11

movement of fluid from interstitial fluid back into capillaries

Question 12

capillary osmotic pressure

Answer 12

OPc large plasma proteins in blood suck fluid from interstitial spaces back into the capillaries

Question 13

interstitial fluid hydrostatic pressure

Answer 13

HPif pressure of water in interstitial spaces pushing fluid back into the capillaries

Question 14

What two forces does filtration depend on?

Answer 14

HPc and OPif

Question 15

What two forces does reabsorption depend on?

Answer 15

OPc and HPIf

Question 16

net filtration pressure

Answer 16

shows whether fluid will enter or leave capillaries (eg. whether net result is filtration or absorption)

Question 17

NFP equation

Answer 17

NFP = filtration - reabsorption

NFP = (HPc + OPif) - (OPc + HPif)

if answer is positive - net filtration
if answer is negative - net reabsorption

Question 18

NFP at the arterial end of the capillary is net __, and NFP at the venus end of the capillary is net __.

Answer 18

filtration; reabsorbtion

Question 19

Some of the fluid filtered at the arterial end is returned to the CV system by ___.

Answer 19

lymphatic vessels

Question 20

edema

Answer 20

when filtration exceeds reabsoprtion, there is an abnormal increase in interstitial fluid, causing tissues to swell

Question 21

The heart is a _ pump, serving _ distinct circulations: _.

Answer 21

double; two; pulmonary circulation and systematic circulation

Question 22

pulmonary circulation

Answer 22

short loop that runs from heart to lungs and back to heart; serves to bring blood into contact with air sacs in lungs so gas exchange can occur

Question 23

What two chambers are involved in pulmonary circulation?

Answer 23

right ventricle and left atrium

Question 24

What are the steps of pulmonary circulation?

Answer 24

Deoxy blood leaves R ventricle > pulmonary trunk > R and L pulmonary arteries > lungs

Inside lungs they divide into smaller arteries > arterioles > pulmonary capillaries where exchange of gasses occurs (CO2 passes from blood into alveoli of lungs, O2 diffuses from lungs into blood)

pulmonary capillaries > pulmonary venules > drain into 2 large pulmonary veins that carry oxy blood away from lungs

4 pulmonary veins return oxy blood to the L atrium of heart, completing the circut

Question 25

systematic circulation

Answer 25

long loop that delivers food and O2 to all body tissues while removing CO2 and wastes

Question 26

What two chambers are involved in systematic circulation?

Answer 26

L ventricle and R atrium

Question 27

What are the steps of systematic circulation?

Answer 27

oxy blood is pumped from L ventricle to aorta

first two branches are coronary arteries supplying the heart muscle itself

the aorta arches upward and curves and runs downward as the descending aorta until it reaches the pelvis, where it splits into the common iliac arteries serving the lower extermities

All systematic arteries branch off from the aorta to supply each body organ; inside the organ they divide into arterioles and then capillary beds to exchange gasses and nutrients

nutrient poor, deoxy blood collects in venules, which unite to form systematic veins

Carry blood back to R atrium through inferior vena cava, superior vena cava, and coronary sinus

Question 28

shock

Answer 28

failure of cardiovascular system to deliver adequate amount of O2 and nutrients to meet the needs of body tissue; if it persists, cells die and organs are damaged

Question 29

What is the main symptom of shock?

Answer 29

Low SBP (< 90)

also cool, clammy, pale skin, sweating, thready (weak but rapid) pulse, thirst, confusion, tachycardia, low urine output

Question 30

hypovolemic shock

Answer 30

due to loss of blood from an acute hemorrhage or excessive fluid loss (vomitting, diarrhea, burns, dehydration)

Question 31

cardiogenic shock

Answer 31

inadequate cardiac function (MI, inflammation of heart, malfunctioning valves, etc) - heart-initated shock

Question 32

neurogenic shock

Answer 32

loss of vasomotor tone caused by anesthesia, CNS damage, drugs, etc - results in widespread vasodilation - nerve-initated shock

Question 33

anaphylactic shock

Answer 33

severe allergic reaction - histamine causes vasodilation and increased vessel permeability (eg. bee sting)

Question 34

septic sock (or toxic shock)

Answer 34

tissue injury caused by bacterial toxins (vasodilators)

Question 35

aneurysm

Answer 35

thin, weaked seciton of blood vessel that balloons outward; high risk of rupture causing massive hemorrhage, shock, stroke or even death

(can be caused by atherosclerosis, congenital vessel defect, trauma, syphylis; repaired with a graft or stent)

Question 36

hypertension

Answer 36

chronically high blood pressure (SBP > 140 or DBP > 90)

cause usually unknown, but contributing factors include diet high in sodium, fat, and chlolesterol, obesity, age, race, stress, smoking, and heredity

controlled by dietary changes, exercise, weight loss, stop smoking, manage stress, take anti-hypertensive drugs

Question 37

What is the danger of hypertension?

Answer 37

heart has to work harder to pump against high resistance > myocardium enlarges and needs more O2 (if it can’t get it, can result in angina or myocardial infarction)

strain on cerebral artery may lead to stroke; may also lead to renal failure and vascular disease