Cardiovascular Related Physiological Adaptation to Disease

Question 1

what pressures are reduced during hemorrhage

Answer 1

1. arterial
2. systolic
3. pulse pressure

Question 2

what are the clinical signs of hemorrhage

Answer 2

1. pulse is rapid and feeble
2. mucous membranes are pale
3. respiration is rapid

Question 3

why does cardiac output drop in hemorrhage

Answer 3

1. decreased CVP
2. decreased preload
3. decreased SV

Question 4

what does a drop in cardiac output lead to

Answer 4

drop in blood pressure

Question 5

what occurs if there is a 40-50% drop in BP

Answer 5

see a partial recovery

some will go on to recover BP over few hours, others begin to decline and BP drops until death

Question 6

how does the baroreceptor reflex work to recover BP drop in a hemorrhage (3)

Answer 6

1. reduction in BP leads to decreased baroreceptor stimulation
2. increased sympathetic activity –> leads to tachycardia, increased contractility, increased vasoconstriction
3. decreased parasympathetic activity

Question 7

what does vasoconstriction lead to

Answer 7

increased CVP

contraction of spleen leading to an increased blood volume –> pumps more RBC into circulation

Question 8

what does arteriole vasoconstriction lead to

Answer 8

increased TPR

Question 9

where is vasoconstriction absent and where is it most severe during hemorrhage

Answer 9

absent: in heart and brain

most severe in skeletal muscle, skin, splanchnic circulation

**renal vasoconstriction only occurs in severe hemorrhage –> sustained will lead to kidney damage and sloughing of mucosa in intestine (only takes few hours in dog)

Question 10

how does the chemoreceptor reflex lead to recovery of hemorrhage

Answer 10

if BP does go very low the baroreceptor reflex is no longer sensitive and chemoreceptor will aid

responds to lack of oxygen, buildup of waste products

Question 11

how does cerebral ischemia assist in recovery from hemorrhage

Answer 11

will occur if BP drops too far

sets off sympathetic discharges as a reflex response

Question 12

what is atrial volume receptor reflex

Answer 12

adds to increased sympathetic activity during hemorrhage (same as baroreflex but responding to volume in atrium)

Question 13

how does reabsorption of tissue fluids lead to recovery from hemorrhage

Answer 13

replacement of body fluids is a combination of capillary fluid shifts and hormone and behavioural changes

starlings forces which revolve around differences in oncotic pressure and filtration

loosing fluids so dropping BP –> accumulation of fluids in wrong places want retention of fluid within the blood vessels to maintain BP

Question 14

what is the RAAS system

Answer 14

increased sympathetic activity increases renin secretion

through angiotensin II and aldosterone there is decreased Na+ excretion

reflexes to increase ADH which reduces water loss

conserves fluid

Question 15

what other changes to the baroreceptor reflexes bring about

Answer 15

1. acts through the hypothalamus to induce sensation of thirst and increase water intake

Question 16

what is the recovery timeline from hemorrhage (3)

Answer 16

1. takes 1-2 days to replace volume
2. replacement of plasma protein by liver takes several days
3. replacement of RBC takes several weeks (take awhile to regenerate)

Question 17

what are decompensatory mechanisms to hemorrhage

Answer 17

there are positive feedback mechanisms making situation worse

they induce vicious cycles leading to death

Question 18

what are the decompensatory mechanisms in hemorrhage (5)

Answer 18

1. cardiac failure
2. acidosis
3. CNS depression
4. change in clotting
5. inhibition of immune system

Question 19

how does cardiac failure occur during hemorrhage

Answer 19

1. hypotension reduces coronary blood flow
2. depresses ventricular function
3. reduces CO
4. reduces pressure
5. reduces Q

Question 20

how does acidosis occur during hemorrhage

Answer 20

1. reduced Q leads to anoxia
2. increased lactic acid production
3. reduced H+ secretion by kidney
4. acidosis reduces CV response to catecholamines

*blood becomes acidic, all organs are less responsive, sympathetic activation which won’t allow increase in BP

Question 21

how does CNS depression occur in hemorrhage (4)

Answer 21

1. reduced Q to CNS leading to increased sympathetic output
2. if Q falls further however the cardiac and vasomotor centres become depressed
3. leads to loss of sympathetic tone
4. reduces CO –> further decreases cerebral Q

Question 22

how do changes in clotting occur in hemorrhage

Answer 22

1. initially there is an increase in clotting
2. eventually clotting time is prolonged
3. aggravates hemorrhage

Question 23

how does inhibition of immune system occur during hemorrhage

Answer 23

1. leads to invasion of endotoxins into systemic circulation
2. induce a form of shock

if blood flow is reduced to the GI system –> anoxic –> ulcers –> bacteria can get into the bood –> endotoxins –> vasodilation –> drop BP further –> endotoxic shock

Question 24

what determines whether or not an animal will recover from hemorrhage

Answer 24

1. the degree of hemorrhage and
2. individual variation

more severe the blood loss the greater chance of going into decompensation

Question 25

draw a flow diagram to explain compensatory and decompensatory mechanisms for hemorrhage

Answer 25

Question 26

what is the definition of heart failure

Answer 26

usually refers to a condition of depressed contractility and an inability of heart to provide the metabolic requirements of the body can be restricted to one side or can be bilateral

Question 27

what are possible causes of heart failure

Answer 27

1. coronary artery disease 2. hypoxia 3. myocarditis 4. valve disease

Question 28

what are the two responses to heart failure and what is their overall mechanism

Answer 28

**depressed contractility will reduce SV and CO --\> depressing BP** 1. **starling mechanism:** if LV fails and SV goes down there is an accumulation of blood in the LA and pulmonary veins --\> leads to increased preload and greater SV 2. drop in BP induces **baroreceptor reflex:** increase in sympathetic activity. This increases HR and contractility **overall --\> maintain BP near normal at rest (exercise intolerance)**

Question 29

draw a flow diagram indicating the responses to heart failure

Answer 29

Question 30

what are the complications of heart failure

Answer 30

1. edema 2. exercise intolerance 3. inadequate perfusion of "non-critical" organs 4. cardiac decompensation 5. vasoconstriction in kidney will increase TPR in HF and thus increase BP --\> renal failure causes uremia, accumulation of waste products leads to depressed cardiac contractility, leads to further vasoconstriction 6. pulmonary edema in LV failure --\> accumulation of blood in LA is normally compensatory in that it increases SV but it also leads to pulmonary edeam

Question 31

how does heart failure lead to edema

Answer 31

accumulation of blood in veins increases hydrostatic pressure (starling forces pushes fluid out to tissues)

Question 32

what type of edema does LV failure lead to

Answer 32

pulmonary edema: pushing of blood and fluid into the parenchyma of lungs (cough)

Question 33

what type of edema does RV failure lead to

Answer 33

systemic edema brisket edema in cattle

Question 34

how does heart failure lead to exercise intolerance

Answer 34

normally during exercise you depend on sympathetic system to increase HR, SV and CO in heart failure if sympathetic system is already active so individual is unable to cope with increased demand from skeletal muscle get a big drop in BP and inadequate Q --\> leads to rapid exhaustion

Question 35

how does heart failure cause inadequate perfusion of "non-critical" organs

Answer 35

in severe HF the BRR responds to a falling arterial pressure to bring about vasoconstriction of kidney, splanchnic, resting skeletal muscle - kidneys cannot form urine in a normal way leading to fluid accumulation - waste products accumulate and lead to uremia - get permanent damage to kidney --\> often renal failure is the terminal event in chronic HF

Question 36

what does indaquate perfusion to the gut cause in heart failure

Answer 36

damage can occur via ischemia to intestinal mucosa lead to bacteria and toxins getting from gut into blood stream leading to septic shock

Question 37

how does cardiac decompensation occur in heart failure (kidney, pulmonary edema, explain these)

Answer 37

once HF goes too far the body's compensation mechanism starts to make matters worse leading to decompensation cycles -vasoconstriction in kidney will increase TPR in HF and thus increase BP --\> renal failure outlined causes uremia and accumulation of waste products leads to depressed cardiac contractility, this in turn leads to further vasoconstriction in LV failure --\> accumulation of blood due to reduced ejection in the LA is normally compensatory in that it increases SV. also leads to pulmonary edema --\> affect blood oxygenation and the heart is critically dependent on oxygen --\> hypoxia will reduce CO --\> viscious cycle