CV Function in Pathology

Question 1

What are the 5 main pathological situations that interfere with the homeostatic fuction of the CV system?

Answer 1

circulatory shock
coronary artery disease
acute coronary occlusion
chronic heart failure
hypertension

Question 2

What is circulatory shock in general terms?

Answer 2

severe reduction in blood supply to the body tissues - metabolis needs ot tissues aren’t met

Question 3

Is arterial pressure low or high in circulatory shock?

Answer 3

low - even with compensatory mechanisms

Question 4

Circulatory shock occurs in what 3 primary disturbances?

Answer 4

1. severely depressed myocardial functional ability
2. grossly inadequate filling due to low mean circulatory filling pressure
3. Profound systemic vasodilation

Question 5

What are the two general cuases a profound systemic vasodilation?

Answer 5

abnormal presence of powerful basodilators

abscence of neurogenic tone

Question 6

What are the five potential consequences of those primary distrubances? i.e. what re the 5 different forms of shock?

Answer 6

cardiogenic shock
hypovolemic shock
anaphylactic shock
septic shock
neurogenic shock

Question 7

What happens in cardiogenic shock?

Answer 7

the cardiac pumping is compromised, leading to decreased CO

Question 8

What are some of the causes of cardiogenic shock>

Answer 8

severe arrhythmia, abrupt valve malfunctions, MI, coronary occlusiosn

Question 9

What happens in hypovolemic shock?

Answer 9

depletion of body fluids leading to decreased blood volume, reduced cardiac filling and reduced SV

Question 10

What are some of the causes of hypovolemic shock?

Answer 10

significant hemorrhage (over 20% blood volume), fluid loss from severe burns, chronic diarrhea, prolonged vomiting

Question 11

What happens in anaphylactic shock?

Answer 11

severe allergic reaction to antigen sensitivity leads to release of histamine, prostaglandins, leukotrienes, bradykinin

this leads to decreased arteriolar vasodilation leading to increased microvascular permeability, loss of venous tone and decreased TPR and CO

Question 12

WHat happens in septic shock?

Answer 12

severe vasodilation due to release of substances into the blood stream by infective agnets - especially endotoxin released from bacteria

Question 13

How does endotoxin lead to vasodilation

Answer 13

it induces the formation of ntiric oxide synthase in endothelial cells which leads t oincreased NO, increased cGMP and increased dephosphorylation and vasodilation

Question 14

What happens in neurogenic shock?

Answer 14

loss of vascular tone due to inhibition of normal tonic activity of sympathetic vasoconstrictor nerves

Question 15

What are some causes of neurogenic shock?

Answer 15

deep general anesthesia
reflex response to deep pain
vasovagal falls under this cateogy, but it’s transient

Question 16

What is the autonomic nervous system response to shock?

Answer 16

grately increased sympathetic nerve activity

Question 17

What symptoms will be seen because of the increased sympathetic nerve activity?

Answer 17

pallor, cold clammy skin, rapid HR, muscle weakness, venous constriction

Question 18

If the compensatory response isn’t working, what symptoms will you see in shock?

Answer 18

abnormally low arterial pressure, reduced cerebral perfusion

results in dizziness, confusion and LOC

Question 19

What are the renal compensations in shock?

Answer 19

1. increased ADH to increased fluid retention
2. Increased aldosterone to increase Na and fluid retention
3. Angiotension increase to cause vasoconstriction

Question 20

The increased sympathetic activity occurs because the body wants to increase CO and MAP. But what’s the downside of this?

Answer 20

you shunt blood to the important heart and brain, but this decreases blood flow to the other organs, so they’ll gradually fail

Question 21

What occurs with breathing in shock?

Answer 21

you go to rapid, shallow breathing, which promotes venous return via action of the respiratory pump

Question 22

Do you get increased or reduced capillary hydrostatis pressure during shock? Why?

Answer 22

You get intense arteriolar constriction, leading to reduced capillary hydrostatic pressure, encouraging fluid retention

Question 23

What does the liver do in shock and why?

Answer 23

it increases glycogenolysis (induced by epi and NE) to release lots of glucose

this glucose causes an increase in extracellular osmolarity, which serves to shift fluid form the itnracellualr space to the extracellular space - essentially taking tissue fluid back into the CV system

Question 24

This increased glycogenolysis and reduced capillary hydrostatic pressure response are collectively referred to as what?

Answer 24

autotransfusion - can move as much as 1 L of fluid into the vascular space in the first hour after onset of shock!

Question 25

What comprises the decompensation in shock?

Answer 25

as the organs continue to lack perusion, they will fail and bodily homeostasis will deteriorate, adversely affecting the CV system further

Question 26

If the ischemia from gradually worsening CAD is not too severe, what is the local response and is it successful?

Answer 26

local metabolic vasodilator mechanisms compensate to reduce arteriolar resistance in order to improve coronary flow can be effective is not too severe

Question 27

What is the response to an acute coronary occlusion?

Answer 27

very similar to cardiogenic shock

Question 28

What are the two general types of dysfunction in heart failure?

Answer 28

systolic and diastolic dysfunction

Question 29

What 5 alterations in the myocytes occur in systolic dysfunction?

Answer 29

1. reduced Ca2+ sequestration in SR 2. increased Na/Ca exchanger, so lower Ca2+ concentrations in the cell 3. low affinity of troponin for Ca2_ 4. altered substrate metaoblism from fatty acids to glucose oxidation 5. Impaired respiratory chain activity with impaired energy production

Question 30

In heart failure, do you have reflexive increase in sympathetic or parasympathetic activity?

Answer 30

sympathetic - you have decreased CO and thus decreased arterial pressure

Question 31

What is the good aspect of long-term compensation with sympathetic activity in systolic dysfunction?

Answer 31

the higher than normal sympathetic activity causes a rise in blood volume (sympathetic induced renin release) which increases mean circulatory filling pressure and raises CO closer ot normal and allows reduction of sympathetic activity back to near normal (the "compensated state of heart failure")

Question 32

What is the bad aspect of long-term compensation with sympathetic activity in systolic dusfunction on the heart?

Answer 32

the fluid retenion will cause both peripheral and central venous pressures to be much higher than normal this causes chronically high EDV and the excessive cardiac dilation further impairs cardiac function because of increased total wall tension and stress - ultimately increased myocardial oxygen demand

Question 33

What is the bad aspect of long-term compensation on overall organ function?

Answer 33

the fluid retention will cause both peripheral and central venous pressure to be high which adversely affects organ function because you get high venous pressure with transcapillary fluid filtration, edema and congestion

Question 34

What are some potential causes of diastolic dysfunction?

Answer 34

1. decreased caridac tissue compliance 2. increased myofibrillar passive stiffness 3. delayed myocyte relaxation in early diastole 4. inadequate ATP levels 5. Residual low-grade cross-bridge cycling during diastole

Question 35

Pulmonary hypertension is above what?

Answer 35

20 mmHg

Question 36

What happens with chronic pulmonary hypertension?

Answer 36

cor pulmonale - you get systemic edema, chest pain and fatigue

Question 37

What is cor pulmonale linked to?

Answer 37

chronic hypoxia as in COPD or cystic fibrosis

Question 38

What percentage of HTN cases are primary or essential HTN?

Answer 38

about 90% - you just treat the symptom and not the cause because you can't find the case