What is the definition of shock?
Inadequacy of blood which results in inadequate delivery of oxygen and nutrients throughout the body to the extent that the tissues are damaged.
What are two types of factors that can severely reduce cardiac output?
- Cardiac abnormalities that decrease the ability of the heart to pump blood.
- Factors that decreases venous return (nothing in=nothing out).
Two examples of circulatory shcok without diminished CO?
- Excessive metabolic rate.
2. Abnormal tissue perfusion patterns.
What is the end result of circulatory shock?
Tissue deterioration.
How much of the blood volume can be lost without effect on ABP or CO?
About 10 percent.
At what point of blood loss will ABP and CO fall to zero?
40-45% blood loss.
T/F: Autoregulation is with changes in blood flow, arterial blood pressure remains the same?
False:
Autoregulation-
-Though arterial blood pressure may change, blood flow through the heart/brain/organ will remain the same.
What three sympathetic reflexes compensate for shock?
- Arterioles constrict.
- Veins and venous reservoir constrict.
- Heart activity increases markedly.
Which two vessel beds do not constrict significantly with sympathetic stimulation?
Cerebral and coronary.
Which three places is vasoconstriction from baroreceptors most prominent?
- Cutaneous vascular beds.
- Skeletal muscle vascular bed.
- Splanchnic vascular bed.
Where is cortisol released from?
Adrenal glands.
What affect does cortisol have on blood volume?
Helps to increase blood volume (which increases MAP)
What are the stages of shock?
- Nonprogressive stage (compensated stage).
- Progressive stage
- Irreversible stage
Why might glucocorticoids be used in shock?
Adrenal cortex hormones would be stimulated and produce catecholemines.
Does capillary recruitment increase or decrease surface are for diffusion?
Increases
Does capillary recruitment shorten or lengthen the distance for diffusion?
Shorten.
How much will oxygen consumption increases with a fifteen fold increase in muscle blood flow?
Sixty fold.
How much of increased CO with exercise due to HR and how much is due to stroke volume changes?
Mostly HR.
10-35% Stroke volume.
What four things enhance venous return during exercise?
- Sympathetic constriction of capacitance vessles.
- Decreased SVR in muscles.
- Contracting muscles pump blood in the veins back to the heart.
- Deeper, more frequent respirations decrease intrathoracic pressure and enhance flow
