PSIO 532 Study Guide - Midterm Guide: Smooth Muscle Tissue, Stroke Volume, Cerebral Circulation
PSL – Cardiovascular System
Veins – Hydrostatic Pressure
Veins – low resistance high compliance vessels
The upright posture is a big deal, because we have to fight gravity. For a dog, quadripad
(standing on 4 legs) → it encounters no problems because 70% of blood volume is at or above
the heart level. Hee, it does’t have ay prole aitaiig vetriular fillig pressure.
Filling pressure is related to the stroke volume via Starling Curves. However, for humans, by
standing up, we have to fight against gravity, which tends to pull blood below the heart level.
This hydrostatic pressure is due to the height of the column, density of the fluid and the pull of
the gravity. We know for the hydrostatic pressure, the density and gravity remain fairly
constant, hence, for the large part, the hydrostatic pressure is due to the height of the column.
We see that in our feet, the transmural pressure can rise as much as 100 mmHg in the upright
posture → we end up pooling a lot of blood below the heart level; this challenges us to
maintain that ventricular filling pressure.
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
The upright posture is a big deal, because we have to fight gravity. For a dog, quadripad (standing on 4 legs) it encounters no problems because 70% of blood volume is at or above the heart level. He(cid:374)(cid:272)e, it does(cid:374)"t have a(cid:374)y pro(cid:271)le(cid:373) (cid:373)ai(cid:374)tai(cid:374)i(cid:374)g ve(cid:374)tri(cid:272)ular filli(cid:374)g pressure. Filling pressure is related to the stroke volume via starling curves. However, for humans, by standing up, we have to fight against gravity, which tends to pull blood below the heart level. This hydrostatic pressure is due to the height of the column, density of the fluid and the pull of the gravity. We know for the hydrostatic pressure, the density and gravity remain fairly constant, hence, for the large part, the hydrostatic pressure is due to the height of the column. If you stand up too quickly, the blood rushes down and this decreases the venous return, which in turn decreases the cardiac filling pressure.
