Class 11 Flashcards
When does an artery tend to collapse?
1) Elastic property of the elastic and collagen fibers enclosing the artery
2) Active tension by vascular smooth muscle cells
What is critical closing pressure?
For a given blood vessel is the blood pressure at or below which the blood vessel will collapse, causing cessation of blood flow through that section of blood vessel
What does the constant force/pressure in blood vessels do?
Keeps the blood vessels open
If blood vessels were ever to close, can you open them?
NO
Critical closing pressure increases with an increase in what?
Vascular tone
When is there zero blood flow?
At critical closing pressure
When does critical closing pressure increase?
When vascular tone is increased through higher intensity of sympathetic activation
When do blood vessels collapse? At what mmHg?
6-7 mmHg
What can be defined as the blood volume within the vasculature that can be utilized to perfuse the organ systems within the body?
Effective circulating volume
Effective circulating volume is related to what aspect of blood vessels?
The fullness of them
What is defined as the force exerted by blood against a vessel wall?
Blood pressure
What can blood pressure be influenced by? (2)
1) Physiological
2) Physical
What are the physiological factors of blood pressure? (4)
- HR
- SV
- CO (HR x SV)
- Peripheral resistance
What are the physical factors influencing bp?
- effective circulating blood volume
- elastic characteristics
What contributes the majority of the resistance to flow in the body?
Arteries and arterioles
What are the 4 components of the bp?
1) systolic pressure
2) diastolic pressure
3) pulse pressure
4) mean arterial pressure
What is the upper limit of the periodic oscillations of bp initiated by ventricular systole?
Systolic pressure
What is he minimum pressure within the arteries during ventricular diastole?
Diastolic pressure
What is the difference between systolic and diastolic pressure?
Pulse pressure
What is the average pressure in the arteries over time?
Mean arterial pressure
MAP =
1/3SP + 2/3DP
Cardiovascular function can be detected by: (4)
1) Blood pressure
2) Blood volume
3) Blood chemistry
4) Blood osmolarity
What are the 2 basic categories of cardiovascular function control?
Neural and humoral
What are baroreceptors?
High pressure sensors for regulation of cardio function
What are the primary sensors for the detection of arterial blood pressure changes?
Baroreceptors, stretch receptors
How do baroreceptors regulate arterial bp?
Through negative feedback, firing baroreceptors cause inhibitory effect on sympathetic and excitatory effect of parasympathetic, thus decrease bp ans hr
What do baroreceptors respond to?
Stretching of vessel walls and increases firing rates
Low pressure baroreceptors detect what?
Venous return, more as volume receptors
Low pressure baroreceptors have two types:
a. Type A fibers
b. Type b fibers
Type A fibers of baroreceptors do what?
Fire during atrial depolarization, monitor HR
Type B fibers of baroreceptors do what?
Fire at ventricular systole, increase firing frequency during atrial filling, monitor atrial volume
What is the primary function of chemoreceptors?
Regulate respiratory activity and maintain blood gas level
What do chemoreceptors detect?
Po2, PCO2, H concentration
How do chemoreceptors work?
Influence medullary cardiovascular centers similarly to that of the high pressure baroreceptors
