Exam 2 – Cardio Ch 17 Flashcards
What does each tissue control its own blood in proportion to?
Its needs
List the tissue needs
- Delivery of oxygen to tissues
- Delivery of nutrients such as glucose, amino acids, etc.
- Removal of carbon dioxide, hydrogen, and other metabolites from the tissues
- Transport various hormones and other substances to different tissues
- Maintenance of proper concentrations of ions in tissues
What is flow closely related to?
Metabolic rate of tissues
What are the mechanisms of blood flow control?
- Acute control
2. Long-term control
Define long-term control
Slow, controlled changes in flow over a period of days, weeks, or even months
Provide even better control of flow in proportion to needs of tissue
Come about as a result of an increase or decrease in Physical sizes and numbers of blood vessels supplying the tissues
Define acute control
Achieved by rapid changes in local vasodilation or vasoconstriction of arterioles, metarterioles, and precapillary sphincters that occur within secs to mins to provide very rapid maintenance of appropriate local tissue blood flow
What are the top three organs that blood flows to?
- Liver 27%
- Kidneys 22%
- Brain 14%
Look at variations in tissue blood flow chart
Look at variations in tissue blood flow chart
What does an increase in tissue metabolism lead to in acute control?
Increases in blood flow
What does a decrease in oxygen availability to tissues lead to in acute control?
Increases tissue blood flow
What are two major theories for local blood flow?
- Vasodilator theory
2. Oxygen demand theory
Define vasodilator theory
The greater rate of metabolism or the less the availability of O2 or some other nutrients to a tissue, the greater rate of formation of vasodilator substances in tissue cells
Define oxygen demand theory
- In absence of adequate O2, its reasonable to believe that blood vessels would relax and dilate
- Increased utilization of O2 in tissues as a result in increased metabolism could decrease availability of O2 to smooth muscle fibers in local blood vessels and would cause local vasodilation
What are the determinants of blood flow?
Q = (P1-P2)/R
What is flow through a blood vessel determined by?
The pressure difference between the two ends of the vessel
Resistance of the vessel
What are the theories of tissue flow?
Vasodilator Oxygen lack (demand)
What is the effect of tissue metabolic rate on tissue blood flow?
Increased tissue metabolism causes increased blood flow
Look at metabolic rate of tissue blood flow chart
Look at metabolic rate of tissue blood flow chart
What is the effect of tissue oxygen concentration on blood flow?
Decreased tissue oxygen concentration causes increased blood flow
Look at the oxygen concentration on blood flow chart
Look at oxygen concentration on blood flow chart
How do changes in tissue oxygen concentration affect blood flow?
- Increase tissue metabolism or decrease oxygen
- Delivery to tissues
- Decrease tissue oxygen concentration
- Decrease arteriole resistance
- Increase blood flow
LOOK AT CHART IN NOTES
What are vasodilators?
CO2 Lactic Acid Adenosine ADP compounds Histamine K ions H ions
What is the vasodilator theory for blood flow control?
- Increase tissue metabolism
- Increase release of vasodilators
- Decrease arteriole resistance
- Increase blood flow
LOOK AT CHART IN NOTES
What is autoregulation?
In any tissues of body, a rapid increased arterial pressure causes an immediate rise in blood flow. However, within less than a minute, the blood flow in most tissues return to normal level, even though arterial pressure is kept elevation. This return of blood flow toward normal is called autoregulation