Concept of Homostasis Flashcards
(68 cards)
What is homeostasis?
The ability to maintain a relatively stable internal environment.
Explain how homeostasis is maintenance of a state of dynamic constancy.
IT means that conditions are stabilized above and below a physiological set point.
What is the ideal normal value of a variable ?
Set point
What are the three interdependent components of control mechanisms?`
Receptor
Control Center
Effector
What is the function of the receptor component of control mechanisms?
Moniter the environment and responds to stimuli
What is the function of the Control center component of control mechanisms?
Determines the set point at which the variable is maintained
What is the function of the effector component of control mechanisms?
Provides the means to respond to the stimulus
What is the pathway of information going into a control center? Leaving the control center?
afferent is incoming
efferent is outgoing.
Explain the process of a Generic negative feedback pathway.
- A deviation is detected by the receptor
- Control center receives information, processes, and initiates effector
- Effector caused value to return to set value
What does is mean when an organ has intrinsic control ?
homeostasis regulation is built into the organ
What does is mean when an organ has extrinsic control ?
homeostasis regulation comes from outside organ
Give an example of extrinsic control
Body temperature (sweating and shivering)
Blood glucose
(hormones)
Explain temperature regulation in regard to an increase in body temp.
- increase in body temp is detected by receptors in the hypothalamus and skin
- The ANTERIOR hypothalamus responds to the receptor and activates heat loss mechanisms.
- A. increased sweating increases evaporative heat loss
3 B. dilation of skin blood vessels increases heat loss from the skin - C. Behavior modification such as taking off jacket or moving to cooler environment
- Body temp returns to set value
Explain temperature regulation in regard to an decrease in body temp.
- decrease in body temp is detected by receptors in the hypothalamus and skin
- The POSTERIOR hypothalamus responds to the receptor and activates heat-generating and heat conserving mechanisms.
- A. Constrictions of skin blood vessels decreases heat loss from the skin
3 B. Shivering increases heat production - C. Behavior modification such as putting on jacket or moving to warmer environment
- Body temp returns to set value
What is the immediate effects of acclimatization to high altitude?
- Hyperventilation resulting in increase proportion of fresh air to alveoli
- Better oxygen loading in lungs
What is the effects of acclimatization to high altitude after a couple days?
Increase oxygen unloading in tissues
What is the effects of acclimatization to high altitude after a couple weeks?
Increase oxygen content of blood
Give four examples of homeostasis regulation in the cardiovascular system.
Blood pressure
Baroreceptor reflex
Volume regulation
Blood osmolality
What is the structure that serves as the command center for blood pressure homeostasis?
Medulla Oblongata
Explain the Blood pressure negative feedback for elevated blood pressure
- increase in blood pressure is detected by receptors in blood vessels
- The control center in the brain that regulates heart rate responds
- Heart rate decreases
- decrease in blood pressure cause decrease in blood pressure
Explain the Blood pressure negative feedback for Decreased blood pressure
- Decrease in blood pressure is detected by receptors in blood vessels
- The control center in the brain that regulates heart rate responds
- Heart rate increases
- increase in blood pressure cause increase in blood pressure
Where are the baroreceptors located?
Aortic arch and carotid sinuses
What does the baroreceptors detect that relates to blood pressure?
Wall Stretching
The baroreceptors send the action potential generated by wall stretching to what locations?
vasomotor and cardiac control centers in medulla