Topic I Flashcards
Homeostasis
ability to maintain relatively stable conditions in the internal environment
- cells can only survive within a narrow range of conditions
- body conditions msut be maintained within physiological limits
Homeostasis
–> controlled conditions
- ph
- temperature
- CO2
- O2
- blood pressure
- ICF + ECF volumes
Homeostasis II
organ systems function together to maintain homeostasis
- disease= failure to maintain homeostasis
- -> nervous + endocrine systems control all other systems
- maintain homeostasis
- permit departures from homeostasis in a controlled manner
Homeostasis Regulation
- change in internal environment must be detected or anticipated
Homeostasis Regulation
–> Types of NS/Endocrine Responses
- Anticipatory Responses
- Feedback Mechanisms
- -> includes Positive + Negative FB mechanisms
Anticipatory Responses
i. e. increase in respiratory rate at start of exercise–> proprioceptors signal movement before a change in internal conditions occurs
- may also be learned or behavioral
Feedback Mechanisms
- mechanisms that respond to a change in the system
- consist of set points receptors, control areas and effectors
- Set point= range of values of variable
- -> variable is monitored by receptors –> info fed back to control area
Negative Feedback
most common homeostatic control mechanisms
result of output variable moves back toward the set point (i.e. in opposite direction to the change that triggered the response
–> i.e. body temp.: set point= 36-37.8 deg. cels. (if temp. increases= 40 deg. cels.)
result= core blood to skin surface and sweat evaporates
= increase in heat loss and decrease in temperatures (opposite direction of change )
- set point can change
Positive Feedback
less common= homeostatic
output intensifies the input
i.e. childbirth- labour
uterine contractions –> NS –> post. pit. gland–> release of oxytocin
Physiology
study of how the body functions
