Topic 1: Intro to Physiology Flashcards
What is physiology?
- study of how the body functions
What is homeostasis?
- the ability to maintain relatively stable conditions in the internal environment (despite changes in external environment)
Cells can only survive within a narrow range of conditions, so body conditions must be maintained within physiological limits. What conditions must be controlled? (6)
- pH
- temperature
- Blood gases (O2 and CO2)
- Blood pressure (b.p.)
- ICF and ECF volumes
- etc.
What function together to maintain homeostasis?
organ system functions
What is disease?
- failure to maintain homeostasis
Which systems control all other systems? In other words, which systems are control centers? (2)
nervous and/or endocrine system
What is the function of the control center systems? (2)
- maintain homeostasis
- Permit departures from homeostasis in a CONTROLLED manner
ex. pregnancy, growth, sudden fright
What is homeostasis regulation?
- change in internal environment must be detected or anticipated
What occurs in homeostasis regulation?
NS and/or endocrine system respond, altering system(s) responsible for that condition
What are the 2 types of NS/endocrine responses in homeostasis regulation?
- Anticipatory responses
- Feedback mechanisms
What is an example of an anticipatory response? What occurs here?
- increased respiratory rate at start of exercise
- proprioceptors (NS sensory receptors) signal movement before a change in internal conditions (gases in blood)
Anticipatory responses can be ____ or behavioral
- learned
ex. putting on a coat
What are feedback mechanisms?
- mechanisms that respond to change in system
What are the three basic components of feedback mechanisms?
- receptors
- control areas
- effectors
What is the function of a receptor?
- monitors variables/conditions
What is the function of control centers?
- integrate info and maintain setpoints by signalling to effectors
What are setpoints?
- range of values of a variable (ex. body temp) that do not bring about a response (ie. normal range)
What is the function of an effector?
- create a response that will alter the variable/condition
Describe the general feedback mechanism pathway (3)
- variable/condition is monitored by receptors
- info (input) is fed back to control area (NS/endocrine gland)
- Controls the effector (output)
Which type of feedback is the most common homeostatic control mechanism?
negative
What occurs to the result of “output” for negative feedback? (2)
- variable moves back toward the set point
- in opposite (negative) direction to the change that triggered the response (input)
ex. body temp
What occurs when you increase body temp?
- set point is 36-37.8 C
- result is core blood goes to skin surface, and sweat evaporates
- heat loss and decrease body temp (opposite direction of input)
What occurs when you decrease body temp?
- decrease temp causes shivering, then increases body temperature
- set point can change (ie. fever)
Is positive feedback homeostatic?
no
- less common feedback
What occurs in positive feedback? (2)
- output intensifies the input
- variable moves further away from set point
What is an example of positive feedback?
childbirth - labour
Childbirth positive feedback diagram
add later after lecture
Diagram of increased temperature negative feedback
