TOPIC 1: INTRODUCTION TO PHYSIOLOGY Flashcards
Physiology
What is Physiology?
Study of how the body functions
Study of physical and chemical processes in cells, tissues, organs, and organ systems that sustain life.
What is Homeostasis?
The ability to maintain relatively stable conditions in the internal environment despite changes in the external environment
Cells can only survive within a narrow range of conditions.
What are examples of conditions controlled by homeostasis?
- pH
- Temperature
- Blood gases (CO2, O2)
- Blood pressure (b.p.)
- Intracellular + extracellular fluid volumes
Many more conditions are controlled to maintain homeostasis.
What is the role of the nervous and endocrine systems in homeostasis?
They control all other systems to maintain homeostasis and permit controlled departures from it
Examples include pregnancy, growth, and sudden fright.
What must happen for homeostasis to be regulated?
Change in internal environment must be detected or anticipated
The nervous and/or endocrine system respond by altering the responsible systems.
What are Anticipatory Responses?
Responses that occur before a change in internal conditions
Example: Increased respiratory rate at the start of exercise.
What are Feedback Mechanisms?
Mechanisms that respond to changes in a system
Consist of receptors, control areas, and effectors.
What is the function of Receptors in feedback mechanisms?
Monitor variables/conditions
They provide input to the control area.
What is a Control Center in the context of homeostasis?
Integrates information and maintains setpoints by signaling to effectors
Examples include the Nervous System and endocrine glands.
Define Setpoint.
Range of values of a variable that do not trigger a response
Also referred to as the ‘normal range’.
What is Negative Feedback?
Most common homeostatic control mechanism that moves the variable back toward the set point
It works in the opposite direction to the change that triggered the response.
Provide an example of Negative Feedback.
Body temperature regulation
If body temperature increases to 40 ºC, effectors like blood vessels and sweat glands work to decrease it.
What is Positive Feedback?
Less common mechanism that intensifies the input, moving the variable further away from the set point
Example: Childbirth labor.
What happens during Positive Feedback in childbirth?
Output continues until an endpoint is reached
The endpoint is the baby being born.
