physio ch. 1

Homeostasis

Ability to maintain relatively constant internal environment.

Internal environment

immediate environment of most cells

External environment

external side of epithelial body barrier

regulated variable

aspect which is maintained

organs

two tissue types performing a specific function

organ system

collection of organs performing a task

what does internal environment include

plasma and tissue fluid

what does external environment include

air in lungs, food in stomach, urine in bladder, and surrounding external to skin

what are examples of a regulated variable

blood glucose and temperature

set point

expected value of regulated variable

negative feedback

effector works opposite of the factor. if regulated variable decreases, system responds to increase

positive feedback

effector pushes factor further from set point

what are the homeostatic control mechanisms

receptors, integrating center, and effectors

receptors

sensors detect stimuli & relay signals to integrating center

intergrating center

receives signal from receptors & makes appropriate response. sends signals (output) to effectors

where is integrating center located

brain or endocrine glands

effectors

body responses & receives signals from integrating center

four cell/tissue types

nervous, muscle, epithelial, and connective