intro to homeostasis

homeostasis

the body’s attempt to maintain ideal internal conditions despite changes in internal/external environment

human body systems functions

transport materials, add/remove substances from blood, communicate w brain/spinal cord, enable body to move, allow responses from external/internal stimuli, secrete chemicals for messaging btwn cells, produce sex hormones to produce and transport gametes

transport materials

circulatory, lymphatic and immune system

add/remove substances from blood

digestive, respiratory, excretory

communicate w brain and spinal cord

nervous via sensory receptors of integumentary system

enable body to move

muscular and skeletal systems

allow respinse form external and internal stimuli

nervous system

secrete chemicals from messaging btwn cells

endocrine system

produce sex hormones and transport and produce gametes

reproductive systems

Where does body wanr to maintain ideal conditions

within interstitial fluid and blood plasma

homeostasis equilibrium

dynamic equilibrium; remains stable within fluctuating limits

body temp fluctuation; how

+2C w exercise and -2C w sleep; able to do so with feedback

feedback (detection correction systems) parts

sensor that detects environmental changes, a control centre that compares existing conditions w ideal ones, an effector that acts to restore ideal conditions

2 types of feedback systems

positive and negative

positive feedback systems

body works to reinforce (amplify) the change detected, less common, effectors enhance the change

positive feedback systems ex

blood clotting and contractions

negative feedback systems

body works to reverse change detected, primary mechanism of homeostasis, effectors oppose change so variable is brought back to normal range

thermoregulation

process of maintaining internal body temperature within a range that enables cells to function efficiently

thermoreceptors

detect temperature deviations from the ideal and trigger behavioral and physiological responses

excessive heating

thermoreceptors detect rise in body temp → send signal to hypothalamus → sends signal to effectors to initiate response → sweat glands + blood vessels

sweat glands in heat

evaporation of sweat from skin causes cooling

blood vessels in heat

vasodilation allows more blood flow to surface

excessive cold

thermoreceptors detect drop in body temp → send signal to hypothalamus → sends signal to effectors to initiate response → blood vessels + smooth muscle surrounding hair follicles

blood vessels in cold

vasoconstriction to reduce blood flow to surface (decreas heat loss)

smooth muscles surrounding hair follicles

contractions cause goosebumps, hair stands up to trap warm air

shivering

rhythmic contraction of skeletal muscle that generate heat by increasing metabolism