Anatomy 1.7-1.8

homeostasis

the existence of a stable internal environment

homeostatic regulation

adjustment of physiological systems to preserve homeostasis

autoregulation

a process that occurs when a cell, tissue, organ, or organ system adjusts in response to some environmental change

extrinsic regulation

a process that results from the activities of the nervous system or endocrine system

nervous system

directs rapid, short-term, and very specific responses

nervous system example

the hand is placed on a hot stove, this system responds by ordering specific muscles to pull your hand away

endocrine system

releases chemical messengers called hormones into the bloodstream

what 3 parts does a homeostatic regulatory mechanism consist of?

Receptor, control center, effector

receptor

a sensor that is sensitive to a particular stimulus or environmental change

control center

receives and processes the information supplied by the receptor and sends out commands

effector

a cell or organ that responds to the commands of the control center and whose activity either opposes or enhances the stimulus

negative feedback

an effector activated by the control center opposes, or negates, the original stimulus

thermoregulation

the relationship between heat loss which takes place mainly at the body surface, and heat production, which takes place in all active tissues, is altered

hypothalamus

thermoregulatory control center, is a region of the brain

What control center receives info from 2 sets of temp receptors (one in skin and one within the hypothalamus)?

hypothalamus

Normal set point of body temp

37 c or 98.6 f

positive feedback

a mechanism that increases a deviation from normal limits after an initial stimulus

example of positive feedback

blood clotting after a cut, labor and delivery

equilibrium

exists when opposing processes or forces are in balance

dynamic equilibrium

each physiological system functions to maintain a state of equilibrium that keeps vital conditions within a normal range

what effector organs are engaged when body temp drops below 37 c?

muscles

what effector organs are engaged when body temp rises above 37 c?

sweat glands

hypothermia

the body loses heat faster than it can produce heat

hyperthermia

the body produces heat faster than it can lose heat

where in the body are temp sensors located?

blood vessels

What are examples of items that are homeostatically controlled?

blood pressure, blood volume, heart rate, blood ph, blood lipid levels, blood potassium levels