Homeostasis Flashcards
What is homeostasis?
process of maintaining a relatively constant/stable internal environment
What is the set point?
the measure that the body is trying to maintain with homeostasis
What is the external environment?
outside the body
What is the extracellular fluid?
internal environment; inside body, outside the cells
What makes up the extracellular fluid?
plasma and interstitial fluid
What is the intracellular fluid?
intracellular environment= inside the cells, cytoplasm
Is homeostasis dynamic or static?
dynamic
-levels change over short period of time but remain constant over long period of time
When homeostasis is maintained it is…
physiology
When homeostasis is not maintained it is…
pathophysiology
What is cellular homeostasis?
function of each cell
cytoplasm of single cell
necessary for normal cell function
relies on component of extracellular fluid
What are the two types of extracellular fluid homeostasis?
local and systemic
What is local homeostasis?
-restricted to one tissue space
-utilizes paracrines and autocrines
-maintain function of tissue
What is systemic homeostasis?
-involves entire body
-utilizes nervous system and endocrine system
-maintain function of heart and brain
What systems are involved with systemic homeostasis?
endocrine and nervous system
What type of signaling are involved with local homeostasis?
autocrine and paracrine
What must be maintained in order for the cells to maintain homeostasis?
extracellular fluid
What is the order of the simple systemic homeostatic process?
-stimulus
-reflex receptor
-afferent pathway
-integrating center
-efferent pathway
-effector
-effector response
What is the stimulus?
first domino
-changes in ECF composition, body temp, BP, etc
What does the threshold stimulus (sensitivity) determine?
the amplitude of the normal range
What actually are the reflex receptors?
cluster of cells, individual cells, cell parts or molecules in the membrane or cytoplasm of cells
What is the reflex receptor?
detects changes in substance
What type of reflexes have afferent pathways?
ONLY nervous system reflexes
-NOT THE ENDOCRINE SYSTEM
What is the threshold stimulus?
determines amplitude of the normal range
why does the endocrine system not have an afferent pathway?
integrating stuff is already in the endocrine system so do not have to bring it to one for signaling
What is the afferent pathway?
carries information from reflex receptors to integrating center
-NS reflexes only
-sensory neurons
What is the integrating center?
receives stimulus, analyzes information and generates appropriate response
What are the integrating center are in the endocrine system?
endocrine gland
What are the integrating centers of the nervous system?
brain/spinal cord
What is the efferent pathway?
carries commands from integrating center to effectors
What is the efferent pathway for the endocrine system?
hormones
What are the efferent pathways of the nervous system?
motor neurons
What is the effector?
any cell affects by efferent pathway
What are the two levels of the effector response?
local effector response and systemic effector response
What is the local effector response?
how the cell (effector) function is changed by the efferent pathway
What is the systemic effector response?
how ECF (whole body) changed by local effector response
Is there only one way to make systemic responses?
no, there are normally many local effectors that will cause the same systemic effector
What is feedback regulation?
how systemic effector response changes the function of the reflex receptor
What are the two types of feedback regulation?
Negative and positive feedback
What is negative feedback?
decreases activity shutting off pathway
-keeps variable fluctuating around the setpoint (homeostatic)
What is positive feedback ?
increases activity further activating pathway (non-homeostatic)
What is tonic level of activity?
at rest, a homeostatic pathway is neither completely shut off or fully active
What is antagonistic control?
in many instances a single systemic effector response is controlled by two different efferent pathways but in opposite directions
What is mechanistic explanation?
describes how something happens
What is an example of positive feedback?
blood clotting
What part of the homeostatic process is involved with tonic level of activity?
efferent pathway
