week 10b Flashcards
(37 cards)
what is homeostasis
process by which cells, tissues, and organs maintain stable internal conditions by responding to changes in the extracellular fluid
what are the 4 components of a homeostatic control system
- set point = normal value for a variable
- sensor = monitors the variable
- integrator = compares sensor signal to set point
- effector = responds to correct the deviation
what is negative feedback
a regulatory mechanism in which a change in a variable triggers a response that reverses the direction of the change, returning it to the set point
why is negative feedback important
prevents overcompensation and maintains balance by bringing conditions back toward normal
how does the body regulate blood pressure via homeostasis
sensor = blood vessels and heart detect pressure changes
integrator = brain processes the change
response = brain stimulates hormone release
effector = hormones cause vasoconstriction to raise blood pressure
what is positive feedback
regulatory mechanism that amplifies changes rather than returning to a set point, accelerating the deviation from normal
2 examples of positive feedback
blood clotting and childbirth
what is feedforward regulation
body anticipates a change in a variable and prepares in advance to minimize the deviation from set point
example of feedforward regulation
salivation and enzyme secretion before eating, increased heart rate before exercise
what is paracrine signaling
type of localized chemical signaling where molecules are released into interstitial fluid to act on nearby cells
what are neurotransmitters
chemical messengers released by nerve cells that act on adjacent nerve or muscle cells
what are hormones
long distance chemical messengers secreted by endorcrine glands into the bloodstream, acting on distant target cells
what are 2 main fluid compartments in animals
intracellular fluid and extracellular fluid
what is hemolymph
combined fluid of blood and interstitial fluid found in invertebrates with an open circulatory system
what is passive transport
movement of solutes down their concentration gradient with no energy required
what is the difference between simple and facilitated diffusion
simple diffusion = no protein needed; for nonpolar molecules or gases like O2 and CO2
facilitated diffusion = requires transport proteins, for most polar or charged solutes
what is active transport
movement of solutes against their concentration gradient using energy (ATP)
how does water move across membranes
through osmosis, driven my pressure differences, and via aquaporins which allow faster water permeability
what happens when cells are in a more concentrated or dilute solution
concentrated = cells shrink
dilute = cells swell and may burst
what is crenation
shrinkage of red blood cells due to water loss when placed in a hypertonic solution
what is hemolysis
swelling and bursting of red blood cells due to excessive water intake in a hypotonic solution
why is maintaing water and ion balance critical
- water is vital for chemical reactions
- dehydration reduces blood volumes
- small changes in ion levels can disrupt cell function
what is osmolarity
the solute concentration of a solution, measured in milliosmoles per liter
what are obligatory exchanges
processes that animals must perform that affect water and ion homeostasis, such as respiration, feeding and waste elimination
