Lecture 11: Homeostasis Flashcards
homeostasis
the steady state of physiological conditions in the body
feedback stimulation
stimulus -> response
increase or reduce stimulus -> stimulus
negative feedback
response to a stimulus reduces stimulus
seq negative feedback
A cause B
B inhibits A
A goes away
B goes away
- opposite direction of stimulus
- equilibrium, maintains set point, normal range
positive feedback
response to stimulus amplifies stimulus
seq positive feedback
A cause B B amplifies A Stronger B, A stronger B - same direction of stimulus - physiological change in birth, contractions, ovulations - more extreme
all animals must do what regarding homeostasis
- regulate internal environment
- exchange with outside environment, food, waste products
regulator mechanism
- uses internal mechanism to control internal change regardless of external fluctuations
what is a result of regulator mechanism
- variable maintained at/near set point ( specific value) or normal range ( upper & lower limit)
- set point or range maintained by negative feedback
seq regulator
- normal range for internal variable
- stimulus: change in internal variable
- sensor
- control center
- response
conformer mechanism
allows internal environment to vary with certain external changes
osmoregulation
- regulation of solutes and water
- osmosis
hyperosmotic
- higher solute concentration
- lower free h2o concentration
hypoosmotic side
- lower solute concentration
- higher free h2o concentration
netwater flow
hypo to hyper
protocells
- maintain homeostasis
- internal environment different from outside
- distinct chemical environment inside vs. outside
paramecium
- unicellular protists (alveolates )
- generally freshwater (hypotonic env) -> water moves in via osmosis
- pumps water out to maintain water balance, prevents lysis
contractile vacuole
organelle for osmoregulation
jellyfish
- Phylum Cnidatria
- Diploblastic development: 2 adult tissue layer
- no circulatory system: all movement via diffusion
- flat morphology
diffusion sufficient for simple animals
- every cell is close to fluid
- inside or outside
- most animals more complex (even tiny ones)
plants
- adapted for terrestrial life, but still require water
- cuticle
- vascular tissue
- seed plants: pollen and seeds
humans
terrestrial animals
- take our marine environment with us on the inside ( maintains conditions, gases, pH, solutes)
terrestrial adaptations
amniotic sac: scales/skin, excretory system
living organisms are
open systems
living organisms must exchange with
environment: nutrients, waste products, and gases
substances dissolve in aqueous solution -> move across PM of each cell
puts limits on body plans
single celled organisms
SA:VOL: good enough to carry out all exchange
animals
- multicellular
- exchange occurs across PM of each cell
- every cell must have access to aqueous environment
compact masses of cells
- most animals
- increase # of celles decrease ration of outer SA to total Vol
specialized surfaces for exchange
- extensive branching or folding -> increases SA
- usually internal -> protected
internal body fluids
link exchange surfaces with body cells
interstitial fliud
fills spaces between cells
circulatory fluid
ex: blood
thermoregulation: endotherms
internal process
ectotherms
exchange from body to environment or environment to body
constraints on animals
- body size/shape limited by physical laws
complexity & orginization of animals
- allows animal to maintain relatively stable internal environment in a changeable external environment
- especially advantageous for terrestrial animals
hierarchical orginization of animal
- cell -> basic unit
- tissue: groups of cells with similar structure and function
- organ: different tissues organized into fucntion unit
- organ system: organs that work tg
- organism: result of emrgent properties
what are the 4 types of tissue in an animal
- epithelial
- connective
- muscle
- nervous
endocrine system
- system for coordinating and controling respoce to stimuli
- signaling by horomones
nervous systems
-signaling by nerve stimuli
endocrine regulation
involves hormones & feedback regulation
hormone is released by specfic cells & travels through body
cause physiological responce
examples of endocrine regulation
blood gluscoe regulation
antagonistic (endocrine system)
insulin -> stores sugar
glucagon -> releases sugar
organs (endocrine system)
pancreas: makes hormones
liver: stores glycogen
