Homestasis Flashcards
anatomy
biological form
physiology
biological function
name a product of evolution
body plan/organization
homestasis
the ability to maintain a constant internal environment in response to environmental changes
what is the basic characteristic of life?
all things regulate internal conditions in some way
feedback regulation
a change/stimulus causes a physiological response that then modifies the stimulus
negative feedback
- response reduces the stimulus
- maintains homeostasis
positive feedback
- response amplifies the stimulus
- DOES NOT maintain homeostasis
- not as common as negative feedback
what are the homeostatic conditions of all organisms
- regulate internal environment
- exchange with outside environment
- mechanisms depend on environment and type of organism
osmoregulation
- regulation of solutes and water
- living things may need different solute concentrations from the environment
- osmosis is passive
protocells
- though not living, do maintain HS -> internal environment different from outside
- purely chemical processes - osmosis and diffusion, across lipid bilayer
paramecium
- unicellular protists (SAR Clade [Alveolates])
- generally aquatic (freshwater)
- [solute] in cell > outside, hypotonic solution (water goes in via osmosis)
- has contractile vacuole: organelle from osmoregulation -> pumps water out to maintain water balance, prevent lysis
jellyfish
- Phylum Cnidaria
- diploblastic- 2 adult tissue layers
- no dedicated circulated system - all movement via diffusion (“Flat” morphology)
land plant
- adapted for terrestrial life, but still require water
- cuticle, stomata, vascular tissue
- seed plants: (pollen [they fly] and seeds [own internal environment])
humans
- terrestrial animals now, but first evolved from oceans
- we take marine environment with us on the inside (have to maintain conditions - gases, pH, water levels, etc)
amniotic sac
-amniotic fluid has salinity similar to sea water
-skin
excretory system
what physical laws is body size/shape limited by?
diffusion, movement, heat exchange
- ex: convergence in shape of swimming animals (tuna, seals, penguins)
- water is denser, more viscous in air
- selection for smooth body, streamlined shape
what does convergent evolution lead to?
the selection of similar adaptation
how does hierarchical organization help animals?
-allows animal to maintain homeostasis using limited cell/tissue types
(Cells -> Tissues -> Organs -> Organ System)
what are the four main tissue types in animals?
epithelial, connective, muscle and nervous
conformer
allows internal environment to vary with external change
regulator
uses internal mechanisms to control internal conditions, independent of external conditions
-many animals will regulate some conditions, conform to others
how is HS maintained for regulators?
variable maintained at/near specific value (set point) on within normal range
-via negative feedback
how is HS maintained for endotherms (warm blooded)?
temperature regulators
list some adaptations for exchange
- large size -> need for transport systems
- branching (increases SA)
- folding
- interstitial fluid (fluid between organs - medium used or different levels of HS)
- blood
Large Branches Fold Into Bark
can tissues, organs, and organ systems work independently of each other?
NO. THEY MUST WORK TOGETHER
what two systems coordinated responses to stimuli
- endocrine: signaling by hormones
- nervous: signaling by nerve impulse
glucose homeostasis
blood sugar regulation
- controlled by 2 antagonistic hormones
- insulin -> store sugar
- glucagon -> release sugar
- controlled by 2 organs
- pancreas: makes hormones
- liver: stores glycogen
