Chapter () - Animal Form and Function Flashcards
homeostasis definition
the maintenance of a relatively stable internal environment despite changing external conditions
how are internal fluctuations coordinated?
by processes of chemical and or electrical signalling
do homeostatic mechanisms maintain internal conditions at a constant value?
no, they maintain it within a relatively small range of values
regulator definition
uses mechanisms of homeostasis to moderate internal change in the face of external fluctuations
conformer definition
allows some conditions within its body to vary with certain external changes
osmoregulation definition
management of the body’s water content and solute composition
what percent of the earth’s surface is covered with water?
71% (mostly seawater)
osmosis definition
diffusion of water across a selectively permeable membrane
osmolarity definition
osmoles of solute particles / volume (L) (1 osmole = 1 mole of osmotically active particles)
osmoconformer definition
animal that does not actively adjust its internal osmolarity because it is isoosmotic with its environment
osmoregulator definition
animal whose body fluid has a different osmolarity than that of the environment
- animal that lives in a hypoosmotic environment must discharge excess water
- animal that lives in a hyperosmotic environment must take in water
- expends energy to control its internal osmolarity
water balance in fresh water. what do the organisms have to deal with?
osmoregulators, gain water by osmosis and food, lose salts by diffusion and in urine, regain salts in food and by active uptake from surroundings, excrete large amounts of dilute urine
water balance in the ocean - what do most marine invertebrates do?
they are osmoconformers, total osmolarity = seawater, individual [solute] does not equal seawater
- they conform to osmolarity of the ocean, but regulate internal ionic composition
water balance in the ocean - what do most marine vertebrates do?
they are osmoregulators, lose water by osmosis, gain water and salt in food and by drinking seawater, dispose of salt by active transport out of gills and in urine, produce small quantities of urine
stenohaline definition
organisms that cannot tolerate substantial changes in external osmolarity
euryhaline definition
organisms that can tolerate substantial changes in external osmolarity
transport epithelium definition
layer(s) of specialized cells that regulate solute movements
- most important feature: the ability to move specific solutes in controlled amounts in particular directions
- cells joined by tight junctions
- in most animals: arranged into tubular networks with extensive surface areas
animals regulate solute content of body fluid that bathes their cells
anhydrobiosis definition
“life without water”, the ability to survive in a dormant state when an organisms habitat dries up
what is the largest problem with osmotic balance on land
desiccation; adaptations that reduce water loss are key to survival on land
how is water loss reduced for organisms that live on land?
body coverings, nocturnal habit, drinking and eating moist foods, using metabolic water
elements of homeostatic systems (3)
sensor, integrator, effector
sensor in a homeostatic system
the sensor perceives a change and notifies the integrator
integrator in a homeostatic system
the integrator compares the sensor’s input with an internal setpoint, it then gives orders to the effector
