bio exam 3 Flashcards by Faith Kalsow

Homeostasis

maintenance of a dynamic equilibrium in the body

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set point

organisms are usually maintained within a tolerable range.

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conformers

allow their internal condition to become similar to the external environment

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why is homeostasis important?

stable internal environments maximize enzyme efficiency

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what helps maintain homeostasis?

Epithelial tissue, homeostatic systems, hormones

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homeostatic system components

sensor, integrator, effector

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homeostasis systems are based on ____feedback and work in _______ pairs

negative, antagonistic

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conduction

direct transfer of heat between two physical bodies that re in contact with each other

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convection

a special case of conduction: heat is exchanged between a solid and a moving liquid/gas

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Radiation

Transfer of heat between two objects that are not in direct contact

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Evaporation

occurs when a liquid becomes a gas; leads only to heat loss

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Endotherm

heat byproduct of chemical reactions warms the body

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ectotherm

heat comes from the environment

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Homeotherm

keep their body heat constant

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poikilotherm

allows body temperature to rise or fall depending on environmental conditions

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Torpor

temporary drop in body temperature

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Hibernation

a larger drop in body temperature

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Advantages of endothermy

enzymes are maintained at constant temperature at all times
can remain active in winter and at night
the high metabolic rate enables them to sustain high levels of aerobic activity, such as running or flying

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Disadvantages of endothermy

Must consume large quantities of energy-rich food
energy used to produce heat is unavailable for growth, reproduction, and other processes

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advantages of ectothermy

survive on much less food
greater proportion of their energy allocated to reproduce

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Disadvantages of ectothermy

temperature-dependent chemical reactions slow down as body temperature drops
molecular activities are slower in cold environments, making these animals more vulnerable to predation
overall, less successful at inhaviting cold environments

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countercurrent heat exchange

bundles of arteries form heat exchangers that minimize heat loss from the cold

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osmoregulation

helps maintain homeostasis by regulating water and solute levels driven by total solute concentration

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osmolarity

concentration of all solutes within a solution

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hyperosmotic

if solution A his a higher osmolarity than solution B, then solution A is hyperosmotic to solution B

Hypoosmotic

If solution A has a lower osmolarity than solution B, then solution A is hypoosmotic to solution B

isosmotic

solution A and solution B have the same osmolarity

Osmotic stress

concentration of dissolved substances in a cell or tissue is abnormal

osmoconformers

in osmotic equilibrium with their environment: have extracellular fluids that are isosmotic to seawater

Osmoregulators

actively maintain a relatively constant blood osmolarity, different than the surrounding environment

Freshwater animals live in a ______ environment

hypoosmotic, water is hypoosmotic to fish's tissues

Saltwater animals live in a ______ environment

hyperosmotic, water is hyperosmotic to fish's tissues

advantages of freshwater fish

drink little to no water, excrete large amounts of dilute urine, actively take up ions through gills

challenges of freshwater fish

tend to gain water by osmosis, tend to lose electrolytes by diffusion

challenges of saltwater fish

tend to lose water by osmosis, tend to gain electrolytes by diffusion

Adaptations for saltwater fish

drink large amounts of sea water, excrete concentrated urine, actively excrete ions through gills

euryhaline species

travel from freshwater to saltwater

aquatic animals excrete

ammonia by diffusion through their gills

sharks, amphibians, and mammals excrete

urea (soluble in water, requires more energy to produce than ammonia)

Birds, terrestrial reptiles and insects excrete

Uric acid (least toxic of 3, requires the most energy to make)

function of urinary system

eleminate nitrogen-containing waste products, aintain the apporpriate water and electrolyte balance

Anatomy of urinary system

kidney, ureter, bladder, Urethra

The renal vein carries filtered blood ____ from the Kidneys

away

The renal artery carries blood containing nitrogenous waste ___ the kidneys

the outer layers of the kidney is called the

cortex

the inner layer of the kidney is called the

medulla

the glomerulus and convoluted tubules are located in the

cortex

the loop of Henle and collecting ducts are located in the

medulla

Renal corpuscle function

filtration

Proximal tubule

reabsorb electrolytes (active transport), nutrients, water

Descending limb

permeabe to water (passive

thin ascending limb

permeable to Na and CL (passive

thick ascending limb

active transport of Na and Cl out of filtrate

Loop of Henle

maintain osmotic gradient of interstitial fluid from outer to innner medulla

collecting duct

regulates water retention

negative feedback loop

turns off

positive feedback loop

turns on, variabes change even more

endocrine signaling

great distance through blood stream

paracrine signaling

short distance

autocrine signaling

on same cell

juxtracrine signaling

not secreted, direct contact

ADH is produced in response to

high plasma osmolarity or decrease in blood volume

ADH

makes cells more permeable to water

Abiotic

environmental stimulus (light, gravity, cold, drought, wind, touch, nutrition)

Biotic

stimulus caused by living things

Gibberellins

promote plant growth

Abscisic acid (ABA)

limits plant growth

Dendrite

recieves info

what ion is released in the depolarization phase?

what ion is released in the repolarization phase?

graded potential is initiated at...

dendrites

graded potential is stimulated by...

external stimulus (temperature, pressure, neurotransmitter from another neuron)

graded potential travels through cell due to...

local current flow (diffusion of ions through cytoplasm)

graded potential's direction of membrane potential change....

depolarizing or hyperpolarizing

graded potential's strength of signal conveyed by...

magnitude of voltage change

Action potential is initiated by....

axon hillock

Action potential is stimulated by...

depolarized membrane potential above threshold

Action potential travels through cell due to...

successive opening of voltage-gated Na+ channels along the axon

Action potential's direction of membrane potential change....

always depolarizing

Action potential's strength of signal conveyed by...

frequency with which new action potentials are generated