Communication & Homeostasis

why animal and plant communicate

-need to be able to respond to changes in internal and external environment

-coordinate activities of different organs

-need different control communication system

homeostasis

-maintenance of internal environment in constant or stead state despite changed in external environment

-to maintain optimum condition for function

-in response to internal and external changes

physiological factors controlled by homeostasis in mammal

-core body temperature

-metabolic waste

-blood pH

-glucose conc in blood

-wp of blood

-conc of O and CO2 in blood

Which two communication systems in mammals transfer information to different parts of the body?

-nervous system

-endocrine system

cell signalling

-process by which cells communicate with each other

-allows multicellular organisms to control and coordinate their bodies and respond to environment

stages of cell signalling

-stimulus

-receptor

-communication system

-effector

-response

receptor

-monitor conditions inside body

-if change detected; receptor stimulated to communicate w/ effector

effector

-cells respond to reverse change

How are signalling molecules adapted to cross cell surface membranes?

-v small

-easy transport across cell membrane

where receptor molecules are

-on or in cell surface membrane

-some in cyto; receptor for steroid hormone as can diffuse membrane

How does the signalling mol ecule cause specific changes in the receiving cell?

by binding to receptor molecule

negative feedback

-response to change in body that counteracts or opposes intial change

components that make up negative feedback loop

-receptor/sensor

-coordination system; nervous/endocrine system

-effector; muscles/gland

positive feedback

-enhances effect of original stimulus

why we need stable core temp

-enzyme activity

-low temps = reduce kinetic energy of molecules and slow down chemical reactions

-high temps = denatures enzyme so rate of reaction drops

peripheral receptors

-thermoreceptors found in skin and mucous membrane in endo animals

-detect heat and cold

-impulse sent from these receptors to hypothalamus

what do receptors in hypothalamus do

-monitor temp of blood flowing thru it

endotherm

-animals that posses physiological mechanisms for internal body temp maintenance

what endotherms do when high body temperature

-vasodilation

-sweating

-hairs flatten

heat and vasodilation

-arteriole muscle relax

-more blood flow to skin capillaries

-heat lost to environment via radiation

heat and sweating

-sweat glands secrete sweat

-heat energy from bod used to evaporate liquid water

-not effective in humid environments

-less water vapour conc gradient between skin and air

heat and hair flattening

-hair erector muscle relax

-stops hair forming insulating layer of air

-allowing air to circulate over skin

-removes heat lost by radiation

how do endotherms respond to low body temperatures

-vasoconstriction

-increased metabolic rate

-shivering

-erection of hairs

heat and vasoconstriction

-muscles in arteriole wall contract

-allow less blood thru skin capillaries

-reduces heat lost by radiation

inc metabolic rate and heat

-most metabolic reaction are exo

-provides warmth to body

-thyroxine inc BMR

-inc heat prod

shivering and heat

-muscles contract and relax in quick concession

-metabolic reactions req to power muscle contraction; releases heat energy to warm blood

-raises core body temp

hair stand on end and heat

-contraction of hair erector muscle

-traps insulating layer of air over skins surface

-reduce heat lost

ectotherm

-animals that rely on behavioural mechanisms to ensure to maintain internal body temperatures

what cant ectotherms do

-respond to environmental changes via internal temp regulation mechanisms

-use behavioural mechanisms instead

What ectotherms do to raise body temperatures

-seek out sun or warmer surfaces; bask in these location till body temp has been inc sufficiently

-huddle tgthr to retain heat. that may have been gained from sun

What ectotherms do to lower body temperature

-seek shade

-move bodies into water

ectotherm benefit

-save energy by not regulating body temperature internally; nutritional requirements are lower

-can survive in environments where food is limited

-aquatic ectotherms have less difficultly maintaining stable internal body temp; water temp less variable than land

-water has high SHC