Animal form (morphology) and function (physiology) 2

Homeostasis

stability of an animal’s internal environment

despite changes in the external environment

what is a regulator

use internal control

mechanisms to regulate and

maintain homeostasis, e.g.

thermoregulation,

osmoregulation

what are Conformers

internal (body)

environment changes with change

in external environment

set point

many physiological variables are

maintained at or near a particular value

human body temp

~37°C

Small bird body temperature

42-44°C

Human blood pH

pH 7.4

Shark plasma osmolarity

1000 mOsm

what is important for cell function

Many plasma metabolites, nutrients and ions are regulated at particular

values, e.g. glucose, calcium, iron and Na+, K+

what does homeostasis depend on

negative-feedback

control which reduces or opposes the change

or perturbation

how do animals achieve homeostasis

negative feedback

negative feedback

some function of the output of a

physiological system is fed back in a manner that

tends to reduce fluctuations or disturbances in the

output

Thermoregulation

-an example of homeostasis integrating form, physiology and behaviour

-he process by which animals maintain an internal body temperature (T body) within certain range

why is thermoregulation important

v. important because physiological/biochemical reaction rates are temperature-sensitive, changing 2-3 fold for every 10°C change in T body

Homeostasis around a “set point” is…

not absolutely fixed or static but can be variable

fever

a resetting of bodies thermostat to higher set point

Regulated changes in homeostasis…

are essential for normal body function

daily cycles

circadian rhythms controlled by biological clock

(expressed by hormone melatonin)

Hibernation (torpor):

abandoning maintenance of high

Tb but not abandoning homeostasis