Thermoregulation

Thermoregulation Process by which animals maintain an internal temperature within a tolerable range. Critical to survival as biochemical & physiological processes are sensitive to changes in temperature (consider enzymatic reactions)

Before Viewing: How are organisms adapted in hot climates? Cold? Create a t-chart & list adaptations. During Viewing: Add adaptations (behavioural, morphological, physiological) to your t-chart. Include specific examples (elephant, penguin)

Homeotherms -maintain a stable internal temperature despite external temperatures. (mammals -including humans- and birds)

Poikilotherms - body temperature fluctuates with the environment eg. Insects, reptile, fish

Endotherms- body temperature is maintained internally through chemical reaction • Generally homeotherms are endotherms (not always)

Ectotherms- body temperature is maintained by external sources

What happens to the metabolic rates of ectotherms and endotherms as the environmental temperature changes?

Control (room temp.) Warm (10o above) Cool water (10o below) Group 1 Group 2 Group 3 Group 4 Group 5 Group 6 Average Purpose: To determine the effect that the environment has on metabolism of Daphnia.

Sketch the response of Daphnia’s metabolism to temperature Sketch the response of Daphnia’s metabolism to temperature. (heart rate, water jumps,etc) Based on the response of her metabolism to environmental temperature can you determine if Daphnia are homeotherms or poikilotherms? Explain.

Balancing Heat Loss and Gain Insulation Circulatory Adaptations Cooling by Evaporative Heat Loss

Insulation Feathers, hair or fat layers Reduces the flow of heat between an animal and its environment Lowers the energy cost of keeping warm

In mammals, the insulating material is associated with skin and hair Epidermis Sweat pore Muscle Dermis Nerve Sweat gland Hypodermis Adipose tissue Blood vessels Oil gland

Most land animals and birds react to cold by raising their fur or feathers Traps a thicker layer of air Increasing its insulating power (the more still air = more insulation!)

Restricts air flow, creating a warmer boundary layer Goosebumps Raise hair on skin Restricts air flow, creating a warmer boundary layer

Circulatory Adaptations We can alter the amount of blood (heat) flowing between the body core and the skin. Vasodilation Increases the diameter of vessels = more blood Increases heat transfer to surroundings.

Vasoconstriction Reduced diameter of blood vessels = less blood Reduces heat transfer Keeps blood (and heat) in the interior of body

Evaporative Heat Loss when the environment is hotter than the body: Sweat, pant, bathe, spread saliva over body surfaces Heat is carried away with water molecules as they change into a gas

What regulates our temperature? Hypothalamus - contains a group of nerve cells that function as a thermostat

What happens in response to heat stress in mammals? body becomes warm (environment, exercise) Thermoreceptors detects a change temperature hypothalamus interprets an increase in temperature skin blood vessels dilate sweat glands sweat increase blood flow to skin evaporation = heat loss heat lost through skin

On the previous chart, identify what is the sensor, integrator, and effector

What happens in response to cold stress in mammals? body becomes cooler (environment, inactivity) Thermoreceptors detects a change temperature Hypothalamus detects decrease in temperature blood vessels near skin constrict Skeletal muscles contract decrease blood flow to skin Shiver response (heat) Hair stands up heat is conserved

A. What is the difference between Topor For Tuesday Know: A. What is the difference between Topor B. What is Osmoregulation? Read section 9.4 Make note of the following: The importance of water balance Osmoregulation Why osmoregulation is tied to excretion What molecules are excreted from mammals, fish, and birds. Where these molecules originate