Controlling Controlling the Internal Environmentthe Internal Environment

Marie ČernáMarie Černá

Three main controls:Three main controls:

• Regulation of body temperature

• Water and Mineral balance

• Nitrogenous wastes

Regulation of body Regulation of body temperaturetemperature

ThermoregulationThermoregulation

The maintenance of

body temperature within

a range that enables

cells to function efficiently.

Four physical processes Four physical processes account for heat gain or lossaccount for heat gain or loss

• Radiation

• Conduction

• Convection

• Evaporation

Aspect of human evolutionAspect of human evolution

Relationship betweenRelationship between radiation and evaporation radiation and evaporation

The relationship between body and The relationship between body and ambient temperaturesambient temperatures

• Endotherms derive body heat mainly from metabolism

• Ectotherms derive body heat mainly from their surroundings

Torpor conserves energy during Torpor conserves energy during environmental extremesenvironmental extremes

is an alternative

physiological state in which metabolism (including body temperature) decreases and the heart and respiratory system slow down

Hibernation –

long-term, winter torpor

Brown fat produces heatBrown fat produces heat

• Thermogenin channel• ATP synthesis block

Vascular toneVascular tone

SweatingSweating

Heat balanceHeat balance

The thermal image of a sea-bear The thermal image of a sea-bear on a rock surrounded by wateron a rock surrounded by water

Water and Mineral balanceWater and Mineral balance

Water balanceWater balance

• Diffusion – the spontaneous tendency of a substance to move down its concentration gradient from a more concentrated to a less concentrated area

• Osmosis - the diffusion of water across a selectively permeable membrane

OsmolarityOsmolarity

solute concentration expressed as molarity

Osmotic pressure – a measure of the tendency of a solution to take up water when separated from pure water by a selectively permeable membrane

Mineral balanceMineral balance

Homeostasis:Homeostasis:Blood osmolarityBlood osmolarity (ADH) (ADH)

Homeostasis:Homeostasis:Blood pressureBlood pressure

Nitrogenous wastesNitrogenous wastes

LiteratureLiteratureBiology, eighth edition,

Campbell, Reece

Unit seven: Animal Form and Function

Chapter 40: Basic Principles …

Concept 40.3

Chapter 44: Osmoregulation and Excretion

Concept 44.1 and 44.2

Pages 862 – 868, 954 – 960