Download 33-Controlling-the-Internal

Controlling
the Internal Environment
Marie Černá
Three main controls:
• Regulation of body temperature
• Water and Mineral balance
• Nitrogenous wastes
Regulation of body
temperature
Thermoregulation
The maintenance of
body temperature within
a range that enables
cells to function efficiently.
Four physical processes
account for heat gain or loss
•
•
•
•
Radiation
Conduction
Convection
Evaporation
Aspect of human evolution
Relationship between
radiation and evaporation
The relationship between body and
ambient temperatures
• Endotherms derive
body heat mainly from
metabolism
• Ectotherms derive
body heat mainly from
their surroundings
Torpor conserves energy during
environmental 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 heat
• Thermogenin channel
• ATP synthesis block
Vascular tone
Sweating
Heat balance
The thermal image of a sea-bear
on a rock surrounded by water
Water and Mineral balance
Water 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
Osmolarity
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 balance
Homeostasis:
Blood osmolarity (ADH)
Homeostasis:
Blood pressure
Nitrogenous wastes
Literature
Biology, 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