SB7f Thermoregulation Flashcards
What is the role of the skin? (4)
Barrier preventing entry of microorganisms
Waterproof layer (impermeable)
Sensing objects, pain, temperature (stimuli)
Prevents loss of water and heat from the body (layer of insulation)
What is the normal body temperature?
37°C
What happens at temperatures higher than 38°C?
Hyperthermia (fever).
What happens at temperatures lower than 36°C?
Hypothermia.
What part of the brain controls thermoregulation?
hypothalamus
What mechanisms occur when it is too hot?
Too hot:
Erector muscles relax and hair lies flat.
Sweat glands produce sweat that spreads over the skin epidermis – heat loss by evaporation.
Vasodilation – heat loss by radiation. The small arteries widen so more blood flows near the skin surface.
What mechanisms occur when it is too cold?
Erector muscles contract so hair is raised – trapped air helps insulate the body.
Vasoconstriction – the capillaries near the skin surface constrict
(become narrow) so less blood flows near the skin and helps
maintain the core temperature.
o Shivering causes muscles to contract so they respire a lot and
produce more heat.
What is vasoconstriction and how does it heat up the body?
Vasoconstriction is caused by contraction of the muscular wall of the blood vessels.
This reduces the volume of blood flowing near the skin surface, and
reduces the amount of heat lost from the body
What is vasodilation and how does it cool down the body?
When core body temperature rises, blood vessels in the skin get wider. This is called vasodilation.
Vasodilation allows a larger volume of blood to flow near the skin surface, transferring heat to the environment. This cools the body down by radiation
How does sweating cool us down?
As the sweat evaporates it transfers heat away from the body. Heat loss by evaporation.
