Confirming my answers :)
Can't remember the exact question but it's along the lines
of,
(a) "In extremely cold conditions, the cells in fingers and toes
die. This is frostbite. Explain why wearing thick gloves, socks and
shoes does not prevent frostbite." [5]
I wrote that the constriction of arterioles
and dilation of shunt vessels(why do these
happen?) prevents
the flow of blood
to the capillaries in the skin, thereby cutting off
blood supply to the skin. Fingers and toes contain capillaries.
When the blood supply is cut off for too long, the cells in fingers and toes do
not receive oxygen for respiration or nutrients vital for
survival, and the cells will eventually
die. This is frostbite. Thick gloves, socks and
shoes only prevent heat loss through radiation or convection, and
do not prevent the cutting off of blood supply to the skin.
(I also added in redundant parts about the sweat production
decreasing and metabolic rate increasing to lengthen my answer)
--> better hope no excess denied
If all goes well, you get the 4-5 marks, depending. Because
you didn't talk about why the arterioles constrict and more blood
flows through the shunt vessels. It is to reduce heat loss through
the skin in cold conditions by having less blood flowing under the
skin.
(b) "In cold conditions, shivering takes place. Explain why this
happens." [3]
When production of sweat is decreased, metabolic rate is
increased and blood flow to the skin is stopped is not sufficient
to reduce heat loss and increase body temperature back to normal,
this stimulates us to shiver. Movements in the muscles warm
the body up.
You don't seem to be answering the question directly in the
first few lines.
(c) "Explain how the mechanics for control of body temperature
are synchronised." [2]
They are synchronised by homeostasis. When the hypothalamus detects the body
temperature rising above or falling to below
average, the brain sends signals to
various body parts to work to increase or decrease body
temperature, depending on if the body temperature
is below or above normal.
When I see this question, I thought it was something on
negative feedback, well, never mind, I ain't sure anyway.
Something like that.
Just my own opinion.