[raman1]

I dont get homestasis and the way to write stuff.

Can you please help me with these questions:

1) Explain how normal core body temperature is maintained when a person moves into a cold room.

[jennifer.tariah]

when they move into a cold room, the receptors on the skin detect the external temperature change then send signals to the brain then yada yada, the hairs on your arm rises to to trap a layer or heat, you shiver to make your muscles move and create heat..

[Madmia]

The temperature of the core of your body is the most important (for obvious reasons) which is why the heat is focused there, rather than on your extremities (finger, toes etc) Signals will be sent to your brain and the arrector pili muscles will force the hairs to stand up and create an insulating layer of air. The shivering reflex uses energy to generate heat too. The blood vessels will also dilate to prevent further heat loss Hope that helps ^^

[thegodofgod]

(Original post by Madmia)
The temperature of the core of your body is the most important (for obvious reasons) which is why the heat is focused there, rather than on your extremities (finger, toes etc) Signals will be sent to your brain and the arrector pili muscles will force the hairs to stand up and create an insulating layer of air. The shivering reflex uses energy to generate heat too. The blood vessels will also dilate to prevent further heat loss Hope that helps ^^

Blood vessels don't dilate - sphincter muscles, which control the diameter of the arterioles, contract, shunting blood away from the surface of the skin, in order to conserve heat.

Shivering occurs because the aerobic respiration in muscles is very inefficient (only around 20% efficiency, I think), meaning a lot of heat is lost and less ATP is generated. The heat loss from respiration is what is used to heat you up.

[Madmia]

*The blood vessels constrict - My mistake
(Vasoconstriction)

[John Locke]

is this labelled correctly? as an undergraduate a substantially more impressive response is required, what do you know so far?

you would need to include the relative significance of different heat loss mechanisms, the role of polymodal C-fibre sensory receptors and ascending spinal pathways. The role of behavioural changes related to temperature via the somatosensory cortex. The role of the hyopothalamic nuclei in both sensing temperature (anterior, preoptic), paraventricular and sympathetic outflow and supraoptic/paravent in initiating endocrine axes (TRH etc). Autoregulation of cutaneous vasculature in addition to the role of the SNS outflow (incl. reduced sweating). could add in some pathologies such as hypothermia (incl. ecg changes etc), frostbite/trenchfoot and Raynaud's.

edit:

(Original post by thegodofgod)
Shivering occurs because the aerobic respiration in muscles is very inefficient (only around 20% efficiency, I think), meaning a lot of heat is lost and less ATP is generated. The heat loss from respiration is what is used to heat you up.

that makes no sense at all, the efficiency of mechanical work is around 20% but in what way does that describe the mechanism of involuntary contraction-relaxation cycles of skeletal muscle specific to cold? it doesn't, shivering is a different phenomena.

heat loss from respiration is an interesting one especially in light of the role of brown adipose, the thyroid hormones and the sympathetic innervation (esp in babies). are you edexcel? if so your case study briefly touches on this kind of thing.

[Madmia]

- Only Doing AS Levels Now, Hence why I couldn't give a more detailed response, and Homeostasis is not part of my As course -