7 - HOMEOSTASIS Flashcards
what is homeostasis?
The maintenance of a stable internal environment
What happens when there is no homeostasis and therefore the body temperature is too high? (5)
- the enzymes denature
- because they vibrate too much
- and the hydrogen bonds that hold their 3D structure break
- The shape of the active site therefore changes
- it cannot longer work as a catalyst and all metabolic reactions are less efficient
What is negative feedback?
Negative feedback is when there is a deviation from the norm that results in a change in the opposite direction (back to the norm)
What is positive feedback?
Positive feedback is a mechanism, which amplifies the change (increases the change)
What are the mechanisms to reduce body temperature?
- Sweating
- Hairs lie flat
- Vasodilation
Explain the sweating mechanism
more sweat is secreted from the sweat glands, and when this sweat evaporates the surface of the skin takes heat from the body and therefore cools it.
Explain the hairs lie flat mechanism
the erector pili muscles relax so the hairs lie flat. Therefore less air trapped, so the skin is less insulated and heat can be lost more easily
Explain the vasodilation mechanism
when its too hot, the arterioles near the surface, dilate. More blood therefore flows through the capillaries in the surface layer of the dermis. Meaning that more heat is lost from the skin by radiation and the temperature is lowered.
What are the mechanisms to increase body temperature?
- Shivering
- Much less sweat
- Hairs stand up
- Vasoconstriction
- Hormones
Explain the shivering mechanism
When its cold muscles contract in spasms. Thus making the body shiver and more heat is produced from increased respiration
Explain the much less sweat mechanism
Less sweat is secreted from the sweat glands when it’s cold, reducing the amount of heat loss
Explain the hairs stand up mechanism
Erector pili muscles contract when It’s cold, which makes the hairs stand up. Thus trapping more air and preventing heat loss.
Explain the vasoconstriction method
When it’s cold, arterioles near the surface of the skin constrict, so less blood flows through the capillaries in the surface layers of the dermis, reducing heat loss.
Explain the hormone method
The body releases adrenaline and thyroxine. And these increase metabolism and so more heat is produced.
How does the hypothalamus control body temperature? (thermoregulation)
1) a change in body temperature is detected by the thermoreceptors
2) The thermoreceptors send impulses along sensory neurones to the hypothalamus
3) The hypothalamus receives this information and sends a response along the motor neurones to the effectors (muscles and glands) - mechanisms
4) The effectors respond to restore the the body temperature back to normal.
