Unit 3.5.4 - Homeostasis Flashcards
What is homeostasis?
Maintenance of a constant internal environment.
What is meant by homeostasis keeps your internal environment in a state of dynamic equilibrium?
It fluctuates about it’s normal level.
Why is keeping the internal environment constant vital in the body?
Allows cells to function normally and stops them being damaged.
What three things have to be particularly controlled in the body?
Core body temperature, blood pH and blood glucose concentration.
What do both temperature and pH affect?
Enzymes that control the rate of metabolic reactions.
What happens to the rate of metabolic reaction as temperature increases up to the optimum temperature.
Molecules have more kinetic energy so move faster, this means there will be more collisions and the energy of the collisions will increase so a reaction will be more likely so the rate of reaction increases.
What happens to the rate of metabolic reactions once temperature is increased passed the optimum temperature?
When the temperature is too high it starts to interfere with the hydrogen bonds that hold the enzyme together so the enzyme and it’s active site will start to change shape. This means the enzyme and sub straight will no longer be complimentary and they can’t form E-S complexes and so the enzyme will be denatured and rate of reaction would decrease.
Why is the rate of reaction low at low temperatures?
Reduced enzyme activity.
How is the rate of metabolic reactions affected if the blood pH is too high or too low.
The pH starts to interfere with the hydrogen bonds holding the enzyme together so the enzyme and it’s active site will start to change shape. This means the enzyme and sub straight will no longer be complimentary and they can’t form E-S complexes and so the enzyme will be denatured and rate of reaction would decrease.
What happens to cell if blood glucose concentration is too high?
The water potential of the blood is reduced to a point where water molecules diffuse out of the cell into the blood by osmosis causing the cell to shrivel up and die.
What happens to cells if the blood glucose concentration is too low?
The cell is unable to carry out normal activities because there isn’t enough glucose for respiration to provide energy.
What are the two different classifications for animals which depends on how they control their body temperature?
Ectotherms and endotherms.
How do ectotherms control their body temp?
By changing their behaviour.
What does the internal temp of ectotherms depend on?
The external temp.
Why do ectotherms have variable metabolic rates?
Because they can’t keep their internal temp constant.
Do the activity ectotherms or endotherms depend on the external temp?
Ectotherms
How do endotherms control their body temp?
Homeostasis as well as altering their behaviour.
Is the internal temp of ectotherms or endotherms most affected by external temp?
Ectotherms
Why do endotherms have a high metabolic rate?
They can keep their internal temp constant.
What things do mammals try to control to control body temp?
Heat loss, heat production and heat conservation - Hollie is a very annoying girl!
What three things can increase heat loss?
- Opening the windows
- Sweating
- Hairs lying flat against the skin
- Vasodilation
How does sweating increase heat loss?
It smells and more sweat will be secreted from sweat glands and the water in the sweat evaporates from the surface of the skin taking heat from the body with it.
How do hairs lying flat against the skin increase heat loss?
Ask Hollie as Hollie’s legs are very hairy
Erector pili muscles relax so the hairs lie flat against the skin so less air is trapped and the skin is less insulated
What is vasodilation?
When the arterioles near the surface of the skin dilate.
Why does vasodilation increase heat loss?
More blood flows through the blood capillaries in the surface layer of the dermis. This means more heat can be lost from the skin by radiation.
What two things can increase heat production?
Shivering and hormones.
