B12 - Homeostasis

Name the part in the brain that controls your core body temperature.

Thermoregulatory centre in hypothalamus

Name the action where surface skin capillaries dilate to allow more blood flow to the surface.

Vasodilation

State one response of the body to high body temperature.

Sweating / Vasodilation / Hair lies flat

State one response of the body to low body temperature.

Vasoconstriction / Less sweating / Shivering

Briefly explain how shivering helps increase our body temperature.

Contractions require energy from respiration (exothermic)

Name the two main poisonous waste products in our body.

Carbon dioxide + Urea

How does high carbon dioxide level affect the body?

Dissolved CO₂ makes acidic solution → denatures enzymes

How is carbon dioxide removed from the cells and out of the body?

Transported to alveoli → exhaled into environment

How is urea produced?

Breakdown of excess amino acids

Name the organ that removes urea from the body.

Kidney

Name the process which removes the amine group from amino acids.

Deamination

Name the product formed from deamination of excess amino acids, before it is converted into urea.

Ammonia

Name the organ that breaks down excess amino acids.

Liver

Name the organ that controls water and mineral ion content of the blood.

Kidney

Name four substances that are filtered out of the blood into the kidney.

Glucose, mineral ions, urea, water

Why can't blood cells and proteins leave the blood to enter the kidney?

Too big to pass through vessel wall

How is glucose reabsorbed back into the blood from the kidney?

Diffusion + Active transport

What is 'selective reabsorption'?

The process in which the kidney reabsorbs certain useful substances back into the blood

Name the hormone that regulates the amount of water reabsorbed back into the blood from the kidney.

ADH

Name the organ that secretes ADH.

Pituitary gland

If there is an increase in ADH release, does the amount of water reabsorbed increase or decrease?

Increase

Briefly describe the volume and concentration of urine produced if there is little ADH release.

High volume, low concentration

Name two treatments of kidney failure.

Dialysis, kidney transplant

What is 'dialysis'?

A process where a machine acts as an artificial kidney, filtering the blood and restoring normal urea/water/ion levels

Which component of the dialysis machine do we rely on to prevent the loss of useful substances from the blood?

Dialysis fluid

What should the concentration of glucose and mineral ions of the dialysis fluid be like, in comparison to the blood of a healthy person?

Same as a healthy person's blood

What is the concentration of urea in the dialysis fluid?

Zero / None

State one disadvantage of dialysis.

Carefully controlled diet / Long periods connected to machine / Poor quality of life / Immobile during dialysis / Inconvenient

State a problem in kidney transplant.

Rejection / Lack of donor kidney

State a component on a donor kidney that causes rejection problems.

Foreign antigen on donor kidney

Name the component of the patient's body that may attack the donor kidney.

Antibodies

State a method that reduces the risk of rejection.

Use close relative's kidney for similar antigens / Immunosuppressant drugs

Name the type of drugs prescribed to a patient with a new organ.

Immunosuppressant drugs

State a disadvantage of taking immunosuppressant drugs.

Weakened immune system means it is harder to defend against diseases effectively