Temperature homeostasisHomeostasis is the maintenance of a constant internal environment

Keeping warm1. Vasoconstriction- blood vessels

_______ and move away from ______ of skin

2. Hairs on skin become erect which trap ______ which is an ________

3. Shivering- muscles moving rapidly which generates heat by ________.

4. Thermoregulatory centre in brain sends messages e.g. to put a jumper on.

Cooling down1. Vasodilation- blood vessels _______

and move towards ______ of skin2. Hairs on skin lay flat.3. Sweating- water _______ from the

surface of the skin using heat energy from the surface of the skin therefore cooling us down.

4. Thermoregulatory centre in brain sends messages e.g. have a cold drink

Can you explain why?1. Imagine you have just walked out of the shower. Why do you feel chilly when you walk

from the bathroom to your bedroom?

2. What 3 ways can we get water into the body? 1.__________ 2.__________ 3._______3. Why does a person who is dehydrated sweat less?

Explain these pictures:

The kidney- water homeostasis

Using the picture above explain:

1. What is filtered out of the blood and how?_______________________________________________________________________________________

2. What stays in the blood and why?________________________________________________________________

3. What is completely reabsorbed into the blood in healthy kidneys and how?_________________________________________________________________________________________________

4. What else is reabsorbed and in what amounts?______________________________________________________________________________________________

Active transport of glucose

Glucose is reabsorbed back into the blood by active transport. Active transport is special type of diffusion where substances move from a lower concentration to a higher concentration (__________ concentration gradient). This process uses ________ from respiration.

Compare osmosis, diffusion and active transport:

Kidney Failure

Summary of kidney function:A healthy kidney produces urine by:

■ first filtering the blood ■ reabsorbing all the sugar ■ reabsorbing the dissolved ions needed by the body ■ reabsorbing as much water as the body needs ■ releasing urea, excess ions and water as urine.

Kidney failure can be treated by either having dialysis of a kidney transplant• In dialysis the persons blood

flows between partially permeable membranes. The dialysis fluid contains same concentration of useful substances as the blood- so glucose and mineral ions are not lost. Urea diffuses out of blood.

• Carried out at regular intervals

Kidney transplants replace a diseased kidney with a normal one. The donor kidney may be rejected by immune system because the antigens on the cells of the donor (proteins on surface of cells) are different to the recipients therefore the recipients antibodies may attack them as they appear foreign

Disadvantages of transplants:any major surgery carries some riskthe kidney may be rejected by the body of the patienta precise match of tissue type is neededthere is a severe shortage of donorsAdvantage- can live a normal life if all goes well

Disadvantages of dialysis:they are expensivethe patient must have his or her blood connected to the machine for several hours every weekpatients must follow a very rigid diet to avoid complicationsthey only work for a limited time for a patient

Glucose homeostasis Blood glucose is controlled by the pancreas

When blood glucose is high (after eating a meal)

Insulin also stimulates the production of glycogen- a store of glucose in the liver

When blood glucose is low (missed lunch)

Pancreas makes another hormone, Glucagon- causing glycogen to be converted back into glucose to raise blood glucose levels

Glycogen is a long chain of glucose molecules