Homeostasis

Question 1

What is homeostasis?

Answer 1

The maintenance of a constant internal environment,

Question 2

What are the three main things the body keeps constant?

Answer 2

• Water and ion content
• Body temperature
• Blood glucose level

Question 3

Why does carbon dioxide need to be removed from the body?

Answer 3

It is highly toxic in large quantities.

Question 4

How is carbon dioxide removed from the body?

Answer 4

The blood carries it to the lungs where it gets breathed out.

Question 5

What is urea?

Answer 5

The waste products from when excess amino acids are broken down and used to make fats and carbohydrates.

Question 6

Why does urea need to be removed from the body?

Answer 6

It’s poisonous.

Question 7

How is urea removed from the body?

Answer 7

The liver releases it into the blood stream an then the kidneys filter it out. It’s temporarily stored in the bladder in urine and then excreted.

Question 8

What are the three functions of the kidneys?

Answer 8

• The removal of urea
• Adjustment of ion content
• Adjustment of water content

Question 9

How do ions enter the body?

Answer 9

In food

Question 10

How does water enter the body?

Answer 10

Food and drink

Question 11

What are the three ways water is lost from the body?

Answer 11

• Urine
• Sweat
• Exhaled air

Question 12

What are nephrons?

Answer 12

Tiny structures in the kidney that filter the blood and produce urine. There are thousands in each kidney.

Question 13

What is stage one of urine production?

Answer 13

Ultrafiltration

Question 14

What happens during ultrafiltration?

Answer 14

Blood from the renal artery enters the kidney. High pressure builds up in the blood vessels which squeezes water, urea, ions and sugar into an area called the capsule in the nephron.

Question 15

Why aren’t proteins and blood cells absorbed during ultrafiltration?

Answer 15

They are too large to fit through the membrane between the renal artery and the capsule.

Question 16

What is stage two of urine production?

Answer 16

Reabsorbtion

Question 17

What happens during reabsorption?

Answer 17

• All glucose is reabsorbed using active transport
• Sufficient ions are reabsorbed using active transport
• Sufficient water is reabsorbed

Question 18

What is stage three of urine production?

Answer 18

The release of waste products

Question 19

What happens during the release of waste products?

Answer 19

The urea, excess ions and excess water go down the ureter to the bladder to be stored as urine. The urine is then excreted when it reaches a certain level.

Question 20

What two treatments are available for kidney failure?

Answer 20

Dialysis and transplant

Question 21

What is dialysis?

Answer 21

A treatment in which a dialysis machine takes over the role of a failing kidney to filter the blood.

Question 22

Why does dialysis need to happen regularly?

Answer 22

To keep the concentrations of dissolved substances in the blood at normal levels.

Question 23

How does a dialysis machine work?

Answer 23

1) The patient’s blood flows alongside a partially permeable membrane surrounded by dialysis fluid.
2) The partially permeable membrane allows the dissolved substances through that the kidney would.
3) Only the right amounts of water and ions diffuse across along with all the urea and the clean blood returns to the patient.

Question 24

What enables the dialysis machine to only take the right amount of ions and water?

Answer 24

The dialysis fluid has the same concentration of dissolved substances as healthy blood so only the waste amounts will diffuse across.

Question 25

What are five disadvantages of dialysis?

Answer 25

* Can require three 3-4 hour sessions a week * Can cause infections and blood clots * Restricted diet go patients too stop too much of one ion building up between sessions * Patients have to limit fluid intake as kidneys usually regulate water content * Expensive

Question 26

What is a kidney transplant?

Answer 26

When a healthy kidney replaces someone's diseased kidney.

Question 27

Where do kidney donations come from?

Answer 27

* People who have died suddenly i.e. In a car crash * Registered organ donors who die * Living donors as we can survive with one kidney

Question 28

What is rejection?

Answer 28

When antigens on a donated organ are recognised as foreign bodies by the immune system so the white blood cells produce antibodies to attack the donor cells.

Question 29

What are two ways that rejection can be prevented?

Answer 29

* A donor with a similar tissue-type can be used | * Immunosuppressant drugs can be used to stop the body attacking the donated organ

Question 30

What are four problems with kidney transplants?

Answer 30

* Rejection * Immunosuppressive drugs can be dangerous * Long waiting lists * Operation-based issues

Question 31

What temperature should the body be kept at?

Answer 31

37 degrees

Question 32

What part of the brain controls your internal temperature?

Answer 32

The thermoregulatory centre

Question 33

In what three ways does the body react to a high core body temperature?

Answer 33

* Hairs lie flat to trap less air * Sweat is produced as evaporation removed heat * Blood vessels dilate - take a path closer to the surface of the skin

Question 34

In what four ways does the body react to a low core body temperature?

Answer 34

* Hairs stand up to trap an insulating layer * No sweat is produced * Blood vessels construct to reduce amount of heat from the blood emitted to the surroundings * Shivering to instigate respiration which releases energy to warm the body

Question 35

What happens when blood glucose gets too high?

Answer 35

1) The pancreas detects high blood glucose levels and secretes insulin into the bloodstream 2) Insulin instigates the liver to take in glucose as its stored form - glycogen 3) Blood glucose level falls

Question 36

What happens when there is not enough glucose in the blood?

Answer 36

1) The pancreas detects low blood glucose levels and secretes glucagon 2) Glucagon causes the glycogen in the liver to be converted back into glucose 3) Blood glucose level rises

Question 37

What is type one diabetes?

Answer 37

When the pancreas cannot produce any/enough insulin.

Question 38

What three ways is type one diabetes controlled by?

Answer 38

* Limit intake of simple carbohydrates as they cause a sharp rise in glucose levels. Starchy carbohydrates take longer to break down so are encouraged * Regular exercise * Insulin therapy

Question 39

What is insulin therapy?

Answer 39

When insulin is manually injected into the blood stream to make sure excess glucose is being stored.

Question 40

What two things determine how much insulin someone needs to inject during insulin therapy?

Answer 40

Diet and exercise

Question 41

What are two modern treatments to type one diabetes?

Answer 41

* Pancreas transplant | * Artificial pancreases and stem cell research