3.3 Homeostasis

Question 1

What is homeostasis?

Answer 1

Maintenance of a constant internal environment

Question 2

Why is homeostasis important? Which components?

Answer 2

Body temperature: enzymes
Blood sugar levels: respiration and blood pressure
Water: cell size
pH: enzymes

Question 3

What waste products are removed from our body?

Answer 3

Carbon dioxide

Urea

Question 4

How and why are the two waste products removed?

Answer 4

Carbon dioxide: breathed out via the lungs because it makes carbonic acid lowing the pH of our blood affecting enzymes

Urea: made in the liver from the breakdown of excess amino acids, removed by the kidneys in urine, temporarily stored in the bladder
Because it is toxic

Question 5

What is negative feedback?

Answer 5

A deviation from the norm initiates corrective mechanisms to restore the norms

Question 6

How is water obtained in the body?

Answer 6

When eating and drinking

Question 7

How do we lose water?

Answer 7

Sweat
Breathing out
Urine

Question 8

What can too much or too little water do to out cells?

Answer 8

Damage them causing them to burst or shrivel

Question 9

What do kidneys do?

Answer 9

Filter the blood excreting substances you don’t want and keep substances the body needs

Question 10

How is blood brought to the kidney?

Answer 10

Via the renal artery

Question 11

What is a nephron?

Answer 11

Microscopic filtering units

Question 12

What is the first stage of the kidney producing urine?

Answer 12

Filtering the blood:
The Glomerulus separates the larger molecules - red blood cells, white blood cells and carbon dioxide
From the smaller molecules - water, ions, urea, glucose and amino acids
The bowman’s capsule collects the filtrate of smaller molecules and they can pass through the renal tubial

Question 13

What is the second stage of the kidney producing urine?

Answer 13

Reabsorbing all the sugar:
In the proximal convoluted tubal glucose and amino acids are reabsorbed by active transport as they ate against a concentration gradient

Lots of mitochondria and ribosomes- for energy and proteins (they carry certain molecules across a membrane)

Question 14

What is the third stage of the kidney producing urine?

Answer 14

Reabsorbing dissolved ions needed:
In the loop of Henle some ions are reabsorbed by active transport
But other salts are left behind to balance what the body needs

Question 15

What is the fourth stage of the kidney producing urine?

Answer 15

Reabsorbing as much water as the body needs:
In the distal convoluted tubal a diuretic hormone is released by the pituitary gland leading to increased reabsorption of water via osmosis

Question 16

What is the fifth stage of the kidney producing urine?

Answer 16

Releasing urea, excess ions and water:
In the collecting duct the molecules left are water, salt and urea forming urine to be temporarily stored in the bladder leaving via the ureter

Question 17

What can Kidney failure be treated with?

Answer 17

Kidney dialysis
Or
Kidney transplant

Question 18

What does dialysis do?

Answer 18

Remove the blood from you body then clean out the urea before sending it back

Question 19

What is an anticoagulant used for in dialysis? Example of drug?

Answer 19

Prevents blood clotting

Heparin

Question 20

What is an air trap used for in dialysis?

Answer 20

Gets rid of air bubbles preventing air embolisms (blood vessels blockages due to air bubbles)

Question 21

What is done to maximise amount of urea moved in the dialysis fluid?

Answer 21

The dialysis fluid flows in the opposite direction to the blood

Question 22

How is urea removed in dialysis?

Answer 22

Urea moves out of the blood via diffusion as there is no urea in the dialysis fluid creating a concentration gradient

Question 23

How do you not lose useful molecules in dialysis?

Answer 23

The fluid contains the same concentration of glucose and mineral ions as the blood so there is no no net movement of the substances needed by the body

Question 24

How often is dialysis done?

Answer 24

Carried out regularly

Changes from person to person

Question 25

What are some similarities between dialysis and a nephron?

Answer 25

Both remove urea | Red blood cell and white blood cells don't leave the blood

Question 26

What are some differences between dialysis and a nephron?

Answer 26

Glucose is removed and then reabsorbed by active transport from the blood in the nephron

Question 27

What are the advantages of dialysis?

Answer 27

Prevents you feeling ill Available to all kidney patients No immunosuppressant drugs

Question 28

What are the disadvantages of dialysis?

Answer 28

``` Time consuming Affects your daily life Expensive Go to hospital al lot Can't eat salt and protein in between ```

Question 29

What does a kidney transplant do?

Answer 29

Enables a diseases kidney to be replaced with a healthy one from a donor (dead or living)

Question 30

What are antigens?

Answer 30

Proteins on the surface of cells

Question 31

Why can kidneys be rejected?

Answer 31

Antigens on someone else's kidney will be different to the recipients antigens White blood cells see the new kidney as a foreign object They produce antibodies to attack the foreign antigens

Question 32

How do we prevent rejection of a kidney?

Answer 32

They kidney must be a good tissue match | Immunosuppressant drugs must be taken to suppress your immune system

Question 33

What are the advantages of a kidney transplant?

Answer 33

No longer need dialysis Lead a more normal life Overall it's cheaper for the NHS

Question 34

What are the disadvantages of a kidney transplant?

Answer 34

``` Immunosuppressant drugs have to be taken Vulnerable to common infections Waiting for an organ can be years Shortage of donors The kidney will only last 8-9 years on average Surgery carries risks ```

Question 35

How is thermoregulation monitored in the body?

Answer 35

It's detected by thermoreceptors of the thermoregulatory centre in the brain It monitors the temperature of blood flow through the brain

Question 36

What is the core temperature of must humans?

Answer 36

37 degrees

Question 37

What responses does your body do if you are too hot?

Answer 37

Sweat: heat evaporates Vasodilation: Capillaries dilate and increased blood means more heat lost at the surface Hairs lie flat: heat isn't insulated Fanning yourself or finding shade

Question 38

What responses does your body do if you are too cold?

Answer 38

Shivering: rapid muscle contractions of skeletal muscles increase respiration increasing heat energy to blood Vasoconstriction: capillaries constrict limiting blood at the surface Hairs on end: insulates heat Goosebumps Huddle: reduces surface area exposed

Question 39

What is glucose monitored by?

Answer 39

The pancreas

Question 40

What is happens if you have high levels of glucose concentration in your blood?

Answer 40

The hormone insulin is released | Allowing glucose to move from the blood into the cells

Question 41

What other ways can glucose by removed from the blood stream?

Answer 41

Increased rate of respiration Convert glucose to glycogen Convert glucose into fat Increase amount taken into the cells

Question 42

Where is glucose converted into glycogen?

Answer 42

The liver

Question 43

What is happens if you have low levels of glucose concentration in your blood?

Answer 43

The hormone glucagon is released | This caused glycogen to be converted back into glucose

Question 44

What other ways can glucose be added to the blood stream?

Answer 44

Break down fats

Question 45

What is Type 1 diabetes?

Answer 45

A disease where a persons blood glucose is too high because the pancreas doesn't produce enough insulin

Question 46

How do you control type 1 diabetes?

Answer 46

Careful attention to diet and exercise | Injections of insulin

Question 47

What new methods are being tried to treat diabetes?

Answer 47

Pancreas transplants Embryonic stem cells Transplanting pancreas cells