Topic 7 – Animal coordination, control and homeostasis

Question 1

What is homeostasis?

Answer 1

The process of controlling things like temperature and water levels inside the body.

Question 2

Why does the body need to control temperature?

Answer 2

Increased temperature can speed up an enzyme reaction because the enzymes and substrates have more energy and therefore move about quicker, causing more collisions and quicker reaction. If the temperature is too low, reactions might be too slow.

High temperatures can cause dehydration, heat stroke, and death if untreated
Low temperatures can cause hypothermia, and death if untreated

Question 3

How does the body detect temperature change?

Answer 3

The hypothalamus has temperature receptors in the dermis of the skin. There is also receptors inside the hypothalamus detect temperature changes in the brain and blood.

Question 4

What changes happen in the body when there is a temperature change?

Answer 4

• Sweating
• vasodilation (blood vessels near the surface swell to allow more blood near the surface where the heat can radiate out)
• shivering
• Hair stand on end to trap warm air
• vasoconstriction (outer blood vessels restrict to force more blood to vital organs when cold)

Question 5

How is temperature control an example of negative feedback?

Answer 5

For example, If the body gets too hot, a cooling mechanism like vasodilation occurs, cooling the body. If the body gets too cold, the body shivers or your hair stands up, warming up.

Question 6

What is heat stroke caused by?

Answer 6

It is an uncontrolled increase in body temperature due to:
Increased body temperature which causes an increase in sweating. This can lead to dehydration which reduces sweating which then allows the core body temperature to rise.
As the body temperature rises, body mechanisms begin

Question 7

Why is adrenalin produced and what are the effects?

Answer 7

prepares the body for fight or flight by:

• increased heart rate
• increased blood pressure
• increased blood flow to muscles
• increased blood sugar levels by stimulating the liver to turn more glucagon into glucose

Question 8

how are hormones transported?

Answer 8

dissolved in the blood

Question 9

what is thermoregulation?

Answer 9

How the body controls your temperature

Question 10

What is osmoregulation?

Answer 10

The process by which the body controls your body’s water levels.

Question 11

What are the uses of the liver?

Answer 11

• detoxification

- breaking down unwanted amino acids into urea

Question 12

What do your kidneys do?

Answer 12

• excrete urine

- filter the blood of unwanted water, salts and urea etc

Question 13

What is the effect of temperature increase on urine production?

Answer 13

As the temperature increases, the body loses water via sweating. This cause the hypothalamus to crenate as water is lost because it diffuse down the concentration gradient into the blood. As the hypothalamus crenates, it sends a message to the pituitary gland to secrete ADH to the kidneys. The affect of ADH causes the kidneys and the nephron to re absorb more water out of the urine meaning overall there is less urine excreted.

Question 14

What does crenate mean?

Answer 14

When cells shrivel up due to loss of water

Question 15

What does lysis mean?

Answer 15

When cells have absorbed too much water and they swell.

Question 16

What is egestion?

Answer 16

Getting rid of undigested waste

Question 17

What are nephrons?

Answer 17

Small structures in your kidneys responsible for producing urine. (through filtering the blood)

Question 18

What processes are performed by the nephron?

Answer 18

• Ultrafiltration
• selective reabsorption
• osmoregulation

Question 19

What happens at the glomerulus and what is it?

Answer 19

The glomerulus is a small network of capillaries in the nephron in which blood enters at high pressure. The glomerulus then acts like a sponge and filters everything small enough to fit through the capillary walls out into the bowman’s capsule. This means all the large molecules like protein and red blood cells are not filtered out of the blood. [ultrafiltration]

Question 20

What is the bowman’s capsule and what does it do?

Answer 20

The bowman’s capsule is a capsule surrounding the glomerulus where the smaller substances filtered out of the blood including water, glucose, amino acids, creatinine and urea. Creatinine and urea are waste products tat need to be removed before they become toxic. [filtration]

Question 21

What is the 1st convoluted tube and what does it do?

Answer 21

Also known as the proximal convoluted tube, it is a part of the nephron where several important substances are reabsorbed. Some of the substances include: water, amino acids and glucose. These are reabsorbed because your body needs them and would be a waste to get rid of them. [ selective reabsorption through active transport]

Some substances like urea are also secreted into the convoluted tube here.

Question 22

What is the loop of henly and what happens here?

Answer 22

It is part of the nephron where more water is reabsorbed out of the nephron so that more waste products are left in than useful products.

Question 23

What is the collecting duct and what does it do?

Answer 23

It is a part of the nephron where further reabsorption of water. The amount of water reabsorbed changes because of your body’s osmoregulation. The rest is then sent to your bladder and then excreted out. This mainly contains water , creatinine and urea.

Question 24

What affect does ADH have on the collecting duct?

Answer 24

It increases the permeability of the collecting duct and therefor increases the amount of water absorbed.

Question 25

Which hormones regulates blood glucose concentration?

Answer 25

Insulin and glucagon

Question 26

How are blood glucose levels regulated?

Answer 26

TOO HIGH
If the glucose levels are too high, more insulin will be released from the pancreas and causes more glucose to be turned into to glycogen in the liver. This causes the glucose levels to go down.
TOO LOW
If the glucose levels are too low, more glucagon will be secreted from the pancreas causing the liver to convert more glycogen into glucose and hence increase the levels of glucose in the blood.

Question 27

How does the body respond to high blood glucose concentration?

Answer 27

The pancreas detect a rise in blood glucose concentration and increase the secretion of insulin and decreases the secretion of glucagon. The insulin cause muscle and liver cells to remove glucose and store it as glycogen.

Question 28

How does the body respond to low blood glucose concentration?

Answer 28

The pancreas will detect the fall in blood glucose concentration and decrease the secretion of insulin but increase the secretion of glucagon. Glucagon then causes liver cells to convert glycogen into glucose and release it into the blood.

Question 29

What does Glucagon do?

Answer 29

It Causes liver cells to convert glycogen into glucose and release it into the blood.

Question 30

What does insulin do?

Answer 30

It causes muscle and liver cells to remove glucose from the blood and store it as glycogen.

Question 31

What happens to the blood glucose concentration after a meal?

Answer 31

The carbohydrates are being digested and absorbed into the blood as glucose so increasing the blood glucose concentration.

Question 32

What is diabetes?

Answer 32

It is a disorder where blood glucose concentration remains too high. This can either be because of lack insulin being produced (type 1)or be because your body has become resistant to insulin (type 2)

Question 33

What is Type 1 diabetes?

Answer 33

When your body doesn’t produce enough insulin

Question 34

How can type 1 diabetes be controlled?

Answer 34

• monitoring the diet

- injecting insulin

Question 35

What is Type 2 diabetes?

Answer 35

When your body (specifically your liver) has become resistant to insulin so that glucose can no longer be stored as glycogen.

Question 36

How is type 2 diabetes controlled?

Answer 36

Through a controlled diet and frequent exercise.

Question 37

How do you calculate BMI?

Answer 37

Weight (kg)/height (meters squared)

Question 38

What are the ureters?

Answer 38

They carry urine from the kidneys to the bladder

Question 39

What is the urethra?

Answer 39

Part of the urinary systems that takes urine from the bladder to the outside of the body.

Question 40

What is the difference between renal veins and arteries?

Answer 40

Renal veins carry clean blood back to the body.

Renal arteries carry blood from the body to the kidneys.

Question 41

What does Kidney failure mean for your body?

Answer 41

Because your kidneys have stopped working properly, excess water, mineral ions and urea build up in the body.

Question 42

How can kidney failure be treated in the short term?

Answer 42

Through a dialysis machine where your blood is piped through a machine containing dialysis fluid. Because the tubing is partially permeable and the dialysis fluid has a lower concentration of toxins but the same concentration of useful substances as blood so that only the toxins (urea, excess water and mineral ions) are removed into the dialysis fluid.

Question 43

How does a kidney transplant occur?

Answer 43

A healthy organ is donated from a donor which must have similar antigens to that of the patient. The donor undergoes an operation to remove the kidney which is the connected to the blood circulation inside the patient.

Question 44

What problems occur from a kidney transplant and how do they overcome this

Answer 44

The patients antibodies may reject the kidney if the antigens on the surface are too different from the antigens of the patient. To overcome this, the kidney must have similar antigens to the patient. However this still usually requires drugs to suppress the immune system leaving them more susceptible to infections.

Question 45

What are the disadvantages of kidney transplants?

Answer 45

• Any major surgery carries some risk.
• The kidney may be rejected by the body of the patient and so drugs (immuno-suppressant drugs) are used —constantly to help prevent rejection.
• A precise match of tissue type is needed. About half the donated kidneys come from family members (this is known as a ‘living donor’).
• There is a severe shortage of donors.

Question 46

What are the disadvantages of dialysis?

Answer 46

• They are expensive.
• The patient must have his or her blood connected to the machine for several hours each week.
• Patients must follow a very strict diet to avoid complications.
• They only work for a limited time for a patient.

Question 47

What is urea?

Answer 47

A toxic substance produced from the breakdown of excess amino acids in the liver.