Homeostasis

Question 1

Osmoregulation: What does an increase in water potential of blood lead to?

Answer 1

1) Detected by osmoreceptors
2) Less ADH released from posterior pituitary gland = less ADH able to bind to receptors on cell surface membrane
3) Collecting duct walls become less permeable
4) Less water reabsorbed into blood = more urine
5) Decreasing water potential in blood

Question 2

Osmoregulation: What does a decrease in water potential of blood lead to?

Answer 2

1) Detected by osmoreceptors
2) More ADH released from posterior pituitary gland
3) Collecting duct walls become more permeable
4) More water reabsorbed into blood = less urine
5) Increase in water potential of blood

Question 3

Where are osmoreceptors?

Answer 3

Hypothalamus (Brain)

Question 4

What does ADH cause?

Answer 4

Makes a person lose water via urination

Question 5

What is ADH?

Answer 5

Anti-Diuretic-Hormone: Increases the aquaporin in the cell surface membrane of the collecting duct.

Question 6

Which substances can travel into the filtrate?

Answer 6

Everything besides plasma proteins, as the basement membrane doesn’t allow larger molecules to be absorbed.

Question 7

What is the glomerulus?

Answer 7

Network of capillaries

Question 8

What is reabsorbed in the PCT?

Answer 8

Mineral Ions (Na-. Cl etc) , Vitamins, Amino acids via co-transport.

Question 9

Where is the Glomerulus?

Answer 9

In the nephron

Question 10

Where does selective reabsorption occur?

Answer 10

In the PCT

Question 11

What happens if blood glucose levels are too high?

Answer 11

High = Lower water potential of blood.
Causing water to diffuse out of the cells via osmosis into the blood.
Leading to a higher blood pressure.

Question 12

What happens when blood glucose levels are too low?

Answer 12

Not sufficient glucose for respiration, declining energy levels

Question 13

Where are changes in blood glucose concentrations detected?

Answer 13

Pancreas

Question 14

Glycogenesis

Answer 14

When blood glucose concentrations are too high, liver cells produce enzymes converting glucose to glycogen which is then stored n the liver cells.

Question 15

Gluconeogenesis

Answer 15

When blood glucose conc is too low, liver cells also form glucose from glycerol and amino acids.

Question 16

Glycogenolysis is…

Answer 16

When blood glucose conc is too low, liver cells produce enzymes that break down glycogen in the cells to glucose.

Question 17

How does insulin return blood glucose levels to normal?

Answer 17

1) Detected by beta cells in islets of Langerhans of pancreas.
2) Insulin secreted, travels in the blood to liver and muscle cells.
3) Binds to muscle cell receptor membranes inserting more glucose channel proteins in the cell membrane causing the rate of glucose uptake by muscle cells to increase as well as the rate of respiration in muscle cells.
4) Glycogenesis - Insulin binds to receptors on the liver cell membrane. Liver cells produce enzymes that convert glucose to glycogen which is then stored in the liver cell’s cytoplasm.

Question 18

Why is insulin important?

Answer 18

Maintains optimum blood water potential by reducing the glucose in the blood, bwp would decrease otherwise. Water in the cells would diffuse out, causing cells to shrink and die.

Question 19

Importance of Glucagon

Answer 19

Increases blood glucose concentration allowing more respiration to occur.

Question 20

How does glucagon work?

Answer 20

1) Detected by alpha cells in islets of Langerhans of the pancreas.
2) Glucagon is secreted and travels via blood to the liver cells.
3) Glycogenolysis - Glucagon binds to receptors on liver cell membranes, liver cells produce enzymes converting glycogen to glucose.
4) Gluconeogenesis - Glucagon binding to liver cell membrane also causes the release of enzymes, forming glucose from glycerol and amino acids.
5) Glucagon also reduces the rate of respiration slowing the rate at which glucose is used up.

Question 21

When is adrenaline released?

Answer 21

In response to low blood glucose concentrations, during exercise and in times of stress.

Question 22

What is the adrenaline response?

Answer 22

1)Adrenaline is secreted from the adrenal gland.
2)Binds to receptors on the liver cell membrane inducing two reactions:
Activation of glycogenolysis and inhibition of glycogenesis
Alsom promotes secretion of glucagon from the pancreas and inhibits secretion of insulin.

Question 23

Features of primary messengers

Answer 23

Do not enter the cell.
Exert action on a cell membrane by binding to receptors and triggering a change within a cell.
Can initiate a reaction or can activate another molecule
(e.g hormones - adrenaline,glucagon)

Question 24

Features of Secondary Messengers

Answer 24

Initiate/coordinate responses that take place inside a cell.
Usually activated by the binding of a primary messenger to a cell surface receptor.
(e.g cAMP)

Question 25

What activates adenylate cyclase?

Answer 25

Adrenaline, Glucagon

Question 26

Function of cAMP

Answer 26

Activates protein kinase A

Question 27

What does adenylate cyclase do?

Answer 27

Converts ATP to cyclic AMP (cAMP)

Question 28

Affects + Causes of Type 1 diabetes

Answer 28

Beta cells in the pancreas are attacked by the body’s own immune system.
B cells of the islets of Langerhans become damaged and can no longer produce insulin.
Some people are more genetically vulnerable.

Question 29

Affects + Causes of Type II Diabetes

Answer 29

Lack of glycoprotein receptors on body cells or they lose responsiveness to insulin.

Question 30

Control of Type I Diabetes

Answer 30

Injections of insulin.

Cannot be taken by the mouth as it would be digested being a protein.

Question 31

Control of Type II Diabetes

Answer 31

Regulating the intake of carbohydrates and matching it to the amount of exercise.