Homeostasis

Question 1

What happens at high glucose levels?

Answer 1

Insuliin secreted
Increase in glucose carriers/channels resulting in increased glucose uptake
glucose is converted to glycogen

Question 2

What happens at low glucose levels?

Answer 2

Glycogenolysis
Gluconeogenesis

Question 3

What is glycogensis?

Answer 3

Glucose to glycogen

Question 4

What is gluconeogenesis?

Answer 4

Amino acids and fats into glucose

Question 5

What is glycogenolysis?

Answer 5

Glycogen into glucose

Question 6

How does adrenaline change blood glucose concentration?

Answer 6

Binds to receptors on the surface of liver cells which activates the enzyme adenyl cyclase which converts ATP into cAMP to activate protein kinase, stimulating glycogenolysis

Question 7

What are the causes of type 1 and type 2 diabetes?

Answer 7

Type 1:
- Genetic origin where B cells are destroyed by the immune system
Type 2:
- Cells become insensitive to insulin due to lifestyle factors

Question 8

How are type 1 and type 2 diabetes controlled?

Answer 8

Type 1:
Insulin injections to regulate blood glucose levels
Type 2:
Oral medication. Strict diet management and increased exercise

Question 9

What is the difference between positive and negative feedback?

Answer 9

Negative feedback is when the body opposes the change to bring it back to normal but positive feedback is the response to the change is to continue the change

Question 10

What is the composition of the filtrate?

Answer 10

Water, glucose, urea and mineral ions can pass through the Bowman’s capsule.

Question 11

Where does ultrafiltration occur?

Answer 11

Bowman’s/renal capsule

Question 12

What features allow ultrafiltration to happen?

Answer 12

• Afferent arteriole is wider than the efferent arteriole building hydrostatic pressure
• Small substances get filtered out and can fit between haps between podocytes to enter the Bowmans capsule

Question 13

How is the proximal convoluted tubule adapted for efficient absorption?

Answer 13

Microvilli increase surface area
High number of mitochondria for ATP for active transport
Foldings near blood capillaries to increase the surface area

Question 14

How does selective reabsorption of glucose and amino acids occur in the proximal convoluted tubule?

Answer 14

Form of co-transport
Sodium ions are moved from the epithelia ccells of PCT into the blood so more sodium ions diffuse into the PCT pulling glucose and amino acids with them

Question 15

How does selective reabsorption of water occur?

Answer 15

Sodium ions are actively transported from the PCT into the blood lowering the water potential so water travels into the blood via osmosis

Question 16

What happens in the descending limb of the loop of Henle?

Answer 16

Walls are permeable to water so it leaves by osmosis

Question 17

What happens in the ascending limb of the loop of Henle?

Answer 17

Sodium and chloride ions diffuse out of the fluid at the base and actively transported at the top. impermeable to water

Question 18

What is the counter current multiplier?

Answer 18

The lower water potential is at the hair pin of the loop of Henle, so there is a counter current flow as the water flows down both the descending loop and collecting duct.

Question 19

Where are the osmoreceptors found?

Answer 19

Hypothalamus

Question 20

What happens to the osmoreceptors at low water levels?

Answer 20

Shrink

Question 21

What happens when blood water levels are too low?

Answer 21

Osmoreceptors in hypothalamus shrink triggering increased released of ADH from pituitary gland. ADH stims the increase in number of aquaporins so the collecting duct is more permeable to water allowing water to return to the blood.

Question 22

What is homeostasis?

Answer 22

The maintenance of a constant internal environment

Question 23

Why must body temp remain constant?

Answer 23

As temp increases, so does kinetic energy. As temperature moves past the optimum, molecules vibrate more and hydrogen bonds within the enzyme break changing the shape of the active site

Question 24

Why must blood glucose concentration remain constant?

Answer 24

If blood glucose is too high, it lowers the water potential of the blood causing water to move from cells into the blood causing the cells to die

Question 25

How does negative feedback work?

Answer 25

Receptors detect change
Communicated by the nervous or hormonal system
Change is brought about by effectors

Question 26

What is the name of the cells that make up the epithelium of the Bowmans capsule?

Answer 26

Podocytes

Question 27

What is the purpose of the microvilli in the proximal convoluted tubule?

Answer 27

Increases the surface area for selective reabsorption

Question 28

Why do some organisms have longer loops of Henle?

Answer 28

Allows organisms that live in dry habitats to reabsorb more water from the glomerular filtrate