Homeostasis

Question 1

Homeostasis definition

Answer 1

Maintenance of internal environment and concentration gradients under restricted limits

Question 2

Negative feedback definition

Answer 2

When any deviation from the norm is returned

Question 3

Role of pancreas

Answer 3

Detects changes in blood glucose

Question 4

Role of islets of langehann

Answer 4

Release insulin and glucagon

Question 5

Insulin

Answer 5

B-cells detect rise in glucose
Insulin secreted, binds to glycoprotein receptors on csm
-enzymes activated in cells
-glucose transport proteins change shape
-more enzymes so GLYCOGENESIS

Question 6

Glucagon

Answer 6

A-cells detect decrease in glucose
Glucagon secreted, binds to receptors found ONLY on the LIVER
-activates kinase enzymes
-hydrolysis of glycogen - GLYCOGENOLYSIS
-synthesis of amino acids and glycerol - GLUCONEOGENESIS
-glucose released into blood plasma

Question 7

Adrenaline

Answer 7

Secreted from adrenal gland
2nd messenger model
-adrenaline binds to receptor
-activates adrenylate cyclase
-converts ATP into cyclic AMP/ cAMP, that activates kinase enzymes for glycogenolysis

Question 8

Type 1 diabetes

Answer 8

Can’t produce insulin
Born with it/ childhood, caused by autoimmune diseases
Insulin injections

Question 9

Type 2 diabetes

Answer 9

Receptors on cells lose responsiveness to insulin
Obesity/ poor diet
Regulate carbs intake, increase exercise, sometimes insulin injections

Question 10

Osmoregulation definition

Answer 10

Control of blood WP

Question 11

Hypertonic

Answer 11

Too low WP in blood

Question 12

Hypotonic

Answer 12

Too high WP in blood

Question 13

Reasons for hypertonic

Answer 13

Too much sweating
Not enough water intake
Lots of salt/ions in diet

Question 14

Reasons for hypotonic

Answer 14

Drinking too much water

Not enough salt in diet

Question 14

Hypertonic corrective mechanisms

Answer 14

Osmoreceptors shrivel
Increased permeability of DCT and CD
More water reabsorbed by tubules of nephrons
Urine more concentrated and less water lost

Question 15

Hypotonic corrective mechanisms

Answer 15

Osmoreceptors increase in size as H2O enters
Decreased permeability of DCT and CD
Less water is reabsorbed by osmosis from tubules of nephrons
Urine more dilute and more water lost

Question 16

Nephron structure

Answer 16

Glomerulus
PCT
Loop of henle
DT
Collecting duct

Question 17

Ultrafiltration

Answer 17

Occurs in Bowman’s capsule
Afferent>efferent arteriole = large hydrostatic pressure, forces small molecules out
-podocytes - specialised epithelial cells, form gaps, increased SA, shorter diffusion pathway
-gaps in epithelial cells - shorter diffusion pathway

Question 18

What occurs in PCT

Answer 18

Co-transport/ selective reabsorption

Question 19

What does loop of henle consist of

Answer 19

2 limbs

Counter current flow

Question 20

Descending limb

Answer 20

Permeable to water
Water moves into interstial spaces via osmosis
Na+ diffuses in
WP decreases

Question 21

Ascending limb

Answer 21

Impermeable to water
Na+ actively transported out into interstial space
WP increases

Question 22

What occurs in DCT

Answer 22

AT of various salts
Removes ions
Maintains optimum pH
Microvilli and mitochondria

Question 23

How is ADH produced

Answer 23

Low WP
Cells in hypothalamus stimulated
Production of ADH increased

Question 24

What is the role of ADH

Answer 24

Binds to receptors
Activates phosphorylase
Aquaporin fuses with membrane
Increases permability

Question 25

What happens when WP is too high (ADH)

Answer 25

Less impulses to hypothalamus to less ADH production

Question 26

How to decrease permeability (ADH)

Answer 26

Removal of aquaporin
CSM folds
Vesicles remove aquaporin
Permeability decrease