Homeostasis

Question 1

what is homeostasis?

Answer 1

physiological control systems that maintain a constant internal environment

Question 2

describe positive feedback

Answer 2

a response that amplifies a change eg) voltage gated channels Na +

Question 3

describe negative feedback

Answer 3

receptors detect change away from normal/optimum and affectors return to normal/ optimum eg) blood temp.

Question 4

what cells secrete insulin?

Answer 4

beta cells in the islets of Langerhan

Question 5

what is the role of insulin?

Answer 5

to decerase bllod sugar conc.

Question 6

describe 3 ways insulin decreses blood sugar conc.

Answer 6

binds to liver and muscle causing increased permeability to glucose……more glucose is absorbed by facilitated diffusion………… glycogenesis…..increased rate of respiration

Question 7

what cells secrete glucagon?

Answer 7

alpha cells in the islets of langerhan.

Question 8

how does glucagon restore normal blood sugar level?

Answer 8

gluconeogenesis - non carbs are converted to glucose……glycogenolysis…..decrease rate of respiration.

Question 9

what is glycogenesis?

Answer 9

the conversion of glucose to glycogen

Question 10

what is glycogenolysis?

Answer 10

the hydrolysis of glycogen into glucose

Question 11

what is gluconeogenesis?

Answer 11

the conversion of non carbs eg)lipids/ amino acids into glucose

Question 12

which hormone decreases blood sugar levels?

Answer 12

Insulin

Question 13

which hormone increases blood sugar levels?

Answer 13

glucagon

Question 14

when is glucagon secreted?

Answer 14

when the blood sugar is low

Question 15

when is adrenaline secreted?

Answer 15

low

Question 16

when is insulin secreted?

Answer 16

when the bloood sugar is HIGH

Question 17

where does glucagon attach to receptors?

Answer 17

liver

Question 18

where does adrenaline attach to receptors?

Answer 18

liver

Question 19

where does insulin attach to receptors?

Answer 19

liver and muscle

Question 20

what are the mechanisms of glucagon?

Answer 20

decreases rate of respiration, glycogenolysis, gluconeogenesis

Question 21

what does adrenaline activate?

Answer 21

glycogenolysis, secretion of glucagon

Question 22

what does adrenaline inhibit?

Answer 22

glycogenesis, and insulin secretion

Question 23

what are the mechanisms of insulin?

Answer 23

icrease rate of respiration, glycogenesis, increasing cell permeability to glucose

Question 24

how does insulin increase cell permeability?

Answer 24

glucose carrier molecules are in vesicles in L + M cells, insulon binds with specific receptors on the cell membrane, causing the fusion of the vesicles with the cell membrane, carrier proteins join the cell membrane (fluid mosaic), so glucose is absorbed by fac dif.

Question 25

Define diabetes

Answer 25

an illness where blood glucose levels are not fully controlled

Question 26

Describe Hyperglycaemia

Answer 26

dangerously high blood glucose concentration

Question 27

Describe hypoglycaemia

Answer 27

dangerously low blood glucose concentration

Question 28

What causes Type I diabetes

Answer 28

immune system destroys B cells on the Islets of Langerhan so cannot make insulin

Question 29

What age does Type I diabetes affect?

Answer 29

Children and adolescents

Question 30

What affect does Type I diabetes have on blood glucose concentration

Answer 30

rise after eating carbohydrates hyperglycaemia - stays high glucose present in urine

Question 31

how can we treat Type I diabetes?

Answer 31

- Insulin injections/ pump - avoid sugars - eat at regular intervals - regular exercise

Question 32

What causes Type II diabetes?

Answer 32

Obesity/ lack of exercise | B don't make enough insulin or liver and muscle stop responding to insulin

Question 33

What age does Type II affect?

Answer 33

adults and elderly

Question 34

What is the affect of Type II on blood glucose conc?

Answer 34

hyperglycaemia

Question 35

What is the treatment for Type II diabetes/

Answer 35

- eat healthy, lose weight, regular exercise - drugs - which increase sensitivity to insulin, produce more insulin - insulin injections

Question 36

describe how secondary messengers aid Glycogenolysis.

Answer 36

- The hormone (first messenger) eg) adrenaline or glycogen is complementary to the receptor protein on the target cell - The enzyme Adenyl Cyclate converts ATP to cAMP - cAMP activates protein kinase A by altering the tertiary structure - cAMP is the secondary messenger

Question 37

What are the 2 parts of the kidney?

Answer 37

medulla and the cortex

Question 38

Describe the process of ultrafiltration

Answer 38

takes place in between the capillaries and the bowmans capsule high hydrostatic pressure forces small molecules out to form the filtrate

Question 39

What is the larger capillary entering the glomelurus?

Answer 39

Afferent arteriole (lArge)

Question 40

What is the smaller capillary entering the glomelurus?

Answer 40

Efferent arteriole

Question 41

What three layers are the small molecules filtered through between the blood and the Bowman's capsule?

Answer 41

capillary membrane, basement membrane, podocyte

Question 42

Define selective reabsorbtion

Answer 42

useful products are reabsorbed by the nephron from the glomerular filtrate.

Question 43

Describe the process of selective reabsorption

Answer 43

Ultrafiltration makes glomerular filtrate capillaries wrap around nephron and useful substances are reabsorbed into the blood Proximal Convuluted Tube (PCT) absorbs most of the molecules (including water)

Question 44

How is the PCT adapted for reabsorption

Answer 44

microvilli increase SA for absorption

Question 45

How are Glucose and Amino acids reabsorbed

Answer 45

Facilitated diffusion

Question 46

How is Urea reabsorbed

Answer 46

simple diffusion

Question 47

How is water reabsorbed?

Answer 47

osmosis

Question 48

What is reabsorbed by Active transport using ATP?

Answer 48

glucose, amino acids, and ions

Question 49

describe what happens at the ascending limb of the loop of Henle (stage one) `

Answer 49

Na+ and Cl- are pumped out This decreases the water potential of the medulla water cannot move out of the ascending limb because it is impermeable to water

Question 50

Describe what happens at the descending limb of the LoH (stage two)

Answer 50

the descending limb is permeable to water water moves out by osmosis this is absorbed by the capillaries that wrap around the nephron water leaving the nephron at the descending limb increases the concentration of the urine

Question 51

How would the length of the LoH be different in a camel?

Answer 51

The loop would be longer increasing the conc of the medulla increasing the amount of water leaving the nephron therefore the urine is more concentrated

Question 52

What is the affect of ADH binding to the receptor at the collecting duct of the nephron?

Answer 52

ADH increases the permeability to water so water moves out by osmosis because the medulla has a more negative water potential

Question 53

describe the process of osmoregulation when dehydrated. (6 steps)

Answer 53

1) dehydration means the water potential of blood is more negative 2) this is detected by osmoreceptors in the hypothalamus 3) posterior pituitary secretes ADH into the blood stream 4) ADH binds to the specific receptor at the collecting duct 5) this increases the permeability to water 6) water moves out by osmosis because the medulla is more negative