hormones

Question 1

define endocrine gland

Answer 1

an organ that secretes hormones directly into the blood

Question 2

define exocrine gland

Answer 2

a gland that secretes something into a duct

Question 3

define target tissue

Answer 3

a group of cells that contain receptors for a particular hormone and are therefore affected by it

Question 4

explain the meaning of the term first messenger with ref to adrenaline and cyclic AMP

Answer 4

a molecule that binds to a receptor in the plasma membrane and causes changes to happen in the cell; adrenaline is an example

Question 5

explain the meaning of the term second messenger with ref to adrenaline and cyclic AMP

Answer 5

a molecule that is affected by the binding of a first messenger to a receptor, cAMP is an example of a second messenger.

Question 6

how do hormones affect their target cells

Answer 6

by attaching to a specific receptor molecule, which sets into action a series of events within the cell, an example of cell signalling

Question 7

what is adrenaline

Answer 7

a hormone synthesised from amino acids,not soluble in lipids.
is a catecholamine.

Question 8

what are adrenalines target cells

Answer 8

liver
muscle
have receptors in their plasma membrane which adrenaline binds to- this alters the shape of the receptor, causing it to interact with another protein in the membrane called a G-protein

Question 9

what happens to the G protein once adrenaline has bound

Answer 9

g protein splits, one part combines with an inactive enzyme called adenylyl cyclase- this activates the enzyme which converts ATP to cyclic AMP (cAMP)

Question 10

describe the functions of the adrenal glands

Answer 10

adrenline secreted from them in response to excitement, danger or stress. target organs and tissues include the SAN in the heart, smooth muscle in the wall of the alimentary canal and the muscles in the iris of the eye.

it brings about changes that prepare the body for vigorous activity, for escaping from danger or fighting against it

Question 11

how does the pancras act as both an exocrine and endocrine gland?

Answer 11

exocrine: secretion of pancreatic juice- which flows along the pancreatic duct into the duodenum- this juice contains enzymes:
lipase, amylase, trypsin

Question 12

lipase

Answer 12

catalyses the hydrolysis of lipids to fatty acids and glycerol

Question 13

amylase

Answer 13

catalyses the hydrolysis of starch to maltose

Question 14

trypsin

Answer 14

catalyses the hydrolysis of proteins to polypeptides

Question 15

what are the islets of langerhan

Answer 15

patches of endocrine tissues scattered throughout the exocrine tissue of th pancreas (form about 15% of the pancreas) contain alpha and beta cells

Question 16

alpha cell

Answer 16

secrete glucagon hormone

Question 17

beta cell

Answer 17

secrete insulin hormone

Question 18

how do alpha and beta cells detect changes to blood glucose concentration

Answer 18

by having receptors in their plasma cell surface membrane that detect these changes

Question 19

explain how blood glucose conc is regulated when the plasma glucose conc RISES

Answer 19

1. both alpha and beta cells detect the rising con of glucose
2. alpha cells cease to secrete glucose but beta cells secrete insulin
3. insulin binds with receptors in the plasma cell surface membranes of muscles fat and liver cells
4. glucose uptake from the blood by these cells is increased
5. use of glucose in respiration by cells is increased
6. liver cells convert glucose to glycogen and stop the reverse reaction.

Question 20

explain how blood glucose conc is regulated when the plamsa glucose conc FALLS

Answer 20

1. both alpha and beta cells detect the falling conc of glucose
2. beta cells cease to secrete insulin
3. alpha cells secrete glucagon
4. target cells the up less glucose
5. the rate of glucose use decreases and fats or amino acids are used in respiration instead.
6. glycogen in the liver is converted to glucose and released into the blood.

Question 21

outline how insulin secretion is controlled with ref to potassium channels and calcium channels in betacells

Answer 21

beta cell- resting potential across it membrane is kept negative inside the cell by ATP sensitive potassium ion channels
when blood glucose rises, glucose enters the beta cell and is respired, allowing ATP production.
the ^ATP conc in the cell closes the potassium ion channels.
membrane depolarises and calcium ions rush into the cell.
insulin is released by exocytosis.
(K+ ion channels control the set point for plasma glucose homeostasis)

Question 22

type 1 diabetes

Answer 22

occurs when there’s a lack of insulin because of the destruction of all or most beta cells of the pancreas by an autoimmune response.
regular injections of insulin are needed for survival.
the uptake of glucose by brain cells and RBC is not dependent of the presence of insulin but even in the presence of abundant glucose mussels do not take up the sugar in the absence of insulin

Question 23

type 2 diabetes

Answer 23

occurs when the body target cells become less responsive to insulin. the type of diabetes can be controlled by diet

Question 24

advantages of genetically modified bacteria to treat diabetes mellitus

Answer 24

• theres less likelihood of an immune response producing anti-insulin antibodies
• there’s a more rapid response and a shorter duration of response
• patients who have become tolerant of pig insulin (require larger doses to have same effect) respond better to human insulin.
• some patients don’t like the idea of using insulin from animals
• extraction and purification of insulin from animal pancreas is expensive.

Question 25

what’s the one and only reported disadvantage of using human insulin

Answer 25

some patients no longer experience any warning signs of low plasma glucose conc (hypo glycaemia)

Question 26

using stem cells to treat diabetes mellitus

Answer 26

one trial therapy: stem cells were isolated from a patients bone marrow and was given chemo to destroy the immune system.
infusion with the stem cells reinstated the immune system
the hoe was to reprogram the immune system so it wouldn’t attach beta cells

Question 27

what was the problem with this trial therapy

Answer 27

insulin is one of the antigens that trigger the immune system to destroy the cells

Question 28

what was the other approach using stem cells to treat diabetes mellitus

Answer 28

human embryonic stem cells have been triggered to produce human insulin in response to rising concs of glucose. these cells can be places in porous capsules to prevent their rejection and transplanted into the patients abdomen

Question 29

outline the hormonal and nervous mechanisms involved in the control of heart rate in humans

Answer 29

heart rate is controlled by altering the rate of firing of the SAN. adrenaline speeds it up. nerve impulses arriving along the sympathetic nervous increase heart rate. nerve impulses arriving along the vagus (parasympathetic) nerve decrease the rate.