hormonal communication

Question 1

what is the endocrine system?

Answer 1

a system made of endocrine gland which secretes hormones around the blood circulatory system and then binds to a target cell causing a response

Question 2

what are the two types of hormones?

Answer 2

steroid and peptide hormones

Question 3

what are steroid hormones?

Answer 3

lipid soluble and can diffuse through the cell membrane and enter the cell through the nucleus to then have a direct effect on the DNA

Question 4

examples of steroid hormones

Answer 4

oestrogen and testosterone

Question 5

what are protein and peptide hormones?

Answer 5

these are insoluble in lipids and cannot diffuse across the cell membrane so bind to receptors and produce a secondary messengerexa

Question 6

examples of protein and peptide hormones

Answer 6

adrenaline, insulin and glucagon

Question 7

what are first messengers?

Answer 7

these are non steroid hormones which bind to a membrane and cause the release of another molecule ( the secondary messenger

Question 8

what ks a secondary messenger?

Answer 8

a g protein is activated when the hormone binds to the receptor and this activates an effector molecules usually adenyl cyclase which converts ATP to cAMP

Question 9

What is the adrenal gland?

Answer 9

an endocrine glands made up of the adrenal cortex and the adrenal m medulla

Question 10

summarise the structure of the adrenal cortex

Answer 10

consists of three distinct layers of cells
1. zona glomerulosa is the outer layer which secretes mineral corticoids like aldosterone
2. zona vasiculata is the middle layer which secretes glucocorticoids like cortisol
3. zona reticularis is the innermost layer which secretes precursor molecules used to make sex hormones

Question 11

summarise the adrenal medulla

Answer 11

it secretes adrenaline and noradrenaline

Question 12

what is the effect of adrenaline?

Answer 12

released during the fight or flight response and causes an increased heart rate, dilated pupils, converts glycogen to glucose

Question 13

How does adrenaline activate the target cells?

Answer 13

adrenaline is a polar molecule which means it cannot enter the cell through the plasma membrane so must be detected on specialised receptors on the membrane of the target cells

Question 14

how do steroid hormones work?

Answer 14

they passs through the cell membrane of target cells then bind with the specific receptor in the cytoplasm, the receptors steroid hormone complex enters the nucleus and binds to another receptors and this stimulates the production of mana

Question 15

what is the pancreas?

Answer 15

an gland located behind the stomach and releases hormones to control blood glucose levels ( endocrine function) and enzymes for digestion (exocrine gland)

Question 16

where are hormones secreted from?

Answer 16

the islets of langerhans

Question 17

what is the endocrine function of the pancreas?

Answer 17

the smelts of langerhans are made up of alpha cells and beta cells which are involved in secretion

Question 18

what do alpha cells secrete?

Answer 18

glucagon

Question 19

what do the beta cells secrete?

Answer 19

insulin

Question 20

how is blood glucose regulated?

Answer 20

the pancreas detects change in the blood glucose levels and causes endocrine cells in the islets of langerhans to release insulin and glucagon to bring blood glucose concentration up or down

Question 21

what happens when there is a rise in blood glucosse concentration ?

Answer 21

this is detected by cells in the islets of langerhans, beta cell secrete insulin into the blood and insulin is detected by receptors on liver and ,isle, these remove glucose from blood and convert glucose to glycogen. so the glucose concentration falls

Question 22

what are the effects of insulin?

Answer 22

• glucose converted to fats
• more glucose used in respiration
• more glucose enter cells
• glycogenesis ( glucose converted to glycogen)

Question 23

what happens when there is a fall in blood glucose concentration?

Answer 23

this is detected by alpha cells in the islets of langerhans and they secrete glucagon into blood. this is detected by the liver receptors, these liver cells then convert glycogen to glucose and release the glucose in the blood

Question 24

what is the effect of glucagon?

Answer 24

more fatty acids used in respiration
amino acids converted into glucose by glycogenesis
glycogen converted to glucose

Question 25

what is diabetes?

Answer 25

when blood glucose concentration cannot be controlled naturally

Question 26

what is type 1 diabetes?

Answer 26

the body is unable to produce insulin because of an autoimmune response in which the body immune system attacks and destroys beta cells

Question 27

how do you treat type 1 diabetes?

Answer 27

• usually by insulin injections
• pancreas transplant
• islet cell transplantation
• insulin pump therapy

Question 28

what is type 2 diabetes?

Answer 28

due to receptors on the target cells losing their responsiveness to insulin as a result of obesity or poor diet

Question 29

how do you treat type 2 diabetes?

Answer 29

a change in lifestyle of insulin injections

Question 30

how is insulin sourced?

Answer 30

extracted from the pancreas of animals in the past, now produced by genetic modification in bacteria

Question 31

how is insulin released?

Answer 31

at a normal blood glucose conc the potassium ion channels are open to maintwan resting potential. if blood glucose concentration increases glucose enters the cell by a glucose transporter protein and the glucose is used in respiration to make ATP
the ATP binds to potassium ion channels which causes them to lose so no more potassium ions can diffuse out of the cells
cells become less negative so calcium ion enter which causes secretory vesicles to move towards the cell membrane and release insulin via exocytosis