HORMONAL COMMUNICATION

Question 1

what is the endocrine system?

Answer 1

is a communication system that releases hormones into the bloodstream

Question 2

what is an exocrine system?

Answer 2

releases hormones into duct

Question 3

what are the 2 types of hormones

Answer 3

peptide and steroid

Question 4

describe steroid hormones

Answer 4

are lipophilic molecules that can easily pass through the phospholipid bilayer and bind to steroid receptor found either in the inside or outside, forming an active hormone-receptor complex which will eventually initiate a response

Question 5

describe peptide hormones

Answer 5

hydophilic and lipophobic molecules that cannot pass through the phospholipid bilayer
they bind to receptor found on the surface of the membrane –> activates G PROTEIN –> move to an effector (enzyme) activated by the G protein –> converts ATP into cAMP (2nd messenger) –> initiate a response like ezyme cascade reaction

Question 6

state some endocrine glands

Answer 6

testes, ovaries, adrenal glands, thyroid gland ,pancreas

Question 7

explain how hormones work?

Answer 7

hormones are relased by endocrine glands which will be transported into the bloodstream and target cells known “target cell” which will have SPECIFIC COMPLEMETARY RECEPTORS to the hormone on the surface of the membrane. As the hormone bind to its complementary receptor, the hormone-receptor complex will initiate a response

Question 8

what is another name given to peptide hormone?

Answer 8

first messengers*

Question 9

describe adrenal glands

Answer 9

found just above the kidneys
divided into the ADRENAL CORTEX and ADRENAL MEDULLA and both secrete hormones

Question 10

explain the structure of the adrenal cortex and what it secretes

Answer 10

zona glomerulosa - secretes MINERALOCORTICOIDS (aldosterone)
zona fasciculata - secretes GLUCOCORTICOIDS (cortisol)
zona reticularis - secretes PRECURSOR/androgens molecules (male sex hormones)

Question 11

what types of hormones does the AC produce and what does it use to produce these and what do these affect?

Answer 11

steroid hormones - use of cholesterol , affect the DNA of the target cell

Question 12

explain the mechanism of steroid hormones

Answer 12

steroid hormones pass through the plasma membrane –> bind to complementary receptors in the cytoplasm –> hormone-receptor complex enter the nucleus and bind to another specific receptor on the chromosomal material –> this causes the stimulation of mRNA production which will code for protein synthesis

Question 13

what is the the function of MINERALOCORTICOIDS and give an example of mineralocorticoids

Answer 13

• help control the Na+ and K+ concentration in blood, therefore blood pressure maitainance

-ALDOSTERONE act on DCT and collecting duct to increase H2O reabsorption, increase Na+ absorption and decrease K+ absorption

Question 14

what is the function of GLUCOCORTICOIDS and give an example

Answer 14

-help control metabolism of carbohydrates,lipid and protein in the liver

• (zona fasciculata) CORTISOL released in response to stress and low blood glucose level as it stimulates glucose production

-(zona reticularis) - release of precursor androgens which are taken up by thr ovaries and testes in order to be converted into sex hormones

Question 15

what hormone is released form the adrenal medulla?

Answer 15

adrenaline + noradrenaline

Question 16

what is adrenaline and what are its function?

Answer 16

is a polar hormone and it prepares body for activity eg the flight or fight response

Question 17

what is the pancreas function?

Answer 17

control blood glucose concentration

Question 18

what are the 2 types of function carried by the pancreas?

Answer 18

exocrine gland - synthesise and secrete pancreatic juice consisting of digestive enzyme in the ACINUS into ducts which leads to the small intestine, release is triggered by hormonal/nervous stimulation

endocrine gland - synthesise and secrete hormones into th bloodstream

Question 19

explain the structure of a pancreas

Answer 19

the pancres consist of multiple ISLETS OF LANGERHANS SURROUNDED BY ACINUS

the islet of langerhans carry out he endrocrine function as they consist of alpha and beta cells which secrete glucagon and insulin respectively into the bloodstream

acinus are lobules surrounding the islet of langerhans that carry out the exocrine function by producing and secreting pancreatic juice intoduct that lead to the small intestine

Question 20

explain the function of the islet of langerhans

Answer 20

they moritor blood glucose concentration and have :
- alpha cells = secrete glucagon when glucose level is low in the blood

-beta cells =secrete insulin when glucose level is high in the blood

Question 21

describe the negative feedback of release of insulin when glucose level is high in the blood.

Answer 21

high glucose level –> detected by beta cells in the islet of langerhans in the pancreas –> beta cell secrete insulin in the bloodstream –> insulin is detected by receptors on the liver and muscle cells –> removal of glucose from blood –> glucose concentration is decreased

Question 22

explain the mechanism by which insulin is secreted

Answer 22

1.potassium channels are open allowing K+ to move out making the membrane potential more negative
2. blood glucose level high –> glucose moves into the cell
3. glucose metabolised to produce ATP which then closes the K+ channels
4. K+ not able to move out, so membrane potential doesnt become more negative and changes
5. this change cause the voltage-gated Ca2+ channels to open allowing Ca2+ to move in
6. Ca2+ cause insulin vesicles to move and fuse with the cell membane to be then secreted by exocytosis

Question 23

what is the normal level of glucose?

Answer 23

4-6 mmol dm-3

Question 24

what is the condition called when glucose level is low

Answer 24

hypoglycaemia

Question 25

what is the condition called when glucose level is high

Answer 25

hyperglycaemia can cause diabetes mellitus

Question 26

what happens when glucose level is high

Answer 26

insulin secreted --> target hepatocytes or muscle cells --> bind to complementary receptor --> TYROSE KINASE activation --> phophorylation of inactive ezymes to make them active --> cause vesicles containing glucose transporters to be INSERTED into the membrane --> glucose can enter the cell

Question 27

what happens to glucose that moves into the cell?

Answer 27

converted to glycogen - GLYCOGENESIS converted to fat used in respiration increased insertion of glucose carrier protein = increased glucose uptake from blood

Question 28

describe the negative effect / negative feedback mechanism when blood glucose level is low

Answer 28

low glucose level --> detected by alpha cells in the islet of langerhans in the pancreas --> alpha cells secrete glucagon into the blood --> glucagon (promotes conversion of glycogen to glucose) detected by receptor on liver cells --> liver cells convert glycogen into glucose and release into the increased use of fatty acids fro respiration

Question 29

what happens when glucose level is low

Answer 29

glucagon secreted --> detected by hepatocytes or muscle cells --> binds to complementary receptor --> G PROTEIN activation --> adenyl cyclase activation --> ATP conversion into cAMP --> enzyme-cascade reaction initiated --> increase of glucose in blood

Question 30

what are the responses produced by the cell after the glucagon detection?

Answer 30

-glycogen converted to glucose - GLYCOGENOLYSIS - fatty acid used in repiration instead of glucose -amino acids fatty acid converted into glucose - GLUCONEOGENESIS

Question 31

what is the issue of diabetes

Answer 31

body is no longer to produce sufficient insulin or is not able to produce insulin

Question 32

how many types of diabetes?

Answer 32

diabetes Type 1 and Type 2

Question 33

describe diabetes Type 1

Answer 33

insulin-dependent young age onset autoimmune genetic causes non- functional pancreas no insulin is produced cannot be prevented cannot be reversed requires insulin injection unless pancreas transplant beta cells are destroyed so no insulin is produced pigs and GM bacteria to produce insulin

Question 34

describe diabetes Type 2

Answer 34

non-insulin dependent adult onset due to insulin resistance (insulin binding to receptors doesn't cause anymore glycogenolysis, doesnt respond), obesity, age partially functional pancreas not enough insulin produced can be prevented through lifestyle changes can be reversed with early diagnosis insulin injection or pills beta cells dont produce enough insulin

Question 35

diabetes symptoms

Answer 35

thirst, frequent urination blurry vision, health complication

Question 36

describe the gestational diabetes

Answer 36

gestational diabetes occur during pregnancy and it can lead the mother to hyperglycaemia which is high glucose concentration in blood meaning that the featus receives more glucuose,respires more, more cell differentiation therefore increased growth which can lead to macrosomia it can lead to hyperglycaemia and hypoglycaemia

Question 37

glycogenesis

Answer 37

process by which excess glucose is stored as glycogen

Question 38

gluneogenesis

Answer 38

process by which amino acids and lipids are converted into glucose

Question 39

experiment

Answer 39

* Independent variable – concentration of GH injected * Dependent variable – rate of growth *Control variables – animal species, foodstuff, (named) conditions * Trial populations over several months * Control group to ensure validity of conclusions * Method for assessing growth – e.g. % mass change or growth rate to allow comparability * Different species of chickens should be investigated * Ensure food is consistent across all trial groups * Sample size needs to be large enough to reduce effect of anomalies * Ethical concerns – chickens should be reared in humane conditions * Consideration of potential negative effects on chickens, e.g. larger muscle mass, so may be unable to move as easily