endocrine system

Question 1

what is endocrine communication?

Answer 1

a communication system using hormones as signalling molecules

Question 2

what is a hormone ?

Answer 2

molecules releases by a gland into the blood to carry a signal to target tissue

Question 3

what are the 2 types of hormone?

Answer 3

protein and steroid

Question 4

describe the protein hormone

Answer 4

not soluble in membrane, so therefore binds to plasma membrane onto a complementary site and causes a release of secondary messenger inside the cell

Question 5

describe the steroid hormone

Answer 5

is lipid soluble so can pass through the membrane so can have a direct effect on target

Question 6

why are steroid hormones lipid soluble ?

Answer 6

synthesised from lipid-based molecules like cholesterol so soluble in fats and dissolve in the lipid bilayer

Question 7

what is an endocrine gland?

Answer 7

ductless group of cells that secreates hormone straight into the bloodstream

Question 8

what is an exocrine gland?

Answer 8

group of cells around a small duct that secrete products into the duct leading to the site requiring the substance

Question 9

why do hormones have specific targets ?

Answer 9

to produce a specific response in specific places

Question 10

why is each hormone different?

Answer 10

so it doesn’t react to everything whilst travelling around the body and only reacts with the target cells

Question 11

what is a first messenger ?

Answer 11

non-steroid hormone - causes release of secondary

Question 12

explain the path of a non steroid hormone binding to target cell

Answer 12

binds to plasma membrane- activates G protein- which activates an effector molecule - which converts ATP to cyclic AMP which is the secondary messenger- this will act on another protein to activate enzyme controlled reactions to alter cell activity

Question 13

where is adrenal gland found?

Answer 13

anterior to kidneys

Question 14

why do the adrenal glands have a good blood supply ?

Answer 14

hormones travel in the blood so their transport network needs to be available near the production site

Question 15

name the outermost layer of the adrenal cortex

Answer 15

zona glomerulosa

Question 16

name the middle layer of the adrenal cortex

Answer 16

zona fasciculata

Question 17

name the innermost layer of the adrenal cortex

Answer 17

zona reticularis

Question 18

state what the zona glomerulosa secretes

Answer 18

mineralocorticoids - aldosterone

Question 19

state what the zona fasciculata secretes

Answer 19

glucocorticoids - cortisol

Question 20

state what the zona reticularis secretes

Answer 20

precursor molecules (androgens)

Question 21

what is the function of mineralcortiocoids?

Answer 21

control concentration of Na and K ions in blood so maintains blood pressure

Question 22

what is the function of aldosterone ?

Answer 22

targets cells of DCT and collecting duct by increaseing absorbency to Na and water and decreasing to K. so therefore increasing blood pressure

Question 23

what is the function of glucocorticoids?

Answer 23

control metabolism of carbohydrates, fats and proteins in liver

Question 24

what is the function of cortisol ?

Answer 24

response to stress or lowered blood glucose so therefore stimulates production of glucose from stored compounds

Question 25

what is the function of precursor molecules ?

Answer 25

targets sex organs to be converted into sex hormones to develop 2nd sexual characteristics and regulate production of gametes

Question 26

what type of hormone does the cortex produce ?

Answer 26

steroid based

Question 27

what do steroid based hormones act upon ?

Answer 27

cause protein synthesis

Question 28

outline the mechanism for steroid hormones causing protein synthesis ?

Answer 28

hormone passes through cell membrane and binds to complementary receptors in cytoplasm- a receptor-steroid complex is formed and travels to nuclear and binds to chromosomal material which stimulates production of mRNA so codes for protein synthesis

Question 29

what type of hormones do the medulla secrete and give 2 examples ?

Answer 29

adrenaline and noradrenaline

Question 30

is adrenaline steroid/non? why?

Answer 30

non steroid - polar and derived from AA tyrosine

Question 31

why do many cells have adrenaline receptors?

Answer 31

effects of flight or fight need to be widespread as different parts of the body will have different but equally important responses

Question 32

state 8 responses of the body to adrenaline

Answer 32

relaxes smooth muscle in lungs, increases stroke volume, vasoconstriction therefore increases blood pressure, glycogen to glucose, pupils dilate, increase in mental awareness, inhibits digestion, hair erects

Question 33

why does adrenaline increase stroke volume in response to adrenaline ?

Answer 33

increase in blood pumped per min so increase blood flow round so increase in oxygen and glucose to muscle so increased activity for flight/fight

Question 34

what are the exocrine cells of the pancreas called?

Answer 34

acinus cell

Question 35

what do the acini make and secrete ?

Answer 35

digestive enzymes including pancreatic amylase, trypsinogen and lipase

Question 36

what is the function of pancreatic enzymes ?

Answer 36

amylase to maltose wha

Question 37

what is the function of lipase ?

Answer 37

digest lipids

Question 38

outline the pathway of an enzyme synthesised in an exocrine gland?

Answer 38

mad win the acinus cell, travels down tubule at centre of acini, down interlobular duct, into pancreatic duct, then enters duodenum

Question 39

what is the purpose of sodium hydrogen carbonate being produced in the exocrine gland ?

Answer 39

is an alkali so neutralises acid coming through duodenum therefore creates optimum environment for enzymes

Question 40

where in the pancreas does the endocrine function take place ?

Answer 40

islets of langerhan

Question 41

what do alpha cells of the islets of langerhan secrete ?

Answer 41

glucagon

Question 42

what do beta cells of the islets of langerhan secrete ?

Answer 42

insulin

Question 43

describe the mechanism for releasing insulin

Answer 43

in the membrane Ca channels shut, K open so K diffuses out therefore inside cell is more negative. when glucose concentration outside increases glucose enters cell and glucose is used in respiration and ATP is produced through use of enzyme glucokinase. extra ATP causes K channels to close so the inside is more positive. therefore the change in charge opens Na channels and therefore Na flows in and causes vesicles containing insulin to move to PM ready for exocytosis

Question 44

what is the role of the enzyme glucokinase?

Answer 44

acts as a glucose sensor and triggers a change in metabolism of glucose

Question 45

how are the acini cells are specialised ?

Answer 45

They need many ribosomes to synthesise proteins: these ribosomes will be on the rough endoplasmic reticulum. They will also have a lot of Golgi apparatus as these are involved with packaging the enzymes into secretory vesicles. Many mitochondria will be present to supply ATP for the active processes

Question 46

why is trypsinogen released in the inactive form ?

Answer 46

It is activated in the intestines so that Active trypsin would digest any proteins in the intestines only, so won't digest anything needed in the pancreatic duct and cells when created if it was activated