hormonal communication

Question 1

what are endocrine glands

Answer 1

organ that secretes hormones directly into the blood

eg adrenal glands, pancreas, pituitary gland

Question 2

what are exocrine glands

Answer 2

a gland that secretes substances such as enzymes/mucus/sweat into a duct
eg stomach, pancreas, salivary glands

Question 3

what is a hormone

Answer 3

chemical secreted from an endocrine gland, brings about a response in another part of the body
eg adrenaline, insulin, glucagon

Question 4

what is target tissue

Answer 4

tissue affected by hormone, tissues carry out specific response to the binding site of the hormone

Question 5

two types of hormones

Answer 5

proteins/peptide

steroid

Question 6

features of a peptide hormone

Answer 6

water soluble,

not soluble in phospholipid bilayer so do not enter cells but bind to specific receptor on cell surface membrane

Question 7

features of steroid hormones

Answer 7

lipid soluble,

can pass through phospholipid bilayer and enter cell, binds to intracellular receptors

Question 8

what’s the first and second messenger

Answer 8

first messenger is the hormone

this triggers the activation of the second messenger such as cAMP

Question 9

action of adrenaline on liver cells

Answer 9

adrenaline (first messenger) is a peptide so unable to enter cell

binds to specific receptor on csm

receptor is associated with enzyme adenyl cyclase

adenyl cyclase converts ATP —> cAMP (second messenger)

cAMP causes an effect in the cell by activating enzyme activity

Question 10

structure of adrenal glands

Answer 10

two small glands that sit above kidneys

adrenal medulla- inner region
adrenal cortex - outer region

Question 11

function of adrenal medulla

Answer 11

releases adrenaline in response to stress produces fight or flight response

Question 12

function of adrenal cortex

Answer 12

uses cholesterol to produce steroid hormones

aldosterone - controls levels of Na+ and K+ in blood

cortisol - controls metabolism of carbohydrates and proteins in liver

Question 13

how do effects of adrenaline help prepare body for activity

Answer 13

• increases heart rate and stroke volume —> increases cardiac output to pump more blood per min, carrying more oxygen and glucose to muscles
• constricts blood flow to digestive system —> more blood to go to brain and muscles

Question 14

what enzymes do exocrine glands in the pancreas release

Answer 14

amylase - hydrolyses carbohydrates

trypsinogen - an inactive protease

lipase - breakdown of fats

these tubules join together to form the pancreatic duct, which releases the fluid containing the enzymes into the small intestine

Question 15

what does the fluid contain in the pancreatic duct

Answer 15

enzymes such as amylase, trypsinogen, lipase

sodium hydrogen carbonate (alkaline) which neutralizes acidity of digestive contents in stomach

Question 16

what are islets of langerhans

Answer 16

endocrine gland in pancrease

alpha cells - secrete secrete glucagon (increases blood glucose

beta cells - secrete insulin (decreases blood glucose)

Question 17

outline how increased blood glucose is controlled

Answer 17

1. beta cells detect if blood glucose is too high
2. secrete insulin to target cells (hepatocytes, muscle cells etc)
3. insulin (first messenger) binds to receptors
   receptors activate adenyl cyclase which converts ATP–> cAMP (second messenger
4. cAMP activates a series of enzyme controlled activity:
   - more glucose channels are placed into csm
   - more glucose enters cells
   - glycogenesis (glucose–>glycogen)
   - more glucose broken down in respiration
5. which lowers blood glucose conc.

Question 18

outline how decreased blood glucose is controlled

Answer 18

1. alpha cells detect lowered blood glucose conc.
2. secrete glucagon to target cells (hepatocytes)
3. binding of glucagon to specific receptors causes these effects:
   - glycogenolysis (glycogen –> glucose)
   - gluconeogenesis (amino acids + fats –> glucose)
4. increases blood glucose conc.

Question 19

outline the process of control of insulin secretion

Answer 19

1. csm has K+ and Ca2+ ion channels, K+ channels are usually open so potassium ions flow out
2. when blood glucose conc. is high, glucose moves into cell
3. glucose is metabolised and ATP is produced
4. ATP causes the K+ ion channels to close
5. potential difference of cell membrane is changed, inside becomes more positive
6. change in potential difference causes Ca2+ ion channels to open
7. Ca2+ ions cause vesicles of insulin to fuse with csm, releasing insulin via exocytosis

Question 20

what is Diabetes Mellitus

Answer 20

a disease where blood glucose concentrations cannot be managed effectively,
can lead to hypoglycaemia / hyperglycaemia

Question 21

difference between type 1 and type 2 diabetes

Answer 21

type 1: sudden onset, due to pancreas’ failure to produce enough insulin due to loss of beta cells

type 2: gradual onset, insulin resistance