hormonal communication

Question 1

what is endocrine gland

Answer 1

gland that releases hormones directly into the blood

Question 2

what is exocrine gland

Answer 2

secretes chemicals not directing in the blood using ducts

Question 3

two types of hormones

Answer 3

steroid
non steroid

Question 4

feature is steroid hormones

Answer 4

lipid soluble so can pass through the lipid component of cell membrane
they bind to receptors inside the cell e.g in cytoplasm
can acts as transcription factors by forming hormone receptor complex

Question 5

features of non steroid hormones

Answer 5

not lipid soluble - hydrophilic
can at pass directly through the cell membrane
binds to receptors in the cell surface
this triggers a cascade of reactions mediated by second messengers

Question 6

action of adrenaline

Answer 6

adrenaline is the first messenger
it binds to receptors sites that has complementary shape to it
this activates the enzyme adenylcyclase
adenyl cyclase converts ATP to cAMP which acts as a second messenger and actives protein kinases which phosphorylase’s and activates other enzymes which convert glycogen to glucose

Question 7

adrenal gland structure

Answer 7

capsule- outer layer

cortex- outer region of the gland. produces hormones essential to life

medulla- inner region. produces non essential hormones

Question 8

3 hormones released in adrenal cortex and function

Answer 8

1. Glucocorticoid (cortisol)
   regulates metabolism, blood pressure and immune system by reducing inflammation
2. Mineralocorticoids (aldosterone)
   controls blood pressure by maintains balance of water conc in blood
3. Androgen- sex hormones
   aid development of the gametes

Question 9

2 hormones release in adrenal medulla and function

Answer 9

1. adrenaline
   increases heart rate. stimulates glycogenosis
   triggers fight or flight response
2. noradrenaline
   increases heart rate, widening of pupils, narrowing of blood vessels in non essential organs thus increasing blood pressure

Question 10

how does pancreas act as exocrine gland

Answer 10

it produces digestive enzymes and pancreatic juice which are secreted into ducts which lead to the pancreatic duct

amylase- break down starch into simple sugars
protease- trypsin’s break down proteins into amino acids
lipase- breaks lipids into fatty acids and glycerol

Question 11

how does the pancreas act as an endocrine gland

Answer 11

produces and secretes insulin and glucagon directly into blood stream

Question 12

structure of pancreas

Answer 12

Islet of Langer - endocrine - lighter colour
contains alpha and beta cells
alpha produce glucagon and beta produce insulin

acini- darker stain - exocrine
where digestive enzymes are produced and secreted

Question 13

normal range of blood glucose

Answer 13

90mg100cm-3
4-6mmoldm-3

Question 14

how to increase blood glucose conc

Answer 14

eating a carbohydrate rich diet
glycogenolysis- break down of glycogen into glucose
gluconeogenesis- production of glucose from non carbohydrates such as proteins

Question 15

how to decrease blood glucose conc

Answer 15

increase respiration
glycogenesis- conversion of glucose into glycogen

Question 16

role of insulin

Answer 16

increases rate of absorption of glucose by cells
increases the respiratory rate of cells
increase rate of glycogenesis
increases rate of glucose to fat conversion
inhibits release of glucagon from alpha cells

Question 17

role of glucagon

Answer 17

increases glycogenolysis - break down of glycogen into glucose
increases gluconeogenesis-
reduce amount of glucose absorbed by liver cells

Question 18

how is blood glucose conc falls

Answer 18

high blood glucose conc is detected by B cells in pancreas
B cells produce and secret insulin directly into blood
blood glucose level falls

Question 19

how blood conc is increases

Answer 19

low conc is detected by alpha cells in pancreas
they produce and secrete glucagon
blood glucose rises

Question 20

Control of insulin secretion

Answer 20

1. at normals levels of blood glucose concentration potassium channels in plasma mbrane of B cells are open. potassium ions diffuse out of cell and inside cell there is a pd of -70mV
2. when glucose conc rises glucose enters the cell by glucose transporters
3. glucose is metabolised in the mitochondria resulting in production of ATP
4. ATP binds to potassium channels causing them to close
5. potassium ions can no longer diffuse out of cell which results in pd increasing to -30mV where depolarisation occurs
6. depolarisation . causes calcium channels to open
7. calcium ions enter the cell and cause secretory vesicles to secrete insulin by exocytosis

Question 21

Producing insulin using stem cells

Answer 21

Stem cells can be treated so that they differentiate into pancreatic β cells
These newly developed β cells can then be transplanted into the pancreas of a diabetic individual, replacing the damaged cells and allowing them to produce insulin
The early-stage research has had some success using mice as model animals however it has not yet advanced to human trials