module 5 - hormonal communication

Question 1

what is the role of the endocrine system?

Answer 1

it is a group of specialised cells that secrete hormones directly into the bloodstream

Question 2

for what reasons might hormone secretion occur?

Answer 2

change in concentrations of a substance e.g blood glucose levels
another hormone
a nerve impulse

Question 3

what are the steps 1-4 for hormone secretion?

Answer 3

1- a glad is stimulated causing a hormone o be secreted directly into the blood
2- once secreted the hormones are transported all over the body via blood plasma
3- hormones then diffuse out of blood and bind to specific receptors on the target cell membrane (on membrane or cytoplasm)
4- once bound the hormone stimulates target cell to produce response

Question 4

what are the properties of STEROID hormones?

Answer 4

they’re lipid soluble meaning they can pass through the membrane of a cell to form hormone-receptor complexes
they act as transcription factors as they prevent transcription of a gene

Question 5

what are properties of NON-STEROID hormones?

Answer 5

they are hydrophobic meaning they cannot pass through the membrane
instead they must bind to specific receptors on cell surface membrane of target cell
this will then trigger a cascade of secondary messengers to mediate a response

Question 6

what is an adrenal gland?

Answer 6

2 small glands located at the top of each kidney
it is made up of 2 components:
> adrenal cortex - outer region
> adrenal medulla - inner region

Question 7

what is the role of the adrenal cortex?

Answer 7

controlled by hormones released bye the pituitary gland
produces 3 main hormones:
GLUCOCORTICOIDS =
> includes cortisol which helps regulate metabolism by controlling how body converts fats etc in to energy
> includes corticosterone which helps regulate immune response
> release of this hormone is controlled by hypothalamus
MINERALCORTICOIDS =
> aldosterone is produced to help control blood pressure by maintaining levels of salt and water in the blood
ANDROGENS =
> small amounts of male and female sex hormones are produced

Question 8

what is the role of the adrenal medulla?

Answer 8

hormones are released when the sympathetic nervous system is stimulated
occurs when body is stresses
produces 2 main hormones:
ADRENALINE =
> increases heart rate sending more blood to muscles and brain
> rapidly increased glycogenolysis
NORADRENALINE =
> dilates pupils and air ways
> narrows the blood vessels of non-essential organs to create high blood pressure

Question 9

what is the function of the pancreas?

Answer 9

endocrine glands = to produce and secrete hormones directly into the blood stream
exocrine glands = to produce enzymes and release them via ducts into the duodenum

Question 10

what is the role of the endocrine gland?

Answer 10

responsible for producing insulin and glucagon
within endocrine tissue there are small regions of islets of Langerhans which are responsible for this production

Question 11

what is the role of the exocrine gland?

Answer 11

most of the pancreas is composed of endocrine tissue
responsible for producing digestive enzymes and pancreatic juice (alkaline liquid)
they are both secreted into ducts leading to the pancreatic duct from which they’re released into duodenum

Question 12

what are the 3 enzymes produced and released by the exocrine gland?

Answer 12

amylase = breaks down starch into simple sugars
protease = breaks down proteins into amino acids
lipase = breaks down lipids into fatty acids and glycerol

Question 13

what does the histology of the pancreas involve?

Answer 13

Pancreatic acini (exocrine tissue)
islets of Langerhans (endocrine tissue)

Question 14

histology of acini:

Answer 14

produces and secretes digestive enzymes into ducts
small berry like structures
darker staining (pink)
exocrine tissue

Question 15

histology of islets of Langerhans:

Answer 15

produce and secret hormone into blood
large spherical clusters
lighter stain (blue)
endocrine tissue
> alpha cells = glucagon (increases BGL)
> beta cells = insulin (reduces BGL)

Question 16

how does the body reduce high blood glucose levels?

Answer 16

1- beta cells detect change in BGL stimulating the release of insulin
2- insulin will travel via the blood (endocrine - IofL) to target cells
3- results in:
> decrease of glucagon released by alpha cells
> increase glucose uptake by cells
> increase glycogenesis
> increase lipogenesis (glucose to fat)
4- all work together to decrease the levels of glucose in the blood

Question 17

how does the body increase low blood glucose levels?

Answer 17

1- decrease in BGL is detected by alpha cells
2- causes release of glucagon which travels to target cells via blood stream (endocrine - IofL)
3- results in:
> increased glycogenolysis
> increased gluconeogenesis
4- all work together to increase the levels of glucose in the blood

Question 18

how is the secretion of insulin controlled?

Answer 18

1- when BGL are high more glucose enters by beta cells via facilitated diffusion
2- more respiration takes place = more ATP
3- rise in ATP triggers K+ channels to close so they can no longer pass through the B cell membrane = positive change builds up on the inside
4- inside of cell is now more positive causing DEPOLARISATION
5- Ca2+ channels open in the membrane allowing Ca2+ to diffuse in
6- this causes vesicles to fuse with B cell membrane
7- insulin is released via exocytosis

Question 19

how many types of diabetes are there?

Answer 19

two

Question 20

what is type 1 diabetes?

Answer 20

body is unable to produce enough insulin sufficiently
beta cells in the islets of langerhans are faulty
begins during childhood
currently incurable

Question 21

what is type 2 diabetes?

Answer 21

body cannot efficiently use insulin to control blood glucose levels
either too little is produced or the body doesn’t respond correctly
starts around 40 yrs old but is more recently being seen in younger children
result of obesity and inactiveness

Question 22

current treatment for Type 1:

Answer 22

regular injections of insulin
regularly check blood glucose levels by pricking finger and using monitor to determine conc
> amount of insulin administrated is based on this conc
(if someone with T1 injures themselves it may lead to them experiencing hypoglycaemia = very low BGL which can result in unconsciousness)

Question 23

current treatment for Type 2:

Answer 23

regulate persons carbohydrate intake = diet
increase exercise levels
sometimes diet and exercise is not enough so drugs must also be prescribed

Question 24

how was medically induced insulin originally obtained and what were the issues with it?

Answer 24

obtained from pigs
many ethical and religious concerns
it was a very expensive process
caused allergic reactions

Question 25

how is medically induced insulin currently obtained and what are the advantages?

Answer 25

made through genetically modified bacteria
produced in pure form =less likely to cause allergic reaction
produced in much higher quantities
much cheaper process
ethical and religious concerns are gone

Question 26

what are the issues with pancreatic transplants and what is a better option?

Answer 26

demand for the transplant outweighs the availability
high chance of body rejecting the new pancreas
immunosuppressant drug must be taken after leaving body vulnerable to infection
STEM CELL THERAPY IS BETTER ALTERNATIVE

Question 27

what are the advantages of stem cell therapy to treat diabetes type 1?

Answer 27

totipotent steam cells are used = can differentiate into any cell including B cells
donor availability would not be an issue - produce unlimited availability of beta cells
reduced likelihood of rejection
people no longer have to inject themselves with insulin

Question 28

what are concerns with stem cell therapy?

Answer 28

ethical issues - embryonic stem cells are used which involves the destruction of the embryo - destroy potential human life
body receiving stem cell therapy may develop tumour as result of unlimited cell growth
> HOWEVER embryos would have been discarded anyways due to being waste form infertility testing
> HOWEVER umbilical stem cells can be used instead

Question 29

what response is used during situations of high stress, fear, aggression?

Answer 29

the Fight or Flight Response

Question 30

what is secreted during the fight or flight response and what is the pathway to its secretion?

Answer 30

threat is detected by autonomic nervous system which is passed to the hypothalamus stimulating the sympathetic nervous system causing the release of adrenaline and noradrenaline

Question 31

where is adrenaline secreted from?

Answer 31

the adrenal gland during fight or flight response

Question 32

how is adrenaline transported round the body?

Answer 32

via the blood stream = rapid effect on cells

Question 33

what effect does adrenaline have on the body?

Answer 33

stimulates muscles in iris to contract causing pupils to dilate
increases diameter of bronchioles by relaxing smooth muscle to increase airflow

Question 34

what are the 3 steps of the body responding to adrenaline?