HORMONAL COMMUNICATION Flashcards
what is the endocrine system?
is a communication system that releases hormones into the bloodstream
what is an exocrine system?
releases hormones into duct
what are the 2 types of hormones
peptide and steroid
describe steroid hormones
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
describe peptide hormones
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
state some endocrine glands
testes, ovaries, adrenal glands, thyroid gland ,pancreas
explain how hormones work?
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
what is another name given to peptide hormone?
first messengers*
describe adrenal glands
found just above the kidneys
divided into the ADRENAL CORTEX and ADRENAL MEDULLA and both secrete hormones
explain the structure of the adrenal cortex and what it secretes
zona glomerulosa - secretes MINERALOCORTICOIDS (aldosterone)
zona fasciculata - secretes GLUCOCORTICOIDS (cortisol)
zona reticularis - secretes PRECURSOR/androgens molecules (male sex hormones)
what types of hormones does the AC produce and what does it use to produce these and what do these affect?
steroid hormones - use of cholesterol , affect the DNA of the target cell
explain the mechanism of steroid hormones
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
what is the the function of MINERALOCORTICOIDS and give an example of mineralocorticoids
- 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
what is the function of GLUCOCORTICOIDS and give an example
-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
what hormone is released form the adrenal medulla?
adrenaline + noradrenaline
what is adrenaline and what are its function?
is a polar hormone and it prepares body for activity eg the flight or fight response
what is the pancreas function?
control blood glucose concentration
what are the 2 types of function carried by the pancreas?
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
explain the structure of a pancreas
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
explain the function of the islet of langerhans
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
describe the negative feedback of release of insulin when glucose level is high in the blood.
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
explain the mechanism by which insulin is secreted
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
what is the normal level of glucose?
4-6 mmol dm-3
what is the condition called when glucose level is low
hypoglycaemia
what is the condition called when glucose level is high
hyperglycaemia can cause diabetes mellitus
what happens when glucose level is high
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
what happens to glucose that moves into the cell?
converted to glycogen - GLYCOGENESIS
converted to fat
used in respiration
increased insertion of glucose carrier protein = increased glucose uptake from blood
describe the negative effect / negative feedback mechanism when blood glucose level is low
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
what happens when glucose level is low
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
what are the responses produced by the cell after the glucagon detection?
-glycogen converted to glucose - GLYCOGENOLYSIS
- fatty acid used in repiration instead of glucose
-amino acids fatty acid converted into glucose - GLUCONEOGENESIS
what is the issue of diabetes
body is no longer to produce sufficient insulin or is not able to produce insulin
how many types of diabetes?
diabetes Type 1 and Type 2
describe diabetes Type 1
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
describe diabetes Type 2
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
diabetes symptoms
thirst, frequent urination blurry vision, health complication
describe the gestational diabetes
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
glycogenesis
process by which excess glucose is stored as glycogen
gluneogenesis
process by which amino acids and lipids are converted into glucose
experiment
- 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
