hormonal communication Flashcards
what is an exocrine
- have ducts
- secrete enzymes into the ducts which opens into the body cavity e.g. small intestine, stomach etc.
what is an endocrine
- ductless gland
- secrete hormones into blood stream
what is the definition of a hormone
- chemical messenger (cell - signalling molecule)
- produced by endocrine gland
- travels in blood plasma
- from gland to their target organ -> specific target
- released in small concentrations + have widespread and long lasting effects.
what are the two types of hormones
- non - steroid (protein and amine)
- steroids
what is a non - steroid hormone
- water soluble (hydrophilic) + polar
- do not enter cells
- bind to specific receptors on the plasma membrane
what is a steroid hormone
- lipid soluble (hydrophobic) + non polar
- diffuse, directly through the phospholipid bilayer + bind to complementary receptors, inside the cell
how can one hormone, have different effects on different targets
- different receptors may be present
- second messenger may activate different channels/enzymes
- different secondary messengers, may be activated
- second messenger level may increase or decrease within the cell
describe how adrenaline controls heart rate
- binds to a G protein coupled receptor, on a plasma membrane of SAN cells in the heart.
- adenyl cyclase activated which converts ATP -> cAMP
describe how steroid hormones move through the bilayer
- dissolves through phospholipid bilayer
- binds to a complementary receptor in the cytoplasm
- forms a hormone receptor complex (HRC)
- HRC acts as a transcription factor
- transcription factors, either assist or inhibit the expression of a certain gene
- if the transcriptions factor promotes gene expression a new protein could be produced.
which responses, are faster, hormonal or neuronal
neuronal
what is an endocrine gland
a ductless gland, that secretes hormones directly into the blood stream.
give 4 examples of steroid hormones
- testosterone
- oestrogen
- cortisol
- insulin
give 4 examples of non - steroid hormones
- adrenaline
- ADH
- glucagon
- insulin
explain why steroid hormones can pass easily through the plasma membrane but other protein hormones cannot
steroid hormones, are lipid soluble (hydrophobic + non polar) thus meaning they can dissolve through the phospholipid bilayer
what are the 3 outer layers of the adrenal gland
- zone glomerulus
- zone fasciculata
- zone reticulosis
what is the function of the Zona glomerulosa
- acts on cells in the collecting duct + diastral conculcated tubule in the nephron
- increases sodium uptake back into blood stream
- increase water potential of blood
what is the function of the Zona fasciculata
- controls metabolism of carbohydrates, fats and proteins in the liver.
- causes glycogenesis
- causes an increase in blood glucose levels
what is the function of the Zona reticularis
- androgens are converted into sex hormones
- e.g. testosterone + oestrogen
- ( secondary sexual characteristics)
describe the action of adrenaline on the liver cells
- the hormone adrenaline is hydrophilic -> cannot pass directly through plasma membrane
- it binds to the receptor on the surface of the cell -> complementary shape
- the G protein binds to and activates adenylyl cyclase enzyme
- this converts ATP into the second messenger cyclic AMP (cAMP)
- this activates other enzymes - protein kinases which activate other enzymes (cascade effect)
- this leads to a response -> glycogen broken down to glucose
why can adrenaline have such a long effect if adrenaline only stays in the blood stream for 1-3 minutes
adrenaline, can be secreted continuously by the adrenal gland, over a long period of time.
what stimulus leads to an increased secretion of insulin
- high blood glucose levels
state the two specific ion channels that span the cell membrane of the beta cells
- K+ channels
- calcium channels
why must blood sugar levels not get too high
to high blood sugar levels, will result in dehydration
why must blood glucose not get low
- starving the body of glucose leads to reduced production in ATP, which in turn can lead to a loss of bodily functions, e.g. drowsiness’s.
how many types of diabetes are there
2
what is type 1 diabetes - insulin dependent diabetes
- autoimmune disease
- immune system destroys pancreatic B - cells, no insulin, therefore muscle/ liver cells have no glycogen stores.
what is type 2 diabetes - non - insulin dependent diabetes
- insulin, produced, but it does not bind to receptor.
- receptors has changed shape.
islets of Langerhans (endocrine)
- lightly stained
- large spherical clusters
- produce and secrete hormones
pancreatic acini (exocrine)
- darker stained
- small, berry like clusters
- produce and secrete digestive enzymes.
what are the risk factors associated with type 2 diabetes
- obesity
- lack of exercise
- high sugar diet
- genetic component
what are the symptoms of diabetes
- BGL remains high from a long time after a meal.
- glucose loss in urine
- dehydration
- no glycogen stores, therefore to high blood glucose levels between meals
what is an example of a past diabetes treatment
- insulin extracted from animal pancreas e.g. pigs
what is one advantage and one disadvantage of past diabetes treatment
- tried and tested method (A)
- needs to purified (D)
what is an example of current insulin treatment
genetically modifying bacteria to produce human insulin
what is one advantage and one disadvantage of current diabetes treatment
- less risk of allergic reaction (A)
- side effects of pump ( such as hared lumps under the skin) (D)
what is a example of future diabetes treatment
transplant of pancreas
what is one advantage and one disadvantage of future diabetes treatment
- patient can now produce insulin, so more physiological control of BGL (blood glucose levels) (A)
- not enough pancreases available due to donor shortage (D)
what is transplant of pancreatic stem cell - derived pancreatic islet cells
pluripotent stem cells, can differentiate into B - cells and increase the mass of the islets and increase the secretion of insulin
what is immunotherapy
pluripotent stem cells can also protect B - cells from autoimmune attack by inhibiting T - cell proliferation and reduce the inflammatory response.
what is gene therapy
there are opportunities to use genetic modification to provide enhanced endocrine function and survival and modulate the immune response.
what is developmental biology
opportunities, to study the function and longevity of human islet cells with varied genotypes, and develop new drugs for treatment.
what is the main treatment for type 2 diabetes
- lifestyle change
- losing weight
- regular exercise
- healthy, balanced diet
