5.1.4 Hormonal communication Flashcards
endocrine gland purpose
produce and secrete hormones directly into the blood, don’t have ducts
exocrine gland purpose
don’t produce hormones
secrete molecules into a duct which carriers them to where they are needed
adrenal medulla location and purpose
centre of adrenal glands
makes and secreted adrenaline and noradrenaline
adrenaline causes
relax smooth muscle in bronchioles increase stroke volume and heart rate vasoconstriction glycogen->glucose dilates pupils increases mental awareness inhibits action of gut body hair erects
non-steroid hormone features
protein/amino acid based hormone
can’t dissolve in cell surface membrane of target cells and get inside
must bind to a receptor
why non-steroid hormones are first messengers
first messenger definition
transmit signal around the body and
initiate change inside the cell when they bind to a receptor
second messenger function
transmits signal inside the cell
causes effect on the cell
adrenal cortex function
uses cholesterol to produce steroid hormones
3 layers of adrenal cortex (outside to inside)
Zona Glomerulosa
Zona Fasciculata
Zona Reticularis
Zona Glomerulosa function
secreted mineralcorticoids (e.g. aldosterone) help to control sodium and potassium levels in blood and blood pressure
Zona Fasciculata function
secretes glucocorticoids (leg. cortisol) hells control metabolism of carbs, protein and fats in liver
Zona Reticularis function
secretes precursors to sex hormones
how steroid hormone causes change in cell
enters cell by dissolving in cell surface membrane
bind with receptor in cytoplasm
receptor-hormone complex enters nucleus, binds to another receptor on chromosome
causes mRNA to be made, produces proteins
how different types of hormones are released and take effect on target cells using adrenal glands as example model answer
endocrine glands release hormones
that travel in the blood
to target cells
adrenal medulla releases non-steroid hormones (e.g. adrenaline)
adrenaline acts as first messenger, binds to complementary shaped receptor on cell surface membrane
G-protein activates adenyl cyclase
converts ATP into cyclic AMP (cAMP)
cAMP is the second messenger (causes effect in cell)
adrenal cortex releases steroid hormones dissolved into cell surface membrane binds to receptor in cytoplasm receptor-hormone complex binds to receptor on chromosome causes mRNA then proteins to be made
how hormones travel all around body in blood yer still have specific effects
endocrine gland make and secrete hormones directly into blood
hormone bind to specific complementary receptors on cell surface membrane of target cells
hormones will not affect cells without these receptors
target cells grouped into target tissue
“pancreatic juice” juice composition
amylase
trypsinogen (precursor to trypsin - protease enzyme)
lipase
sodium hydrogen carbonate (alkali to neutralise stomach acid)
exocrine function of pancreas
majority of cells produce digestive enzymes (“pancreatic juice”)
these cells form groups (acini) that secrete enzymes into tubules that lead to pancreatic duct which takes them to the small intestine
endocrine function of pancreas
islets of Langerhans contain alpha and beta cells
they detect changes in blood glucose levels
they produce and secrete hormones directly into closely associated capillaries
alpha cells function
produce and secrete glucagon
beta cells function
produce and secrete insulin
pancreas under micrograph
most cells = exocrine
group of cells surrounding smallest hollow tubes = acini
slightly larger circular(ish) hollow tubes = branch of pancreatic duct
patches (circularish) with different staining = islets of Langerhans
releasing of insulin beta cell mechanism
cell membrane has potassium and calcium ion channels
calcium ion channels normally closed, potassium ion channels normally open - potassium ions flow out
when blood glucose concentration is high, glucose moves into cell
glucose metabolised, produces ATP
ATP closes potassium ion channels
potassium ions accumulates, alters potential difference across cell membranes, inside becomes less negative
change in potential difference open calcium ion channels and Ca2+ ions enter cell
calcium ions causes vesicles of insulin to fuse with cell membrane, releasing insulin by exocytosis
diabetes mellitus definition
disease when you can’t control blood glucose levels effectively
hyperglycaemia definition
blood glucose concentration too night
leads t organ damage in the long term
hypoglycaemia definition
blood glucose concentration too low
not enough glucose to cells esp. to brain
causes tiredness and irritability
to brain damage, seizures, death
Type I diabetes features
insulin dependent diabetes
autoimmune response - attack and destroy own B cells
can’t produce sufficient insulin
can’t store glucose as glycogen, excess glucose remains in blood, hyperglycaemia
when blood glucose falls, no/little glycogen to release glucose, causes hypoglycaemia
Type II diabetes features
non insulin-dependent diabetes
number of receptors on target cells for insulin decline and cells unresponsive to insulin
can still produce insulin (less though)
risk factors of Type II diabetes
age obesity refined sugar rich diet certain ethnicities family history
treating Type 1 diabetes
monitor blood glucose levels
insulin injections
insulin pump, permanently pumps insulin at steady rate into bloodstream
islet/beta cell transplant (healthy beta cells from dead donor implanted into pancreas of patient)
pancreas transplant
advantages of obtaining insulin from genetically engineered bacteria perfect answer
old method of obtaining insulin was from pigs
engineered insulin is cheaper (food stock cheaper than that for pigs)
less risk of infection than with pig insulin
human insulin produced is more effective on humans than pig insulin
avoids side effects/allergies/immune response some people may experience with pig insulin
ethically advantageous as no animal rights associated with bacteria as there are with pigs
also caters to more people (e.g. Jews)
future treatment of type I diabetes
stem cells could be used to grow new Islets of Langerhans with B cells can produce insulin, cures Type I diabetes
Type II diabetes treatment
control of carbohydrate intake
regular exercise
sometimes insulin injectors or drugs to slow down absorption of glucose
what happens when hyperglycaemia detected
beta cells secrete insulin
insulin reached target cells (e.g. muscle cells, liver cells)
binds to receptors on target cells causing:
more transporter proteins for glucose placed into cell surface membrane
more glucose entering cells
glucose in cells converted to glycogen (glycogenesis) or fats for storage
more glucose used in respiration
what happens when hypoglycaemia detected
glycogen converted to glucose (glycogenolysis)
more fatty acids used in respiration
amino acids and fats converted into additional glucose, gluconeogenesis
gluconeogenesis definition
metabolic pathways that results in generation of glucose from pyruvate and lactate
