Hormonal Communication Flashcards
what is thermoregulation
control of body temp
what is osmoregulation
control of water potential
what is a hormone
chemical messenger produced by endocrine gland + transported in blood
alter activity of one or more specific target organs
what is a gland
group of cells that secrete (produce + release) hormones
what are the 3 types of hormones
peptide hormones
steroid hormones
amino acid derivative hormones
OR
steroid vs non-steroid hormones
what are steroid hormones derived from
cholesterol
how do steroid hormones carry out their function
lipid soluble – pass through membrane
bind to receptors in nucleus or cytoplasm
form hormone-receptor complex
act as transcription factor = facilitates / inhibits transcription
what are non steroid hormones made from
amino acid / peptides
how do non steroid hormones carry out their function
hydrophilic / water-soluble
receptors on surface of cell membrane
enzyme cascade
examples of steroid hormones - 5
testosterone
oestrogen
progesterone
cortisol
aldosterone
examples of non-steroid hormones - 5
insulin
glucagon
adrenaline
noradrenaline
ADH
compare hormonal + nervous system
- how they communicate
- how they transmit
- speed of transmission
- targets
- response
- response speed
- effect
where are the 2 adrenal glands found
top of each kidney
how large are adrenal glands
approx. 3cm in height + 5cm in length
state the 3 main structures of the adrenal glands
capsule
adrenal cortex
adrenal medulla
what is the capsule
fibrous layer that surrounds adrenal glands
what is the adrenal cortex
outer region of glands
produces hormones vital to life – cortisol + aldosterone
what is the adrenal medulla
inner region of glands
produces non-essential hormones – adrenaline
what controls the release of hormones from the adrenal cortex
pituitary glands
state the hormones produced by the adrenal cortex
cortisol
corticosterone
androgens - oestrogen + progesterone
aldosterone
what type of hormone is cortisol
steroid hormone
what is the main function of cortisol
regulates metabolism by controlling how body converts fats / proteins / carbs into energy
describe the effects of cortisol
can stimulate gluconeogenesis = maintain blood glucose levels
can inhibit glucose uptake by tissue other than brain
regulates blood pressure
regulates cardiovascular function in response to stress
what is the main function of corticosterone
works with cortisol to regulate immune system + supress inflammatory reactions
what is the release of corticosterone from the cortex controlled by
hypothalamus
what type of hormone are androgens
steroid hormones
effects of androgens
development of sexual attributes
what type of hormone is aldosterone
?
what are the effects / function of aldosterone
regulates sodium + potassium ion levels
maintain blood pressure + pH balance
when are hormones from the adrenal medulla released
when sympathetic nervous system stimulates the medulla
in times of fight or flight
state the hormones released from the medulla
adrenaline
noradrenaline
what type of hormone is adrenaline
non steroid
what are the effects of adrenaline
prepares for fight or flight
increases heart rate
increases blood pressure
vasodilation / vasoconstriction
diverts blood away from digestive system to muscles
dilates smooth muscles in airway – increase airflow
increases blood glucose levels – stimulates break down of glycogen + inhibits insulin secretion from pancreas
what type of hormone is noradrenaline
non steroid
what are the effects of noradrenaline
increased heart rate
widening of pupils
widening of air passages in lungs
diverts blood to muscles
difference between adrenaline + noradrenaline
?
where is the pancreas found
upper abdomen
what type of functions can the pancreas carry out - 2
endocrine + exocrine
what is the majority of tissue of the pancreas
exocrine glandular tissue
what is the main function of the exocrine tissue in the pancreas
to produce digestive enzymes + pancreatic juice (alkaline fluid)
what happens after the digestive juice is secreted from the exocrine pancreatic tissue
these secreted into ducts which leads to pancreatic duct
then released into duodenum (top part of small intestine)
what is in the pancreatic juice
pancreatic amylases – break down starch into simple sugar
trypsin (protease) – break down proteins into amino acids
pancreatic lipases – break down lipids into fatty acids + glycerol
where is the pancreatic endocrine tissue found
in exocrine tissue there are small sections of endocrine tissue
what is the overall purpose of pancreatic endocrine tissue
produce insulin + glucagon
whats the name of exocrine tissue in the pancreas
pancreatic acini
whats the name of endocrine tissue in the pancreas
islets of langerhans
describe the histology of islets of langerhans
lightly stained
large spherical clusters
describe the histology of pancreatic acini
darker stained
small berry like clusters
what are the two types of cells in the islets of langerhans
alpha
beta
what do alpha + beta cells secret
alpha - glucagon
beta - insulin
histological difference between alpha + beta cells
alpha cells larger + more numerous than beta cells within an islet
need differential staining to differentiate between the two
what functions increases blood glucose conc
Diet – carbohydrates broken down to glucose
Glycogenolysis – glycogen stored in the liver + muscle cells broken down into glucose
Gluconeogenesis – production of glucose from non-carbohydrate sources e.g form glycerol + amino acids
what functions decreases blood glucose conc
Respiration – higher levels of physical activity, higher demand for glucose
Glycogenesis – production of glycogen from excess glucose stored in liver
main role of insulin
Lowers blood glucose concentration
how does insulin lower blood conc
Increasing rate of absorption of glucose – especially skeletal muscle cells
Increasing respiratory rate of cells – increases demand for glucose
Increasing rate of glycogenesis – stores glycogen into liver + muscle cells
Increasing rate of glucose into fat conversion
Inhibiting release of glucagon from alpha cells
is insulin broken down
yes by the liver
what type of feedback is blood glucose control
negative feedback
which cells have insulin receptors
most - except RBC
what is the main role of glucagon
raise blood glucose concentration
which cells have glucagon receptors
only liver and fat cells
how does glucagon increase blood conc
Glycogenolysis – liver breaks down glycogen store into glucose
Reducing amount of glucose absorbed by liver cells
Increasing gluconeogenesis
describe the process of how the secretion of glucagon results in glycogenolysis
Secreted by alpha cells
Binds to receptors in cell surface membranes of liver cells
Causes conformational change in receptor protein
Activates G protein
Activates adenylyl cyclase
Catalyses conversion of ATP to secondary messenger – cAMP
cAMP binds to + activates protein kinase A enzyme
activate phosphorylase kinase enzymes by adding phosphate group to them
activate glycogen phosphorylase enzymes
catalyse breakdown of glycogen to glucose
describe how insulin secretion is controlled when glucose level is stable
normal levels of glucose – potassium channels in membrane of beta cells are open
potassium ions diffuse out of cell
inside cell = -70mV
describe how insulin secretion is controlled when glucose level is increased
when glucose rises – glucose enters beta cells by glucose transporter
glucose metabolised in mitochondria – produce ATP
ATP binds to potassium channels + causes them to close
(ATP sensitive potassium channels)
Potassium ion stay in cell – depolarises cell to -30mV
Voltage gated calcium channels to open
Calcium ions enter cell + cause secretory vesicles to release insulin by exocytosis
how does insulin increase uptake of glucose by cells - mechanism
Rate of glucose uptake limited by number of glucose transporter protein
Insulin binds to specific receptors on membranes of target cell
Causes them to activate more glucose transporter proteins
Increases permeability to glucose
Rate of facilitated diffusion increases
target cells of insulin
muscle cells
fast storage cells
adipose tissue
liver cells
what is type 1 diabetes
when the body is unable to produce sufficient insulin
what type of disease is type 1 diabetes
autoimmune
normally begins in childhood
what is type 2 diabetes
Receptors reduced in number // do not work properly– body cant respond to insulin
Reduced glucose uptake in liver + fat storage tissues
High blood glucose concentration
Cause beta cells to produce larger amounts of insulin – damages cells
what are the risk factors for type 2 diabetes
Obesity + Physical inactivity
High blood pressure
High blood cholesterol
Genetics + ethnic groups
describe the treatment for type 1 diabetes
Fast-acting / slow-acting insulin
Insulin dependent – controlled by insulin injections
what happens if you inject too much insulin
hypoglacaemia
Too low blood glucose conc
Unconsciousness
what happens if you inject too little insulin
hyperglacaemia
Death + unconsciousness
treatments for type 2 diabetes
Sugar + fat-controlled diet
Exercise regime
Drugs that stimulate insulin production
Drugs that slow down rate at which body absorbs glucose from intestine
Insulin injections
where did insulin use to come from
pancreas of cows / pigs
what are the benefits of using human insulin
Produced in pure form – less likely to cause allergic reaction
Insulin can be produced more
Cheaper
ethics
what are some potential treatments for diabetes
stem cells
how can stem cells be used to treat diabetes
totipotent stem cells – from embryos
grow into pancreatic beta cells in islets of Langerhans
transplanted into pancreas – replace damaged cells
