hormonal communication Flashcards
list the 9 major glands of the body
hypothalamus
pituitary gland
parathyroid gland
thyroid gland
thymus gland
adrenal glands
pancreas
ovaries
testes
where is the hypothalamus located
it is the region at the base of the brain
what hormones does the hypothalamus secrete
various hormones which stimulate the pituitary gland
where is the pituitary gland located
located at the base of the brain below the hypothalamus
what hormones does the pituitary gland secrete
anterior pituitary secretes TSH - thyroid stimulating
FSH + LH - menstrual regulation
ACTH - stimulates adrenal cortex
posterior pituitary secretes oxytocin - antistress + reproduction + birth contractions
ADH - water control
pituitary gland regulates other glands and hormones, and influences growth + metabolism + reproduction + water balance
where is the parathyroid gland located
in the neck, behind the thyroid gland
- it works alongside the thyroid gland for some functions
what hormones does the parathyroid gland secrete
it produces parathyroid hormone PTH - this regulates Ca levels in the blood by stimulating release of Ca from bones or reabsorption of Ca by kidneys
where is the thyroid gland located
located in the neck consisting of 2 lobes around the trachea
what hormones does the thyroid gland secrete
thyroxine and triiodothyronine - responsible for regulating metabolism + growth + development in the body
calcitonin which works antagonistically with PTH
function of the thymus gland
a lymphatic organ
it is involved in the maturation and regulation of T-cells, and is prominent in childhood development, its size decreases with age
where are the adrenal glands located
there are 2, each located above each kidney
what hormones do the adrenal glands secrete
consists of 2 parts
adrenal cortex secretes steroid hormones - cortisol, aldosterone, androgens
adrenal medulla secretes peptide hormones - adrenaline, noradrenaline
these hormones impact metabolism + blood pressure + stress response
what gland secretes aldosterone + what does it do
secreted by adrenal cortex
it regulates salt levels and water balance of blood, therefore impacting volume and pressure
what gland secretes cortisol + what does it do
secreted by adrenal cortex
it is the primary stress hormone, regulates metabolism of glucose + proteins + fats to release useable energy
what gland secretes adrenaline + what does it do
secretes by adrenal medulla
it is produced at times of stress or excitement that affects many organs in the body, preparing the body to respond to emergency situations - fight or flight
where is the pancreas located
located in the upper abdomen, by the stomach
what hormones does the pancreas secrete
insulin + glucagon - used to regulate blood glucose concentration
where are the ovaries located
located on either side of the uterus in females
what hormones do the ovaries secrete
oestrogen + progesterone + small amounts of testosterone - these regulate the menstrual cycle + reproductive system + development of secondary sexual characteristics in puberty
where are the testes located
located in the scrotum
what hormones do the testes secrete
testosterone - the primary male sex hormone, responsible for developing secondary sexual characteristics in puberty + regulating sperm production + reproductive tissues in males
what is an essential feature of endocrine glands
they must have a good blood supply
why do endocrine glands have good blood supplies
this allows them to secrete hormones directly into the blood stream (specifically blood plasma)
how do hormones work
they are transported around the body via the blood stream to target cells and tissues, which have complementary receptors on cell surface membrane, allowing them to interact with the hormone to bring about a response
what kind of response is achieved by hormones + why
slower and longer lasting responses (compared to nervous system)
- transmission is slower as it takes longer for hormones to reach target cells
- effect lasts longer as it takes time before hormone has been completely removed from the blood or be broken down so no longer binding to target cells
what are the 2 types of hormone
steroid - derived from cholesterol and insoluble in blood, activates cell internally as it can move through membrane - e.g. testosterone, oestrogen, cortisol
peptide - globular proteins made of amino acid chains, soluble in blood, activates cell externally via glycoprotein receptors - e.g. adrenaline
outline the role of hormones in the flight or flight resposne
the pituitary gland stimulates the release of adrenaline + noradrenaline
adrenaline increases heart rate by sending blood to the muscles + brain and increases blood glucose levels by causing the conversion of glycogen to glucose in the liver
noradrenaline works with adrenaline, increasing heart rate, causing pupil dilation, widens air passages in the lungs, and narrows blood vessels
how does the pancreas act as an exocrine gland
it can secrete substances via ducts
the pancreas produces pancreatic juice containing digestive enzymes, which is delivered to the small intestine where digestion of food takes place
how can endocrine and exocrine tissues in pancreas be identified
most of the pancreas is exocrine tissue - there are small regions of endocrine tissue called islets of Langerhans
the histology of the pancreas can be examined when looking at stained samples of pancreatic tissue under a microscope - darkly stained = exocrine acinar cells
- lighter clusters = islets of Langerhans
what are the 2 types of cells in islets of Langerhans
alpha cells - secrete glucagon
beta cells - secrete insulin
how can alpha and beta cells be identified
using a differential stain, such as a stain complementary to either glucagon or insulin
what is the structure + function of insulin
STRUCTURE
- peptide hormone
- made of 2 polypeptide chains, globular structure, made of alpha helix
FUNCTION
- secreted when blood glucose conc is high
- most cells have insulin receptors e.g. liver + muscle cells
give 1 type of cell that doesn’t have insuline receptors
red blood cells
outline the history of medical insulin
insulin is used to treat diabetes
pig insulin has a similar structure and was often used for medical treatment
now human insulin is artificially produced by GM bacteria
what is the structure + function of glucagon
STRUCTURE
- peptide hormone
- globular protein structure
FUNCTION
- secreted when blood glucose conc is low
- only liver cells have glucagon receptors
outline the mechanism of action for peptide hormones
1- peptide hormone, the primary messenger, floating in blood attaches to complementary receptor on cell surface membrane - as it binds it forms a complex
2- this activates the G protein, allowing the receptor to interact with adenyl cyclase (an enzyme)
3- this causes ATP to be converted to cyclic AMP, a secondary messenger
4- this initiates a cell specific response from within the cell, in the form of an enzyme cascade - depending on the primary messenger + cell, the result will be different
enzyme cascade definition
a series of enzyme controlled reactions which builds up
e.g. 1 hormone activates many cAMPs, which then activates many other enzymes…
gluconeogenesis definition
the production of new glucose from other things
glycogenesis definition
production of glycogen
glycogenolysis definition
break down of glycogen to produce glucose
give a brief outline of the regulation of blood glucose levels
- eating increases blood glucose levels
- pancreas secretes insulin so glucose»_space;> glycogen
- causes blood glucose levels to decrease
- pancreas secretes glucagon
so glycogen»_space;> glucose
where is glycogen stored
liver
what can cause blood glucose levels to increase + how is it dangerous
blood glucose can come from diet, glycogenolysis or gluconeogenesis
if blood glucose conc gets too high, organ damage can occur, also affects water potential of blood and cells which can cause damage
what happens when blood glucose increases
1- stimulus is detected by beta cells in islets of Langerhans - insulin is secreted + alpha cells stop secreting glucagon
2- insulin circulates in blood stream and bind to insulin receptors on target cells e.g. muscle or liver cells
3- insulin receptor activates tyrosine kinase, an enzyme which phosphorylates other enzymes in cell - enzyme cascade
4- glucose transporter proteins are inserted into cell surface membranes so more glucose is taken into cells and converted to glycogen (glycogenesis) or fats, or used in respiration
what happens when blood glucose decreases
1- beta cells stop releasing insulin so cells take up less glucose + alpha cells in islets of Langerhans respond to low glucose conc by secreting glucagon
2- glucagon circulates in bloodstream and binds to glucagon receptors on liver cells
3- glucagon receptor interacts with adenyl cyclase, an enzyme which increases cAMP conc in liver cells - enzyme cascade
4- liver is stimulated to activate enzyme glycogen phosphorylase which converts glycogen to glucose (glycogenolysis) and converts fats/proteins to new glucose (gluconeogenesis)
outline the mechanism of insulin release
1- beta cell starts with K+ channels open and Ca2+ channels closed, at -70mV
2- glucose conc increases and travels into cell via transport proteins
3- glucose is metabolised into ATP via phosphorylation via glucokinase
4- ATP closes K+ channels so K+ cannot move out, cell charge increases to -30mV
5- Ca2+ voltage gated channels open so Ca2+ can move into cell
6- Ca2+ causes snare proteins to contract so vesicles move and fuse with membrane and insulin is secreted via exocytosis
why is there a delay between blood glucose conc increasing and insulin being released
the increase in blood glucose conc has to be detected by beta cells, and it takes time to depolarise beta cells + release insulin
what is diabetes
a condition in which the homeostatic control of blood glucose has failed or deteriorated, specifically by the disruption of insulin function leading to high blood glucose levels
how can diabetes be tested for
urine tests - as there is so much glucose in the blood, which all gets filtered out during ultrafiltration, the kidney is unable to reabsorb it all in PCT as transporter proteins are so saturated, therefore it often appears in urine
how does high glucose conc lead to feelings of thirst or dehydration
often high glucose conc causes the kidneys to produce very large quantities of urine, so greater water loss in urine, leading to this feeling of thirst
what are the variants of diabetes
type 1 and type 2
TYPE 1 DIABETES
- what is it
- why does it occur
- when does it occur
- how is it treated
- risk factors
- type 1 diabetes is a condition in which the pancreas fails to produce sufficient insulin to control blood glucose levels
- this happens because of an autoimmune response where T-cells attack beta cells of islets of Langerhans
- it normally begins in childhood
- treated with regular blood tests, insulin injections, specialised diet, if this condition is managed well it is very liveable
- risk factors = genetics
TYPE 2 DIABETES
- what is it
- why does it occur
- when does it occur
- how is it treated
- risk factors
- type 2 diabetes is a condition where the pancreas still produces insulin but receptors have reduced in number or no longer respond (reduced sensitivity)
- leads to reduced glucose uptake, which leads to an uncontrolled high blood glucose conc and causes beta cells to produce larger amounts of insulin, which damages them
- this mostly occurs in liver + fat storage tissues
- usually occurs in those aged 40+, but appearing more in young people recently
- treated with a sugar + fat controlled diet + exercise
- risk factors = obesity, low physical activity, high blood pressure + cholesterol, genetics
what is a common symptom of diabetes + why
high blood pressure
this is because high blood glucose conc causes water to move into blood, increasing the volume and pressure
what are 5 common treatments for diabetes
- exercise
- regular monitoring through blood tests
- diet - more fruit and veg, restricting processed food, consuming more polysaccharides over mono/disaccharides
- insulin injections - can be fast or slow acting, which allows for different levels of control
- drugs when diet therapy fails
why can’t insulin be taken orally
insulin is a protein, if taken orally it would be digested by enzymes so not absorbed into blood stream
how is insulin for diabetes treatment produced
produced by GM bacteria - E.coli specifically
- recombinant plasmids with human insulin gene are placed in E.coli
- the transgenic bacteria are identified by markers
- these are then isolated and placed into fermenters that provide optimal conditions
- bacteria multiply by binary fission and produce human insulin
- insulin is extracted + purified
recombinant DNA definition
DNA that has been altered by introducing nucleotides from another source
recombinant proteins definition
manipulated forms of an original protein, produced from recombinant DNA, and often by eukaryotic cells e.g. yeast, cultured animal cells, as they contain golgi bodies and so can carry out post translational modifications
transgenic organism definition
an organism containing DNA from a different/multiple different species
give 5 advantages of recombinant insulin
- it is identical to human insulin unless otherwise modified
- there is a reliable supply available to meet demand
- fewer religious/moral concerns as cows/pigs not killed
- fewer rejections problems + side effects + allergic reactions
- cheap to make in large volumes
how could stem cells be used in diabetes treatment
stem cells can differentiate into insulin producing beta cells, which could then be transplanted into patients
how can fast and slow acting insulin be produced
recombinant insulin from GM bacteria can be modified to create this
hyperglycaemia definition
high blood glucose
hypoglycaemia definition
low blood glucose
