endocrine system Flashcards
what are the two pharmacological effects of glucocorticoids?
anti-inflammatory effects, immunosuppressant effects
describe the pharmacodynamics of glucocorticoids?
they prevent the formation of key chemicals that mediate inflammation
in which three ways does glucagon work to increase blood glucose levels?
increases glycogenolysis (breakdown of glycogen into glucose in liver and skeletal muscle)
increases gluconeogenesis (synthesis and release of glucose by the liver)
increases ketogenesis (breakdown of fat to fatty acids in adipose tissue)
what does insulin do?
allows glucose transport into cells
increases rate of glucose utilisation/ATP generation
inhibits hepatic glycogenolysis and gluconeogenesis
increases conversion of glucose into glycogen for storage in liver and skeletal muscles
increases amino acid absorption and protein synthesis
increases triglyceride synthesis in adipose tissue
where is glucagon released from?
alpha cells in the pancreatic islets
what kind of hormone is glucagon?
peptide hormone
what controls the release of glucagon?
decreased blood glucose levels
what is the function of cortisol?
anti-inflammatory; affects glucose metabolism
where is cortisol released from?
the adrenal cortex
what controls the release of cortisol?
stimulated by ACTH
what kind of hormone is cortisol?
steroid hormone (glucocorticoid)
what hormone is released by adipose tissue, and what does it do?
leptin targets the hypothalamus to suppress the appetite
what are the cells of the pancreatic islets and what type of hormones does each produce?
alpha cells: glucagon
beta cells: insulin
delta cells: GH-IH
f cells: pancreatic polypeptide (PP)
what are the four functions of adrenaline?
increased cardiac activity
increased blood pressure
increased glycogen breakdown
increased blood glucose levels
where is adrenaline released from?
the adrenal medulla
what controls the release of adrenaline?
sympathetic innervation by the hypothalmus
what kind of hormone is adrenaline?
amine hormone
what is the function of aldosterone?
increases the reabsorption of Na+ and water
where is aldosterone released from?
the adrenal cortex
what controls the release of aldosterone?
angiotensin II; also elevated blood K+ or fall in blood Na+
what inhibits the release of aldosterone?
ANP and BNP
what kind of hormone is aldosterone?
a steroid hormone
what are glucocorticoids?
“stress hormones”
steroid hormones
affect glucose metabolism
suppress the immune system
anti-inflammatory
what are the glucocorticoids and where are they produced?
cortisol, corticosterone are produced in the adrenal cortex
cortisone is made in the liver from circulating cortisol
what is a synergistic interaction between hormones?
hormones act together and have an increased effect greater than the sum of their parts
eg. glucagon and cortisol and adrenaline together greatly increase blood glucose levels
what are first messengers and second messengers?
first messenger: hormone binding to protein receptor in cell membrane activates second messenger.
second messenger is in cytoplasm; changes rates of metabolic reactions
which hormones are necessary for normal growth and development?
growth hormone insulin parathyroid hormone calcitonin calcitriol thyroid hormones reproductive hormones
what is the network of arteries that transports hormones from the hypothalamus to the anterior lobe of the pituitary gland?
the hypophyseal portal system
define regulatory hormone
a special hormone released by the hypothalamus, controls endocrine cells in the anterior lobe of the pituitary gland
what tissue or organ is targeted by the hormone ACTH?
adrenocorticotropic hormone targets the adrenal cortex
what class of drug is metformin? what are its main pharmacological effects?
oral hypoglycaemic (biguanides)
decreased synthesis of glucose
increased insulin sensitivity
which hormone regulates the secretion of potassium in the nephron?
aldosterone
ADH
- where?
- what?
anti-diuretic hormone
made in the hypothalamus, secreted by the posterior pituitary gland
causes kidney to retain water; less urination leads to increased blood volume, therefore increased BP
what hormones are released by the anterior lobe of the pituitary gland?
TSH - thyroid stimulating hormone ACTH - adrenocorticotropic hormone FSH - follicle stimulating hormone LH - lutenising hormone PRL - prolactin GH - growth hormone MSH - melanocyte stimulating hormone
list the hypothalamic releasing hormones
- CRH - corticotropin releasing hormone –> ACTH –> glucocorticoids
- TRH - thyrotropin realeasing hormone –> TSH –> thyroid hormones
- GH-RH - growth hormone releasing hormone –> GH
- GH-IH - growth hormone inhibiting hormone
- PRF - prolactin releasing factor
- PIH - prolactin inhibiting factor
- GnRH - gonadotropin releasing hormone –> LH and FSH
how does ADH work?
causes a second messenger (cAMP) to cause vesicles containing aquaporins to exocytose, creating channels for water to exit into hypertonic ISF and from there into the bloodstream
which hormone stimulates RBC production? where is it made?
EPO - erythropoietin, made in the kidneys and liver
name three lipid-soluble hormones
cortisol
oestrogen
androgens
aldosterone
what do thyroid hormones do? how are they written?
they increase the metabolic rate of cells
T3 and T4
which cells do thyroid hormones affect? what is their role in normal childhood development?
thyroid hormones work on almost all cells
they are essential for normal development in growing children.
where can hormone receptors be located?
cell membrane
cytoplasm
nucleus
what effect would increased PTH secretion have on blood calcium levels?
calcium levels in blood would increase
which three organs do calcitonin and PTH work on?
bones
intestines
kidneys
thyroxine: function? released from? what controls release? what kind of hormone?
increases metabolism (and lots more)
released from thyroid gland
because of thyroid-stimulating hormone (TSH)
amine hormone (made like peptides, behave like steroid from release onwards)
calcitonin: function? released from? what controls release? what kind of hormone?
decreases calcium levels in blood by inhibiting osteoclast activity and increasing rate of excretion at kidneys
released from thyroid gland
because of calcium levels in the plasma
peptide hormone
what does growth hormone do?
stimulates rate of cell growth and replication by increasing rate of protein synthesis
what things trigger the release of hormones?
nervous signals (eg the stretching of the digestive tract)
chemical changes in the blood or ECF (eg glucose levels, calcium levels)
other hormones
where is aldosterone made? what does it do?
made in the adrenal glands
adjusts the rates of fluid, sodium and potassium reabsorption in the kidneys
which two antagonist hormones control the production of GH?
what stimulates or inhibits these hormones?
GH-RH
GH-IH
somatomedin levels regulate GH-RH and GH-IH
primary function of the endocrine system?
production of hormones or paracrine factors
name the hormones of the thyroid gland?
T3
T4
calcitonin
what are hormone receptors?
protein molecules
define hormone
a chemical secretion transported via ESF or bloodstream to target cells in other sites of the body
(it’s a blood-borne chemical messenger)
what does calcitriol do?
increases serum calcium levels:
increases calcium absorption in the intestines
and reabsorption in the kidneys
stimulates osteoclast activity
what are the structural classes of hormones?
amino acid derivatives (amine hormones)
peptide hormones
lipid derivatives
what tissue or organ is targeted by the hormones LH and FSH?
follicle-stimulating hormone and lutenising hormone target the testes and ovaries
compare the control exerted by the endocrine system vs. the nervous system
endocrine is
longer term slower more sustained via blood uses hormones
what effect does GH have on the liver?
stimulates production of somatomedins which stimulate growth of skeletal muscle, cartilage and other tissues
which tissue or organ is targeted by the hormone MSH?
melanocyte-stimulating hormone: melanocytes in the skin
what is the major integrating link for the nervous and endocrine systems?
the hypothalamus
what is a tropic hormone?
a hormone that acts on another gland, making it secrete another hormone
which hormones are released by the posterior pituitary gland? which tissues/organs do they target?
ADH - kidneys
oxytocin - mammary glands, uterus, ductus deferens (sperm duct) and prostate gland
how/where does PTH work?
parathyroid hormone
- bones: stimulates osteoclasts
- intestines: increases calcium absorption
- kidneys: calcium retained, more calcitriol produced
where is glucagon released from?
alpha cells of the pancreatic islets
how does the hypothalamus integrate the activities of the nervous and endocrine system?
- acts as an endocrine gland by producing oxytocin and ADH (transported via axons to the posterior pituitary)
- secretes regulatory hormones (transported via blood to the anterior pituitary)
- nervous control over the adrenal medulla = secretion of adrenalin and noradrenalin
where is calcitonin released from?
the thyroid gland
what is an antagonistic interaction between hormones?
hormones that act together to maintain homeostasis but have opposing effects
what are the hormones responsible for calcium homeostasis? which does what?
calcitonin decreases blood calcium
calcitriol increases blood calcium levels (day-to-day control)
parathyroid hormone increases blood calcium levels (minute-to-minute control)
erythropoietin:
what does it do?
what triggers its release?
where is it produced?
EPO stimulates RBC production in bone marrow
decreased renal oxygen levels
produced in the kidneys
name the organs with secondary endocrine functions
heart thymus digestive tract kidneys gonads
what class of hormones are most common?
peptide hormones
broadly, what are the four functions of hormones?
growth and development
coping with stress
regulation of metabolism
maintaining homeostasis (fluids, electrolytes, nutrients)
what stimulates the release of aldosterone?
angiotensin II
decrease in circulating sodium
increase in circulating potassium
what is the difference between endocrine and exocrine secretions?
endocrine: no duct, direct to blood stream
exocrine: duct
which hormones stimulate WBC production?
interleukins
colony stimulating factors (CSF)
what actions may hormones cause? (as in, what are their mechanisms of action?)
- change rates of enzymatic reaction/shape/function
- open/close channels in cell membrane
- control gene expression
name the organs of the endocrine system
hypothalamus pituitary gland thyroid gland adrenal glands pancreas (pancreatic islets) pineal gland parathyroid glands
what effects do adrenaline and noradrenaline have?
increased cardiac activity
increased BP
increased glycogen breakdown (more APT!)
increased blood glucose levels
where are the receptors for thyroid hormone?
in the cell nucleus and mitochondria of almost all cells
which hormones depress immune response and reduce inflammation?
glucocorticoids
what do ANP and BNP do?
inhibit secretions of ADH and aldosterone
decrease sodium and water reabsorption in PCT
= more urine –> decreased blood volume –> decreased BP
what triggers the release of ANP and BNP?
stretch receptors in the heart
renin: where is it produced? what triggers its release? what does it do? what does this result in?
secreted by the kidneys in response to decreased renal blood flow
converts angiotensinogen into angiotensin I
resulting in increased BP
what stimulates the release of ADH?
stimulation of osmoreceptors in the hypothalamus
angiotensin II
what effect does angiotensin II have on the CNS?
increased stimulation of thirst centres
increased production of ADH
what’s the difference between the anterior and posterior lobes of the pituitary gland?
anterior - makes and releases its own hormones
posterior - stores and releases hormones made by the hypothalamus
what act in opposition to RAAS, decreasing BP?
natriuretic peptides released by the heart
which hormones are responsible for glucose homeostasis? which responds to high blood glucose levels?
insulin
glucagon
insulin is released when blood glucose levels are high
where is insulin produced?
in the beta cells of the pancreatic islets
which hormone increases the rate of platelet formation?
thrombopoietin
what are the two regions of the adrenal glands and what hormones do they release?
adrenal cortex:
aldosterone
glucocorticoids
small amounts of androgens
medulla: adrenaline (SNS stimulation)
PTH: where is it produced? what triggers its release? what does it do? what kind of hormone is it?
produced in the parathyroid glands in response to falling circulating calcium levels
actions:
- bones: stimulates osteoclasts
- intestines: increases calcium absorption
- kidneys: calcium retained, more calcitriol produced
it’s a peptide hormone
GH: function? released from? what controls release? what kind of hormone is it?
growth hormone stimulates cell growth and reproduction by stimulating protein synthesis
produced in the anterior pituitary
regulated by GH-IH and GH-RH
peptide hormone
ADH: function? released from? what controls release? what kind of hormone is it?
antidiuretic hormone decreases water loss at the kidneys
it’s made in the hypothalamus and released from the posterior pituitary
in response to stimulation of osmoreceptors, angiotensin II
pepetide hormone
what is sometimes referred to as the ‘master gland’?
the pituitary gland
