Endocrine Flashcards
Why does the endocrine system take a while to work
- Don’t need rapid response
- Long term response
- Longer than nervous system because it’s transmitted via blood
What are neurotransmitters
chemical messengers that work via the neurons for a short-term response
Are neurotransmitters pre or post synaptic
The neurotransmitter is released in a regulated fashion from the presynaptic neuron into the synaptic cleft. The neurotransmitter binds to a post synaptic receptor and produces a response in the postsynaptic neuron
How does a post-synaptic cell receive a signal
They have receptors that are designed to receive that specific signal so it doesn’t bind to random cells in the body
What are hormones and what type of model do the cells have
chemical messengers secreted by endocrine glands or tissue that circulate in the blood. most are bound to proteins
they carry instructions from one part of the body to another
lock & key model for interaction with receptors
what is a gland
a collection of epithelial cells that produce secretions
- endo and exo crine
what is the diff between endocrine & exocrine glands
the difference is the location in which secretions are released
exocrine secretions are released into ducts e.g. tears, saliva, digestive enzymes in the pancreas
endocrine secretions are released into the blood and transported via the blood to target cells e.g. insulin & glucagon in pancreas, and 9 different hormones of the pituitary gland
what is the process of a hormone circulating in the blood and binding to it’s receptor
- hormone is secreted by endocrine glands or tissue & circulate in the blood
- hormones carry instructions from one part of the body to another
- hormone reacts with specific receptors on or inside the target cell
- a cell response is activated & alters metabolic activities of many tissues & organs simultaneously
how long can bound and unbound hormones remain in the circulation
unbound < 1hr, bound = days
what are the structures of hormones [EXAM Q DONT NEED TO KNOW STRUCTURE]
- lipid soluble = steroid, T3, T4
- water soluble = lipid insoluble = amino acid derivatives, peptides, protein hormones
what do hormones activate
a cellular response
where are the receptors of lipid-soluble hormones
pass through lipid rich plasma membrane to bind with receptor in nucleus or cytoplasm
how do water soluble hormones bind
second messenger system to get information to nucleus
they can only interact with the surface of the target cell
activates G protein –> amplifier enzyme –> adencylate cylcase –>
how are endocrine glands controlled
- feedback mechanism (-ve & +ve)
- simple control: changes in comp of extracellular fluid e.g. blood glucose = insulin / glucagon
- complex control: several hormones e.g. stress = crh, acth, cortisol. ovarian cycle = GnRH, FSH, LH, estrogen, progesterone
what is simple endocrine control
vital parameter –> sensor –> control centre –> effector –> response
blood gluc –> pancreatic beta cells –> pancreatic beta-cells again –> insulin –> cells in liver etc. take & store glucose = normal levels of blood sugar –> pancreatic cells will stop producing insulin
what is complex endocrine control
vital parameter –> sensor –> control centre –> MULTIPLE EFFECTORS –> response
stress –> hypothalamus –> hypothalamus –> CRH –> ACTH in pituitary –> cortisol (adrenal) –> cortisol targets body cells
describe feedback control of endocrine secretion at hypothalamus
diagram
don’t need to know names of hypothalamus anatomy but what their functions are
what is the exception to the hypothalamus releasing hormones that act on the anterior or posterior pituitary
directly stimulates release of 2 hormones (epi & norepi) from adrenal glands
what are the ways the hypothalamus controls hormones
- synthesises & secretes 7 regulatory hormones
- synthesises ADH (antidiuretic) & OXT (oxytocin)
- directly stimulates release of epinephrine & norepinephrine
what 7 regulatory hormones does the hypothalamus synthesize & secrete & what is their purpose
GHRH = growth hormone releasing hormone
GHIH = growth hormone inhibiting hormone
PRF = prolactin releasing factor
PIF = prolactin inhibiting factor
TRH = thyrotropin releasing hormone
GnRH = gonadotropin releasing hormone
CRH = corticotropin releasing hormone
the hypothalamus stimulates the adenohypophysis to secrete which 6 hormones
GH: stimulates liver, cartilage, bone, muscle etc. to synthesise and secrete insulin like growth factors
PRL: prolactin for milk secretion by mammary glands
TSH: thyroid stimulating hormone
FSH: follicle stimulating hormone for secretion of estrogen from ovaries in women & sperm from testes in men
LH: lutenizing hormone for estrogen & progesterone during ovulation & testosterone from testes
ACTH: adrenocorticotropic hormone for secretion of glucocorticoids (mainly cortisol) by adrenal cortex
MSH: melanocyte stimulating hormone, exact purpose unknown but causes skin darkening
learn general details of the hormones
what is the purpose of oxytocin apart from emotions
contractions during labour
what are the effects of a pituitary tumour on GH
tumor has more cells so more growth hormone is being secreted at excessive levels:
1. pituitary gigantism
2. acromegaly: excess growth hormones after growth plates have closed
where is the thyroid gland and what is made of
made of follicles that secrete thyroid hormones
what are the thyroid gland hormones & their difference
calcitonin: secreted by parafollicular/C cells for homeostasis of calcium
T3: pre-cursor
T4: active form
difference: iodine group (extra in T4)
what is the purpose of thyroid hormones
- increase metabolic rate
- increase protein synthesis via O2 consumption and ATP production
- inc carb & lipid metabolism
how is the thyroid hormone controlled [EXAM Q ON INPUTS, OUTPUTS, CONTROLLERS]
negative feedback loop
- TRH via hypothalamus regulatory hormone
- TSH via anterior pituitary hormone
- T3 & T4
- effector cells
what is hypothyroidism [EXAM Q]
name causes & clincial features
causes = autoimmune e.g. hashimoto’s or iodine deficiency
clinical features = incr TSH, decr metabolic rate, muscle weakness, CNS dysfunction, goitre
what is hyperthyroidism & it’s causes & distinguishing clinical features [EXAM Q]
excess T3 & T4
causes = Grave’s autoimmune disease (most common), metastatic thyroid tumour, no -ve feedback
clinical features = incr metabolic rate, excessive sweating, weight loss, nervousness, hyperactivity, incr systolic pressure, decr diastolic pressure, incr peripheral vasodilation
CT of normal vs enlarged thyroid gland
what is the purpose of the parathyroid glands & what are it’s pathologies
malfunction = parathyroid adenoma
what are calcium homeostasis abnormalities
hypoparathyroidism
hyperparathyroidism
how are pancreatic hormones controlled
when blood glucose levels increase, beta cells secrete insulin to transport it across plasma membranes
when blood glucose levels decrease, alpha cells release glucagon to stimulate glucose release from glycogen stores in the liver
why do you need to fast before a blood test
how is excess glucose stored
as glycogen in the liver
what are the abnormal functions of pancreas
diabetes:
1. type 1:
- insulin dependent, autoimmune disorder
- inadequate insulin production
- type 2:
- reduced insulin sensitivity, or insulin resistant
-caused by obesity, age, family history
what are clincial signs of type I diabetes
hyperglycemic
excessive hunger (polyphagia)
incr glusone in urine
dehydration (polydipsia)
decr blood volume & pressure
coma & death
what are clinical signs of type II diabetes
(same as type 1)
hyperglycemic
excessive hunger (polyphagia)
incr glusone in urine
dehydration (polydipsia)
decr blood volume & pressure
coma & death
what are the adrenal glands & another term for them
suprarenal
what are the parts of the adrenal glands & their functions
what are the disorders of adrenal function
medulla:
- formed from neuroendocrine cells, so associated with nervous system
- pheochromocytoma = neuroendocrine tumour that can be fatal if untreated
- addison’s disease
cortex:
- cushing’s syndrome
- cushing’s disease
- high levels of cortisol in general = toxic to cells, disturbance of cells and homeostasis
what is leptin
peptide hormone that produces adipocytes
signals size of fat stores
regulates energy expenditure by inhibiting hunger
what are clinical signs of leptin deficiency
- abnormal eating behaviours
- delayed puberty
what is another name for the pituitary gland
hypophysis
what bone does they hypophysis lie with in
sella turcica
how are anterior pituitary hormones transported
via systemic blood supply to target cells
what is addison’s disease, it’s causes & symptoms
insufficient amounts of adrenal cortex hormones, particularly cortisol
caused by stress
symptoms are fatigue, muscle weakness, weight loss, vomiting, diarrhoea
what is cushing’s disease, it’s causes
tumour in pituitary gland that stimulates excessive ACTH release = excess glucocorticoids from adrenal gland = mainly cortisol
what is cushing’s syndrome, it’s causes
exposure to excessive levels of cortisol via excess steroid medication or excess production of an endogenous hormone
what are symptoms of cushings
rapid weight gain, sweating, hirsutism, insomnia, reduced libido, infertility
what is hypoparathyroidism, causes & symptoms
decr parathyroid hormone = decreased Ca in blood = hypocalcemia
causes are intestinal malabsorption of Ca
kidney disease causing decreased Ca absorption
decr mobilisation of Ca from bone
symptoms are neurological e.g. neuromuscular excitability
what is hyperparathyroidism, causes & symptoms
overactivity of the parathyroid gland = over secretion of PTH = high sustained Ca = hypercalcemic
causes are PT tumours, or response to low Ca and it’s causes
what is cretinism
congenital hypothyroidism that’s left untreated and results in severe physical & mental stunting
