intro to the endocrine system
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- Created by: Millie Smith08
- Created on: 23-04-23 18:08
what is a healthy body?
one that is in homeostasis
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homeostasis
respiration rate, blood pressure, heart rate, glucose, calcium, growth, reproduction, energy balance
there are physiological processes to control all of the listed
there are physiological processes to control all of the listed
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endocrine glands
release hormones to control homeostatic processes
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PTH
in the neck
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pineal gland
the role of melatonin can be considered as hormonal or as a neurotransmitter
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heart, kidney and digestive tract
have secondary function
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endocrine glands
major morphological feature is that glands are ductless (cf. salivary glands) (not connected by ducts to other organs(
richly vascularised (have a good blood supply)
secrete messengers directly into circulation (bloodstream)- hormones can circulate and ef
richly vascularised (have a good blood supply)
secrete messengers directly into circulation (bloodstream)- hormones can circulate and ef
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endocrine glands may be primary glands
eg pituitary, thyroid, adrenals
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other organs may have secondary endocrine function
eg brain (hypothalamus), heart, kidney, GI tract
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endocrine organs release hormones that are important in four broad areas:
- reproduction
- growth and development
- maintenance of internal env
- regulation of energy (BMR is under the control of hormones)
- growth and development
- maintenance of internal env
- regulation of energy (BMR is under the control of hormones)
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hormones
produced by glands and released directly into circulation
present in low concentrations (10-7 - 10-12 M)
bind to specific, high affinity recognition sites or receptors on/ in target cells
present in low concentrations (10-7 - 10-12 M)
bind to specific, high affinity recognition sites or receptors on/ in target cells
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can a single hormone have different tissue-specific effects?
yes
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single function may be regulated by
different hormones
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hormone structures and synthesis
three major chemical classes of hormones:
- amino acids/ amines eg thyroid hormones, tyrosine
- peptides and proteins eg insulin
- steroids eg vitamin D/ calcitriol
- amino acids/ amines eg thyroid hormones, tyrosine
- peptides and proteins eg insulin
- steroids eg vitamin D/ calcitriol
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steroid hormones
intracellular receptors
gene expression
gene expression
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release of these hormones is regulated by
positive feedback and negative feedback mechanisms
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amine hormones
catecholamines derived from tyrosine
- adrenaline, noradrenaline (here we are talking about them as hormones released from the adrenal gland NOT as neurotransmitters)
thyroid hormones also derived from tyrosine
- thyroxine, triidothyronine
indoleamines de
- adrenaline, noradrenaline (here we are talking about them as hormones released from the adrenal gland NOT as neurotransmitters)
thyroid hormones also derived from tyrosine
- thyroxine, triidothyronine
indoleamines de
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tyrosine -> mono-iodotyrosine (MIT)
di-iodotyrosine (DIT)
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DIT + DIT ->
Thyroxine (T4)
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DIT + MIT ->
triidothyronine (T3)
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T3 and T4
thyroid hormones produced in the thyroid
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steroid hormones
adrenal hormones
adrenal hormones
cortisol
aldosterone
aldosterone
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steroid hormones
sex hormones
sex hormones
testosterone
estradiol
estradiol
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vitamin D
calcitriol
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all steroid hormones are derived from the precursor molecule
cholesterol
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peptide hormones
Peptides
Short amino acid chains e.g.
o ADH (vasopressin/ antidiuretic hormone) (9 AA)
o Oxytocin (9 AA)
Polypeptides e.g.
o Insulin (135 AA)
o Prolactin (198 AA)
Short amino acid chains e.g.
o ADH (vasopressin/ antidiuretic hormone) (9 AA)
o Oxytocin (9 AA)
Polypeptides e.g.
o Insulin (135 AA)
o Prolactin (198 AA)
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proteins
thyroid stimulating hormone
follicle stimulating hormone
growth hormone
follicle stimulating hormone
growth hormone
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peptide and protein hormones
synthesis
synthesis
release by exocytosis as prohormone or hormone into bloodstream
hormone released when vesicles fuse with membrane
hormone released when vesicles fuse with membrane
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hormone receptors
the ability of a cell to respond to a hormone depends upon the presence of receptors for that hormone on or in the target cell
may be:
- cell surface receptors
- intracellular receptors
may be:
- cell surface receptors
- intracellular receptors
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the number of receptors for a hormone can increase or decrease
up-regulation or down-regulation
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cell surface receptors
GPRCs - adrenaline
RTKS (receptor tyrosine kinases) - insulin
RTKS (receptor tyrosine kinases) - insulin
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cell surface receptors activate
intracellular signalling cascades
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hormones act at specific intracellular receptors eg corticosteroids
activate gene transcription
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lipids can always cross lipid bilayers and act
intracellularly
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can enter nucleus and regulate what?
gene transcription
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does this take longer than a neurotransmitter activated receptor?
yes
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neuroendocrine regulation
stimulus -> hypothalamic neurone -> regulatory hormone released -> endocrine cells anterior pituitary -> hormone 1 released -> target endocrine organ -> hormone two released -> target cells -> response
adrenals, thyroids, gonads
more complex
adrenals, thyroids, gonads
more complex
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endocrine communication
slow
messages disseminated from glands to effector via circulation
relatively slow transfer of info
can be long lasting
do not need millisecond to millisecond control of blood glucose
all cells contacted, however specificity is conferred by receptors
slow
messages disseminated from glands to effector via circulation
relatively slow transfer of info
can be long lasting
do not need millisecond to millisecond control of blood glucose
all cells contacted, however specificity is conferred by receptors
slow
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patterns of hormone release
mean levels
transient fluctuations
most of your hormones have a 24h pattern of release
transient fluctuations
most of your hormones have a 24h pattern of release
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positive-positive feedback loops
rare
seen mostly in the reproductive system
seen mostly in the reproductive system
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negative feedback loops
most common
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feedback loops may be
positive or negative and long or short
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endocrine disorders
hypo-secretion
hyper-secretion
hypo-responsive
hyper-responsive
hyper-secretion
hypo-responsive
hyper-responsive
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hypo-secretion
too little hormone secreted
typically caused by destruction of the primary
endocrine gland
autoimmune mediated destruction of pancreas
eg type I diabetes
typically caused by destruction of the primary
endocrine gland
autoimmune mediated destruction of pancreas
eg type I diabetes
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hyper-secretion
too much hormone secreted
eg pancreatic endocrine tumour
eg pancreatic endocrine tumour
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hypo-responsive
not able to respond to hormone being produced (receptors)
eg insulin resistant type II diabetes
eg insulin resistant type II diabetes
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hyper-responsive
inappropriate response (receptors)
receptors are turned on even in the absence of the hormone- constitutive activation
eg TSH receptor constitutive activation -> hyperthyroidism
receptors are turned on even in the absence of the hormone- constitutive activation
eg TSH receptor constitutive activation -> hyperthyroidism
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common endocrine problems
thyroid
- hyperthyroidism
- hypothyroidism
- goitre
- thyroid cancer
pancreas
- type I diabetes
- type II diabetes
kidney
- renin-dependent hypertension
testes
-subfertility
- testicular failure
bone
- osteoporosis
- osteomalacia
pituitary and hypothalam
- hyperthyroidism
- hypothyroidism
- goitre
- thyroid cancer
pancreas
- type I diabetes
- type II diabetes
kidney
- renin-dependent hypertension
testes
-subfertility
- testicular failure
bone
- osteoporosis
- osteomalacia
pituitary and hypothalam
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exocrine glands
ducted
eg salivary glands, sebaceous glands, lacrimal glands
eg salivary glands, sebaceous glands, lacrimal glands
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Other cards in this set
Card 2
Front
homeostasis
Back
respiration rate, blood pressure, heart rate, glucose, calcium, growth, reproduction, energy balance
there are physiological processes to control all of the listed
there are physiological processes to control all of the listed
Card 3
Front
endocrine glands
Back

Card 4
Front
PTH
Back

Card 5
Front
pineal gland
Back

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