Endocrine Flashcards
Define endocrinology
The study of hormones, their receptor, intracellular signalling pathways and their diseases
Define endocrine w examples
Glands release their secretions ductlessly and dirctley into the bloodstream
B cells of pancrease, thyroid, adrenal gland
Define exocrine w examples
Glands pour its secretions through a duct into site of action
Pancrease- amylase, lipase`
What is endocrine action?
action of a substance on cells of a distant site, travels through blood
What is paracrine action?
Action of a substance on an adjacent cell from which it was secreted from
What is autocrine action?
Feedback on the same cell that secreted the hormone- acts on itself
Do hormones affect neural tissue?
no
Give examples of peptide hormones
Insulin
Glucagon
Corticotrophins
Growt
Which 2 classes of hormones are water soluble?
Peptide and monoamines
What are the properties of lipid soluble hormones?
Travel blood protein bound
Diffuse through lipid bilayer
Slow clearance
Long half life
What are the properties of water soluble hormones?
Travel dissolved in blood
Attach onto specific cell surface receptor
Short half life
Fast clearance
Compare the transport of water and lipid soluble hormones
Water- travel unbound- dissolved in blood
Fat - Travel bound w proteins
Compare the entry into cells of fat and water soluble hormones
Water- attach onto a specific receptor
Fat- diffuse into cell through CSM
Compare the half-life and clearance of water and fat soluble hormones
Water- small half-life and quick clearance
Fat- long half-life and slow clearance
Which classes of hormones are water soluble?
Peptides (cck, anp, insulin)
Monoamines (adrenaline)
Which classes of hormones are lipid soluble?
Steroids and thyroid hormones
Give examples of fat-soluble + steroid hormones hormones
Steroids - cortisol, testosterone, oestrogen, aldosterone
Fat soluble- thyroid hormones
Name 4 different classes of hormones
Peptides, amines, iodothyronines, cholestrerol derivatives and steroids
Give examples of steroid hormones
Testosterone (androgen)
Oestrogen
Aldosterone
Cortisol
Progesterone
Give examples of peptide hormones
ADH
LH / FSH
GH
Prolactin
Gve 3 examples of amine based hormones
dopamine, adrenaline, noradrenaline
What is needed to convert norepinephrine to epinephrine
cortisol
What are the effects of alpha adrenoreceptor activation
vasoconstriction
bowel muscle contraction
sweating
anxiety
pupil dilation
What are the effects of beta adrenoreceptor activation?
vasodilation
incr. heart rate, force of muscle contractility
relaxation of bronchial and visceral smooth muscle
Are iodothyronine hormone protein bound?
yes
Which thyroid hormone is more active?
T3
Which hormones bind to cell membrane receptors?
Peptide- insulin
Which hormone class binds to cytoplasm receptors
steroids- glucocotricoids (cortisol), mineralocorticoids (aldosterone), androgens (testosterone), progesterone
Where do thyroid hormones bind to
nuclear receptors (vit d, oestrogen, thyroid hormones)
Circadian rhythm controls which hormones?
ACTH, cortisol, prolactin, GH
Which hormone inhibits prolactin?
Dopamine
Name a hormone that has continuous release
prolactin
Name a hormone which has a pulsatile release
insulin/ growth hormone
Give an example of hormone synergism
glucagon with adrenaline- both released in hypoglycaemia to increase blood glucose
Give an example of hormone antagonism
glucagon and insulin
What is the effect of hormone metabolism on hormone function?
reduces function
What are the 2 hormones released by the posterior pituitary gland?
ADH and oxytocin
What receptors do hypothalamic and pituitary hormones bind to?
G-protein coupled receptors
What type of tissue makes up the anterior pituitary?
Glandular
What is the arterial blood supply to the anterior pituitary?
The hypothalamo-hypophyseal portal veins
What type of tissue and main cell type makes up the posterior pituitary?
Nerve tissue with glial cells
Where are post. pit. hormone produced and stored
produced- hypothalamus
stored PP
What is the action of ADH
water retention in collecting ducts- maintain blood volume via acting on principle cells
Which factors stimulate the secretion of ADH?
decr. blood volume,
nausea and vomiting,
stress,
incr. osmolality
incr. blood co2
decr. blood o2
What are the main 2 functions of oxytocin
ejection of milk during breast-feeding
stimulates contraction of uterine smooth muscle during labour
What class of hormones do anterior pit. secrete
6 main peptide hormones
Name 6 main hormones ant. pit. secrete
- growth hormone
- lutenising hormone
- follicle stimulating hormone
- thyroid stimulating hormone
- prolactin
- adrenocorticotrophic hormone
Where does ant. pit recieve arteial blood supply from
portal venous circulation - hypothalamo-hypophseal portal veins
Function of growth hormone
stimulates growth and proteinsynthesis
fat and carb metabolism
gluconeogenesis and lipolysis
Function of ACTH
Acts on adrenal gland to secrete
- adrenaline from adrenal medulla
- mineralocorticoids (aldosterone) from zona granulosa
- glucocorticoids (cortisol) from zona fasciulata
- androgens from zona reticularis
What are the effects of cortisol?
inhibits insulin, stimulates gluconeogenesis, lipolysis
immunosuppressant
anti-inflam effects
incr cardiac output
Effect of TSH
stimulates the release of thyroid hormone to incr. metabolism
cardiac output and rate
food metabolism
protein synthesis
What inhibts growth hormone
somatostatin
Presentation points of pit. tumour causing pressure on local strutures
- CSF leak
- Can cause hydrocephalus
- Bitemporal hemianopia from pressing on optic chiasm
Effects of hyperpituitarism- increased secretion of pit hormone
acromegaly- inc. GH
prolactinoma - inc. prolactin
cushings disease- incr. cortisol
What is the definition of hunger
need to eat food
What is the definition of appetite?
Desire to eat food
Which cells express leptin
white adipose cells
What is the effect of leptin
Reduces appetite
What is the function of peptide YY?
inhibits gastric motility and reduces appetite
What is TSH level with underactive thyroid and why?
Elevated due to lack of -FB from T3/4 from thryoid gland
Which 2 classes of hormones are water soluble?
Peptide and amine derived
What are the properties of lipid soluble hormones?
Travel blood protein bound
Diffuse through lipid bilayer
Slow clearance
Long half life
