Hormones Flashcards

1
Q

what is a hormone?

A

any substance secreted by one cell to regulate another cell

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2
Q

what do hormones do?

A

they can be delivered by autocrine, paracrine or endocrine (involves circulatory system)

amplification of a signal transduction cascade usually causes biologic response

many hormones can evoke cellular and tissue effects at very low conc.

most hormones effect multiple targets in the body
duration of hormonal action can vary from seconds to days

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3
Q

hormone secreting glands

A
pineal 
hypothalamus 
pituitary 
thyroid 
parathyroids 
thymus 
adrenals 
pancreas
ovary / testes
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4
Q

hypothalamic control

A

hypothalamus - endocrine director, it has the highest level of endocrine control

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5
Q

how does the hypothalamus integrate the activities of the nervous and endocrine system

A
  1. secretion of regulatory hormones (these control activity of anterior pituitary cells)
  2. synthesis of hormones (and then transports them to the posterior pituitary via the infundibulum)
  3. direct neural control (hypothalamic autonomic centres control secretion of adrenaline and noradrenaline by the adrenal medulla)
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6
Q

what is the diurnal control of hormone levels (circadian rhythm)

A

external cues (light/dark) cause fluctuations in hormone secretions (e.g. cortisol)

hormonal levels are also influenced by the rate at which they are eliminated by the body

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7
Q

example of complementary actions of hormones

A

sympathetic response and actions of adrenaline, cortisol and glucagon on BG levels

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8
Q

examples of antagonistic actions of hormones

A

hormonal control of glucose homeostasis

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9
Q

what are the 3 classes that hormones are grouped into based on their structure?

A

Steroids (e.g. oestrogen, bind to intracellular receptors generally have a prolonged time of action)

Amine-derived (e.g. adrenaline/epinephrine, generally bind to membrane-bound receptors e.g. GCPR)

Peptides and proteins (e.g. oxytocin and ADH, growth hormone and insulin)

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10
Q

what are steroid hormones?

A

lipids derived from cholesterol
amount is controlled by the synthesis rate
once secreted, synthesised steroids are NOT stored
they are hydrophobic/lipophilic and are mostly (90%) transported in the blood plasma by binding to carrier proteins

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11
Q

what is the 2 step process initiated when steroid hormones pass through the plasma membrane?

A
  1. formation of activated hormone-receptor complex within the cell
  2. complex binds to DNA and activates specific genes (gene activation leads to production of key proteins)
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12
Q

cortisol

A

secreted from the adrenal cortex involved in mediating stress responses

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13
Q

testosterone and oestradiol

A

secreted form the gonads and placenta, responsible for male and female characteristics

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14
Q

what are amine hormones?

A

derived from amino acids (e.g. tyrosine)
secreted from the thyroid and adrenal medulla
they bind to membrane bound receptors to evoke cellular responses

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15
Q

catecholamine amine hormones

A

hydrophilic, transported unbound or ‘free’ in blood plasma

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16
Q

thyroid amine hormones transport

A

bound to carrier proteins

17
Q

adrenaline (epinephrine) transport

A

stored as vesicles in the cytoplasm until needed

18
Q

what are peptide and protein hormones?

A

peptide hormones = short chains of amino acids (generally <50 AAs)
protein hormones = larger molecules
they make up a large majority of the hormones produced

19
Q

how are peptide and protein hormones transported?

A

they are hydrophilic and are transported unbound/’free’ in blood plasma

20
Q

what secretes peptide and protein hormones?

A

pituitary, parathyroid, heart, stomach, liver, kidneys
synthesised as precurost molecules and stored in secretory vesicles
can cleave a common precursor with a different enzyme to make different end hormones

21
Q

how are steroid and thyroid hormones transported?

A

insoluble in plasma so transports in blood via carrier proteins
carrier proteins also increase the half-life of the hormone and acts as a reservoir for the hormone

22
Q

examples of carrier proteins

A

cortisol-binding globulin (CBG) - binds cortisol in a selective manner (also some aldosterone)
Thyroxine-binding globulin (TBG) - binds thyroxine (T4) selectively (also some triiodothyronine (T3))
Sex steroid-binding globulin (SSBG) - binds mainly testosterone and oestradiol

23
Q

hormones of the pancreas

A

insulin - protein - acts on liver, muscle and adipose tissue for growth, metabolism and homeostasis

glucagon - protein - acts on liver, muscle, adipose tissue for growth, metabolism and homeostasis

somatostatin - protein - acts on gut for growth, metabolism, homeostasis

24
Q

hormones of the ovaries

A

oestradiol - steroid - act on ovaries and uterus for reproduction

oestriol - steroid - act on ovaries and uterus for reproduction

progesterone - steroid - act on ovaries and uterus for reproduction

25
testosterone
steroid hormone acts on the testes for reproduction
26
hormones of the placenta
hCG - human chorionic gonadotrophin - peptide - acts on uterus for reproduction oestradiol - steroid - act on ovaries and uterus for reproduction
27
hormones of mammary gland
oestrogen - steroid - acts on ovaries and uterus for reproduction
28
hormones of the hypothalamus
thyrotropin releasing hormone (TRH) - peptide - anterior pituitary to stimulate the release of TSH and prolactin corticotrophin releasing hormone (CRH) - peptide - anterior pituitary, stimulates release of ACTH
29
hormones of the pituitary
TSH - thyroid stimulating hormone - peptide - acts on thyroid for growth and metabolism ACTH - adrenocorticotrophic hormone - peptide - adrenal cortex for metabolism LH - luteinizing hormone - peptide - acts on the gonads for reproduction FSH - follicle stimulating hormone - peptide - acts on the gonads for reproduction GH - growth hormone - protein - acts on liver, bones, muscle for growth Prolactin - peptide - acts on mammary gland for reproduction MSH - melanocyte stimulating hormone - peptide - melanocytes for homeostasis Oxytocin - peptide - acts on mammary glands and uterus for reproduction ADH - antidiuretic hormone - peptide - kidney for homeostasis
30
what is hyperthyroidism?
excess of T4-T3 secretion enhanced BMR hyper-excitability goitre formation
31
what is hypoparathyroidism?
parathyroid gland destruction | hypocalcaemia
32
what is hyperparathyroidism?
parathyroid gland tumour increased PTH secretion hypercalcaemia
33
what is Conn's disease (hyperalosteronism)?
``` adrenal cortical tumour excess aldosterone secretion ADH hypernatremia hypertension hypovolemia ```
34
what is Addison's disease?
``` adrenal destruction/ lack of ACTH secretion hypoglycaemia hyperkalaemia hyponatremia hypotension fatigue weight loss skin hyperpigmentation ```
35
what is Cushing's syndrome?
``` adrenal tumour (excess cortisol secretion) hyperglycaemia hypokalaemia hypenatremia hypertension weight gain skin hyperpigmentation hirutism ```
36
what is congenital hypothyroidism
lack of T4-T3 secretion lowered BMR stunted growth
37
what is myxedema (adult hypothyroidism)
lack of T4-T3 secretion lowered BMR goitre formation