intro to the endocrine system Flashcards

1
Q

hormones types

A

peptides/proteins
Amines/AAs
Steroid hormones

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2
Q

Amines/AAs

A

derivatives of tyrosine
Gives rise to thyroid hormones (thyroxine, triiodothyrine) and adrenaline and noradrenaline (catecholamines- derived from tyrosine)

Indoleamines derived from tyrptophan (melatonin)

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3
Q

Thyroid hormones

A

bind to nuclear receptors and regulate gene transcription

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4
Q

What types of receptors do adrenaline and noradrenaline bind to

A

GPCR

alpha and beta

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5
Q

Peptides/proteins

A

eg insulin
Receptor tyrosine kinase
Activates intracellular signalling via phosphorylation cascade

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6
Q

Steroid hormones

A

eg sex hormones, glucorticoids, adrenal hormones

Activate nuclear receptors - work as TFs regulating gene transcription

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7
Q

2 endocrine glands

A

Parathyroid (PTH)
- stimulated by Ca
Pancreas (insulin and glucagon)
-stimulated by glucose

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8
Q

medulla

A

adrenaline, noradrenaline

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9
Q

Thyroid

A

Thyroxine (T4)

Triodothyronine (T3)

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10
Q

endocrine glands

A

ductless
extensive blood supply
may be primary glands eg pituitary, thyroid, adrenals
Other organs may have secondary endocrine function eg brain (hypothalamus), heart, kidney

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11
Q

intracrine

A

within cell signalling

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12
Q

autocrine

A

cell releases signal that acts back on the cell

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13
Q

paracrine

A

affects neighbouring cells

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14
Q

endocrine

A

releases into circulation, affects distant target cells

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15
Q

Neuroendocrine

A

modified nerve cells that secrete directly into blood and travel to distant target cells

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16
Q

endocrine organs release hormones important in

A

reproduction, growth and development, maintenance of internal environment, regulation of energy

17
Q

Hormones

A

produced by glands and released directly into circulation
Present in low conc
Bind to specific, high affinity recog sites or receptors on/in target cells
Single hormone may have different tissue-specific effects

18
Q

Adrenal catecholamine synthesis

A
Tyrosine
(tyrosine hydroxylase)
L-DOPA
( dopa decarboxylase)
Dopamine
(Dopamine Beta hydroxylase)
Noradrenaline
(phenylethanolamine N-methyl transferase)
Adrenaline
19
Q

Thyroid hormone synthesis

A

in thyroid gland
requires iodine and tyrosine
Add 1 iodine- forms mono-iodotyrosine (MIT)
Add 2 - di-iodotyrosine (DIT)

20
Q

steroid hormones produced by

A

adrenal gland

21
Q

steroid hormone synthesis

A

hormone producing cells stimulated by by binding of anterior pituitary gland hormone to its plasma membrane receptor
These receptors link to Gs proteins, which activate adenylyl cyclase and cAMP production. Activates protein kinase A (cAMP) which results in phosphorylation of numerous intracellular proteins- these convert cholesterol into final steroid hormone

22
Q

Steroids lipophilic

A

means they do well in hydrophobic environments so can cross CSMs

23
Q

Peptides examples

A

Short AA chains eg ADH, Oxytocin

Polypeptides eg Insulin, Prolactin

24
Q

Proteins example

A

Thyroid Stimulating hormone
Follicle “ “
Growth hormone

25
Q

Peptide and protein hormones synthesis

A

Synthesised on ribsosomes, Packaged into secretory vesicles from the golgi as a prohormone and prohormone cleaved into active hormone
Release by exocytosis into bloodstream

26
Q

up/down regulation

A

number of receptors for a hormone can incr or decr

27
Q

cell surface receptors

A

GPCRs eg adrenaline
and RTKs eg insulin
Activate intracellular signalling cascades

28
Q

Intracellular receptors

A

activate gene transcription
eg corticosteroids
Attach to a carrier protein in the blood

29
Q

Carrier proteins

A

Bind lipophilic molecules in the blood

30
Q

2 models to hormone release

A
  1. stimulus provokes hormone release from endocrine cells which acts on target cells to produce response
  2. Stimulus acts on hypothalamic neurone which releases regulatory hormone. Stimulates endocrine cells anterior pituitary to release another hormone, stimulates target endocrine organ to releasea hormone which activates target cells and leads to a response
31
Q

endocrine communication

A

messages via circulation
slow transfer of info, long lasting
All cells contacted, but specificity conferred by receptors
Slow maintenance of cellular homeostasis

32
Q

Positive and negative feedback loops

A

Contribute to circadian rhythm

33
Q

endocrine disorders

A

hyposecretion, hypersecretion, hypo responsive (produce hormone but don’t respond to it) , hyper responsive

34
Q

steroid hormones produced by

A

adrenal cortex and gonads

35
Q

all steroid hormones are derived from

A

cholesterol

36
Q

once they are synthesised steroid hormones

A

diffuse into the circulation across Plasma membrane, because lipophilic

37
Q

which hormones are water soluble

A

most peptide and all catecholamine - transported in dissolved plasma

38
Q

How are steroid and thyroid hormones transported

A

bound to plasma proteins