intro to the endocrine system

Question 1

hormones types

Answer 1

peptides/proteins
Amines/AAs
Steroid hormones

Question 2

Amines/AAs

Answer 2

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

Indoleamines derived from tyrptophan (melatonin)

Question 3

Thyroid hormones

Answer 3

bind to nuclear receptors and regulate gene transcription

Question 4

What types of receptors do adrenaline and noradrenaline bind to

Answer 4

GPCR

alpha and beta

Question 5

Peptides/proteins

Answer 5

eg insulin
Receptor tyrosine kinase
Activates intracellular signalling via phosphorylation cascade

Question 6

Steroid hormones

Answer 6

eg sex hormones, glucorticoids, adrenal hormones

Activate nuclear receptors - work as TFs regulating gene transcription

Question 7

2 endocrine glands

Answer 7

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

Question 8

medulla

Answer 8

adrenaline, noradrenaline

Question 9

Thyroid

Answer 9

Thyroxine (T4)

Triodothyronine (T3)

Question 10

endocrine glands

Answer 10

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

Question 11

intracrine

Answer 11

within cell signalling

Question 12

autocrine

Answer 12

cell releases signal that acts back on the cell

Question 13

paracrine

Answer 13

affects neighbouring cells

Question 14

endocrine

Answer 14

releases into circulation, affects distant target cells

Question 15

Neuroendocrine

Answer 15

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

Question 16

endocrine organs release hormones important in

Answer 16

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

Question 17

Hormones

Answer 17

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

Question 18

Adrenal catecholamine synthesis

Answer 18

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

Question 19

Thyroid hormone synthesis

Answer 19

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

Question 20

steroid hormones produced by

Answer 20

adrenal gland

Question 21

steroid hormone synthesis

Answer 21

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

Question 22

Steroids lipophilic

Answer 22

means they do well in hydrophobic environments so can cross CSMs

Question 23

Peptides examples

Answer 23

Short AA chains eg ADH, Oxytocin

Polypeptides eg Insulin, Prolactin

Question 24

Proteins example

Answer 24

Thyroid Stimulating hormone
Follicle “ “
Growth hormone

Question 25

Peptide and protein hormones synthesis

Answer 25

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

Question 26

up/down regulation

Answer 26

number of receptors for a hormone can incr or decr

Question 27

cell surface receptors

Answer 27

GPCRs eg adrenaline
and RTKs eg insulin
Activate intracellular signalling cascades

Question 28

Intracellular receptors

Answer 28

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

Question 29

Carrier proteins

Answer 29

Bind lipophilic molecules in the blood

Question 30

2 models to hormone release

Answer 30

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

Question 31

endocrine communication

Answer 31

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

Question 32

Positive and negative feedback loops

Answer 32

Contribute to circadian rhythm

Question 33

endocrine disorders

Answer 33

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

Question 34

steroid hormones produced by

Answer 34

adrenal cortex and gonads

Question 35

all steroid hormones are derived from

Answer 35

cholesterol

Question 36

once they are synthesised steroid hormones

Answer 36

diffuse into the circulation across Plasma membrane, because lipophilic

Question 37

which hormones are water soluble

Answer 37

most peptide and all catecholamine - transported in dissolved plasma

Question 38

How are steroid and thyroid hormones transported

Answer 38

bound to plasma proteins