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Endocrine and metabolism > signal transdruction and hypothalamus/pituitary > Flashcards

signal transdruction and hypothalamus/pituitary Flashcards

1
Q

3 types of cellular signalling pathways

A

physical/chemical signals, signal transduction, signal amplification/response

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2
Q

what is extracellular domain

A

binding site for hormones/other molecules

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3
Q

what is transmembrane domain

A

anchors receptor in cell membrane

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3
Q

what is ion channel linked receptors

A

membrane is impermeable to ions, channels open and ions flood in, rapid response, specific for sodium, potassium, calcium, chlorine ions

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3
Q

what is intracellular domain

A

effectors domains, transduce the signal

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4
Q

what do GPCRs do

A

G protein coupled receptors, can regulate ion channels, channels opened or closed by g protein, slow acting

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5
Q

how do enzyme linked receptors works

A

mostly tyrosine kinase, hormone binds to enzyme linked receptors, conformational changes induced, enzyme activity activated

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6
Q

signal amplification steps

A

1 messenger binds to 1 receptor, multiple G proteins activated, each G protein activates an adenylate cyclase, and each adenylate cyclase generates hundreds of cAMP molecules which activates a protein kinase A, each protein kinase A phosphorylates hundreds of proteins

messenger–>receptor–>G proteins–>adenylate cyclase–>cAMP–>protein kinase A–>phosphorylates hundreds of proteins

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7
Q

5 major second messenger molecules

A

cAMP, cGMP, DAG, IP3, calcium

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8
Q

other types of signalling molecules

A

neurotransmitters, cytokines, neurohormones, eicosanoids

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9
Q

what is endocrine axis

A

independent glands working together to control body functions

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10
Q

master regulators (hypothalamic pituitary axis)

A

thyroid, adrenal cortex, gonads

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11
Q

features of hypothalamic pituitary axis

A

pineal gland, hypothalamus, pituitary gland, spinal chord

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12
Q

what is autocrine signalling

A

bind receptors on the same cell

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13
Q

what is paracrine signalling

A

targets neighbouring cell

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14
Q

what is endocrine signalling

A

targets distant cells via bloodstream

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15
Q

what is neuroendocrine signalling

A

neurons target distant cells via bloodstream

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16
Q

what is the hypothalamus

A

small brain region, grey matter, contains multiple neural centres and neural fibres, connects to other brain regions

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17
Q

what does the hypothalamus control

A

hunger, thirst, body temp, blood pressure, childbirth, emotion, sex drive, social bonding, circadian rhythms

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18
Q

what is the pituitary

A

neural and vascular connections

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19
Q

describe the structure of hypothalamus and pituitary

A

hypothalamus, pituitary stalk, anterior pituitary, posterior pituitary (balls lmao)

20
Q

two hormones secreted by the posterior pituitary and the role of them

A

antidiuretic hormones (ADH)- regulates water reabsorption in kidney

oxytocin- regulates birth and lactation

21
Q

where is antidiuretic hormones produced

A

neurons in paraventricular nucleus

22
Q

where is oxytocin produced

A

neurons in supraoptic nucleus

23
Q

describe how the posterior pituitary works

A

neuronal centres in hypothalamus receive neural signals, neuroendocrine cells release peptide hormones by exocytosis at axon terminals, neurohormones permeate into capillary beds, no blood brain barrier

24
Q

what connects the hypothalamus and anterior pituitary

A

hypothalamic-pituitary portal system

25
Q

what does the hypothalamic pituitary portal system consist of

A

two capillary beds in series

26
Q

how does the anterior pituitary work

A

neuronal centres in hypothalamus release peptide hormones by exocytosis at axon terminals, hormones enter first capillary bed and carried through portal vein to anterior pituitary, pituitary endocrine cells stimulated to release other tropic hormones which act on tissues/endocrine glands

27
Q

list some tropic hormones produced by the hypothalamus

A

PRH- prolactin releasing hormone
PIH- prolactin inhibiting hormone
TRH- thyrotropin
CRH- corticotropin
GHRH- growth hormone
GHIH- growth hormone
GNRH- gonadotropin

28
Q

name some tropic hormones released by the anterior pituitary

A

prolactin
TSH- thyroid stimulating hormone
ACTH- adrenocorticotropin
GH- growth hormone
FSH- follicle
LH- luteinising hormone

29
Q

what are pituitary tumours

A

hyper/hyposecretion of hormones, common, benign, slow growing

30
Q

symptoms of pituitary tumours

A

visual disturbances, headaches, endocrine disturbances

31
Q

types of feedback loosp

A

short and long loop negative/positive feedback

32
Q

what is the thyroid gland

A

butterfly shaped gland on trachea, produces thyroid hormones and calcitonin

33
Q

what does calcitonin do

A

lowers serum calcium ions and promotes calcium ion deposition in bones

34
Q

what do thyroid hormones T3 and T4 do

A

regulate metabolism and basal metabolic rate

35
Q

what are parathyroid glands

A

4 small glands on the back of the thyroid gland, secretes parathyroid hormone

36
Q

what do parathyroid hormones do

A

regulate calcium ion and phosphate levels in blood, promote release of calcium ions from bones, promote ca2+ reabsorption in kidney

antagonistic action to calcitonin and vitamin D to balance ca2+ and maintain phosphate levels

37
Q

molecular structure of T4

A

2 molecules of L-tyrosine and 4 iodide ions

38
Q

where are thyroid hormones produced

A

follicles of thyroid gland

39
Q

difference between T3 and T4 hormones

A

T3 is 5 fold more active, T4 is more abundant

both lipophilic hormones

40
Q

where are T3 and T4 generated

A

thyroglobulin

41
Q

what do thyroid hormones do

A

increase metabolic activity in most tissues, stimulate fatty acid metabolism/gluconeogenesis/glycogenolysis

42
Q

what are thyroid hormones needed for

A

growth and development, development of neonatal brain, visual system/retinal function

43
Q

what is a colloid

A

viscous protein rich fluid which acts as a store of thyroid hormone precursors in glycoprotein form and iodide ions

44
Q

how is T3 and T4 synthesised in follicle cells

A

thyroid hormone precursors stored as a form of glycoprotein and iodide ions in colloid, enzyme generates iodinated tyrosine and combine the iodotyrosines and they get converted into T3/T4 in follicular cells

45
Q

describe the structure of thyroid gland follicles

A

(on one note) inside area is colloid, surrounding is follicular cells

46
Q

what produces calcitonin

A

parafollicular cells

47
Q

how many iodide ions in T3

A

3

48
Q

how is the storage of T3 and T4 increased

A

follicular cells take up iodide ions via Na+ channel receptor, iodide ions transported to colloid, Tg released into colloid by exocytosis, TPO stimulates Tg iodination and conjugation of MIT and DIT, store of T3 and T4 increased

49
Q

how is the release of T3 and T4 stimulated

A

serum levels of T3/4 decrease, hypothalamic pituitary axis produce TSH, TSH leave capillary and binds to receptors on follicular cell to activate channel receptor and signal cascade, endocytosis of Tg-T3-T4 which gets broken down into lysosomes, T3 and T4 released into capillary

50
Q

what regulates the synthesis and release of thyroid hormones from thyroid follicles

A

serum TSH and T3/4 levels

Endocrine and metabolism (12 decks)

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