PSL300 > 8 > Flashcards

8 Flashcards

(57 cards)

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1
Q

two classes of hormones

A

hydrophilic and hydrophobic hormones

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2
Q

hydrophilic hormones

A
  • water soluble, can dissolve in plasma
  • not lipid soluble (lipophobic), cannot cross plasma membranes (which are hydrophobic)
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3
Q

examples of hydrophilic hormones

A

peptide hormones, protein hormones and catecholamines

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4
Q

hydrophobic hormones

A
  • not water soluble, do not dissolve in plasma
  • lipid soluble (lipophilic), readily cross plasma membrane
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5
Q

examples of hydrophobic hormones

A

steroid and thyroid hormones

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6
Q

compare the synthesis of hydrophilic and hydrophobic hormones

A

hydrophilic are synthesised in advance and stored in vesicles

hydrophobic are synthesised on demand as they are not easy to store

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7
Q

compare the release of hydrophilic and hydrophobic hormones

A

hydrophilic are released via exocytosis

hydrophobic are released via diffusion

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8
Q

compare the transport in blood of hydrophilic and hydrophobic hormones

A

hydrophilic are dissolved in the blood

hydrophobic are bound to carrier proteins in the blood

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9
Q

three main types of hormones

A
  • peptide/protein (3 or more amino acids)
  • steroid (derived from cholesterol)
  • amine (derived from single amino acids)
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10
Q

chemistry, examples, and transport of steroid hormones

A
  • derived from cholesterol
  • sex steroids (estrogen), cortisol
  • hydrophobic, so bind to transport proteins in the blood
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11
Q

chemistry, examples, and transport of monoamine hormones

A
  • made from amino acids
  • catecholamines (epinephrine), thyroxine
  • hydrophilic, so mix easily with blood plasma
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12
Q

chemistry, examples, and transport of peptide hormones

A
  • made from chains of amino acids
  • insulin
  • hydrophilic, so mix easily with blood plasma
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13
Q

half life of peptide hormones

A

short half life in pasta

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14
Q

peptide/protein hormones bind to

A

membrane receptors

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15
Q

peptide/protein hormones are released by

A

exocytosis upon a signal

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16
Q

peptide/protein hormones are synthesised like

A

secreted proteins

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17
Q

peptide/protein hormones are stored in

A

vesicles

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18
Q

peptide/protein hormones are made

A

in advance

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19
Q

synthesis, packaging and release of peptide/protein hormones

A
  1. preprohormone synthesised from mRNA by ribosomes on the ER
  2. signal sequence is cleaved off to form a pro hormone
  3. transport vesicle is pinched off the ER and joins the Golgi complex
  4. the prohormone is cleaved and altered to form an active hormone
  5. release signal allows it to be exocytosed and carried to target cells
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20
Q

— ——– ——- produces biologically active peptide

A

post-translational processing

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21
Q

2 examples of the content of preprohormones

A

several copies of the same hormone (eg preproTRH)
- processed into hormone, other peptides, and signal sequence

more than one type of hormone (eg pro-opiomelanocortin)
- processed into active hormones and other peptide fragments

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22
Q

active peptides released depend on

A

specific proteolytic processing enzymes

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23
Q

how is insulin processed?

Study These Flashcards
A

Proinsulin folds and forms disulfide bonds between its A and B chain regions. The C-peptide (connecting peptide) is then cleaved off by proteases

24
Q

steroid hormones are synthesised only from

25
steroid hormones are made
on demand
26
steroid hormones are stored in
NOT vesicles
27
steroid hormones are released from cell by
simple diffusion
28
steroid hormones are transported in the blood
by carriers
29
do steroid hormones have a long or short half-life?
long
30
steroid hormones act on
cytoplasm or nucleus receptors (but can also act on plasma membrane receptors)
31
how do steroid hormones reach their targets?
diffuse into target cells or taken up by endocytosis of steroid hormone carrier proteins
32
give an example to showcase how the type of hormone made depends on which enzymes are present in the cell
cholesterol: in adrenal cortex, can become aldosterone or cortisol in ovary, can become estradiol (an oestrogen)
33
how are amine hormones synthesised?
only from tryptophan or tyrosine tryptophan derivative: melatonin (behaves like peptides or steroids depending on the receptor/target aimed) tyrosine derivatives: catecholamines (behave like peptides) and thyroid hormones (behave like steroids)
34
melatonin
- darkness hormone - secreted at night (sleep) - made in pineal gland (also GI tract, leukocytes, and other brain regions) - transmits information (light-dark cycles to govern the biological clock), immune modulation, and anti-oxidant
35
two examples of thyroid hormones
thyroxine (tetraiodothyronine, T4) and triiodothyronine (T3)
36
three examples of catecholamines
dopamine, norepinephrine, epinephrine
37
catecholamines are synthesised in
the adrenal medulla (mainly cytosol)
38
catecholamines are stored in
vesicles prior to release
39
catecholamines are released via
exocytosis
40
chemical properties of catecholamines
lipophobic, water soluble
41
catecholamines bind to
membrane receptors
42
how is hormone release controlled?
endocrine cells directly sense stimuli, then secrete the hormone
43
4 types of stimuli sensed by endocrine cells
metabolite, hormone, neurohormone, neurotransmitter
44
give an example of the control of hormone release
stimulus: glucose endocrine cell: pancreatic beta cell hormone release: insulin
45
6 ways in which stimuli act through intracellular pathways
- change membrane potential - increase free cytosolic Ca2+ - change enzymatic activity - increase the transport of hormone substrates into the cell - alter transcription of genes coding for hormones or for enzymes needed for hormone synthesis - promote survival and in some cases growth of the endocrine cell
46
process of glucose stimulation of insulin release
1. glucose uptake by GLUT2 2. glucokinase leads to respiration and glycolysis, leading to increased concentrations of ATP 3. ATP-sensitive potassium channels are inhibited by ATP 4. this leads to depolarisation 5. this change in MP leads to opening of voltage-gated calcium channels 6. insulin is stored in storage granules and released via exocytosis
47
hormones released from the hypothalamus and anterior pituitary regulate
the release of several hormones
48
label brain
49
draw a flow chart of hormone regulation by hormones
50
describe the function of the anterior pituitary
1. neurons synthesising trophic hormones in the hypothalamus release them into capillaries of the portal system 2. portal vessels carry the trophic hormones directly to the anterior pituitary 3. stimulated endocrine cells release their hormones into the second set of capillaries for distribution to the rest of the body
51
trophic hormones
releasing and inhibiting hormones
52
why are hormone interactions important?
most cells are sensitive to more than one hormone, causing them to exhibit interactive effects
53
three types of hormone interactions
synergistic effects, permissive effects, antagonistic effects
54
synergistic effects
multiple hormones act together for greater effect - eg synergism between FSH and testosterone on sperm production
55
permissive effects
one hormone enhances the target organ's response to a second later hormone - eg estrogen prepares uterus for action of progesterone
56
antagonistic effects
one hormone opposes the action of another - eg insulin lowers blood glucose and glucagon raises it
57
glucagon + epinephrine + cortisol
cause blood glucose levels to be much higher (synergistic effect) than if they were released individually
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