15- Hormones and Signalling

Question 1

Paracrine messengers

Answer 1

Locally acting. short distance,

Diffusion

Question 2

Autocrine

Answer 2

secreted to self

Diffusion

Question 3

Cytokine

Answer 3

Chemical messengers typically secreted by blood cells

Question 4

Hormone

Answer 4

secreted into the blood from endocrine cells

Blood

Question 5

Neurohormone

Answer 5

like hormones but secreted by neural cells

Blood

Question 6

Chemical classes for chemical messengers

Answer 6

amines

amino acids

peptides

steroids

eicosanoids

Question 7

Hormons and neurohormones are never what type of chemical class?

Answer 7

Amino acids or eicosanoids

Question 8

Types of hydrophilic chemical messengers

Answer 8

Peptides (most common)

Some amines (E, NE, dopamine)

hydrophillic bind to membrane receptor

Question 9

Types of hydrophobic chemical messengers

Answer 9

Steroids (androgens, estrogens, cortisol)

few amines (Thyroid– T3, T4)

Question 10

Hydrophillic receptor types

Answer 10

Integrins (linked to cyto)- ligand binds, change in cyto skel.

Ligand-gated ion channel- ligand binds, open/close gate

receptor enzyme- receptor catylyzes reaction

G protein linked receptor-

Question 11

Ligand-gated ion channels

Answer 11

Fast response of target cell. Common with neurotransmitters, also seen in hormones and neurohormones

Ion specific, some are non specific

Always down conc. gradient. PASSIVE

Question 12

G protein signal transduction (simplified)

Answer 12

1. G protein receptor binds ligand
2. a subunit activated by binding GTP
3. a subunit controls regulated protein

Question 13

How do hydrophobic signals work?

Answer 13

DIFFUSE directly across cell membrane

Receptor in cytosol or nucleus

Transcription factor

Longer half life

Question 14

Hydrophillic peptide half life

Answer 14

short mins to hours.

Starts once it hits the blood.

Synthesized in rough ER (stored in vesicles)

Question 15

Steroid Hormones

Answer 15

Synthesized in SMOOTH ER (because lipids)

Modified from cholesterol

Not stored– synthesized on demand

Bound to protein to increase solubility in blood

Long half lives (hours to days)

Slow effect

Question 16

# carbons to identify steroids
21, 19, 18

Answer 16

21C– corticoids and progesterones

19C– Androgens

18C– Estrogen

Question 17

Two main classes of amino acids

Answer 17

Catecholamines: E, NE, dopamine
— hydrophillic

Thyroid hormones: T3, T4
— hydrophobic

Question 18

Up regulated

Answer 18

Lots of receptors to grab any chemical signal for that thing that comes along

Question 19

Down regulated

Answer 19

overexposure of a chemical can cause less receptors. May need more chemical to get the effect.

Related to opioid addiction.

Question 20

Antagonistic Control

Answer 20

Opposite messages given to cell.

Ex. Pituitary releases GH in response to which hormone stimulates it more. Growth hormone RELEASING hormone (GHRH) or Growth hormone INHIBITING hormone (GHIH)

Question 21

Tonic control

Answer 21

controlled by one hormone

ex. Thyroid secretes thyroid hormones according to how much thyroid stimulating hormone is in the blood.

Question 22

System amplification

Answer 22

one chemical messenger can lead to a very large response in cell.

Question 23

Hormone half-life

Answer 23

Amount of time for hormone to drop by half.

Question 24

Primary ligand

Answer 24

Chemical that binds to receptor and delivers normal response

ex. endorphines

Question 25

Agonist

Answer 25

Chemical that binds to a receptor and delivers a similar response to primary ligand

Question 26

Antagonist

Answer 26

Delivers no response while binding to receptor and blocking primary ligand

ex. naloxone - opioid receptor antagonist

Question 27

Receptor modulation

Answer 27

Allosteric modulators. Bind to part of the receptor to help increase or decrease signal transduction

ex. benzodiazepines- GABA receptor activators