C1 Steroids and hormones

Question 1

state some things that hormones can have effects on

Answer 1

growth
sleep cycle
mood
immune system
metabolism
flight / flight
puberty
reproduction
menopause

Question 2

what part of the body sends signals to warm the body up?

Answer 2

hypothalamus

Question 3

state an example of a scenario using negative feedback

Answer 3

thermoregulation

Question 4

state an example of a scenario using positive feedback

Answer 4

contractions during labour

Question 5

what is a steroid?

Answer 5

• a class of compounds defined by a specific structure of 17 carbon atoms in 4 rings
• can be thought of as a functional group / class of compound

Question 6

what is a hormone?

Answer 6

a class of signalling molecules which regulate physiology and behaviour in organisms

Question 7

what is a steroid hormone?

Answer 7

• a signalling molecule which has a specific structure of 17 carbon atoms in 4 rings
• behave very differently to peptide hormones

Question 8

state 4 types of hormones and give examples of some

Answer 8

• steroids
• proteins and peptides (eg. insulin, glucagon, oxytocin)
• amino acid derivatives (eg. norepinephrine, melatonin, thyroxine)
• eicosanoids (eg. prostaglandin)

Question 9

state 2 types of steroid hormones and give examples of each

Answer 9

• corticosteroids (eg. glucocorticoids, mineralocorticoids)
• sex hormones (eg. androgens, oestrogens, progestogens)

Question 10

what are mineralocorticoids to do with?

Answer 10

water and controlling osmolality of blood

Question 11

example of an androgen

Answer 11

testosterone

Question 12

example of an oestrogen

Answer 12

estradiol

Question 13

example of an progestogen

Answer 13

progesterone

Question 14

contrast insulin and glucagon in terms of their chemical class and function

Answer 14

insulin:
- peptide hormone
- promotes the absorption of glucose into cells and subsequent conversion into fats such as glycogen

glucagon:
- peptide hormone
- promotes glycogenolysis (converting glycogen into glucose which is released into the bloodstream)

Question 15

describe the signalling of endocrine hormones

Answer 15

signal carried in the bloodstream

Question 16

describe the signalling of paracrine hormones

Answer 16

• intercellular
• if a cell releases a hormone it will affect other surrounding cells

Question 17

describe the signalling of autocrine hormones

Answer 17

affects the very same cell that secreted it

Question 18

describe the signalling of intracrine hormones

Answer 18

• intracellular
• refers to more closed systems

Question 19

state the steps of the general hormone lifecycle (it is not the same for all hormones)

Answer 19

synthesis
storage
secretion
transport
recognition
relay
degradation

Question 20

describe an agonist

Answer 20

activates a receptor to produce a response

Question 21

describe an antagonist

Answer 21

blocks action of an agonist

Question 22

describe an inverse agonist

Answer 22

induces an opposite response to agonist

Question 23

what is a selective receptor modulator? give an example

Answer 23

• has different effects in different tissues (effect depends on the receptors present on cells)
• eg. Tamoxifen is a selective oestrogen receptor modulator

Question 24

how do steroids vary?

Answer 24

• by the position and nature of their attached groups
• small modifications can have high effects on biological activities

Question 25

how are the rings of carbons structured in steroids and how are they numbered? (ignore words on picture)

Answer 25

Question 26

where are the high interest regions on steroid molecules?

Answer 26

- carbon 17 - carbons 3&4

Question 27

draw the simplest structure of a sterol

Answer 27

steroid with an alcohol group

Question 28

describe cholesterol

Answer 28

- forms 30% of the cell membrane and modulates fluidity - biosynthetic precursor for steroid hormones, vitamin D and bile acids

Question 29

what are glucocorticoid receptors?

Answer 29

- transcription factors that are activated upon hormone binding

Question 30

what are transcription factors?

Answer 30

- proteins that control the rate of transcription by binding to a specific DNA sequence - they turn genes 'on and off'

Question 31

which sort of hormone activates the glucocorticoid receptor?

Answer 31

glucocorticoids

Question 32

what is glucocorticoid short for?

Answer 32

glucose cortex steroid

Question 33

where are corticosteroids produced?

Answer 33

the adrenal gland

Question 34

state the function and some examples of glucocorticoids

Answer 34

- affect metabolism of carbohydrates, fats and proteins - eg. cortisol / hydrocortisone - synthetic examples: Beclometasone, Dexamethasone

Question 35

what do mineralcorticoids do? state an example

Answer 35

- regulate electrolytes in the body by acting on ion transport in kidneys - eg. Aldosterone

Question 36

what is signal transduction?

Answer 36

- when a signal is transmitted through a cell

Question 37

explain the permeability of steroid hormones

Answer 37

- generally membrane-permeable - due to their lipophilicity

Question 38

explain the permeability of peptide hormones

Answer 38

- cannot enter cells because they are too hydrophilic - we need a transporter that spans the membrane

Question 39

what is meant by 'like dissolves like'?

Answer 39

- lipophilic compounds will dissolve in lipophilic solvents - hydrophilic compounds will dissolve in hydrophilic solvents

Question 40

what does lipophilicity refer to?

Answer 40

ability of a molecule to dissolve in lipids

Question 41

sort these 6 words into 2 categories: polar, non-polar, lipophilic, hydrophilic, hydrophobic, lipophobic

Answer 41

polar, lipophobic, hydrophilic non-polar, hydrophobic, lipophilic

Question 42

explain why drug solubility is important in transport across membranes

Answer 42

- if a drug is too polar, it cannot passively diffuse across the lipophilic cell membrane - if a drug is too lipophilic, it is more susceptible to metabolism and other disadvantages - need to hit the lipophilicity 'sweet spot'

Question 43

what can steroid hormones do if they get into a cell? what does this ultimately lead to?

Answer 43

- steroid hormones can pass through the cell membrane and activate a glucocorticoid receptor - this receptor then enters the nucleus as a transcription factor - ultimately leads to increased transcription

Question 44

how can a peptide hormone ultimately cause increased transcription?

Answer 44

- attaches to GPCR and activates it as it can't pass through the membrane - this induces a signalling cascade which also ultimately causes increased transcription

Question 45

why can peptide hormones not pass through the cell membrane?

Answer 45

they are too hydrophilic

Question 46

state 2 examples of synthetic androgens and what they are associated with

Answer 46

associated with bodybuilders - testosterone esters - nandrolone esters

Question 47

state an example of a synthetic oestrogen and where it is important

Answer 47

ethinylestrogen important in contraception

Question 48

state 3 examples of synthetic progestogens (progestins)

Answer 48

levonorgestrel norethisterone desogestrel