Receptors and Signalling

Question 1

What is an endocrine gland?

Answer 1

Individual cells or groups of cells which are organised into endocrine glands
They release hormones into the ECF where the hormone will diffuse into the capillary system

Question 2

What is the function of exocrine glands?

Answer 2

Secrete into a ductal system which then secretes into specific places

Question 3

How can a hormone be transported throughout the body?

Answer 3

Can be dissolved in the blood or be bound to proteins

Question 4

What is determines the specificity of signaling?

Answer 4

Chemically distinct hormones
Specific receptors for each hormone
Distance distribution of receptors across target cells

Question 5

What are the major endocrine glands?

Answer 5

Pituitary
Thyroid
Parathyroid
Adrenal
Pancreas
Ovary
Testis

Question 6

What are the 4 classes of horomes?

Answer 6

Modified amino acids
Steroids
Peptides
Proteins

Question 7

What are some examples of modified amino acid hormones?

Answer 7

Adrenaline
Thyroid hormones (T3 and T4)

Question 8

What are some examples of steroid hormones?

Answer 8

Cortisol
Progesterone
Testosterone

Question 9

What are some examples of peptide hormones?

Answer 9

ACTH
ADH
Oxytocin

Question 10

What are some examples of protein hormones?

Answer 10

Insulin

Question 11

What does the chemistry of the hormone determine?

Answer 11

Half life of hormone
Whether the hormone will stay in the ECF or ICF
Volume of distribution

Question 12

What is autocrine signalling?

Answer 12

The cell signals to itself

Question 13

What is paracrine signalling?

Answer 13

Cell signals to its close neighbours

Question 14

What is endocrine signalling?

Answer 14

The signalling molecule enters the bloodstream

Question 15

How is the action of an endocrine hormone terminated?

Answer 15

Enzyme-mediated metabolic inactivation in the liver or sites of action

Question 16

What hormones contribute to the response of the body to short-term intense exercise?

Answer 16

Adrenaline
Cortisol
Glucagon

Question 17

What hormones contribute to normal growth?

Answer 17

GH
Insulin
IGF-1
Sex steroids

Question 18

What is the basic action of insulin?

Answer 18

Lowers plasma glucose by inhibiting hepatic glycogenolysis and gluconeogenesis and stimulating glucose uptake into muscle and adipose tissue

Question 19

What is the basic action of glucagon?

Answer 19

Increased plasma glucose levels by stimulating hepatic glycogenolysis and gluconeogenesis

Question 20

What hormone antagonizes glucose uptake into muscle and adipose tissue?

Answer 20

Adrenaline

Question 21

What is the synthesis, storage and release of amines?

Answer 21

Pre-synthesised and stored in vesicles
Released in response to calcium induced exocytosis
Hydrophilic so are transported freely around the bloodstream

Question 22

What is the synthesis, storage and release of peptides and proteins?

Answer 22

Pre-synthesised from a longer precursor
Stored in vesicles
Released in response to stimuli by Ca2+ dependent exocytosis
Hydrophilic so are transported freely around the blood

Question 23

What is the synthesis, storage and release of steroids?

Answer 23

Synthesised and secreted upon demand
Stimuli will increase cellular uptake and availability of cholesterol and the rate of conversion of cholesterol to pregnenolone
There is no storage in vesicles, it is released as soon as its made
They are hydrophobic so are transported bound to plasma proteins

Question 24

What is the function of carrier proteins?

Answer 24

Increase the amount of hormone carried in the blood
Provide a reservoir of hormone
Extend the half life of the hormone in circulation

Question 25

What will bind to cortisol-binding globulin?

Answer 25

Cortisol

Question 26

What binds to thyroxin-binding globuin?

Answer 26

Thyroxine (T4) and also some T3

Question 27

What binds to sex steroid binding globulin?

Answer 27

Testosterone and oestradiol

Question 28

What binds to albumin?

Answer 28

Steroids and thyroxine

Question 29

What binds to transthyretin?

Answer 29

Thyroxine and some steroids

Question 30

When will steroid hormones be biologically active?

Answer 30

Only once they have dissolved in the plasma and dissociated from the carrier protein

Question 31

How is the concentration of steroid hormones in the plasma kept relatively constant?

Answer 31

Free hormone removed from the plasma by elimination is replaced by bound hormone dissociating from the carrier protein - the carrier protein acts as a reservoir

Question 32

Describe the HPA axis?

Answer 32

Hypothalamus secretes CRF which stimulates the anterior pituitary to release ACTH which acts on the adrenal cortex to release cortisol

Question 33

How does the HPA axis act as a negative feedback loop?

Answer 33

Cortisol acts on the anterior pituitary and hypothalamus to reduce the ability to release CRF and ACTH

Question 34

What is the equation for plasma conc of hormones?

Answer 34

Plasma conc = rate of secretion - rate of elimination

Question 35

What are the different chemical classes half life?

Answer 35

Amines: seconds Proteins and peptides: minutes Steriods: hours to days

Question 36

What hormones activate GPCR receptors?

Answer 36

Amines and some proteins/ peptides

Question 37

What hormones activate receptor kinases?

Answer 37

Insulin - protein

Question 38

What hormones activate nuclear receptors?

Answer 38

Steroid hormones and thyroid hormones

Question 39

What are the different classes of nuclear receptors?

Answer 39

Class 1: located in cytoplasm bound to inhibitory heat shock protein and dissociate from this when ligand binds and moves to nucleus Class 2: activated by lipids - present in nucleus

Question 40

What is the signalling pathways of GCRP receptors Gi and Gs?

Answer 40

Gs, Gi proteins via adenyly cyclase, cAMP and PKA

Question 41

What effect does Gs have on adenyly cyclase?

Answer 41

Increased rate of production of cAMP from ATP

Question 42

What effect does Gi have on adenyly cyclase?

Answer 42

Reduces the rate of production of cAMP from ATP

Question 43

What does cAMP do?

Answer 43

Phosphorylates PKA which causes the phosphorylation of Ser/Thr residues in target proteins causing the cellular effects

Question 44

What is the signalling pathways of GCRP receptor Gq?

Answer 44

Via PLC, PKC, IP3 calcium and DAG

Question 45

What hormones act through the Gq signalling?

Answer 45

Angiotensin 2 Gonadotropin releasing hormone Thyrotropin releasing hormone

Question 46

What hormones act through the Gs signalling?

Answer 46

Adrenaline Corticotrophin releasing factor (CRF) Glucagon

Question 47

What hormone acts through the Gi signalling?

Answer 47

Melatonin

Question 48

What happens when insulin binds to its receptor kinase?

Answer 48

Autophosphorylation of intracellular tyrosine residues that causes the recruitment of multiple adapted proteins such as insulin receptor substrate protein that is phosphorylates by tyrosine

Question 49

What does the insulin receptor substrate protein do?

Answer 49

Activates protein kinase B which causes the desired metabolic effects

Question 50

What hormones does the anterior pituitary produce? | These are all peptide or protein

Answer 50

``` ACTH (acts on adrenal cortex) GH (acts on liver, bones and muscle) FSH (acts on gonads) Luteinizing hormone (acts on gonads) Prolactin (acts on mammary glands) TSH (acts on thyroid) ```

Question 51

What hormones does the posterior pituitary produce? | These are all protein or peptide

Answer 51

ADH (acts on renal cortex) | Oxytocin (acts on mammary glands and uterus)

Question 52

What hormones does the thyroid produce? | These are all modified amino acids

Answer 52

Thyroxine (acts on most tissues) | T3 (acts on most tissues)

Question 53

What hormones does the parathyroid produce? | These are all peptide or protein

Answer 53

Calcitonin (acts on bone and gut) | PTH (acts on bone and gut)

Question 54

What hormones does the adrenal cortex produce? | These are steroid

Answer 54

Zona glomerulosa - aldosterone Zona fasciculata - cortisol Zona reticularis - androgens SALT, SUGAR, SEX

Question 55

What hormones does the adrenal medulla produce? | These are modified amino acids

Answer 55

Adrenaline and noradrenaline

Question 56

What hormoens do the female and male gonads produce? | These are steroids

Answer 56

Male: testosterone Female: Oestroadiol and progesterone

Question 57

What hormones do the placenta produce? | These are peptides and steriods

Answer 57

hCG Oestradiol Progesterone