Introduction to endocronology

Question 1

What are the different types of cell to cell communication?

Answer 1

Endocrine signalling
Autocrine signalling
Paracrine signalling
Neural signalling

Question 2

What are the 3 categories of chemical structure of hormones?

Answer 2

Protein or small peptides = ADH

Steroids = cholesterol derivatives

Amines = derivatives of amino acids

Question 3

What are examples of steroid hormones?

Answer 3

Mineralocorticoids - aldosterone

Glucocorticoids - cortisol

Androgens - oestrogen

Question 4

Is cholesterol a hormone?

Answer 4

No - it is a common precursor for many steroid hormones

Question 5

What are examples of amines?

Answer 5

Epinephrine - adrenaline

Thyroxin

Question 6

What do epinephrine and thyroxin have in common?

Answer 6

Both derive from the amino acid tyrosine

Question 7

What determines the way hormones are transported in the blood?

Answer 7

Chemical structure

Question 8

How do peptide hormones and amines travel?

Answer 8

They are hydrophilic

Travel free in solution

Question 9

How do steroid and thyroid hormones travel?

Answer 9

They are hydrophobic

Carried bound to plasma proteins

Question 10

Are protein bound hormones filtered easier at the kidney glomerulus than free floating hormones?

Answer 10

No

Question 11

What types of bonds hold the proteins and the hormones together?

Answer 11

Van der Waals forces

Question 12

Names of proteins that bind to hormones

Answer 12

Sex hormone-binding proteins

Thyroxin-binding protein

Albumin

Question 13

Where are the hormones receptors found?

Answer 13

Some are on the CSM and Some are on nucleus

Question 14

What types of hormones have receptors on CSM?

Answer 14

Hydrophylic hormones

Question 15

What happens when hydrophilic hormones bind to their receptor on CSM?

Answer 15

They relay the information outside the cell into an intracellular response

Interaction of receptor and hormone results in a conformational change in the protein shape

This activates intracellular proteins and releases second messengers that bring about cell responses

Second messengers affect targets inside the cell

Question 16

What are common second messengers?

Answer 16

cAMP

CGMP

Ca2+

IP3

Question 17

What happens when hydrophobic hormones enter cells?

Answer 17

Can cross the nuclear membrane

Interact with genetic material to enhance or decrease gene expression

Question 18

How does oestrogen bring about changes in the cell?

Answer 18

Activates receptors in the cell nucleus

Activated receptors dimerise

These receptors directly affect gene expression - no need for second messengers

Question 19

What are the two types of cell membrane receptors?

Answer 19

Tyrosine kinase receptors

G-protein coupled receptors

Question 20

How does activation of the G-protein coupled receptors bring about cellular changes?

Answer 20

Interaction of hormone with the receptor brings about a change in shape

There is separation of the subunits of the G-proteins - alpha, beta and gamma

G - protein alpha targets the protein adenynyl cyclase which catalyses formation of cAMP

cAMP carries out different funcitons

Question 21

What are the structural features of G-protein coupled receptors

Answer 21

They cross the membrane 7 times

Linked to G-proteins via GDP

G-protein is made of 3 sub-untis: alpha, beta and gamma

Question 22

What effect does cAMP have in different tissues?

Answer 22

In cardiac cells - increases heart rate and contractility

In lung cells - causes bronchodilation via relaxation of bronchial smooth muscle

In liver - enhances glycogenolysis to increase blood glucose

Question 23

What happens upon activation of tyrosine kinase receptors?

Answer 23

Two subunits form the receptor - dimerise when hormone activates it

Dimerised receptors catalyse phosphorylation of proteins

When proteins become phosphorylated = become active and activates other proteins inside the cell

Question 24

What is a kinase?

Answer 24

Enzyme that catalyses the transfer of phosphate group s from high energy molecules to proteins