Hormones and Receptors

Question 1

What are the major endocrine glands in the body?

Answer 1

Thyroid and parathyroid 
Pancreas 
Hypothalamus and pitutary gland 
adrenal glands 
ovaries/testes 
placenta in pregnant female

Question 2

What does “paracrine” mean?

Answer 2

specialised cells releases substance and act locally to adjacent cells

Question 3

What does “autocrine” mean?

Answer 3

cells release chemical substance which has effect limited to the cell which released it – numerous white blood cells use this

Question 4

List the chemical classes of hormone

Answer 4

Glucoproteins and peptides
Steroids
Tyrosin and trytophan derivatives (amines)

Question 5

Describe the general idea of the endocrine system

Answer 5

Communication between glands and other tissues achieved by the secretion of a hormone into the blood stream and transport to a target site.
Glands are anatomically distinct but form a functional system.

Question 6

How is specificity of signalling achieved?

Answer 6

• chemically distinc hormones
• specific receptors for each hormone
• distinct distribution of receptors across target cells

Question 7

What are the 6 overall functions of the endocrine system?

Answer 7

• regulation of nutrient metabolism, H20 and electrolyte balance
• enabling changes to stress
• promoting growth and development
• conrolling reproduction
• regulating red blood cell production
• controlling and integrating the activites of the cardiovascular and digestive systems

Question 8

In terms of synthesis, storage, release and transport what happens to amine hormones?

Answer 8

pre-synthesised, stored in vesicles
released in response to increased intracellular Ca2+ - Ca2+ dependent exocytosis
hydrophilic - transported mainly free in plasma

Question 9

In terms of synthesis, storage, release and transport what happens to peptides and proteins hormones?

Answer 9

pre-synthesised (usually from a longer precursor) stored in vesicles
released in response to increased intracellular Ca2+ - Ca2+ dependent exocytosis
hydrophilic - transported mainly free in plasma

Question 10

What synthesises the precursor protein in peptide and protein hormone synthesis?

Answer 10

Rough ER

Question 11

In terms of synthesis, storage, release and transport what happens to peptides and proteins hormones?

Answer 11

Synthesised and secreted on demand (not stored in vesicles!)

Hydrophobic and transported in plasma mainly bound (~90%) to plasma proteins - only “free” is biologicaly active

Question 12

What are all steroid hormones derived from?

Answer 12

Cholesterol

Question 13

What is the purpose of carrier proteins?

Answer 13

• increase amount transported in blood

- prevent rapid excretion by filtration at the kidney

Question 14

Give some exaples of important general carrier proteins.

Answer 14

Albumin and transthyretin

Question 15

Name 3 importat specific carrier proteins.

Answer 15

Cortisol-binding globulin
Thyroxine-binding globulin
Sex steroid- binding globulin

Question 16

Give another function of circulating carrier proteins?

Answer 16

Act as a buffer and reervoir that helps to maintain relatively constant concentrations of free lipophiic hormone in the blood - free and bound hormone are in equilibrium

Question 17

What are the 3 methods of control of hormonal levels?

Answer 17

• negative feedback
• neuroendocrine (elicits a sudden burst in secretion to meet a specfic stimulus)
• diurnal rhythm

Question 18

What are the 3 groups of hormone receptors?

Answer 18

GPCR
Receptor kinases
Nuclear receptors (3 classes)

Question 19

Of the 3 types of hormone receptor, which one is the odd one out and why?

Answer 19

Nuclear receptors - they are intracellular receptors whereas GPCR and receptor kinases are cell surface receptors

Question 20

Which class of nuclear receptors is when unbound, found in the cytoplasm bound to inhibitory heat shock protein?

Answer 20

Class 1

Question 21

Which class of nuclear receptors does thyroiod hormone bind to?

Answer 21

Hybrid class