Endocrine signalling

Question 1

Who pioneered the study of endocrinology?

Answer 1

Arnold Adolph Berthold (1803-1861)

Question 2

What is the chemical messenger of the endocrine system?

Answer 2

Hormone

Question 3

What are the endocrine glands of the body?

Answer 3

Pineal, Pituitary, Hypothalamus, Thyroid, Parathyroid, Thymus, Adrenal glands, Pancreas, Gonads (ovaries and testis).

Question 4

What is a ligand?

Answer 4

Any molecule such as hormones, growth factors, neurotransmitters that are able to bind to cell receptors.

Question 5

What is an Agonist?

Answer 5

Activate a response from the receptor. Can be a primary ligand which has a physiological role, or a drug molecule that mimics the action of the primary ligand.

Question 6

What is an Antagonist?

Answer 6

Inhibit a response from the receptor. Can be a primary antagonist, or a drug molecule that mimics the action of the primary antagonist.

Question 7

What is true about ligands?

Answer 7

The concentration at which they are present dictates whether they are agonists or antagonists.

Question 8

What are some functions of endocrine molecules?

Answer 8

Alter plasma membrane permeability or electrical potential.
Activate or deactivate enzymes.
Stimulate synthesis of proteins.
Induce secretory activity.
Stimulate cell death (apoptosis).
Stimulate mitosis.

Question 9

What are Autocrines?

Answer 9

Chemicals which exert effects only on themselves. E.g. Cytokines and interleukins.

Question 10

What are Paracrines?

Answer 10

Locally acting chemicals which affect nearby cells. E.g. Histamine, prostaglandins, nitric oxide, growth factors, blood coagulation factors and neurotransmitters.

Question 11

What is the definition of a hormone?

Answer 11

Chemical substances secreted into the blood in very small amounts to other parts of the body where they interact with specific receptors in the target tissue to produce a particular response.

Question 12

What are the chemical classes of hormones?

Answer 12

Amino-acid based, Steroids, Eicosanoids

Question 13

What hormones are hydrophilic?

Answer 13

Peptide and amine hormones.

Question 14

What hormones are hydrophobic?

Answer 14

Steroids.

Question 15

Name the steps of steroid hormone.

Answer 15

1. diffusion through plasma membrane to bind to receptor.
2. Receptor/hormone complex enters the nucleus.
3. Binds to a specific DNA region.
4. Binding initiates transcription.
5. mRNA directs protein synthesis.

Question 16

What is the exception to the water soluble amine hormones? What is the function?

Answer 16

Thyroid hormone.
Increase basal metabolic rate, body temperature.
Synthesis of Na+/K+ ATPase. Enhances actions of Catecholamines.

Question 17

What 3 factors affect the degree of target cell activation?

Answer 17

Blood level of the hormone, relative number of receptors on the target cell, affinity of those receptors for the hormone.

Question 18

A change in the number of receptors can be either due to?

Answer 18

Up-regulation and Down-regulation.