Introduction to endocrinology

Question 1

Hormone definition

Answer 1

A chemical signal released from an endocrine cell to influence the activity if another cell via a receptor

Question 2

6 endocrine systems

Answer 2

pituitary, thyroid, parathyroid, pancreas, adrenal, gonads

Question 3

What is the master gland + function

Answer 3

pituitary- controls all of the other endocrine systems

Question 4

3 different types of endocrine systems

Answer 4

endocrine gland- a well defined collection of endocrine cells

neuroendocrine systems- neurons that release hormones into the blood in the brain and CNS

diffuse endocrine systems- endocrine cells not arranged in glands but dispersed- scattered individually amongst epithelial cells

Question 5

Three methods of endocrine communication

Answer 5

endocrine- to blood- far acting

paracrine- from one cell to the next

autocrine- automatic feeback loop

Question 6

What does the speed of endocrine actions depend upon?

Answer 6

rapidity of release, half-life of hormone and rapidity of action

Question 7

Example of fast response

Answer 7

adrenaline- fight or flight response

Question 8

Example of intermediate response

Answer 8

insulin- response to a meal

Question 9

example of slow response

Answer 9

cortisol from fetal adrenal causes the production of surfactant, which lowers the surface tension in alveoli in the lungs

Question 10

How are hormones released?

Answer 10

in pulses

Question 11

Explain pulsatile secretion

Answer 11

biochemical phenomenon where chemical products are secreted in a regular pattern

ensures that the delicate homeostatic balance necessary for essential life processes is maintained

Question 12

Name a specific type of pulsatile secretion

Answer 12

diurnal rhythms

Question 13

explain diurnal rhythms

Answer 13

processes with 24-hour oscillations that control sleep patterns, such as cortisol

Question 14

different chemical types of hormone

Answer 14

amino acid derived- adrenaline

polypeptide- insulin

protein- prolactin

glycoprotein- LH

steroids- testosterone

prostaglandins

gaseous mediators- nitrous oxide

Question 15

Different types of hormone secretion explained

Answer 15

constitutive- hormones that are produced constantly such as cytokines

regulated - respond to a stimulus e.g insulin

Question 16

key features of regulated secretion

Answer 16

proteins concentrated and stored in secretory vesicles

secretory vesicles stored in cell

vesicles quickly release their contents by exocytosis in response to a stimulus

Question 17

constitutive secretion

Answer 17

proteins are not concentrated

vesicles are not stored in cell

contents released as they are produced

regulation is by control of transcription

Question 18

what is the hormones precursor?

Answer 18

prohormones, which are cleaved at dibasic sites

Question 19

What can one prohormone form?

Answer 19

many different hormones, or many of the same type- due to different dibasic cleavage sites

Question 20

How are hormones transported in blood?

Answer 20

hydrophilic hormones can circulate freely in plasma

most steroid and thyroid hormones are bound to specific binding proteins in plasma

binding of hormones reduces their clearance and extends their half-life

Question 21

How are hormones metabolised and excreted?

Answer 21

hormones internalised with their receptor are degraded by lysosomes

steroid hormones degraded in the liver

hydrophilic hormones also lose by excretion through kidneys

Question 22

Functions of the endocrine system

Answer 22

promote survival of the individual and control processes involved in reproduction

Question 23

Explain how the endocrine system promotes the survival of the individual

Answer 23

effects development, growth and differentiation

helps in preservation of a stable internal environment

responds to an altered external environment, especially during emergency stress responses

Question 24

normal concentrations of protein and polypeptide hormones

Answer 24

nanomolar

Question 25

normal concentrations of steroids

Answer 25

sub-micromolar

Question 26

which hormones are produced enzymatically as they are needed?

Answer 26

prostaglandins, nitric oxide and angiotensin II