Principles of Endocrine Control

Question 1

Secretion definition

Answer 1

Biochemical release from a particular type of cell upon stimulation

Question 2

Exocrine

Answer 2

Gland with ducts that channels its secretion into a particular place- localized e.g. salivary gland

Question 3

Endocrine

Answer 3

Secretion into bloodstream, ductless gland

Question 4

Autocrine cell signalling

Answer 4

Cell secretes and then acts on itself

Question 5

Paracrine cell signalling

Answer 5

Localised action, doesnt go into blood

Secreted by one cell but acts on other type of cell

Question 6

Hormone

Answer 6

Secreted from endocrine glands, go into systemic circulation, travel to distant site

Question 7

Neuroendocrine

Answer 7

Like endocrine but located in CNS. Specialised neurones capable of secreting hormones

Question 8

Which hormones are hydrophilic

Answer 8

Peptides
Catecholamines
Adrenaline
Noradrenaline

Question 9

Which hormones are lipophilic (lipid soluble)

Answer 9

Steroids

Thyroid hormones

Question 10

Mechanism of action of peptides

Answer 10

1) Produced by protein synthesis, transcription, translation
2) Travel in blood
3) Cannot enter cell directly-lipid bilayer cell membrane
4) Bind to cell surface receptor
5) Trigger event on inside of membrane
6) Fast acting

Question 11

Mechanism of action of steroids

Answer 11

1) Produced by modification of cholesterol molecule by enzyme
2) Travel in blood bound to plasma proteins
3) Enter cell, intracellular receptors
4) Act on DNA to alter cell function
5) Act as transcription factor, switch on certain genes that are required for physiological function of hormones- get converted into mRNA, then protein
6) New protein bring about action in cell
6) Slow acting (transcription delay)

Question 12

Why can’t peptides be taken orally?

Answer 12

Will be broken down by proteases , absorbed as aa

Question 13

Once peptide inside the cell, what cascade of events does it cause?

Answer 13

Protein binds to receptor cause conformational change
Causes receptor to bind to adenylyl cyclase and activate it
Adenylyl cyclase convert ATP to cAMP
etc.

Question 14

What is the link between anterior pituitary and hypothalamus?

Answer 14

Vascular link

Hormones released from hypothalamus, secreted into capillaries, reach anterior pituitary, stimulate secretion of hormones there

Question 15

What is the link between posterior pituitary and hypothalamus?

Answer 15

Neuronal connection

Produced hormones in hypothalamus, reach posterior pituitary when required, stored, released after stimulation

Question 16

Hormones released from posterior pituitary

Answer 16

ADH/vasopressin

Oxytocin

Question 17

What is the function of testosterone?

Answer 17

Masculinizes the reproductive tract and external genitalia
Promotes growth and maturation or reproductive system at puberty
Spermatogenesis
Develops sex drive
Secondary sexual characteristics

Question 18

What is the site of testosterone production?

Answer 18

Leydig cells

Question 19

Hypogonadism

Answer 19

Lack of production of testosterone due to testicular dysfunction

Question 20

What is T3?

Answer 20

Triiodothyronine

Question 21

What is T4?

Answer 21

Thyroxine

Question 22

What hormones do kidneys release?

Answer 22

Release renin if BP low

Release erythropoietin when hypoxic - increases red blood cell formation in bone marrow

Question 23

What are catecholamines?

Answer 23

Adrenaline, Noradrenaline (epinephrine, norepinephrine)

Question 24

Where is cortisol produced from?

Answer 24

Adrenal cortex