Endocrine System

Question 1

Hormones

Answer 1

Chemical messengers secreted into the bloodstream by a gland, which act to regulate processes in target cells and tissues

Question 2

Endocrine Signalling

Answer 2

From one cell to another via the blood

Question 3

Paracrine Signalling

Answer 3

From one cell to a neighbouring cell

Question 4

Neurocrine Signalling

Answer 4

From the CNS to a cell

Question 5

Autocrine Signalling

Answer 5

From a cell to itself

Question 6

What is negative feedback and give an example

Answer 6

A mechanism which decreases a response to prevent a system from becoming overactive and returns it back to a set point
E.G. stress response, blood glucose levels, blood volume

Question 7

What is positive feedback and give an example

Answer 7

Mechanism which amplifies a response by increasing levels further away from the set point
E.G. oxytocin secretion during childbirth or oestrogen secretion in menstruation cycle before ovulation

Question 8

Describe the layout of the pituitary gland

Answer 8

Posterior and Anterior
Located at the inferior part of the hypothalamus

Question 9

What does the posterior pituitary gland store and what are their functions?

Answer 9

Stores antidiuretic hormone (ADH)
- allows increased water reabsorption by increasing the permeability of the collecting duct
Stores oxytocin
- stimulates smooth muscle contraction
Doesn’t synthesise its own hormones

Question 10

What does the anterior pituitary gland produce?

Answer 10

Receives neurohormone signals from the hypothalamus
Produces these hormones:
- follicle stimulating hormone (FSH) and luteinising hormone (LH)
- thyroid stimulating hormone (TSH)
- growth hormone (GH)
- prolactin
-adrenocorticotropic hormone (ACTH)

Question 11

What are FSH and LH released by and what do they act on?

Answer 11

Released by gonadotropes
Act on testes and ovaries to stimulate sex steroid production

Question 12

What is TSH released by and what does it stimulate?

Answer 12

Released by thyrotropes
Stimulates thyroid hormone production to control your metabolism

Question 13

What is ACTH released by and what does it stimulate?

Answer 13

Released by corticotropes
Stimulates cortisol release

Question 14

What is GH released by and what does it stimulate?

Answer 14

Released by soma tropes
Stimulates growth

Question 15

What is prolactin released by and what does it stimulate?

Answer 15

Released by lactotropes
Stimulates milk production

Question 16

Where are the adrenal glands located, what are they controlled by and what are they divided into?

Answer 16

Located above the kidneys
Controlled by the sympathetic nervous system
Controlled by the ACTH
Divided into the medulla and the cortex

Question 17

What is the adrenal cortex split into and what do they produce?

Answer 17

Split into:
Zona glomerulosa
- produces mineralocorticoids which regulates blood volume
Zona fasciculata
- produces glucocorticoids which allows the stress response
Zona reticularis
- produces androgens for sexual development and glucocorticoids

Question 18

What does the adrenal medulla produce?

Answer 18

Produces adrenaline and noradrenaline catecholamines for the stress response

Question 19

What are steroid hormones synthesised by and describe their solubility in relation to how they’re released

Answer 19

Synthesised by cholesterol
Instantly released by diffusion due to their lipid solubility
Hydrophobic

Question 20

Describe the reception and response of steroid hormones

Answer 20

Reception:
- diffuse across the cell membrane
- bind to intracellular receptors
- causes a conformational change which exposes the DNA-binding site

Response:
- bind to DNA
- alters transcription of specific genes into mRNA, which is translated into protein & alters cellular activity

Question 21

How are non-steroid hormones produced, stored and synthesised?

Answer 21

Produced from polypeptides
Stored in secretory vesicles
Hydrophilic and lipophobic
Synthesised via transcription and translation

Question 22

Describe the reception, transduction and response of non-steroid hormones

Answer 22

Reception:
- can’t diffuse across the cell membrane so binds to cell surface receptors

Transduction:
- G-protein coupled receptors
–> binds to effector protein & causes release of second messengers
- Tyrosine kinase receptors
–> autophosphorylate & activate relay proteins

Response:
- protein phosphorylation enzyme cascade to activate or inhibit proteins & alter cellular activity