Neurohormones

Question 1

Principal endocrine organs of the body

Answer 1

Hypothalamus
Pituitary gland 
Thyroid gland 
Parathyroid gland 
Adrenal gland 
Pancreas 
Ovary/ Testess

Question 2

Endocrine system

Answer 2

Mediators travel within blood vessels
Utilises chemical mediators (hormones)
Slow communication
Effects can be long-lasting

Question 3

Nervous system

Answer 3

Signalling along nerve fibres
Transmission of electrical impulses
Fast communication
Effects are generally short-acting

Question 4

Types of hormones

Answer 4

Protein & peptide hormones
Amino acid derivatives
Steroid hormones

Question 5

Proteins/ peptide hormones

Answer 5

• Vary considerably in size
• Can be synthesised as a large precursor and processed prior to secretion (e.g. GH, somatostatin, insulin)
• Can be post- translationally modified (e.g. glycosylation)
• Can have multiple subunits synthesised independently and assembled (e.g. FSH, LH, TSH)

Question 6

Amino acid derivatives

Answer 6

• Mostly tyrosine derived Neurotransmitter that can also act as a hormone
• E.g. epinephrine, norepinephrine, dopamine

Question 7

Steroid hormones

Answer 7

• Steroid is a class of lipids derived from cholesterol

* Include cortisol, aldosterone, testosterone, progesterone, oestradiol

Question 8

CRH

Answer 8

Corticotrophin releasing hormone

41 amino acid peptide that controls the release of adrenocorticotrophin (ACTH)

Question 9

TRH

Answer 9

Thyrotropin-releasing hormone

3 Amino acid peptide that controls the release of thyroid-stimulating hormone (TSH) and prolactin (PRL)

Question 10

GnRH

Answer 10

Gonadotrophin releasing Hormone

10 amino acid peptide that controls the release of LH and FSH

Question 11

GHRH

Answer 11

Growth Hormone releasing hormone

44 amino acid peptide that controls the release of growth hormone (GH)

Question 12

Somatostatin

Answer 12

Growth Hormone release inhibiting hormone.
14 amino acid peptide that inhibits the release of GH, gastrin vasoactive intestinal polypeptide (VIP), glucagon, insulin, TSH and PRL

Question 13

What do Gonadotroph cells d?

Answer 13

Secrete LH and FSH in response to GnRH

Question 14

Somatotrophs

Answer 14

Control GH secretion in response to GHRH

Question 15

Corticotropes

Answer 15

Control ACTH secretion in response to CRH

Question 16

Thyrotrophs

Answer 16

Regulate TSH secretion in response to TRH

Question 17

Vasopressin & oxytocin

Answer 17

• Synthesised in the supraoptic and paraventricular nuclei in the hypothalamus
• Transported to the terminals of the nerve fibres located in the posterior pituitary
• Structurally quite similar, yet have very different functions

Question 18

Oxytocin

Answer 18

Released in response to peripheral stimuli of the cervical stretch receptors and suckling at the breast. It may also be involved in responses to stroking, caressing, grooming.

Question 19

Oxytocin and smooth muscles

Answer 19

Regulates contraction of smooth muscles (e.g. uterus during labour, myoepithelial cells lining the mammary duct, contraction of reproductive tract during sperm ejaculation).

Question 20

Vasopressin/ADH

Answer 20

Release in stimulated by changes in the activity of the osmoreceptor complex in the hypothalamus

Question 21

ADH and smooth muscle

Answer 21

Stimulates vascular smooth muscle contraction in the distal tubules of the kidney to reduce loss of water and raise blood pressure.

Question 22

Kidneys and hypothalamus: two-way interaction

Answer 22

• Kidneys
• Secrete renin
• Renin converts Angiotensinogen to Angiotensin I.
• Angiotensin I is converted in Angiotensin II
• Angiotensin II is detected by the subfornical organ
• Subfornical organ projects to vasopressin cells and neurons in the lateral hypothalamus
• Vasopressin affects kidneys

Question 23

CNS and oxytocin

Answer 23

• Anti-OCD
• Induces trust
• Social cognition
• Treatment of autism
• Anxiolytic
• Hypnotic
• Antidepressant
• Antipsychotic