Neurohormones Flashcards
Principal endocrine organs of the body
Hypothalamus Pituitary gland Thyroid gland Parathyroid gland Adrenal gland Pancreas Ovary/ Testess
Endocrine system
Mediators travel within blood vessels
Utilises chemical mediators (hormones)
Slow communication
Effects can be long-lasting
Nervous system
Signalling along nerve fibres
Transmission of electrical impulses
Fast communication
Effects are generally short-acting
Types of hormones
Protein & peptide hormones
Amino acid derivatives
Steroid hormones
Proteins/ peptide hormones
- 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)
Amino acid derivatives
- Mostly tyrosine derived Neurotransmitter that can also act as a hormone
- E.g. epinephrine, norepinephrine, dopamine
Steroid hormones
- Steroid is a class of lipids derived from cholesterol
* Include cortisol, aldosterone, testosterone, progesterone, oestradiol
CRH
Corticotrophin releasing hormone
41 amino acid peptide that controls the release of adrenocorticotrophin (ACTH)
TRH
Thyrotropin-releasing hormone
3 Amino acid peptide that controls the release of thyroid-stimulating hormone (TSH) and prolactin (PRL)
GnRH
Gonadotrophin releasing Hormone
10 amino acid peptide that controls the release of LH and FSH
GHRH
Growth Hormone releasing hormone
44 amino acid peptide that controls the release of growth hormone (GH)
Somatostatin
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
What do Gonadotroph cells d?
Secrete LH and FSH in response to GnRH
Somatotrophs
Control GH secretion in response to GHRH
Corticotropes
Control ACTH secretion in response to CRH
Thyrotrophs
Regulate TSH secretion in response to TRH
Vasopressin & oxytocin
- 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
Oxytocin
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.
Oxytocin and smooth muscles
Regulates contraction of smooth muscles (e.g. uterus during labour, myoepithelial cells lining the mammary duct, contraction of reproductive tract during sperm ejaculation).
Vasopressin/ADH
Release in stimulated by changes in the activity of the osmoreceptor complex in the hypothalamus
ADH and smooth muscle
Stimulates vascular smooth muscle contraction in the distal tubules of the kidney to reduce loss of water and raise blood pressure.
Kidneys and hypothalamus: two-way interaction
- 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
CNS and oxytocin
- Anti-OCD
- Induces trust
- Social cognition
- Treatment of autism
- Anxiolytic
- Hypnotic
- Antidepressant
- Antipsychotic
