hypothalamus axis Flashcards
what is the posterior lobe made out of
The posterior lobe is made of nerve endings coming from
specific hypothalamic neurones, and glial-like cells
what is vasopressin
VP also causes vasoconstriction (via V1 receptors), platelet
aggregation and mobilisation of coagulation factor.
what is oxytocin
Nonapeptide, stimulates contraction of the uterus during
labour and contraction of contractile cells
what is the therapeutic use of oxytocin
to stimulate contraction during delivery
(overdose very dangerous), to assist breastfeeding, to reduce post-partum or miscarriage
bleeding, late therapeutic abortion.
what can oxytoxin help with
weight loss
decreased anxiety
improved sleep
better sex
what are 4 tropic hormones
TSH ACTH LH FSH
WHAT IS TSH
stimulates thyroid gland and secretion of Thyroid hormones
WHAT IS ACTH
Stimulates adrenal cortex and the secretion of glucocorticoids
WHAT IS LH
stimulate secretion of oestrogens by the
ovaries and secretion of testosterone by the testes, regulate
menstrual cycle.
WHAT IS FSH
stimulate secretion of oestrogens by the
ovaries and secretion of testosterone by the testes, regulate
menstrual cycle.
WHAT IS PRL
Prolactin initiates milk production and
development of mammary gland.
WHAT IS GH
Growth hormone, (somatotropin ) controls general
body growth, increases protein synthesis, cell proliferation and
bone growth, metabolic effects, induces the release of IGF
(insulin like growth factor) from liver.
WHAT IS a-MSH:
Melanocyte-stimulating hormone, synthesised
from the same precursor than ACTH, some effects on skin
pigmentation. In the brain MSH neurons regulate appetite
WHAT ARE HYPOTHALAMAUS FACTORS
TRH
GNRH
GNRH
GHIH
CRH
DOPAMINE
WHAT IS TRH
Thyrotropin releasing hormone (tripeptide), stimulates the release
of TSH from the thyrotroph cells
WHAT IS GNRH
Gonadotropin releasing hormone, stimulates the release of the
gonadotropins LH and FSH from the gonadotroph cells
WHAT IS GHRH
Growth hormone releasing hormone (GHRH), stimulates the
release of growth hormone from the somatotroph cells
WHAT IS GHIH
Growth hormone inhibitory hormone (GHIH), or somatostatin,
inhibits the release of growth hormone
WHAT IS CRH
Corticotropin releasing hormone, stimulates the release of ACTH
from the corticotroph cells
WHAT ARE 4 CHARACTERISTICS OF HYPOTHALMIC RELEASING FACTORS
release dependant on neuronal impulse
* secretion is pulsatile (1 pulse/60-180 min)
* regulated by the feed back of secreted hormones or other
upstream components
* relatively small peptides (except dopamine!)
WHAT DOES TOTAL DEFICIENCY OF GROWTH HORMONES CAUSE
PITUATARY DWARFISM
WHAT DOES PARTIAL DEFICIENCY OF GROWTH HORMONES CAUSE
GROWTH RETARDATION
WHAT IS THE TREATMENT OF GROWTH DEFICIENCY
GH recombinant, like humatrope, protropin
(treatment very expensive), also used to treat
Turner’syndrome.
WHAT DOES HYPERSECRETION CAUSE
Acromegaly (adults), rare, enlargement of
extremities, soft tissues swelling;
Giantism (children), very rare
HOW IS HYPERSECRETION OF GROWTH HORMONES TREATED
ablation of the tumour and
somatostatin analogue (octeotride)
WHAT IS THE ACTION OF PROLACTIN
Growth during puberty
and pregnancy, stimulate milk synthesis
WHAT IS HYPERPROLACTINAEMIA
Growth during puberty
and pregnancy, stimulate milk synthesis
WHAT ARE THE CAUSES OF HYPERPROLACTINAEMIA
PREGNANCY
TUMOURS
CONTRACEPTION WITHDRAWAL
WHAT IS THE HYPOTHALMIC FACTOR OF THE Hypothalamo-pituitary-adrenal axis
CRH, stimulates release of ACTH from corticotroph cells.
Secretion negatively modulated by cortisol.
Pulsatile secretions which drive secretions of ACTH and consequently
cortisol.
Highest peak at early morning hypersecretion in major
depression.
WHAT IS THE PITUITARY HORMONE RELEASED BY THE Hypothalamo-pituitary-adrenal axis
acth
what is the hypothalmic factor in the Hypothalamo-pituitary-thyroid axis
TRH
tripeptide, pulsatile secretion,
activate of TSH from pituitary.
Secretion inhibited by thyroid hormone and stimulated by cold
exposure (negative feedback overridden during cold exposure),
suckling, , stress, inhibited by fasting.
what is the pituatry hormone released by the Hypothalamo-pituitary-thyroid axis
TSH
what is precocious puberty
hyper secretion of LH FSH
what is the treatment of precorcious puberty
GnRH agonists are prescribed
eg leuprorelin, nafarelin also given in fertility treatment)
what is the target of tsh
thryoid gland
what is the pathology of tsh
Excessive secretion
in most cases of
hypothyroidism
what is the pathology of acth
Excessive secretion in
Cushing’s disease
(tumour of corticotroph)
what is the pathology of lh and fsh
Excessive secretion in
Precocious puberty (due to
abnormal secretion of
GnRH)
what is the pathology of prolactin
Excessive secretion in
Gynecomastia, Galactorrea
what is the pathology of growth hormones
Excessive secretion in
acromegaly, gigantism
Absence of secretion in
pituitary dwarfism
