L23 - hypothalamus and pituitary Flashcards
what is released from the posterior pituitary
hormones made in hypothalamus
oxytocin
ADH
what is the origin of posterior pituitary
neuronal
downgrowth from brain
what is the origin of anterior pituitary
ectodermal
up growth from roof of mouth
what is released from the median eminence
peptide hormones
what does the anterior pituitary secrete
growth hormone (GH) Follicle Stimulating Hormone (FSH) Leutinising Hormone (LH) Adrenocorticotrophic Hormone (ACTH) Thyroid Stimulating Hormone (TSH) Prolactin (PL)
does the anterior or posterior pituitary appear darker in a histological image?
anterior
what are the main classifications of cells of the anterior pituitary
chromophobes
chromophiles
how do chromophobes appear in a histological image and why
pale stained
these cells have secreted the hormone they once contained
how do chromophiles appear in a histological image and why
strong cytoplasm staining
contain chromaffin granules as they are hormone releasing cells
(basophils and acidophils)
what type of cells are baso/acidophiles
chromophiles
what do somatotrophs secrete
GH
what do mammatatrophs secrete
prolactin
what do corticotrophins secrete
ACTH
name cells of anterior pituitary
somatotrophs mammatatrophs corticotrophins tyrotrophs gonadotrophs
what do tyrotrophs secrete
TSH
what do gonadotrophs secrete
LH , FSH
functions of endocrine systems
development
reproduction
homeostasis
metabolism
how is hormone release from the posterior pituitary controlled
neurons straight from hypothalamus through pituitary stalk to posterior pituitary
how is hormone release from anterior controlled
- hypothalamus sends axons to median eminence
- neuropeptide hormones released from median eminence into portal veins
- neuropeptide hormones bind to receptors on anterior pituitary
where are posterior hormones synthesised
hypothalamus
where are anterior hormones synthesised
anterior pituitary
name basophilic cells and what they secrete
corticotrophins - ACTH
tyrotrophs - TSH
gonadotrophs - FSH, LH
name acidophilic cells and what they secrete
somatotrophs - GH
mammatotrophs - Prolactin
what hormones are released from hypothalamus
releasing hormones inhibitory hormones (somatostatin , dopamine)
what does somatostatin inhibit
release of :
GH
TSH
what does dopamine inhibit the release of
Prolactin
function of FSH and LH
- control production of oestrogen and progesterone by ovary and testosterone by testes
function of GH
stimulates growth in many tissues
anabolic effect in many tissues
targets liver to produce IGF-1
function of TSH
acts on thyroid to generate T3 & T4 which regulate growth and development
function of Prolactin
stimulates lactation after birth
function of ACTH
acts on cortex of adrenal gland to produce and release steroid hormones
what does ACTH stand for
adrenocorticotrophic hormone
what do steroid hormones regulate
Na
blood pressure
metabolism
responses to stress
how is release of hormones controlled? what feedback mechanism?
negative feedback
- the pituitary hormone will inhibit the release of the releasing hormone from hypothalamus
- the response will inhibit the release of the hormone from the pituitary, and the release of the releasing hormone from the hypothalamus
example of the negative feedback mechanism of hormone release
GHRH, GH and somatostatin
- GH from pituitary inhibits release of GHRH from hypothalamus
- IGF-1 (response) inhibits GH release from pituitary and also increases SS release
what is meant by
short negative feedback loop
long negative feedback loop
the hormone released from pituitary causes inhibition
the hormone/molecule released as response causes inhibition (eg IGF-1 / cortisol)
