Lecture 14 Flashcards
what are NEUROSECRETORY CELLS?
Nerve cells that produce hormones and secrete them into the bloodstream
In humans, neurosecretory cells are found in the?
HYPOTHALAMUS
where is the hypothalamus and pituitary gland located? lies inferior to what?
Small but complex appendage that sits at the base of the brain – in the sella turcica – most median depression in the medial cranial fossa of the sphenoid bone.
how are the hypothalamus and pituitary connected?
connected by stalk containing nerve fibers and blood vessels.
the pituitary is composed of what two parts?
ANTERIOR PITUITARY and POSTERIOR PITUITARY
Embryological Derivation of Hypothalamus/Post Pituitary/Anterior Pituitary
Hypothalamus is an outgrowth of brain, neural ectoderm.
Posterior Pituitary (Neuro(brain) hypophysis) is an outgrowth of hypothalamus, neural ectoderm.
Anterior Pituitary (Adeno(MEANS GLAND) hypophysis) develops as a superiorly directed outgrowth of roof of mouth, ectoderm.
what is the innervation of the HYPOTHALAMUS & PITUITARY GLAND?
Part of brain or very close to it in case of pituitary. Some hypothalamic neurons secrete neurohormones – they pass down connecting stalk to terminate close to the capillaries serving posterior pituitary.
arterial supply and venous drainage of the HYPOTHALAMUS & PITUITARY GLAND
Arterial Supply: circulus arteriosus cerebri
Venous Drainage: cavernous venous sinus
describe the hormones released by the hypothalamus- where are they enclosed? how do they move?how/where are they released?
(Released by Neurohypophysis)
Hypothalamic hormones enclosed in vesicles that move down axon and accumulate near terminal ends that are close to the posterior pituitary’s capillaries.
In response to an action potential– hormones are released from vesicles (much like a neurotransmitter), in this case into venous capillaries.
POSTERIOR PITUITARY GLAND HORMONES
two main ones manufacutred in the hypo but released in the post. pituitary
Oxytocin and Vasopressin are manufactured in the hypothalamus, but released in the posterior pituitary.
HYPOTHALAMUS HORMONES (Released by Adenohypophysis)
Hypothalamic hormones enclosed in vesicles that move down axon and accumulate near terminal ends that are close to the pituitary stalk.
In response to an action potential– hormones are released from vesicles (much like a neurotransmitter), in this case into the pituitary portal system(begins and ends with a capillary bed) (hypophyseal portal system).
HYPOTHALAMUS HORMONES (FUNCTION)
Most hormonal interactions of the hypothalamus-pituitary complex follow a common pattern:
Hypothalamic hormones can have the effect of stimulating or inhibiting the release of anterior pituitary hormones.
Called RELEASING HORMONES (“RH”) or INHIBITING HORMONES (“IH”) respectively.
HORMONES MANUFACTURED IN THE HYPOTHALAMUS (FUNCTIONS)
Includes two peptide hormones: OXYTOCIN and VASOPRESSIN (also called antidiuretic hormone, or ADH)
OXYTOCIN –
initiates labor
stimulates mammary glands to release milk
Stimulates uterine contractions in activities other than labor
VASOPRESSIN (ADH) – decreases urine output by increasing DCT and collecting duct permeability.
ANTERIOR PITUITARY GLAND HORMONES
(Note: these are manufactured & released by the adenohypophysis)
GROWTH HORMONE (GH)
regulates growth; affects protein, fat and carbohydrate metabolism.
ANTERIOR PITUITARY GLAND HORMONES
(Note: these are manufactured & released by the adenohypophysis)
THYROID STIMULATING HORMONE (TSH)
controls secretion of thyroxin.
ANTERIOR PITUITARY GLAND HORMONES
(Note: these are manufactured & released by the adenohypophysis)
ADRENOCORTICOTROPIC HORMONE (ACTH
controls secretion of hormones released by adrenal cortex, specifically glucocorticoids