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
ANTERIOR PITUITARY GLAND HORMONES
(Note: these are manufactured & released by the adenohypophysis)
FOLLICLE-STIMULATING HORMONE (FSH)
in females, stimulates maturation of egg cells; in males, stimulates nurse cells for sperm maturation.gonadotropins
ANTERIOR PITUITARY GLAND HORMONES
(Note: these are manufactured & released by the adenohypophysis)
LUTENIZING HORMONE (LH)
– iyello body, corpuslutenium – release estrogen- and pedistirones n males, stimulates secretion of testosterone by testes. In females, stimulates release of ovum by ovary. gonadotropins
ANTERIOR PITUITARY GLAND HORMONES
(Note: these are manufactured & released by the adenohypophysis)
MELANOCYTE-STIMULATING HORMONE (MSH)
along with ACTH, affects pigment release in skin.
ANTERIOR PITUITARY GLAND HORMONES
(Note: these are manufactured & released by the adenohypophysis)
PROLACTIN (PRL)
PROLACTIN (PRL) – stimulates milk production.
Remember the Pituitary Portal System!!
The hypophyseal portal system is a system of blood vessels in the brain that connects the hypothalamus with the anterior pituitary. Its main function is the transport and exchange of hormones to allow a fast communication between both glands. The fenestrated structure of capillaries in the hypophyseal portal system facilitates a rapid exchange between the hypothalamus and the pituitary, with only a small amount of hormones needed to stimulate an accurate effect in the respective target organs in the body.
PINEAL GLAND Location and Development: Innervation: Arterial Supply: Venous Drainage: Function:
Location and Development: outgrowth of the roof of the diencephalon. Found near the posterior margin of the corpus callosum, slightly cranial and superior to cerebellum.
Innervation: (Already) Part of brain.
Arterial Supply: circulus arteriosus cerebri
Venous Drainage: cavernous venous sinus
Function: MELATONIN – amino acid derivative thought to have connection with regulating sleep cycle.Regulating sleep cycles- sex drive
THYMUS GLAND Location and Development: Innervation: Arterial Supply: Venous Drainage: Function:
Location: Located just deep to sternum and just ventral to great vessels of heart. Until puberty, a large structure, after which it begins to atrophy and gets replaced with adipose tissue.
Development: from epithelial cells derived from endoderm of third pair of visceral pouches (3rd gill slit pouch).
Innervation: Vagus Nerve (X), like any posterior gill slit structure!
Arterial Supply: branches from internal thoracic artery (branch of subclavian).
Venous Drainage: thymic veins to brachiocephalic vein.
Function: THYMOSIN, THYMUS HUMERAL FACTOR, THYMOPOIETIN – convert embryonic lymphocytes into T-cells.
explain the aduly thymus
Replaced by fat cells as you get older
Why don’t you have a thymus? Because body already produced t lymphocytes, don’t need it to mature lymphocytes they can divide and replicate they have a nucleues- once they mature- those cells can divide and produce daughter cells
THYROID GLAND Location and Development: Innervation: Arterial Supply: Venous Drainage: Function:
Location: Located close to thyroid cartilage. Has two lateral lobes connected by thyroid isthmus medially. Isthmus covers cricoid cartilage in ventral view.
Development: first endocrine gland to appear during development. Develops from endodermal thickening in floor of early pharynx and epithelium of 3rd and 4th gill slit pouches.
Starts out caudal to tongue, but ultimately comes to be wrapped around laryngeal cartilages.
Innervation: Vagus Nerve (X)
Arterial Supply: superior and inferior thyroid arteries.
Venous Drainage: Superior, middle, & inferior thyroid veins. These are tributaries of internal jugular veins (superior & middle) and left brachiocephalic vein (inferior) respectively.
Functions:
THYROXIN – regulate/increase rate of metabolism conversion of fat into energy- breakdown of carbs- use of protein
CALCITONIN – decreases levels of calcium in the blood by inhibiting osteoclasts (dissolve the mineralized portions-releases calcium) and increasing calcium excretion (partially antagonistic to parathyroid hormone).
PARATHYROID GLAND
Location/Development
Location:
Usually paired.
Very small (less than 5 mm).
Called parathyroid glands because of their position on posterior margins of outer surface of thyroid gland.
Development: Like thyroid gland, develop from endodermal thickening in floor of early pharynx and epithelium of 3rd and 4th gill slit pouches.
ADRENAL GLAND Location and Development: Innervation: Arterial Supply: Venous Drainage: Function:
Location : on cranial (superior) surface of kidney (“suprarenal” gland). Have inner medulla and outer cortex.
Development:
Adrenal cortex – mesoderm of posterior abdominal wall.
Adrenal medulla – neural crest cells that are derived from adjacent sympathetic ganglion.
Innervation: adjacent sympathetic fibers. No significant parasympathetic innervation.
Arterial Supply: adrenal arteries
Venous Drainage: adrenal veins
Similar to kidney- medulla and cortex
**Exception to pattern-
Medulla comes from neural crest- becomes nervous structures for ex. Adjacent symp ganglion where adrenal medulla come from
Moved away from symp chain- formed medulla portion of adrenal gland
ADRENAL GLAND hormones/Adrenal Cortex, Function :
MINERALOCORTICOIDS
regulate sodium retention and potassium loss (e.g. aldosterone).
ADRENAL GLAND hormones/Adrenal Cortex, Function :
GLUCOCORTICOIDS
act as anti-inflammatory agents; affect metabolism of food.
ADRENAL GLAND hormones/Adrenal MEDULLA, Function :
ADRENALINE (EPINEPHRINE)
ADRENALINE (EPINEPHRINE) – increases heart rate and blood pressure.
ADRENAL GLAND hormones/Adrenal MEDULLA, Function :
NORADRENALINE (NOREPINEPHRINE)
NORADRENALINE (NOREPINEPHRINE) – constricts arterioles. Increase bp- send blood to different locations- be able to send blood to different
ADRENAL GLAND hormones/Adrenal Cortex, Function :
ANDROGENS
ANDROGENS – regulates control over rapid growth spurts in preadolescents. Testerone- coming from an adrenal gland-
PANCREAS
Location and Development: Innervation: Arterial Supply: Venous Drainage: Function:
Location : inside notch of duodenum; retroperitoneal. Has body,
and tail.
Development: diverticulum of embryonic foregut. Dorsal and
ventral embryonic buds eventually fuse.
Innervation: foregut: sympathetic – greater splanchnic nerve;
parasympathetic – Vagus nerve (X).
Arterial Supply: pancreaticoduodenal arteries (branches of celiac &
superior mesenteric) theres a sup/inf because it recienved from celiac
and superior mesenteric
Venous Drainage: pancreaticoduodenal veins is tributary of splenic
vein
Function: pancreas is not only an exocrine gland for
digestion.
PANCREAS
GLUCAGON /INSULIN
GLUCAGON – from alpha cells of pancreatic islets, raises
blood glucose level.
INSULIN – from beta cells of pancreatic islets, lowers
blood glucose level.
OVARY Location and Development: Innervation: Arterial Supply: Venous Drainage: Function:
Location : near kidneys, anchored by fallopian tubes to uterus.
Development: intermediate mesoderm. Ovaries migrate somewhat
caudally, retain position near kidneys.
Innervation: sympathetic – similar to hindgut, level T12, follows
least splanchnic nerve; parasympathetic – sacral outflowS2-4
Arterial Supply: ovarian artery, branch of abdominal aorta.
Venous Drainage: ovarian vein, dump into inferior vena cava.
Ovary, Function:
ovaries produce ova (eggs; singular ovum) in
regular cycle determined by hormonal secretions (covered
in later lectures). Functions of ovarian hormones and their
secretions are tied to secretion of FSH and LH from
anterior pituitary gland.
Ovary,
ESTROGENS
PROGESTERONE + ESTROGENS
stimulate development of female sex
organs and sexual characteristics.
regulate menstrual
cycle; maintain pregnancy in presence of developing
embryo or fetus.
TESTES
Location
Development
Location : in postnatal males, in scrotal sac, connected to inner
workings of body by spermatic cord.
Development: from intermediate mesoderm.
TESTES
Innvervation
Arterial Supply
Venous Drainage
Innervation: sympathetic – similar to kidney, T10-T12,
follows least splanchnic nerve, hook a ride down spermatic
cord via testicular blood vessels; parasympathetic – sacral
outflow.
Arterial Supply: testicular artery. Branches off of
abdominal aorta, however developmental proximity of
kidney means they sometimes branch off of renal artery.
Arteries follow the developmental track of testes, and can
thus be very long.
Venous Drainage: testicular vein, dump into inferior vena
cava. Form the pampiniform plexus(veins spread out
become a mesh).
Pampiniform
plexus
The pampiniform plexus is a network of many small veins found in the human male spermatic cord. It is formed by the union of multiple spermatic veins from the back of the testis and tributaries from the epididymis.
Veins are going back Arteries toward testes Counter current exchange in testes Temperature-thermal regulation Regulate temp of testes for sperm regulation
TESTES
function:
define testosterone
Function: Responsible for sperm production and synthesis
of male sex hormones.
TESTOSTERONE – stimulate development of male sex
organs, secondary sexual characteristics, and behavioral
features. Functions of testosterone and its secretion is tied
to secretion of LH from anterior pituitary gland.
Gubernaculum explain location, function
As transitory stage of kidney degenerates, a ligament called the
GUBERNACULUM descends on each side of abdomen from inferior
pole of gonad.
Gubernaculum passes obliquely through developing anterior
abdominal wall at site of future inguinal canal and attaches at
internal surface of labioscrotal swelling (future position of scrotum
in males or labia majora in females).
Gubernaculum is thought to guide descent of testes into scrotum,
and ultimately anchors testis to scrotal wall.
