Lecture 14

Question 1

what are NEUROSECRETORY CELLS?

Answer 1

Nerve cells that produce hormones and secrete them into the bloodstream

Question 2

In humans, neurosecretory cells are found in the?

Answer 2

HYPOTHALAMUS

Question 3

where is the hypothalamus and pituitary gland located? lies inferior to what?

Answer 3

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.

Question 4

how are the hypothalamus and pituitary connected?

Answer 4

connected by stalk containing nerve fibers and blood vessels.

Question 5

the pituitary is composed of what two parts?

Answer 5

ANTERIOR PITUITARY and POSTERIOR PITUITARY

Question 6

Embryological Derivation of Hypothalamus/Post Pituitary/Anterior Pituitary

Answer 6

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.

Question 7

what is the innervation of the HYPOTHALAMUS & PITUITARY GLAND?

Answer 7

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.

Question 8

arterial supply and venous drainage of the HYPOTHALAMUS & PITUITARY GLAND

Answer 8

Arterial Supply: circulus arteriosus cerebri

Venous Drainage: cavernous venous sinus

Question 9

describe the hormones released by the hypothalamus- where are they enclosed? how do they move?how/where are they released?

Answer 9

(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.

Question 10

POSTERIOR PITUITARY GLAND HORMONES

two main ones manufacutred in the hypo but released in the post. pituitary

Answer 10

Oxytocin and Vasopressin are manufactured in the hypothalamus, but released in the posterior pituitary.

Question 11

HYPOTHALAMUS HORMONES (Released by Adenohypophysis)

Answer 11

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).

Question 12

HYPOTHALAMUS HORMONES (FUNCTION)

Most hormonal interactions of the hypothalamus-pituitary complex follow a common pattern:

Answer 12

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.

Question 13

HORMONES MANUFACTURED IN THE HYPOTHALAMUS (FUNCTIONS)

Includes two peptide hormones: OXYTOCIN and VASOPRESSIN (also called antidiuretic hormone, or ADH)

Answer 13

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.

Question 14

ANTERIOR PITUITARY GLAND HORMONES
(Note: these are manufactured & released by the adenohypophysis)

GROWTH HORMONE (GH)

Answer 14

regulates growth; affects protein, fat and carbohydrate metabolism.

Question 15

ANTERIOR PITUITARY GLAND HORMONES
(Note: these are manufactured & released by the adenohypophysis)

THYROID STIMULATING HORMONE (TSH)

Answer 15

controls secretion of thyroxin.

Question 16

ANTERIOR PITUITARY GLAND HORMONES
(Note: these are manufactured & released by the adenohypophysis)

ADRENOCORTICOTROPIC HORMONE (ACTH

Answer 16

controls secretion of hormones released by adrenal cortex, specifically glucocorticoids

Question 17

ANTERIOR PITUITARY GLAND HORMONES
(Note: these are manufactured & released by the adenohypophysis)

FOLLICLE-STIMULATING HORMONE (FSH)

Answer 17

in females, stimulates maturation of egg cells; in males, stimulates nurse cells for sperm maturation.gonadotropins

Question 18

ANTERIOR PITUITARY GLAND HORMONES
(Note: these are manufactured & released by the adenohypophysis)

LUTENIZING HORMONE (LH)

Answer 18

– iyello body, corpuslutenium – release estrogen- and pedistirones n males, stimulates secretion of testosterone by testes. In females, stimulates release of ovum by ovary. gonadotropins

Question 19

ANTERIOR PITUITARY GLAND HORMONES
(Note: these are manufactured & released by the adenohypophysis)

MELANOCYTE-STIMULATING HORMONE (MSH)

Answer 19

along with ACTH, affects pigment release in skin.

Question 20

ANTERIOR PITUITARY GLAND HORMONES
(Note: these are manufactured & released by the adenohypophysis)

PROLACTIN (PRL)

Answer 20

PROLACTIN (PRL) – stimulates milk production.

Question 21

Remember the Pituitary Portal System!!

Answer 21

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.

Question 22

PINEAL GLAND
Location and Development:  
Innervation:  
Arterial Supply:  
Venous Drainage: 
Function:

Answer 22

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

Question 23

THYMUS GLAND
Location and Development:  
Innervation:  
Arterial Supply:  
Venous Drainage: 
Function:

Answer 23

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.

Question 24

explain the aduly thymus

Answer 24

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

Question 25

``` THYROID GLAND Location and Development: Innervation: Arterial Supply: Venous Drainage: Function: ```

Answer 25

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).

Question 26

PARATHYROID GLAND | Location/Development

Answer 26

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.

Question 27

``` ADRENAL GLAND Location and Development: Innervation: Arterial Supply: Venous Drainage: Function: ```

Answer 27

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

Question 28

ADRENAL GLAND hormones/Adrenal Cortex, Function : MINERALOCORTICOIDS

Answer 28

regulate sodium retention and potassium loss (e.g. aldosterone).

Question 29

ADRENAL GLAND hormones/Adrenal Cortex, Function : | GLUCOCORTICOIDS

Answer 29

act as anti-inflammatory agents; affect metabolism of food.

Question 30

ADRENAL GLAND hormones/Adrenal MEDULLA, Function : | ADRENALINE (EPINEPHRINE)

Answer 30

ADRENALINE (EPINEPHRINE) – increases heart rate and blood pressure.

Question 31

ADRENAL GLAND hormones/Adrenal MEDULLA, Function : | NORADRENALINE (NOREPINEPHRINE)

Answer 31

NORADRENALINE (NOREPINEPHRINE) – constricts arterioles. Increase bp- send blood to different locations- be able to send blood to different

Question 32

ADRENAL GLAND hormones/Adrenal Cortex, Function : | ANDROGENS

Answer 32

ANDROGENS – regulates control over rapid growth spurts in preadolescents. Testerone- coming from an adrenal gland-

Question 33

PANCREAS ``` Location and Development: Innervation: Arterial Supply: Venous Drainage: Function: ```

Answer 33

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.

Question 34

PANCREAS GLUCAGON /INSULIN

Answer 34

GLUCAGON – from alpha cells of pancreatic islets, raises blood glucose level. INSULIN – from beta cells of pancreatic islets, lowers blood glucose level.

Question 35

``` OVARY Location and Development: Innervation: Arterial Supply: Venous Drainage: Function: ```

Answer 35

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.

Question 36

Ovary, Function:

Answer 36

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.

Question 37

Ovary, ESTROGENS PROGESTERONE + ESTROGENS

Answer 37

stimulate development of female sex organs and sexual characteristics. regulate menstrual cycle; maintain pregnancy in presence of developing embryo or fetus.

Question 38

TESTES Location Development

Answer 38

Location : in postnatal males, in scrotal sac, connected to inner workings of body by spermatic cord. Development: from intermediate mesoderm.

Question 39

TESTES Innvervation Arterial Supply Venous Drainage

Answer 39

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).

Question 40

Pampiniform | plexus

Answer 40

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 ```

Question 41

TESTES function: define testosterone

Answer 41

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.

Question 42

Gubernaculum explain location, function

Answer 42

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.