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83 Cards in this Set

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  • Back
adenohypophysis
Anterior pituitary
neurohypophysis
Posterior pituitary
Embryologic origin of Ant Pituitary? Post Pituitary?
-A thickened area of ectodermal cells on the roof of the pharynx that invaginates RATHKE's POUCH
- Invagination of the floor of the developing ventricular system
What type of general cells are contained within the anterior pitutiary
granular cells
Does the post pituitary contain grandular cells?
No; instead it contains glial-type and axons and nerve terminals of neurons whose cell bodies lie in the hypothalamus.
The hypothalamus forms the walls and floor of what structure?
3rd ventricle
The cell bodies of axons and terminals that are within the post pituitary arise where?
The supraoptic and paraventricular nuclei of the anterior (supraoptic) region of the hypothalamus
Separates the hypothalamus and thalamus
Hypothalamic sulcus
On the ventral surface of the brain, the hypothalamus lies just posterior to what structure?
The tuber cinereum and mammilary bodies lie posterior to the optic chiasm
A bulge located between the optic chiasm and the mammilary bodies. What arises from this posterior portion of this structure and continues inferiorly?
Tuber cinereum
The pituitary stalk arises here
Anterior portion of the infundibulum. Why is this important?
Median eminence: Region where hypothalamic neurons release regulating factors that are carried by portal vessels to the anterior pituitary
A bulge located between the optic chiasm and the mammilary bodies. What arises from this posterior portion of this structure and continues inferiorly?
Tuber cinereum
The pituitary stalk arises here
Where does the pituitary gland sit?
Within the pituitary fossa in the sella turcica.
What structure lies immediately beneath the floor of the sella turcica? lateral?
Sphenoid sinus
The cavernous sinuses
Dura covering the superior portion of the pituitary fossa
Diaphragma sella
the fibers of what structure pass through the hypothalamus dividing it into medial and lateral areas
Fornix
Controls circadian rhythms
Suprachiasmatic nucleus
Largest amount of anterior pituitary cells. How do they stain?
Somatotropes stain acidophilic
Actions of Somatotropes
Stimulates body growth, lipolysis and secretion of IGF-1. Inhibits action of insulin on carbohydrate and lipid metabolism.
How are hormones conducted from the hypothalamus to the ant pituitary? From the ant pituitary?
Small arteries pass through the median eminence and form the primary capillary plexus. Here hormones diffuse into the blood and are carried via the hypophysial portal veins to the anterior pituitary. Then, hormones released in the anterior pituitary are picked up by the secondary capillary plexus and carried by draining veins to the cavernous sinus. the cavernous sinus drains via the superior and inferior pertrosal veins to the internal jugular vein.
Where do the cell bodies of oxytocin and vasopressin hormones that are transmitted through neuronal terminals lie?
Supraoptic and paraventricular regions
Describe the blood supply of the ant pituitary
Receives arterial blood from superior and inferior hypophysial arteries that originate from the internal carotid.
Descending autonomic fibers mainly originate where?
paraventricular nucleus of the hypothalamus
How do the neurons of the hypothalamus differ from the rest of the CNS
Their function is to secrete the hypothalamic releasing and inhibiting hormones into the ant pituitary. Their nerver fibers are sent to the median eminance and the tuber cinereum. This differs from the usual function of neuronal signal transmission
Controls circadian rhythms
Suprachiasmatic nucleus
What is the function of dopamine within the hypothalamus
Inhibits prolactin secretion. Also called Prolactin inhibiting Hormone
Somatostatin
Growth Hormone Inhibiting Hormone: Inhibits secretion of growth hormone
Largest amount of anterior pituitary cells. How do they stain?
Somatotropes stain acidophilic
Actions of Somatotropes
Stimulates body growth, lipolysis and secretion of IGF-1. Inhibits action of insulin on carbohydrate and lipid metabolism.
How are hormones conducted from the hypothalamus to the ant pituitary? From the ant pituitary?
Small arteries pass through the median eminence and form the primary capillary plexus. Here hormones diffuse into the blood and are carried via the hypophysial portal veins to the anterior pituitary. Then, hormones released in the anterior pituitary are picked up by the secondary capillary plexus and carried by draining veins to the cavernous sinus. the cavernous sinus drains via the superior and inferior pertrosal veins to the internal jugular vein.
Where do the cell bodies of oxytocin and vasopressin hormones that are transmitted through neuronal terminals lie?
Supraoptic and paraventricular regions
What hypothalamic nucleus lies closest to the 3rd ventricle
Periventricular nucleus

see p 741 in neuro
The preoptic area of the hypothalamus is derived from what? How is this different?
Telencephalon
This differs in that the rest of the hypothalamus is derived from the diencephalon
Where are GABA neurons located in the hypothalamus? Histamine? Why is this important?
Ventral lateral preoptic area
Tuberomammillary nucleus
The Gabaergic neurons contribute to non-REM sleep by inhibiting the histaminergic neurons
What nucleus is important for appetite and a lesion here may cause a decrease in body weight? What nucleus inhibits appetite?
Lateral hypothalamus
Ventromedial nucleus
Leptin may bind to what receptors in the hypothalamus to control food intake and obesity?
Ob receptors
Lesions here may cause hyperthermia?
Anterior hypothalamus detects increased body temperature and activates mechanisms of heat dissipation
Bilateral lesions here cause poikilothermia
Posterior hypothalamus that function to conserve heat. A lesion here causes the body temp to vary with the environement because they also destroy descending fibers for heat dissipation from the anterior hypothalamus
thirst results from activation of what
Osmoreceptors in the anterior hypothalamus
Where is melonocyte producing hormone produced
Pars intermedia of the pituitary
What are the general affects of growth hormone?
Causes growth of almost all tissues of the body, increases the size of cells, increases mitosis, and specific differentiation of certain types of cells such as bone growth and early muscle cells.
How does growth hormone affect metabolism
Increased rate of protein synthesis; increased mobilization of fatty acids, with increased FFA's in the plasma, and increased fatty acids used for energy; decreased rate of glucose utilization throughout the body.
Growth hormones affects on protein synthesis
Increases the transport of AA's through the cell membrane (similiar to insulin's actions), increases transcription and translation, and acts as a protein sparer by increased fatty acid utilization.
Growth hormone enhances the conversion of fatty acids to what? In excess growth hormone states, what serious condition may occur as a result?
acetyl-Coa
Excess acetyl-CoA may combine to form acetoacetic acid and thus cause ketoacidosis. A fatty liver may also result.
How does growth hormone affect glucose uptake and insulin?
Growth hormone decreases glucose uptake in the cells, increase glucose production in the liver, and increases insulin secretion. this occurs because of growth-hormone induced INSULIN RESISTANCE. This may be due to increased fatty acids that decrease the sensitivity of the muscle and liver to insulin
What disease may growth hormone mimic the actions of?
Type II Insulin resistant diabetes
What organ is essential for growth hormone's effects to increase growth rates?
Pancreas: Without the pancreas, there is not adequate insulin and carbohydrate availability, and energy is not provided for metabolism. Insulin may also increase the transport of some AA's into the cell.
In adults, what tissue grows considerably under the influence of growth hormone?
Soft tissues and organs
How do the long bones grow in response to growth hormone? How does this affect bony fusion in the adolescent?
The long bones elongate at the epiphyseal cartilages, where new cartilage is deposited and transformed into bone, thus elongating the shaft. At the same time the epiphyseal cartilage is used up so that by late adolescence not additional cartilage remains and bony fusion occurs at the shaft and epiphysis.
What is the affect of growth hormone on osteoblasts?
Growth hormone greatly stimulates osteoblasts, thereby increasing the rate of deposition and increasing the thickness of bones. This is especially true of the membranous bones.
What affect does growth hormone have on chondrocytes?
Increases their rate of transformation into osteogenic cells.
Growth hormone exerts its effects through what intermediate substances? Where are these made?
Somatomedins also called Insulin like growth factors are formed via the influence of growth hormone. They are made in the liver.
What is the most important somatomedin? What would a deficiency cause?
Somatomedin C
Dwarfism
What is the length of action of growth hormone as compared to somatomedin C.
Because growth hormone binds weakly to plasma proteins, its length of action is very short. Somatomedins bind strongly to plasma proteins, so their mechanism of action
Growth hormone is released in what pattern
Pulsatile
What factors are known to increase growth hormone release?
Starvation w/ protein deficiency, hypoglycemia, low fatty acid blood concentration, trauma, exercise, stress and excitement.
In acute conditions what is the most potent stimulator of growth hormone? Chronic conditions?
Hypoglycemia
Degree of cellular protein depletion
What part of the hypothalamus controls GHRH secretion?
Ventromedial nucleus, the same that controls appetite by monitoring blood glucose levels.
What neurotransmitters have been shown to increase growth hormone secretion?
Dopamine and serotonin
Most of the control of growth hormone is mediated through what?
GHRH
How does GHRH cause release of growth hormones at the cellular level? What are the short term and long term effects?
GHRH binds to receptors and activates adenylyl cyclase which activates cAMP.
The short term effects are an increase cell permeability to Ca2+, thereby increasing the intracellular calcium concentration, and allowing the secretory growth hormone vesicles to fuse with the membrane and be released into the blood.
The long term effect is to increase transcription in the nucleus.
What are the effects of exogenous growth hormone on endogenous growth hormone
Causes endogenous levels to decline either via GHRH or through enhancement of somatomedins which cause levels to decline
Most common cause of panhypopituitarism?
pituitary tumor
Most instances of dwarfism result from what?
Generalized deficiency of the anterior pituitary secretion during childhood. The physical parts grow in appropriate proportion, but the rate of growth is much slower.
How is human growth hormone synthesized?
From E Coli bacteria via recombinant DNA.
A new mother develops circulatory shock after giving birth. How could this affect the pituitary gland?
It could cause thrombosis of the gland with subsequent panhypothyroidism
In the adult what are the effects of panhypothyroidism?
hypothyroidism, decreased glucocorticoid secretion, and suppressed gonadotropic hormones
What types of tumors may cause hypopituitarism?
Craniopharyngiomas or chromophobe tumors may compress and destroy the gland
Gigantism is associated with what physiologic condition? If not treated, what may this lead to? What condition occurs later in the course of the disease?
Hyperglycemia- if not treated this will cause degeneration of pancreatic beta cells and diabetes mellitus
Panhypopituitarism occurs later in the course because the pituitary tumor eventually destroys the gland
What type of cells compose the posterior pituitary gland? What is their function?
Glial-like cells called pituicytes
They do not secrete hormones, but instead work as supporting cells for terminal nerve fibers and endings.
Through what structure are hormones from the hypothalamus transferred to the post pituitary? How are the hormones carried How are they secreted into the capillaries
Pituitary stalk
The hormones are carried in secretory proteins called neurophysins
Secreted via exocytosis
In what nuclei is ADH formed? Oxytocin?
Supraoptic
Paraventricular
In the absence of ADH what occurs in the kidney?
The tubules and collecting ducts become impermeable to water, which prevents reabsorption of water.
How does ADH increase reabsorption of water?
ADH binds to membrane receptors that activate adenylyl cyclase and cAMP. This phosphorylates and activates elements within special vesicles called aquaporins. The aquaporins bind to the membrane and increase permeability.
How does a concentrated solution affect ADH secretion?
Specialized osmoreceptors within the hypothalamus become dehydrated and shrink due to osmosis of fluid out of the cell. These receptors work to activate the supraoptic nuclei to release ADH.
High concentrations of ADH are released when? What is the main effect? How does this occur?
Decreased blood volume
Constriction of arterioles to increase blood pressure
Stretch receptors in the atria and aortic/carotid bodies are not excited and cannot send inhibitory signals to the nucleus solitarius.
How may the absence of oxytocin affect birth?
Oxytocin acts to increase uterine contractions during labor, so it would cause a prolonged labor. The cervix works to stimulate ADH secretion.
Oxytocin has what effect on milk letdown
Contraction of myoepithelial cells that form a lattice-work around the alveoli of the mammary gland.
Somatostatin from the hypothalamus inhibits what hormones?
TRH and GHRH
Most common pituitary adenoma
Prolactin, GH is second
Are pituitary adenoma's histologically benign
Yes, arising from glandular epithelial tissue
Nonfunctioning pituitary adenomas may cause headache from what? What other symptom is very common?
Irritation of pain fibers in the cavernous regions
Compression of the optic chiasm causes bitemporal hemianopia
What are the clinical effects of prolactinomas?
Amennhorrea, hypogonadism, galactorrhea, hair loss, decreased libido, and weight gain