Hypothalamus/Pituitary

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What's really the function of the hypothalamus/pituitary?: To allow the brain to communicate with the circulatory system.
How is the pituitary formed?: During embryonic development; -posterior pituitary moves down from the hypothal;
-anterior pituitary moves up from the ectoderm
What exactly does the anterior pituitary originate from again?: Ectodermal tissue of the upper pharynx - the roof of the mouth.
Which part of the pituitary is -Nervous tissue? -Endocrine tissue?: Nervous = posterior
Endocrine = anterior
What are the names of the neuron cells in the hypothalamus whose axons extend to posterior pit?: M cells = Magnocellular cells.
What are the real names of the M cells in the hypothalamus? What do they produce?: Paraventricular nucleus
Supraoptic nucleus

-Produce HORMONES instead of neurotransmitters. Oxytocin and ADH.
How are the hormones produced by the hypothalamus excreted?: By traveling down the axons of the m cells down the stalk to the posterior pituitary.
Where are Oxytocin and Vasopressin stored?: In synaptic vesicles in the posterior pituitary.
What are the two functions of Oxytocin?: 1. Milk letdown
2. Uterine contraction
What stimulates the hypothal to release oxytocin?: Suckling, also baby crying. A REFLEX.
What type of cells surround the mammary alveoli? What is their function?: Myoepithelial cells - contract, squish alveoli to eject milk.
How does oxytocin stimulate uterine contraction?: 1. Baby's head pushes
2. Cervix stretches
3. Cervix dilates; fires nerves to brain/hypothalamus to release oxytocin.
4. Response: uterus contracts; cervix dilates more. Pos fdbck
What are 2 additional functions of oxytocin?: -Reduces postpartum bleeding
-Induces labor
What can inhibit milk letdown?: Epinephrine - blocks oxytocin; you need to relax when breast-feeding!
What are 3 functions of ADH?: 1. Increases blood osmolarity
2. Senses decreased blood vol and responds to increase it.
3. Constricts arterioles to increase arterial pressure.
does ADH act to increase or decrease blood osmolarity? WHY?: DECREASE it; b/c increased osmolarity stimulates the osmoreceptors in the hypothal; ADH release increases H2O reabsorption; decreases conc.
How does blood osmolarity stimulate ADH release?: -Increased osmolarity stimulates OSMORECEPTORS in the hypothalam.
-M cells are stimulated to make ADH
-ADH is released by the axons in the posterior pituitary
-ADH acts on the kidneys to increase H2O reabsorption
How does decreased BLOOD VOLUME stimulate ADH release?: by stimulatng BARORECEPTORS (bp) which stimulate M cells the same way as osmoreceptors do..
what inhibits the release of ADH, and what is the result?: ALCOHOL; you urinate lots of dilute urine.
how does ADH cause increased blood pressure?: by constricting the arterioles.
what is lack of vasopressin called? (pathologic condition): Diabetes Insipidus - makes you pee insipidously
What causes you to excrete glucose - sweet pea?: Diabetes Mellitus
what is the other type of cell in the hypothalamus other than M?: #1 cells
what is the main difference between M cell and 1 cell?: M cell extends to the posterior pituitary; 1 cell only extends to the median eminence, then converges with the capillaries
How does the 1 cell release its hormones?: By storing in synaptic vesicles to release with stimulus; then they cross into capillaries by diffusion.
what types of tissue are the -posterior hypothalamus? -anterior hypothalamus?: Post = nervous tissue
Ant = glandular tissue
What type of messenger does the hypothalamus 1 cell make?: Neurohormones.
how do hormones from the hypothalamus travel to the anterior pituitary?: by the portal vessel; from the primary capillary plexus to the secondary.
What are the Anterior pit hormones?: Acth, TSH, FSH, LH, GH, Prl
What are the Hypophysiotropic hormones?: CRH
TRH
GnRH
GHRH
Somatostatin, Dopamine
What anterior pituitary hormone does CRH act on?: ACTH, and the adrenal glands
What anterior pituitary hormone does TRH act on?: TSH, and the thyroid gland
AND
Prolactin and the breasts
What anterior pituitary hormone does GnRH act on?: LH and FSH - thus the gonads
What anterior pituitary hormone does GHRH act on?: GH, and thus many tissues
What else acts on growth hormone, and how?: Somatostatin - inhibits the release of growth hormone
What two hypothalamic hormones act on Prolactin, and how?: -Dopamine; inhibits Prl release
-TRH; stimulates Prl release
In general how does Longloop feedback work?: The hormone produced by the target tissue inhibits release of hypothalamic and pituitary hormones.
In general how does Short loop feedback work?: The hormone released by the PITUITARY inhibits hypothalamic release
What happens when you have a pituitary tumor? Use ACTH for an example: The pituitary makes too much hormone, thus incr. ACTH causes increased Cortisol levels
How would you know if someone has an ADRENAL tumor vs. Pituitary?: Adrenal tumors cause low cortisol levels because of negative loop feedback.
If a person had blotchy pigmentation, what type of tumor?: Pituitary
What is another name for growth hormone?: Somatotropin
What two hormones regulate somatotropin?: GHRH and Somatostatin
What is SRIF?: Somatotropin releasing inhibiting factor - another name for somatostatin.
What is a somatotroph?: The ant pituitary cell that makes GH
When is GHRH commonly produced, and how?: During the 1st hour of sleep, in pulses.
what are the effects on GH by -Exercise -Obesity: Exercise stimulates GHRH
Obesity inhibits GHRH
How does GH act on the liver, and what is the effect?: Stimulates the liver to produce IGF1 - insulin-like growth factor 1.
What was IGF-1 formerly known as?: Somatomedin C
What are the 4 main functions of Growth hormone?: 1. Cartilage and bone growth
2. Protein metabolism
3. Carbohydrate metabolism
4. Lipid metabolism
How does GH cause carilage/bone growth?: By stimulating stem cells in the long bone epiphyseal plates to grow more bone/cartilage.
How does GH cause Protein metabolism?: 1. Helps cells take up amino a.
2. Stimulates protein synthesis.
3. Increases muscle formation
How does GH affect carbohydrate metabolism?: With an ANTI-INSULIN effect.
-Decreases glu uptake by cells
-Increases glu prodctn by liver
Net: increases plasma glucose.
What is HSL?: Hormone sensitive lipase; an enzyme that breaks down Triglycerides in fat cells to Fatty acids + Glycerol
Why is HSL related to Growth hormone, and what else acts on it?: GH acts on HSL to activate it.
Insulin inhibits HSL to store glucose instead of using it.
What is the effect of GH deficiency in childhood? Adulthood?: Child: Pituitary dwarfism; Body is proportionate, but small.

Adults: more body fat, depression, and decreased muscle mass (ironic huh)
What is the effect of GH excess in Childhood? Adulthood?: Child: gigantism
Adults: Acromegaly, membranous bone growth, tongue thickens, etc.
What is especially unique about PROLACTIN?: It's the only pituitary hormone predominantly inhibited by the hypothalamus directly.
What hypothalamic hormones act on Prolactin?: Thyroid releasing hormone (TRH)
Dopamine (DA)
What is the name of the anterior pituitary cells that make prolactin?: Lactotrophs
What type of feedback occurs to regulate Prolactin release?: ONLY SHORTLOOP!!
When is Prolactin production increased? What stimulates it?: ONLY DURING PREGNANCY

-Stimulated by Suckling
What are the 2 main functions of prolactin?: 1. Stimulates growth of mammary alveoli and ducts in milk anticipation during pregnancy.
2. Causes Milk synthesis
What is the effect of increased prolactin on the hypothalamic hormones?: -Prl shortloop fdbck inhibits TRH, stimulates DA.
How do Estrogen and Progesterone affect milk production during pregnancy? How?: Inhibit it; but stimulate more Prolactin PRODUCTION.
By Overwhelming Dopamine levels.
What happens at birth to estrogen and progesterone?: Levels suddenly plummet; allows milk to be produced
How does Prl affect GnRH?: Prl inhibits GnRH so that the follicles and gonads aren't stimulated; don't want sex hormones during childbirth and breast-feeding.
A lot of Antipsychotics are DA antagonists; what is the effect?: DA is blocked, so Prl is abundnt and Sex hormones are not; can become infertile, decreased labido, female lactation.

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