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78 Cards in this Set

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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. Sense increased blood osmolarity, respond to increase H2O reabsorption.
2. Sense decreased blood vol and responds to increase it.
3. Constricts arterioles to increase arterial pressure.
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.