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78 Cards in this Set
- Front
- Back
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What's really the function of the hypothalamus/pituitary?
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To allow the brain to communicate with the circulatory system.
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How is the pituitary formed?
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During embryonic development; -posterior pituitary moves down from the hypothal;
-anterior pituitary moves up from the ectoderm |
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What exactly does the anterior pituitary originate from again?
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Ectodermal tissue of the upper pharynx - the roof of the mouth.
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Which part of the pituitary is
-Nervous tissue? -Endocrine tissue? |
Nervous = posterior
Endocrine = anterior |
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What are the names of the neuron cells in the hypothalamus whose axons extend to posterior pit?
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M cells = Magnocellular cells.
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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. |
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How are the hormones produced by the hypothalamus excreted?
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By traveling down the axons of the m cells down the stalk to the posterior pituitary.
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Where are Oxytocin and Vasopressin stored?
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In synaptic vesicles in the posterior pituitary.
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What are the two functions of Oxytocin?
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1. Milk letdown
2. Uterine contraction |
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What stimulates the hypothal to release oxytocin?
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Suckling, also baby crying. A REFLEX.
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What type of cells surround the mammary alveoli?
What is their function? |
Myoepithelial cells - contract, squish alveoli to eject milk.
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How does oxytocin stimulate uterine contraction?
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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 |
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What are 2 additional functions of oxytocin?
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-Reduces postpartum bleeding
-Induces labor |
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What can inhibit milk letdown?
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Epinephrine - blocks oxytocin; you need to relax when breast-feeding!
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What are 3 functions of ADH?
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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. |
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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. |
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How are the hormones produced by the hypothalamus excreted?
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By traveling down the axons of the m cells down the stalk to the posterior pituitary.
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Where are Oxytocin and Vasopressin stored?
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In synaptic vesicles in the posterior pituitary.
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What are the two functions of Oxytocin?
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1. Milk letdown
2. Uterine contraction |
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What stimulates the hypothal to release oxytocin?
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Suckling, also baby crying. A REFLEX.
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What type of cells surround the mammary alveoli?
What is their function? |
Myoepithelial cells - contract, squish alveoli to eject milk.
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How does oxytocin stimulate uterine contraction?
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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 |
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What are 2 additional functions of oxytocin?
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-Reduces postpartum bleeding
-Induces labor |
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What can inhibit milk letdown?
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Epinephrine - blocks oxytocin; you need to relax when breast-feeding!
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What are 3 functions of ADH?
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1. Increases blood osmolarity
2. Senses decreased blood vol and responds to increase it. 3. Constricts arterioles to increase arterial pressure. |
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does ADH act to increase or decrease blood osmolarity? WHY?
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DECREASE it; b/c increased osmolarity stimulates the osmoreceptors in the hypothal; ADH release increases H2O reabsorption; decreases conc.
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How does blood osmolarity stimulate ADH release?
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-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 |
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How does decreased BLOOD VOLUME stimulate ADH release?
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by stimulatng BARORECEPTORS (bp) which stimulate M cells the same way as osmoreceptors do..
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what inhibits the release of ADH, and what is the result?
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ALCOHOL; you urinate lots of dilute urine.
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how does ADH cause increased blood pressure?
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by constricting the arterioles.
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what is lack of vasopressin called? (pathologic condition)
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Diabetes Insipidus - makes you pee insipidously
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What causes you to excrete glucose - sweet pea?
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Diabetes Mellitus
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what is the other type of cell in the hypothalamus other than M?
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#1 cells
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what is the main difference between M cell and 1 cell?
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M cell extends to the posterior pituitary; 1 cell only extends to the median eminence, then converges with the capillaries
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How does the 1 cell release its hormones?
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By storing in synaptic vesicles to release with stimulus; then they cross into capillaries by diffusion.
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what types of tissue are the
-posterior hypothalamus? -anterior hypothalamus? |
Post = nervous tissue
Ant = glandular tissue |
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What type of messenger does the hypothalamus 1 cell make?
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Neurohormones.
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how do hormones from the hypothalamus travel to the anterior pituitary?
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by the portal vessel; from the primary capillary plexus to the secondary.
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What are the Anterior pit hormones?
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Acth, TSH, FSH, LH, GH, Prl
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What are the Hypophysiotropic hormones?
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CRH
TRH GnRH GHRH Somatostatin, Dopamine |
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What anterior pituitary hormone does CRH act on?
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ACTH, and the adrenal glands
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What anterior pituitary hormone does TRH act on?
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TSH, and the thyroid gland
AND Prolactin and the breasts |
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What anterior pituitary hormone does GnRH act on?
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LH and FSH - thus the gonads
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What anterior pituitary hormone does GHRH act on?
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GH, and thus many tissues
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What else acts on growth hormone, and how?
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Somatostatin - inhibits the release of growth hormone
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What two hypothalamic hormones act on Prolactin, and how?
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-Dopamine; inhibits Prl release
-TRH; stimulates Prl release |
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In general how does Longloop feedback work?
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The hormone produced by the target tissue inhibits release of hypothalamic and pituitary hormones.
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In general how does Short loop feedback work?
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The hormone released by the PITUITARY inhibits hypothalamic release
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What happens when you have a pituitary tumor? Use ACTH for an example
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The pituitary makes too much hormone, thus incr. ACTH causes increased Cortisol levels
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How would you know if someone has an ADRENAL tumor vs. Pituitary?
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Adrenal tumors cause low cortisol levels because of negative loop feedback.
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If a person had blotchy pigmentation, what type of tumor?
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Pituitary
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What is another name for growth hormone?
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Somatotropin
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What two hormones regulate somatotropin?
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GHRH and Somatostatin
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What is SRIF?
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Somatotropin releasing inhibiting factor - another name for somatostatin.
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What is a somatotroph?
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The ant pituitary cell that makes GH
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When is GHRH commonly produced, and how?
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During the 1st hour of sleep, in pulses.
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what are the effects on GH by
-Exercise -Obesity |
Exercise stimulates GHRH
Obesity inhibits GHRH |
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How does GH act on the liver, and what is the effect?
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Stimulates the liver to produce IGF1 - insulin-like growth factor 1.
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What was IGF-1 formerly known as?
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Somatomedin C
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What are the 4 main functions of Growth hormone?
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1. Cartilage and bone growth
2. Protein metabolism 3. Carbohydrate metabolism 4. Lipid metabolism |
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How does GH cause carilage/bone growth?
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By stimulating stem cells in the long bone epiphyseal plates to grow more bone/cartilage.
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How does GH cause Protein metabolism?
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1. Helps cells take up amino a.
2. Stimulates protein synthesis. 3. Increases muscle formation |
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How does GH affect carbohydrate metabolism?
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With an ANTI-INSULIN effect.
-Decreases glu uptake by cells -Increases glu prodctn by liver Net: increases plasma glucose. |
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What is HSL?
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Hormone sensitive lipase; an enzyme that breaks down Triglycerides in fat cells to Fatty acids + Glycerol
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Why is HSL related to Growth hormone, and what else acts on it?
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GH acts on HSL to activate it.
Insulin inhibits HSL to store glucose instead of using it. |
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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) |
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What is the effect of GH excess in Childhood?
Adulthood? |
Child: gigantism
Adults: Acromegaly, membranous bone growth, tongue thickens, etc. |
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What is especially unique about PROLACTIN?
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It's the only pituitary hormone predominantly inhibited by the hypothalamus directly.
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What hypothalamic hormones act on Prolactin?
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Thyroid releasing hormone (TRH)
Dopamine (DA) |
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What is the name of the anterior pituitary cells that make prolactin?
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Lactotrophs
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What type of feedback occurs to regulate Prolactin release?
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ONLY SHORTLOOP!!
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When is Prolactin production increased?
What stimulates it? |
ONLY DURING PREGNANCY
-Stimulated by Suckling |
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What are the 2 main functions of prolactin?
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1. Stimulates growth of mammary alveoli and ducts in milk anticipation during pregnancy.
2. Causes Milk synthesis |
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What is the effect of increased prolactin on the hypothalamic hormones?
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-Prl shortloop fdbck inhibits TRH, stimulates DA.
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How do Estrogen and Progesterone affect milk production during pregnancy? How?
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Inhibit it; but stimulate more Prolactin PRODUCTION.
By Overwhelming Dopamine levels. |
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What happens at birth to estrogen and progesterone?
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Levels suddenly plummet; allows milk to be produced
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How does Prl affect GnRH?
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Prl inhibits GnRH so that the follicles and gonads aren't stimulated; don't want sex hormones during childbirth and breast-feeding.
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A lot of Antipsychotics are DA antagonists; what is the effect?
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DA is blocked, so Prl is abundnt and Sex hormones are not; can become infertile, decreased labido, female lactation.
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