Lecture Three Intro To Pituitary Flashcards
FSH LH secretions in gonads
FSH LH testis - testosterone
Ovary
FSH - estrogen
LH- progesterone
Hormones secreted by anterior pituitary
ACTH- adrenal cortex TSH- thyroid FSH/LH- gonads Prolactin - mammary glands GH - muscle, adipose tissue, bone
Posterior pituitary hormone so
Oxytocin - uterus and mammary gland
Vasopressin - kidney
Five hypothalamic functions
Temperature regulation Neuro endocrine control Appetitive behavior Defensive reactions Control of body rhythms
Temperature regulation afferent so and integrating areas
Temp receptors in skin, deep tissues, spinal cord, hypothalamus, and other parts of the brain
Anterior hypothalamus, response to heat;
Posterior hypothalamus response to cold
Neuro endocrine control of seven things
Catecholamines Vasopressin Oxytocin TSH via TRH ACTH via CRH FSH and LH via GnRH Prolactin via PIH AND PRH GH via somatostatin and GHRH
Catecholamines afferents and integrating areas
Limbic areas concerned with emotion
Dorsal and posterior hypothalamus
Vasopressin afferents and integrating areas
Osmose rotors, volume receptors, others
Supra optic and paraventricular nuclei
TSH afferents and integrating areas
Temp receptors in infants, perhaps others
Paraventricular nuclei and neighboring areas
Oxytocin afferents and integrating area
Touch receptors in breasts, uterus and genitalia
ACTH afferents and integrating area
Limbic system, reticular formation, hypothalamic and anterior pituitary cells sensitive to circulating blood cortisol levels, suprachiasmatic nuclei
Paraventricular nuclei
FSH and LH afferents and integrating area
Hypothalamic cells sensitive to estrogens, eyes, touch receptors in skin and genitalia of reflex ovulating species
Preoptic area, other areas
Prolactin afferents and integrating area
touch receptors in breasts, other unknown receptors
Arcuate nucleus, other areas (hypothalamus inhibits secretion)
GH afferents and integrating area
Unknown receptors
Peri ventricular nucleus, arcuate nucleus
Thirst afferents and integrating area
Osmoreceptors, probably located in organum vasculosum of the lamina terminalis; angiotensin II in the subfornical organ
Lateral superior hypothalamus
Hunger afferents and integrating area
Glucostat cells sensitive to rate of glucose utilization; leptin receptors; receptors for other polypeptides
Ventromedial, arcuate, and paraventricular nuclei; lateral hypothalamus
Sexual behavior afferents and integrating area
Cells sensitive to circulating estrogen and androgen, others
Anterior ventral hypothalamus plus in the male, piriform cortex
Defensive reactions (rage, fear) afferents and integrating area
Sense organs and neocortex
Paths unknown
Diffuse, in limbic system and hypothalamus
Control of body rhythms afferent and integrating area
Retina retinohypothalamic fibers
Suprachiasmatic nuclei
Where does pituitary develop
From diencephalon and ectodermal region from the roof of the mouth
Rathke’s cyst
Benign tumor in pituitary gland
Where are vasopressin and oxytocin synthesized
In the neurons of the supraoptic and paraventricular nuclei, respectively
Hypothalamoneurohypophysial tract
Axons that transport vasopressin and oxytocin, along with neurophysin, from hypothalamus to posterior pituitary
Where are oxytocin and vasopressin released
At the axon terminals
Fenestrated capillaries
Derived from inferior hypophysial artery. What released oxytocin and vasopressin enter as they leave axon terminal
What makes up the neurohypophysis
Median eminence
Infundibular process
Pars nervosa (neural lobe)
Herring body
Neuro secretory bodies in posterior pituitary. Represent terminal end of axons from the hypothalamus
Pituicyte
Glial cells of the posterior pituitary. Their main role is to assist in the storage and release of neurohypophysial hormones
Neurohypophysis
Posterior pituitary
Why are capillaries of neurohypophysis fenestrated
To permit diffusion of secretions into circulation
Glial Fibrillary acidic protein
Intermediate filament protein characteristic of astrocytes
How do hormones travel down axon
In neuro secretory granule containing the neurophysin-hormone complex
Is axon between hypothalamus and posterior pituitary myelinated
No
Synthesis and processing steps of neural lobe hormones
(ER) pre-hormone
Pro hormone
Neuro secretory granule (NSG)
Neurophysin + hormone
Prehormone happens where
Protein synthesis; Magnicellular neuron ribosomes
Prohormone
Glycosylation and membrane packaging; Magnicellular neuron Golgi apparatus
Neuro secretory granule
Transport down supraopticohypophyseal tract as osmotic ally inactive granules
Neurophysin plus hormone
Storage in posterior pituitary; cleavage within NSG
Where does oxytocin act
Myoepithelial cells of mammary glands
Uterus
What some oxytocin cause in Myoepithelial cells
Milk ejection
What causes positive feedback to hypothalamus for oxytocin in mammary glands
Suckling
What does oxytocin do in uterus
Cervical dilatation via uterine contractions that lead to labor
What in uterus provides positive feedback to hypothalamus on oxytocin
Uterine contractions
Where is oxytocin synthesized in neuron
Paraventricular neuron
What is role of oxytocinase
Decreases the plasma level of oxytocin
What do progesterone and relaxin do during pregnancy to the myometrium
Decrease its intrinsic contractility
What happens to oxytocin levels during parturition
They increase dramatically
When is binding of oxytocin maximal
During labor
How does oxytocin bind in mammary gland
Gradual increase during pregnancy with maximal binding during lactation
Ptocin
Synthetic oxytocin used in obstetrics to induce labor and maintain progression and reduce post partum bleeding
Oxytocin cycle in uterine contractions
Oxytocin released by posterior pituitary
Causes uterine contraction
Baby’s head pushed downward
Cervical stretch
Cervical stretch provides positive feedback to posterior pituitary about oxytocin, to uterus to contract
Uterine contraction causes uterus to release prostaglandins
What kind of receptor is oxytocin receptor
G protein coupled
What are the second messengers of oxytocin receptor
Calcium
DAG
IP3
Why is calcium required in cell
For calmodulin binding in smooth muscle of uterus and activation of specific kinase in the smooth muscle
What does activation of kinase result in
Smooth muscle cell contractility
What does calcium-calmodulin combo activate
Myosin light chain kinase that causes contraction of smooth muscle
How does oxytocin affect ACTH
It has an inhibitory effect on ACTH secretion from anterior pituitary
What behavior does oxytocin regulate
Maternal behavior
What part of hypothalamus regulates female mating behavior. What does it express
The ventromedial nuclei, which express oxytocin receptors regulated by estrogen
What happens to oxytocin levels during human sexual arousal
Plasma oxytocin levels are elevated
How do oxytocin and vasopressin regulate social behavior
They may regulate social recognition such as “pair bonding” and social interaction such as trust among group of individuals
