Pineal Gland, Hypothalamus, & Pituitary Flashcards
Pineal gland location
Adjacent to the 3rd ventricle (cavity)
Functions Of Pineal
- Produces Melatonin (at night)
- Regulationg of circadian Rhythm (fascilitates sleep cycle)
- Regulate seasonal biorythms (in animals- where they give birth when more food is available)
- Produces Serotonin (daytime)
- Suppresses Gonadal function
What turns serotonin to melatonin at night to facilitate sleep cycle
HIOM- hydroxyindole-o-methyltransferase
What promotes melatonin synthesis
Direct autonomic sympathetic input from superior cervical gangion (at night)
What Inhibits melatonin synthesis
Visual input from retina through suprachiasmatic nucleus (hypothalamus) (DURING THE DAY-interrupting melatonin synthesis)
(JETLAG)
Pinealcyte secretes hormones into…
fenestrated cappilarries and carried into body to carry its function
Location Of pinneal gland
Center of the brain- PIC
Pinneal Gland Structure
Lobular parenchyma invaginated by connective tissue trabeculae
-Surrounding capsule
Specific characteristic of pinneal gland
Corpora Arencea- Specific characteristic– the concentration of them accumulate with age
-AKA Brain Sand
Pinealocytes Function
They secrete melatonin during darkness
What do glial cells in Pinneal gland do?
Direct from monocytes- have phagocytic function
Hypothalamus Location
- Above the pituitary
- Indistinct (not encapsulated)
- Cluster of neurons tht secrete hormones
Hypothalamus is composed of different types of specialized neurons that are grouped together and called…
Nuclei
Anterior hypothalamus regulates
Parasympathtic autonomic NS and body temperature
Posterior Hypothalamus regulates
Sympathetic Autonomic NS
Ventro Medial Nucleus in hypothalamus
Project to median eminence of pituitary to regulate Appetite, sleep and wake center, emotions, behavior
Median Eminance
part of pituitary gland-
in the imfundibuluary stem which contains vascular bed (primary capillary plexus)
Supraoptic Nucleus
Regulates water/mineral/metabolism (vasopressin/ Anti deuretic Hormone-ADH)
Paraventricular Nucleus
Regulates parturition and milk ejection (oxytocin)
Regulation of adenohypophysis in Hypothalamus
Regulates Pituitary
Neurons in the ventral medial, dorsal medial, and infundibulary nuclei project and terminate to the…
Median Eminenece and infundibular stalk
Neurons in the supraoptic and paraventricular nuclei project down to and terminate at the…
Pars Nervosa
What artery supplies median eminence and infundibular stalk?
Superior Hypophyseal-branches to form capillaries of median eminance
What artery supplIes neurohyphophysis?
Inferior hypophyseal- branches to form fenestrated capillaries of pars nervosa
Releasing and inhibiting hormones/factors of the hypothalamus
SEE TABLE
Location of Pituitary gland
Attached to the hypothalamus and lies in the sella turcica of the sphenoid bone- Used to localize base of brain
Subdivisions of Pituitary: Neurohypophysis (Neuronal)
pars nervosa, infundibular stalk includes 1)stem and 2)median eminence (contains vascular bed)
Subdivisions of Pituitary: Adenohypophysis (epithelial)
3 Parts:
- Pars Distalis (or pars anterior)- Largest part of lobule
- Pars intermedia
- Pars Tuberalis- a projection from the adenohypophysis extends doral along the anterior and lateral aspects of the infundibular stalk
What does Neural Diencephalon form?
Neurohypophysis
What does Oral Ectoderm form?
Adenohypophysis
Infundibulary Stalk and Pars Nervosa found in…
Neurohypophysis
ADH (Antidiuretic Hormone/Vasopressin)
- Secretion by cell bodies in the Supraoptic Nucleus
- Promotes water reabsorption in kidney collecting ducts
Oxytocin Secretion by Paraventricular Nucleus
-Stimulates milk ejection in mammary glands and uterine smooth muscle (myometrium) contractions
Neurohypophysis Contains
- Pars Nervosa
- Infundibular Stalk includes A) Stem and B) Median Eminence (vascular bed)- and herrings bodies which has ACH and Oxytocin
Adenopophysis 3 Parts
- Pars Distalis (pars anterior)
- Pars Intermedia- space between pars distalis and pars nervosa
- Pars Tuberalis
Chromophobes
Types of parenchymal cells in Pars Distalis: –Lack Granules
- Follicular (support cells)
- Undifferentiated cells
Chromophils
Types of parenchymal cells in Pars Distalis: Secretory Cells
-Acidophils: Stain with eosin and organge G (simple proteins)
-Basophils: Stain with hematoxilin and PAS (glycoproteins) and stain purple
Cell types of pars Distalis
Chromophobes, Acidophils, Basophils
In Chromophil Cells, Acidophils Secrete…
- Somatotrophs (GH) 40-50%
- Mammotrophs (Prl) 15-25%
In Chromophil Cells, Basophils Secrete…
-Thyrotrophs: TSH/thyrotropin 5%
-Gonadrtrophs:
FSH (follicle-stimulating hormone) 10%
LH (Luteinizing Hormone) 10%
-Corticotrophs: 10-20%
ACTH (adrenocorticotrophic H)
B-Lipotropin
B-Endorphin
MSH (melanocyte stimulating H)
Pars Tuberalis
Forms a partial collar around infuncdibular stalk
- Histology (basophils) similar to pars distalis
- Most Cells secrete gonadotrophins (LH and FSH)
- Contains primary capillary plexus
Location of Pars Tuberalis
PIC
-Right above Distalis
Pars Intermedia
-Contains Basophilic Cells (melanotrophs)
-Organized in cords
Secrete MSH
Rathke’s Cysts (remnats of Rathke’s pouch) filled with…
Colloid and lined by cuboidal epithelium
Pineal Gland Embryology
Neuroectodermal Cell origin (Neural Tube Epithelium)
What is a ventricle
Spaces between folds
Herrings Body’s Function
Little terminat dialations at the end of axons which store ADH and Oxytocin
Sela Turcica
Cup-like stucture of bone where pituitary sits in- used to localize in brain
Pituitary Sub-DIvisions
Adenohypoophysis (epithelial) and Neurohyphysis (neuronal)
Neural diencephalon forms…
Neurohypophysis–formed because growing tissue of brain grows DOWN
Oral Ectodern forms..
Adenohypophysis- formed because growing roof of mouth grows UP
Nuclei Often seen in Pars Nervosa are…
Pituicytes (glial cells)
Hormones and binding protein in the Neurohypophysis
- ADH- Antidiuretic Hormone/ Vasopressin
- -Secretion by Cell Bodies in the Supraoptic nucleus
- -Promotes water reabsorption in kidney collecting ducts - Oxytocin secretion by Paraventricular Nucleus
- -Stimulates milk ejection in mammary gland and uterine contraction - Neurophysin: Carrier glycoprotein associated with the 2 hormones
(follicular liquor).
accumulations of hyaluronic acid-rich fluid in the Antrum Cavity
