Endocrine - Pituitary and Pineal Gland Flashcards
What are the two feedback mechanisms utilized by the endocrine system?
Positive Feedback
Negative Feedback
What is the hypophysis?
Pituitary Gland
What two glands provide endocrine and neuroendocrine control of other endocrine glands?
Hypothalmus and pituitary gland
Is the pituitary gland paired?
No
Where is the pituitary gland located in the skull?
Sella turcica
What connects the pituitary gland to the hypothalmus?
Infundibular stalk
What type of tissue surrounds the pituitary gland?
Dense irregular CT
Continuation of dura mater of the brain
What are the two functional components of the pituitary gland?
Adenohypophysis - anterior
Neurohypophysis - posterior
What is the adenophysis derived from? The neurohypophysis?
Adenophysis - oral ectoderm
Neurohypophysis - downgrowth of neurectoderm or diencephalon
What is Rathke’s pouch?
The invagionation of the ectogerm of the oral cavity during embryology that develops into the adenohypophysis
How is endocrine tissue, like that of the pituitary gland, typically organized?
Organized into clumps and cords around fenestrated capillaries
What are the three regions of the adenohypophysis? Where are each located?
Pars distalis - anterior most, largest portion
Pars intermedia - thin remnant of posterior all of Pathke’s pouc
Pars tuberalis - collor/sheath around infundibular stalk
What are remnants of the Rathke’s pouch lumen called? Where are they found? What are they lined with
Rathke’s cysts
Pars intermedia
Lined with cuboidal epithelium
What are chromophiles? Chromophobes?
Chromophiles - cells with secretory granules that pick up dye
Chromophobes - do not have intensely staining secretory granules
What are two types of chromophobes found in the adenohypophysis?
Stromal cells
Degranualted chromophiles
What are two sub-categories of chromophiles?
Basophils
Acidophils
What are the two cells types of acidophils in the anterior pituitary?
Somatotropes
Lactoropes
What do somatotropes secrete? What endocrine organ controls this secretion? Which things causes production? Inhibition?
Secrete somatotropin (growth hormone)
Hypothalmus
GHRH - stimulates
Somatostatin - inhibits
What do lactoropes secrete? What are they stimulated and inhibited by? Where do each of those come from?
Secrete prolactin
Stimulated by TRH
Inhibited by dopamine
What happens to lactorope cells during pregnancy?
Increase in size and number
What is the most abundant cell in the adenohypophysis?
Somatotropes
What are the three basophil cells in the anterior pituitary?
Corticotropes, gonadotropes, thyrotropes
What do corticotropes produce? What stimulates this release? From where?
Adrenocorticotropic hormone (ACTH) CRH (corticotropin-releasing hormone) stimulates ACTH release. It is produced in the hypothalmus
What two hormones are secreted from gonadotropes? controlled by what? From where?
FSH and LH
Controlled by hypothalmus by secretion of GnRH (gonadotropin-releasing hormone)
What to thyrotropes produce? What controls this secretion?
Secrete TSH
Controlled by TRH
What two parts comprise the neurohypophysis?
Pars nervosa
Infundibulum
What two cell types are contained in the neurohypophysis?
Axons of hypothalamic neurons
Pituicytes - glial cells
What two things do the hypothalamic neurons secrete into pars nervosa?
Oxytocin
ADH
What are Herring bodies?
Large distended axon terminals of hypothalamic neurons located in the pars nervosa of the neurohypophysis
What two arteries supply the pituitary?
Superior and inferior hypophyseal arteries
What 4 parts are supplies by the superior hypophyseal artery?
Pars tuberalis
Infundibulum
Median eminence
Pars distalis
What is the most prominent feature of the hypophyseal blood supply?
Hypophyseal portal system
What does the hypophyseal portal vein run between?
Primary capillary plexus to secondary capillary plexus (around pars distalis)
What type of capillaries are contained in the capillary plexi?
Fenestrated sinusoidal capillaries
What artery supplies the pars nervosa?
Inferior hypophyseal artery
Where is the pineal gland located?
Posterior end of third ventricle of the brain
What does the pineal gland form as an outcropping of? Similarly to what structure?
Dicephalon
Neurohypophysis
What covers the pineal gland?
Pia matter
Pia matter extends into the pineal gland as what? What runs in them?
Septa
Blood vessels
What are corposa aernacea? Where are they found?
Aggregates of calcium phosphate
Located in pineal gland
How do the corposa aernacea change with age?
Increase in number and size with age
What two cell types are found in the pineal gland?
Pinealocytes
Glial Cells
What are the principal cells of the pineal gland? What did they likely evolve from? They are considered modified ______ cells
Pinealocytes
Photoreceptors
Neuronal
Where are axons located in the pineal gland in relation to the pinealocytes?
Spacers between clusters of pinealocytes
Describe the characteristics of the pineolcyte nucleus and nucleolus
Nucleus - large euchromatic
Nucleolus - prominent
What do pinealocytes secrete?
Melatonin
What tract conveys information about light/dark cycles to the pineal gland?
Retinothalamic tract
What controls the systhesis and secretion of melatonin?
NE released by sympathetic neurons
What activity does melatonin inhibit?
Steroidogenic activity of gonads is inhibited by melatonin
What are the supporting cells of the pineal gland?
Glial cells
What percent of the pineal gland is pinealocytes? Glial cells?
Pinealocytes - 90%
Glial cells - 5-10%
How do glial cell nuclei compare to pinealocytes?
Smaller and heterochromatic
