Lecture 17 - Pineal, Hypothalamus, Pituitary

Question 1

Pineal gland embryology

Answer 1

neuroectodermal cell origin (neural tube epithelium)

Question 2

Pineal gland location and structure

Answer 2

adjacent to the third ventricle. lobular parenchyma invaginated by CT trabeculae

Question 3

Function of pineal gland

Answer 3

produced melatonin and serotonin; regulation of circadian rhythm; seasonal biorhythms; suppresses gonadal functions

Question 4

How is serotonin converted to melatonin

Answer 4

HIOM - hydroxyindole-o-methyltransferase

Question 5

Innervation that promotes melatonin synthesis

Answer 5

direct autonomic sympathetic input from superior cervical ganglion

Question 6

Innervation that inhibits melatonin synthesis

Answer 6

visual input from retina through suprachiasmatic nucleus (hypothalamus)

Question 7

Cells found in the pineal gland

Answer 7

pinealocytes - producing the melatonin and serotonin.

glial cells - derivatives of monocytes.

Question 8

Corpora arenacea

Answer 8

brain sand, accumulation of material that cant be secreted.

Question 9

Hypothalamus location and structure

Answer 9

adjacent to the third ventricle and above the pituitary gland (anterior to pineal). clusters of different neurons in an indistinct region of the brain

Question 10

Nuclei in hypothalamus

Answer 10

(whole cell) different types of specialized neurons that are grouped together.

Question 11

Anterior hypothalamus function

Answer 11

regulates parasympathetic autonomic NS (decreases heart rate, vasodialation), and body temp

Question 12

Posterior hypothalamus function

Answer 12

regualtes sympathetic autonomic NS (increases heart rate, vasoconstriction)

Question 13

Ventro-medial nucleus function

Answer 13

project to median eminence to regulate appetite, sleep and wake center; emotions, behavior

Question 14

Supraoptic nucleus

Answer 14

regulates water/mineral metabolism (vasopressin/ADH). projects to the pars nervosa of the pituitary

Question 15

Paraventricular nucleus

Answer 15

regualtes parturition and milk ejection (oxytocin). projects to pars nervosa of the pituitary

Question 16

Bed of capillaries in the median eminence and where they come from

Answer 16

primary capillary plexus from the superior hypophyseal artery

Question 17

Herring’s bodies

Answer 17

terminal dialation points in the pars nervosa where the supraoptic and paraventricular neurons deposit vasopressin and oxytocin to be stored.

Question 18

What artery supplies the pars nervosa and pars distalis?

Answer 18

inferior hypophyseal artery

Question 19

Anterior pituitary (pars distalis) hormones that terminate in the medial eminence

Answer 19

FLAT PiG and M- FSH, LH, ACTH (adrenocorticotropic hormone), TSH, Prolactin, GH; Melanocyte-stimulating hormone

Question 20

Hypothalamic releasing hormone

Answer 20

intermediate secreting hormones. Will drain to the pars distalis. They are ‘releasing’ hormones.

Question 21

Pituitary location

Answer 21

in the sella turcica - cup of bone

Question 22

Neurohypophysis and its embryology

Answer 22

pars nervosa, infundibular stalk (stem and medial eminence). Neuronal development from the base of brain (diencephalon)

Question 23

Adenohypophysis and its embryology

Answer 23

pars distalis, pars intermedia, and pars tuberalis. Epithelial in origin from the oral region (oral ectoderm)

Question 24

Pars intermedia appearance

Answer 24

between the pars nervosa and pars distalis. small cyst like region.

Question 25

Type of axons in the neurohypophysis

Answer 25

unmyelinated axons (~ 100,000)

Question 26

Pituicytes in the neurohypophysis

Answer 26

highly branched glial cells.

Question 27

What type of nuclei are found in the pars nervosa?

Answer 27

only pituicytes. no neuron nuclei since those will be in the hypothalamus.

Question 28

Where does the fenestrated capillary bed of the pars nervosa drain to?

Answer 28

cavernous sinuses

Question 29

Hormones in the neurohypophysis

Answer 29

ADH (promotes water reabsorption in the kidney collecting ducts); oxytocin (stimulates milk ejection in mammary gland & uterine smooth muscle (myometrium) contraction

Question 30

binding protein in the neurohypophysis

Answer 30

neurophysin - carrier glycoprotein associated with the two hormones

Question 31

What controls the pars distalis?

Answer 31

hypothalamic releasing/inhibiting hormones that are released in the medial eminence.

Question 32

2 types of parenchymal cells in the pars distalis

Answer 32

Chromophobes (stain poorly) and Chromophils (stain intensely)

Question 33

Chromophobes

Answer 33

lack granules. follicular cells (support cells). undifferentiated.

Question 34

Chromophils

Answer 34

secretory cells. separated into acidophils and basophils

Question 35

Acidophils

Answer 35

stain with eosin and orange G (stain yellow/orange). Mammotrophs (prolactin) and somatotrophs (GH)

Question 36

Basophils

Answer 36

stain with hematoxilin and PAS (stain purple/blue). Thyrotrophs (TSH), Gonadotrophs (FSH and LH), Corticotrophs (ACTH, B-Lipotropin, B-Endorphin, MSH)

Question 37

How are corticotrophs secreted?

Answer 37

type of chromophil - basophil. secreted as one large molecule (pro-opio-melano-cortin)

Question 38

Pars tuberalis

Answer 38

partial collar around infundibular stalk. Basophils which secrete gonadotrophins (LH and FSH).