Pituitary Gland

Question 1

Steroid secreting cells contain……while peptide hormone secreting cells contain…..

Answer 1

Mitochondria & sER (containing enzymes for hormone synthesis + lipid droplets, store the precursor
Golgi apparatus, rER, secretory granules containing the hormone

Question 2

Enumerate scattered cells with endocrine function & hormones they secrete

Answer 2

1. Enteroendocrine cells e.g. ghrelin
2. Juxtaglomerular cells of the kidney, renin. Fibroblasts adjacent to renal tubules, erythropoietin
3. Cardiac muscle fibers, ANF
4. White adipocytes, leptin
5. Epithelial reticular cells hormones for maturation & differentiation of T-lymphocytes

Question 3

An example of paracrine secretion is…….

Answer 3

Gastrin from Pyloric G cells reaches target cells in fundic glands

Question 4

Define juxtacrine secretion

Answer 4

In which a signaling molecule remians on secreting cell surface or adjacent ECM and affects target cells when they contact

Question 5

Stroma of pituitary is composed of……while parenchyma is composed of….

Answer 5

Fibrous capsule & reticular CT
Epithelial endocrine cells arraned in branching and anastomosing cords separated by fenestrated capillaries

Question 6

Enumerate types (theories) regarding chromophobic cells

Answer 6

1. Partly degranulated chromophils containing sparse granules representing resting state in secretory cycle.
2. Undifferentiated stem cells
3. Follicular stellate joined by gap junctions may be supoorting or phagocytic cells

Question 7

Subtypes of acidophils and basophils can be identified by……

Answer 7

TEM granular morphology or immunohistochemistry

Question 8

Acidophil granules are stained by……

Answer 8

Eosin/Orange G

Question 9

Function of somatotrophs

Answer 9

Secrete somatotropic/growth hormone that induces liver cells to secrete somatomedins which stimulate protein syntehsis in all tissues with particular effects on chondrocytes of epiphyseal plate leading to growth & elongation of bone.

Question 10

Describe control of GH secretion

Answer 10

Stimulated by GHRH from hypothalamus & ghrelin
Inhibited by GHIH (somatostatin, -feedback) from hypo.

Question 11

Granules of mammotrophs are stained….by…..

Answer 11

Red
Erythrocin

Question 12

Hypertrophy & hyperplasia of mammotrophs occurs under effect of……

Answer 12

High estrogen during pregnancy & lactation

Question 13

Mention function & control of secretion of mammotrophs

Answer 13

Secrete prolactin which stimulates mammary gland development during pregnancy. It initiates & maintains milk secretion during lactation.
Controlled by PRH & PIH which is dopamine (-feedback) from hypothalamus

Question 14

The least cells with smallest granules are…..

Answer 14

Thyrotrophs

Question 15

Function & control of secretion of thyrotrophs

Answer 15

They secrete TSH
It is stimulated by TRH from hypthalamus & inhibited by -feeback inhibition by thyroid hormones at levels of pit & hypo.

Question 16

Mention the function of gonadotrophs

Answer 16

Secrete:
FSH: In f regulates maturation & growth of ovarian follicles. In m initiates spermatogenesis & stimulates synthesis of androgen binding protein by sertoli cells
LH: in f, induces ovulation & differentiation of cells of corpus luteum. In m called ICSH, stimulates interstitial cells to secrete testosterone.

Question 17

Function of corticotrophs

Answer 17

Secrete propiomelanocortin which is cleaved into:
1. ACTH stimulates zona fasciculata of adrenal cortex
2. B-lipotrophin: regulates lipid metabolism

Question 18

Decsribe control of corticotrophic hormone secretion

Answer 18

Stimulated by CRH from hypo, inhibited by -feedback by cortisol at pit & hypo.

Question 19

Granules of basophils are staine by…….bec……

Answer 19

PAS
Glycoprotein in nature

Question 20

Releasing & release inhibiting hormones reach capillaries from…….then to ant pituitary by….., thus the connection is……

Answer 20

Tuberoinfundibular tract
Hypothalamic-hypophyseal portal circulation
Nervous & vascular

Question 21

LH & FSH are stimulated by…..

Answer 21

GnRH

Question 22

Pars tuberalis contains mostly……

Answer 22

Basophil gonadotrophs

Question 23

Describe microscopic structure of pars intermedia

Answer 23

Contains colloid containing cysts lined by cuboidal cells
It also posseses basophilic cells like corticotrophs secrete POMC cleaved into ACTH, B-lipoprotein & MSH (induce melanocytes to produce melanin)

Question 24

Mention contents of neurohypophysis

Answer 24

1. Pituicytes
2. Herring bodies
3. Fenestrated blood capillaries
4. Reticular fibers
5. Hypothalamo-hypophyseal tracts (from PV & SO nuclei)

Question 25

Describe function of pars nervosa

Answer 25

Secretes: 1. Oxytocin stimulates uterine smooth muscle contraction during delivery & myoepithelial cells contraction for milk ejection
2. Vasopressin: acts on cells of distal convuluted tubukes & collecting tubules causing reabsaorption of water & urine concentration.

Question 26

Deficiency of ADH leads to…..

Answer 26

Diabetes insipidus (polyuria)

Question 27

Detail blood supply of pituitary

Answer 27

Arterial:
1. Right & left superior hypophyseal arts serve pars tuberalis, infundibulum, median eminence
2. Rt & lt inferior hypophyseal arts serve pars nervosa
2. Hypophyseal portal system:
a. Primary capillary plexus arises from superior hypophyseal art, located in median eminence where hypothalamic neurosecretory hormones enter the blood. It is drained by hypophyseal portal veins which descend through the infundibulum to adenohypophysis
b. 2ry capillary plexus found in pars distalis where neurosecretory hormones are released
Both capillary sers are fenestrated

Question 28

Hypothalamus is connected to post pit by……

Answer 28

Hypothalamo-hypophyseal tract (axons of PV & SO nuclei)

Question 29

Classify cells of pars distalis with percentage

Answer 29

1. Chromophobes (50%)
2. Chromophils (50%)
   A. Acidophils (35%)
   i. Somatotrophs (50%)
   ii. Mammotrophs (15-20%)
   B. Basophils (15%)
   i. Thyrotrophs (5%)
   ii. Gonadotrophs (10%)
   iii. Corticotrophs (15-20%)