Anatomical Basis Of Hormonal Control

Question 1

Characteristics of hormone secreting cells

Peptide/protein hormone cell

Answer 1

Lots of RER
GOlgi
Secretory vesicles

Question 2

Characteristics of hormone secreting cells

Steroid secreting cells

Answer 2

Lots of SER
Abundant mitochondria
Lipid droplets

Question 3

Describe the stricture of the neurohypophysis

Answer 3

Consists of axons of modified neurones, supported by glial like cells (pituicytes)
Cell bodies of these neurone lie in supraoptic and paraventricular neuclei of hypothalamus

Made up of the infundibulum and pars nervosa

Question 4

Hormones of the neurohypophysis and their functions

Answer 4

ADH
Increases water retention in kidneys

Oxytocin
Contraction of smooth myocytes of uterus in parturition
Contraction of myoepithelial cells of mammary glands in lactation

Question 5

Describe the method of peptide hormone release from the neurohypophysis

Answer 5

ADH, oxytocin made in cell bodies of different neurone in hypothalamus, cleaved to yield hormone and a binding protein (neurophysin)

Transported down axon to terminals
Released from terminals into fenestrated capillaries on stimulation of cell bodies in hypothalamus
Accumulations of hormone within axons (Herring bodies)

Question 6

Describe the type of cells in the adenohypophysis

Answer 6

Cords of cuboidal epithelial secretory cells around fenestrated capillaries

Classified as
Acidophils
-Somatotrophs (GH)
-Mammotrophs (P)

Basophils

• Thyrotrophs (TSH)
• Corticotrophs (ACTH)
• Gonadotrophs (FSH, LH)

Chromophobes
-Generate acidophils/basophils

Question 7

Function of the pars intermedia

Answer 7

Secrete melanocytes stimulating hormone (MSH)

Increase skin pigmentation

Question 8

What hormones stimulate secretions from the adenohypophysis

Answer 8

TRH => TSH
GnRH => FSH, LH
GRH => GH
CRH => ACTH

Question 9

What hormones inhibit release of hormones from the adenohypophysis

Answer 9

Somatostatin, blocks GH, TSH release

Dopamine, blocks P release

Question 10

Describe the structure of the thyroid

Answer 10

Intimately relegated to trachea (2-4th ring)

Isthmus may join to hyoid bone by fibrous cord, remnant of embryological thyroglobulin duct

Question 11

Describe the cellular organisation of the thyroid

Answer 11

Epithelial cells organised into follicles

Secrete thyroglobulin, accumulates in follicles at colloid

Question 12

Describe the thyroid follicular cells and iodide

Answer 12

Iodide oxidised to iodine
Covalently attached to tyrosine of thyroglobulin within lumen of follicle

When stimulated by TSH

• Follicular cells endocytose iodinated thyroglobulin
• Break it down in lysosomes
• Release iodinated tyrosine derivatives (T3, T4)

Question 13

Describe the function, location and derivation of the C cells/parafollicular cells

Answer 13

Scattered cells in follicular epithelium or as clusters between follicles
Secrete calcitonin (inhibits Ca2+ mobilisation)
Derived from neural crest, migrate=>thyroid in development

Question 14

Describe the structure and location of the parathyroid glands

Answer 14

Normally 2 pairs
Normally found/embedded in posterior border of lateral lobes of thyroid
No functional significant association with thyroid

Question 15

Describe the cellular organisation of the parathyroid

Answer 15

Densely packed chief cells in irregular cords around blood vessels
Small cells, round central nucleus in cytoplasm, eosinophilia
Secretes parahormone, stimulates calcium mobilisation
Oxyphil cells, no secretory vesicles

Question 16

Describe the shape and structure of the adrenal glands

Answer 16

Pyramidal (R), crescent (L) shape, contact with upper kidney pole
Separated from kidneys by connective tissue, surrounded by renal fascia

Question 17

Describe the structure of the adrenal glands and the embryological derivation

Answer 17

Cortex, from coelomic epithelium lining the posterior abdominal wall
Medulla, from adjacent sympathetic ganglion

Question 18

Describe the structure of the adrenal cortex and its function

Answer 18

Cells secrete steroids

• Zona glomerulosa
• Zona fasciculata
• Zona reticular is

Question 19

What is the function of the zona glomerulosa

Answer 19

Rounded clusters surrounded by capillaries
Secrete mineralcoricoids (aldosterone)
Target, Na+ retention in distal convoluted tubule

Renin/angiotensin regulated

Question 20

What is the function of the zona fasciculata

Answer 20

Radial cell cords
Secrete glucocorticoids (cortisol)
Target, glucose, lipid, protein metabolism
ACTH regulated

Question 21

What is the function of the zona reticularis

Answer 21

Irregular cell cords
Secrete glucocorticoids and sex steroids (weak androgens, sex steroid precursors)
ACTH regulated

Question 22

Describe the function of the adrenal medulla

Answer 22

Modified sympathetic ganglion, a on less
Large polyhedral cells in cords
Receives cholinergic preganglionic sympathetic input from greater, lesser splanchnic nerve via coeliac ganglion
Secrete catecholamines into blood on stimulation

Mainly secrete adrenaline, less secreted noradrenaline

Question 23

Describe the structure of the Islets of Langerhans

Answer 23

Round clusters embedded in exocrine pancreas

Irregular cords around capillaries

Question 24

Cell types and their secretions in the Islets of Langerhans

Answer 24

A, glucagon
B, insulin
S, somatostatin
F, pancreatic polypeptide
Minor cells, VIP, P, motioning, serotonin