Block 4: Histology 10/18 - Endocrine System

Front 1

What's another name for the pituitary gland? What are its lobes?

Back 1

Pituitary Gland AKA Hypophysis
Comprised of:
Anterior pituitary (adenohypophysis)
Posterior pituitary (neurohypophysis)

Front 2

To what structure is the functionality of the pituitary gland linked? What links these two structures?

Back 2

Linked to hypothalamus by pituitary stalk

Front 3

What is Rathke's pouch? What does it give rise to?

Back 3

Rathke's pouch is a depression in the roof of the mouth (during development); gives rise to the ANTERIOR pituitary

Front 4

Why do the hypothalamus and anterior pituitary employ a portal system? Does this apply to the posterior pituitary?

Back 4

Allows for "private" communication between the two capillary beds; thus hormone of the hypothalamus would be secreted directly to ANTERIOR pituitary without having to go to systemic circulation.

Applies to ANTERIOR pituitary only.

Front 5

What cell types can be identified in the anterior pituitary? What do they produce?

Back 5

Chromophobes - pale (degranulated chromophils or undifferentiated)
Chromophils:
--Acidophils (pink) - produce GH, prolactin

--Basophils (blue) - produce FSH, LH, TSH, ACTH, MSH (Melanocyte stimulating hormone)

Front 6

What is the function of Growth Hormone? What would excess GH result in? A deficiency of GH?

Back 6

GH stimulates growth (indirectly) of epiphyseal cartilage, causing an increase in long bone growth

Excess: leads to acromegaly in adults (no epiphyseal plates for long bone growth; only get thickening of bones) and gigantism in children

Deficiency results in hypopituitary dwarfism

Front 7

What is the function of Prolactin?

Back 7

Stimulate milk synthesis by mammary glands

Front 8

What is the function of Follicle Stimulating Hormone?

Back 8

Stimulates follicle development in ovary and spermatogenesis in testes

Front 9

What is the function of Luteinizing Hormone?

Back 9

Aids in maturation of follicles (ovaries), stimulates increase in progesterone; stimulates androgen secretion in men (by Leydig cells)

Front 10

What is the function of ACTH (Adrenocorticotropic Hormone)?

Back 10

Stimulates adrenal gland to increase corticosteroid production

Front 11

Describe the cellular structure of the posterior pituitary. Where are hormones stored? What hormones does the pituitary release?

Back 11

Posterior pituitary contains unmyelinated axons of secretory nerve cells.

Cell bodies reside in hypothalamic centers.

Hormones are stored in Herring Bodies.

Posterior pituitary produces Vasopressin (ADH) and Oxytocin

Front 12

What is the function of Vasopressin?

Back 12

Vasopressin = ADH; promotes vasoconstriction, resulting in increased blood pressure. Increases water permeability of DCT in kidney, promoting reabsorption of water.

Front 13

What is the function of Oxytocin?

Back 13

Promotes labor contractions, promotes lactiferous gland and duct secretion (for breast milk)

Front 14

What hormone in the pituitary makes use of positive feedback?

Back 14

Oxytocin--its secretion stimulates release of more oxytocin

Front 15

What is the embryonic germ layer origin of the thyroid?

Back 15

Endoderm--from floor of oral cavity (foramen cecum)

Front 16

What is the epithelial cell type of the cells that line the follicles of the thyroid?

Back 16

Simple cuboidal

Front 17

What is the effect of TSH on thyroid follicles?

Back 17

Secretion of TSH causes follicular cells to secrete thyroglobulin (or COLLOID) which is stored in interior.

When stimulated, colloid is iodinated and prepared for BASAL secretion as T3 or T4.

Front 18

What is the function of T3 and T4?

Back 18

Regulate metabolic rate (cellular respiration)

Front 19

How is the thyroid gland, as an endocrine, atypical?

Back 19

-Stores appreciable amount of product

-Follicular cells secrete thyroglobulin APICALLY but T3 and T4 are secreted BASALLY

-Exogenous product (iodine) needed to complete its product and must be supplied via diet

Front 20

What's another term for parafollicular cells? What is their function?

Back 20

Parafollicular cells AKA C-cells

Produce calcitonin

Front 21

What is the function of calcitonin?

Back 21

Inhibits bone resorption and reduces Ca2+ in blood

Front 22

What is Cretinism?

Back 22

Stunted physical and mental growth due to untreated CONGENITAL deficiency of TH

Front 23

What is Myxedema?

Back 23

Puffiness (edema) of soft tissues in a prolonged HYPOTHRYOID state

Front 24

What is Graves' Disease?

Back 24

Autoimmune disease in which auto-antibodies bind to TSH-receptors and chronically stimulate them; results in overproduction of TH's and HYPERTHRYROIDISM

Front 25

What is the embryonic layer origin of the adrenal glands?

Back 25

Intermediate mesoderm and neural crest

Front 26

What are the three regions of the adrenal cortex?

Back 26

Zona Glomerulosa
Zona Fasciulata
Zona Reticularis

Front 27

What factors act on the Zona Glomerulosa of the adrenal gland? What hormones are secreted?

Back 27

Angiotensin & Corticotropin (ACTH) to release Mineralocorticoids (Aldosterone)

Aldosterone stimulates Na+ reabsorption

Front 28

Describe the appearance of the Zona Glomerulosa.

Back 28

Zona Glomerulosa consists of clusters of cells

Front 29

What factors act on the Zona Fasciculata of the adrenal gland? What hormones are secreted?

Back 29

Corticotropin-->Glucocorticoids (Cortisol)

Front 30

What is the effect of glucocorticoids?

Back 30

Affect carbohydrate metabolism

Anabolic effect inside liver; catabolic effect outside liver

Front 31

What factors act on the Zona Reticularis of the adrenal gland? What hormones are secreted?

Back 31

Corticotropin-->Androgens

Front 32

Describe the appearance of the Zona Reticularis.

Back 32

Irregular, anastamosing cords

Front 33

What is Cushing's Syndrome?

Back 33

Adrenal Cortical Hyperfunction: prolonged elevation of cortisol levels; symptoms include central obesity, moon face, excess sweating

Front 34

What is Addison's Disease?

Back 34

HYPOfunction of all three adrenal zones; chronic adrenal insufficiency

Front 35

What is the embryonic origin of the adrenal medulla? What are its secretions?

Back 35

Neural Crest

Secretes catecholamines (Norepi and Epi)

Front 36

What is the effect of the catecholamines?

Back 36

Catecholamines = Epi and Norepi; involved in fight or flight syndrome

Front 37

What is the embryonic germ layer origin of the Islets of Langerhans? What is its function?

Back 37

Endoderm (endocrine = endoderm)

Function is to regulate blood glucose

Front 38

What cells comprise the Islets of Langerhans? How do they differ? What are other products of the Islets of Langerhans?

Back 38

Beta Cells: produce insulin to lower blood glucose and increase glucose uptake by liver

Alpha cells: produce glucagon; promotes glycogenolysis; thus increase blood glucose

Other products: Somatostatin, Pancreatic Polypeptides

Front 39

What are the two main cells of the Parathyroid? Functions?

Back 39

Chief cells (principal) produce parathyroid hormone (increases blood calcium and decreases blood phosphate--essential for neuromuscular activity; promotes bone resorption by osteoclasts; promotes phosphate excretion by kidneys)

Oxyphils: larger, more acidophilic (pink); function unknown

Front 40

What are symptoms of hyperparathyroidism?

Back 40

High blood calcium, low phosphate

Front 41

What is the function of the Pineal gland? How would you recognize it under the microscope?

Back 41

Produces melatonin

Brain Sand!

Front 42

What is the embryonic origin of the thyroid?

Back 42

Endodermal; migrated to sub-pharyngeal locale

Front 43

What is the embryonic origin of the pituitary?

Back 43

Dual: Neural and epithelial