Endocrine System 😌

Question 1

Components of the Endocrine System:

1. 4 Major Endocrine Organs
2. 4 Endocrine components w/in solid organs
3. 2 Diffuse neuroendocrine system (DNES)

Answer 1

Major Endocrine Organs:
Pituitary, Pineal, Adrenal, Thyroid - Gland

Endocrine components w/in solid organs:
Pancreas, Testis, Ovary, Kidneys

Diffuse neuroendocrine system:
Most of the time scattered in GIT, Respiratory tract

Question 2

Pituitary gland

1. Other name
2. Housed where?
3. Parts

Answer 2

1. Hypophysis cerebrii
2. Housed in sella turcica
3. Adenohypophysis (anterior part) and Neurohypophysis (posterior part)

Question 3

What is the master endocrine gland?

Answer 3

Pituitary gland

Question 4

Embryology of the Pituitary gland

1. Originates from which structure/s?
2. How is it formed?

Answer 4

1. Partly from the developing brain (neural ectoderm) and partly from the developing oral cavity (oral ectoderm)
2. 3rd week of development:
   Neurohypophyseal bud grows caudally from the diencephalon but it is still connected through the future infundibulum -> becomes the posterior pituitary

An outpocketing grows cranially from the roof of the pharynx and eventually becomes the anterior pituitary

Late 2nd month of development:
The hypophyseal pouch would detach from the roof of the pharynx and merge with the neurohypophyseal bud.

Fetal period:
During this period, the anterior and posterior parts of the pituitary would complete their development.

Question 5

Determine the divisions of the Pituitary Gland

1. Typically glandular
2. Resemble CNS tissue
3. Dark-staining
4. Pale staining

Answer 5

1. Adenohypophysis/Anterior lobe
2. Neurohypophysis/Posterior lobe
3. Adenohypophysis
4. Neurohypophysis

Question 6

Pars distalis

1. Relative size and location
2. Group of cells

Answer 6

1. Largest and most anterior
2. Chromophils - secretory cells of the anterior pituitary with hormones stored in the cytoplasmic granules; further classified into acidophils and basophils
   Acidophils:
   >Somatotophs (constitute half the cells in PD)
   >Lactotrophs: PRL
   Basophils:
   >Corticotrophs: synthesize POMC which forms ACTH and LPH upon cleavage
   >Gonadotrophs: FSH & LH
   >Thyrotrophs: leas abundant

Chromophobes:

• few to no secretory granules
• have pale nuclei and cytoplasm
• SMALLER than chromophils
• represent a heterogeneous grp including SCs, undx progenitor cells

Question 7

Funnel-shaped region hugging around the infundibulum of the neurohypophysis. What cells does this area contain?

Answer 7

Pars tuberalis

>Contain mostly gonadotrophs

Question 8

Thin zone of basophilic cells between pars distalis and pars nervosa. Cells?

Answer 8

Pars intermedia
>Often invaded by basophils and chromophobes
>Usually contain small, colloid-filled cysts of various sized derived from the lumen of the embryonic hypophyseal pouch

Question 9

Neurohypophysis (Posterior Pituitary)

1. Composition
2. Unique char in relation to hormones

Answer 9

1. Consists mainly of unmyelinated axons of large secretory neurons with cell bodies in the supraoptic and paraventricular nuclei of the HP
2. DOES NOT contain the cells that synthesize the two hormones it stores (ADH and OT)

Question 10

Pars Nervosa

1. Location
2. Function
3. Translocation of hormones down the hypothalamic-hypophyseal tract utilizes this protein

Answer 10

1. Neurohypophysis (Posterior pituitary)
2. Storage site of OT and ADH
3. Neurophysin

Question 11

Infundibular stalk

1. Location
2. Function

Answer 11

1. Neurohypophysis

2. Bridges the hypothalamic and hypophyseal regions in the median eminence

Question 12

Identify the type of cell in the posterior pituitary.

1. Highly branched glial cells that resemble astrocytes (helper cells) because it comes from diencephalon
2. Most abundant cell type in posterior pituitary
3. Axonal dilatations where hormones accumulate

Answer 12

1. Pituicytes
2. Pituicytes
3. Neurosecretory bodies (Herring Bodies)

Question 13

Hormones of the posterior pituitary gland? Synthesized where? Function?

Answer 13

1. ADH/Arginine Vasopressin
   - synthesized in the supraoptic nucleus
   - increases water permeability of renal collecting ducts
2. Oxytocin
   - synthesized in the PVN
   - stimulates contraction of the mammary gland myoepithelial cells and uterine smooth muscle

Question 14

Hypothalamic-Hypophyseal Tract System

1. Pathway
2. ADH and OT undergo what transport and accumulate where temporarily before release and uptake by what?
3. What enables distribution of the hormones throughout the body? Be specific.

Answer 14

1. SON + PVN -> infundibulum -> Pars Nervosa of Neurohypophysis
2. ADH and OT undergo axonal transport and accumulate temporarily in the axons of the hypothalamic-hypophyseal tract before release and uptake by capillaries
3. Inferior hypophyseal artery

Question 15

Hypothalamic-Hypophyseal Portal System
1. Carries neuropeptides from where to where?
2. Blood supply?
3. Venous drainage?
4. Superior Hypophyseal Arteries
>Supplies what?
>Divides into what as it passes down the infundibulum.
Branches?
5. Inferior Hypophyseal Arteries
>Supplies what?
>Arises as a single branch from?

Answer 15

1. From the median eminence to the adenohypophysis to simulate or inhibit hormone release by endocrine cells
2. Internal Carotid A.
3. Hypophyseal V.
4. Superior Hypophyseal Arteries
   >Supplies the median eminence and infundibular stalk
   >Divides into anterior and posterior branches as it passes down the infundibulum
   >Branches:
   A. artery of trabecula - goes down to supply pars distalis
   B. Primary plexus of fenestrated capillaries which rejoin to form venules that branch again as larger secondary capillary plexus in your adenohypophysis
5. Inferior Hypophyseal Arteries
   >Supplies neurohypophysis
   >From ICA

Question 16

Identify.
1. Hyperactive corticotrophs which release ACTH which stimulates adrenal glands to increase secretion of corticosteroids

2. Hypersecretion of somatotrophs
   A. In childhood = proportionate growth
   B. During adulthood = disproportionate growth
3. Hypersecretion of most pituitary hormones due to a benign tumor

Answer 16

1. Cushing’s disease

2.
A. Gigantism
B. Acromegaly

3. Pituitary Adenoma

Question 17

Pineal gland

1. Other term
2. Function
3. Histologically covered by?
4. Embryonic origin
5. Hormone

Answer 17

1. Epiphysis cerebrii
2. Regulates the daily rhythm of bodily activities
3. CT of the pia mater
4. Neuroectoderm in the posterior wall of 3rd ventricle
5. Melatonin
   - regulates/promotes sleep in humans
   - production is influenced by the detection of light (inhibited) and dark (promoted) by the retina

Question 18

Identify the structure in the pineal gland

1. Major secretory organ, Basophilic cytoplasm, irregular euchromatic nuclei
2. Modified astrocytes, elongated nuclei that are more heavily stained than #1, usually found in perivascular areas between groups of #1
3. The “brain sand”, extracellular mineral deposit with no apparent significance, excellent marker for pineal gland

Answer 18

1. Pinealocyte
2. Glial cells
3. Corpora arenacea

Question 19

Thyroid gland

1. Located anterior and inferior what structure
2. Consists of two lobes united by?
3. Embryonic origin
4. Hormone/s

Answer 19

Thyroid gland

1. Larynx
2. Isthmus
3. Foregut endoderm near base of developing tongue
4. T3, T4, Calcitonin

Question 20

Embyonic Development of the Thyroid Gland?

Answer 20

3rd week: Begins as an entodermal thickening in the midline of the pharynx floor between tuberculum impar and copula —> Thickening involutes to become the thyroglossal duct —> Duct elongates and its distal end becomes bilobed —> Bilobed terminal swellings becomes the thyroid gland —> Gland migrates inferiorly in the neck —> By 7th week, it reaches final position wrt trachea and pharynx

Question 21

Thyroid gland neurovasculature
Arterial Supply
1. Superior thyroid artery
>Branch of
>Accompanied by?
>Mainly supplies what?

2. Inferior thyroid artery
   >Branch of?
   >Supplies what?

Venous Drainage (3)

Lymphatic drainage (2)

Innervation (3)

Answer 21

1. Superior thyroid a.
   >Branch of ECA
   >Accompanied by external laryngeal n.
   >Mainly supplies the anterosuperior aspect of the gland
2. Inferior thyroid artery
   >Branch of thyrocervical trunk
   >Supplies posteroinferior aspect of the gland

Venous Drainage:
Superior, Middle, Inferior Thyroid V.

Lymphatic Drainage
>Mainly drains into deep cervical lymph nodes
>Few lymph vessels descend to the paratracheal nodes

Innervation
>Superior, Middle, Inferior Cervical Sympathetic Ganglia

Question 22

Identify the structure in the thyroid gland.
1. Composed of millions of rounded, epithelial, colloid-filled thyroid follicles

2. Filled with large gelatinous protein (thyroglobulin)
3. Cells lining the thyroid follicle.
   >Epithelium classification/s?
4. Found in the basal lamina of follicles or isolated in clusters; larger than #3; derived from neural crest cells; more uniform in size than #3.

Answer 22

1. Parenchyma
2. Colloid
3. Thyrocytes/Follicular cells
   >If active, low columnar. If hypoactive, squamous
4. C cells/Clear Cells/Parafollicular cells

Question 23

Chronic dietary iodine deficiency?

Answer 23

Goiter

Question 24

Parathyroid glands

1. Embryonic Origin
2. Location, specific embryonic origin

Answer 24

1. Pharyngeal Pouches
   2.
   A. 2 superior parathyroid glands (PTH IV)
   >More constant position
   >Lies ~1cm superior to pt of entry of inferior thyroid arteries
   >Dx from 4th pharyngeal pouch

B. 2 inferior parathyroid glands (PTH III)
>Position may vary among individuals
>Dx from 3rd pharyngeal pouches

Question 25

Neurovasculature of the Parathyroid Glands Blood supply 1 main 5 others Venous Drainage (1) Lymphatic Drainage (2) Innervation (1)

Answer 25

Blood supply: >Inferior thyroid artery >Others: Superior thyroid arteries, thyroid ima a., laryngeal a., tracheal a., esophageal a. ``` Venous Drainage Parathyroid veins (draining into the thyroid plexus of veins of the thyroid gland and trachea) ``` Lymphatic >Deep cervical LN >Paratracheal LN Innervation >Vasomotor, NOT secretomotor!! >Thyroid branch of the cervical (sympathetic) ganglia

Question 26

Identify type of cells of the Parathyroid Gland 1. Small polygonal, round nuclei, pale staining, slightly acidophilic cytoplasm, more abundant in younger people, secretes which hormone? 2. Degenerated/transitional derivatives of principal cells exhibiting low levels of PTH synthesis → Larger than principal cells with very acidophilic cytoplasm → Smaller population and clustered → More common in older individuals; Replaces principal cells and thus accumulate with age

Answer 26

1. Principal (chief) cells. Secrete PTH which raises blood Ca2+ lvls 2. Oxyphilic (acidophilic) cells

Question 27

Identify disease. 1. Diminished secretion of PTH ▪ Bones become denser and more mineralized ▪ Striated muscles exhibit abnormal contractions due to an inadequate concentration of calcium ions 2. → Increased secretion of PTH >Stimulates osteoclasts for breakdown of bones >Exhibited by increased blood calcium that can be deposited in cartilages, arteries, or kidneys

Answer 27

1. Hypoparathyroidism | 2. Hyperparathyroidism

Question 28

Adrenal glands 1. Other name 2. Major attachment?

Answer 28

1. Suprarenal glands | 2. Diaphragmatic crura

Question 29

Two concentric regions of the adrenal medulla | >Include their color and embryonic origin

Answer 29

1. Adrenal Cortex - Yellowish - Mesoderm 2. Adrenal Medulla - Reddish-brown - Neural crest ectoderm

Question 30

Dual blood supply of the adrenal medulla?

Answer 30

Medullary arterioles (arterial blood) and capillaries of the cortex (venous blood)

Question 31

Adrenal cortex hormones

Answer 31

Cortisol and androgens

Question 32

Three concentric zones of the adrenal cortex

Answer 32

GFR Zona glomerulosa Zona fasciculata Zona reticularis