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2021 The Endocrine System

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a. develops as outgrowth of diencephalon. b. forms: ... c. reticular fibers. 4. extensive capillary plexuses. III. Adrenals. B. Adrenal cortex (21.2) ... – PowerPoint PPT presentation

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Title: 2021 The Endocrine System


1
20-21 The Endocrine System
  • I. Overview
  • II. Pituitary
  • III. Adrenals
  • IV. Pancreas
  • V. Thyroid
  • VI. Parathyroids
  • General structure fenestrated capillaries

http//www.ama-assn.org/ama/pub/category/7157.html
2
I. Pituitary
  • A. Development
  • 1. neurohypophysis (post. Lobe) (20.1)
  • a. develops as outgrowth of diencephalon
  • b. forms
  • 1) pars nervosa (posterior lobe note
    error in 20.1)
  • 2) infundibulum

3
I. Pituitary
  • A. Development
  • 2. adenohypophysis ( ant. Lobe) (20.1)
  • a. develops from Rathkes pouch
  • 1) oral ectoderm
  • b. forms
  • 1) pars distalis (anterior lobe)
  • 2) (pars tuberalis pars intermedia)

4
I. Pituitary
  • B. Hypothalamo-hypophyseal portal system (20.2)
  • 1. primary capillary plexus
  • a. base of infundibulum / hypothalamus
  • 2. veins to anterior lobe
  • 3. secondary capillary plexus
  • 4. transports neurohormones
  • a. releasing hormones
  • b. inhibiting hormones

5
I. Pituitary
  • C. Pars distalis 20.6
  • 1. Chromophobes chromophils
  • 2. basophils
  • a. gonadotrophic cells
  • 1) FSH
  • 2) LH
  • b. thyrotropic cells
  • 1) TSH
  • c. corticotrophic cells
  • 1) ACTH

6
I. Pituitary
  • C. Pars distalis
  • 3. acidophils
  • a. somatotropic cells
  • 1) GH
  • b. mammotropic cells
  • 1) PRL

7
I. Pituitary
  • D. Neurohypophysis (20.3)
  • 1. pituicytes
  • 2. neurosecretory cells
  • 3. 100,000 unmyelinated axons from
    hypothalamus

8
I. Pituitary
  • D. Neurohypophysis 20-9

9
I. Pituitary
  • D. Neurohypophysis 20.7
  • 4. vasopressin / ADH
  • a. contraction of smooth muscle in arteries
  • b. increase reabsorption of H2O in
    collecting tubules
  • 5. oxytocin
  • a. contraction in pregnant uterus

10
III. Adrenals
  • A. Overview (21.2)
  • 1. adrenal cortex
  • a. steroids
  • 2. adrenal medulla
  • a. E NE
  • 3. stroma
  • a. capsule
  • b. trabeculae
  • c. reticular fibers
  • 4. extensive capillary plexuses

11
III. Adrenals
  • B. Adrenal cortex (21.2)
  • 1. zona glomerulosa (21.3)
  • a. 15 of adrenal cortex

12
III. Adrenals
  • B. Adrenal cortex
  • 1. zona glomerulosa
  • b. clusters of cells (21.3)
  • c. mineralocorticoids (aldosterone)
  • 1) increase DCT absorption of Na

13
III. Adrenals
  • B. Adrenal cortex
  • 2. zona fasciculata (21.3)
  • a. 65 of adrenal cortex
  • b. cells in cords (21.3)

14
III. Adrenals
  • B. Adrenal cortex
  • 2. zona fasciculata
  • c. many lipid droplets in cytoplasm (21.3)
  • d. glucocorticoids (cortisol
    corticosterone)
  • 1) influence CHO metabolism
  • 2) suppress immune response

15
III. Adrenals
  • B. Adrenal cortex
  • 3. zona reticularis (21.3)
  • a. 7 of adrenal cortex

16
III. Adrenals
  • B. Adrenal cortex
  • 3. zona reticularis
  • b. irregular cords in network (21.5)
  • c. lipofuscin granules
  • d. androgens
  • e. little effect vs. testicular hormones

17
III. Adrenals
  • C. Adrenal medulla (21.3)
  • 1. cells in cords
  • 2. secrete E NE
  • 3. innervated by preganglionic sympathetic
    (myelinated) axons

18
III. Adrenals
  • Adrenal medulla
  • Look for
  • Preganglioni sympathetic fibers
  • Blood vessels

19
IV. Pancreas (Islets of Langerhans)
http//diabetes.niddk.nih.gov/dm/pubs/dictionary/P
-T.htm
20
IV. Pancreas (Islets of Langerhans)
  • A. Cluster of cells in cords (21.9)
  • 1. network of fenestrated capillaries

21
IV. Pancreas (Islets of Langerhans)
  • A. Cluster of cells in cords
  • 2. A cells glucagon, incr. blood sugar
    (21.11)
  • immunohistochemistry for glucagon cells

22
IV. Pancreas (Islets of Langerhans)
  • A. Cluster of cells in cords
  • 3. B cells insulin, decr. blood sugar (21.12)
  • 4. D cells somatostatin inhibits A B cells
  • 5. E cells unknown function
  • immunohistochemistry for insulin

23
V. Thyroid
  • A. Gross Anatomy (21.15)
  • 1. anterior to larynx
  • 2. two lobes connected by isthmus
  • 3. well vascularized

24
V. Thyroid
  • B. Follicles (21.16,21.17)
  • 1. squamous to columnar epithelium
  • a. squamous inactive
  • b. columnar active
  • 2. colloid
  • a. thyroxine / T4
  • b. triiodothyronine / T3
  • 3. stimulates rate of metabolism
  • 4. Influenced by TSH

25
V. Thyroid
  • C. Parafollicular cells (21.18)
  • 1. calcitonin
  • a. decr. blood Ca

26
VI. Parathyroid glands
  • A. Gross anatomy (21.22)
  • 1. four small glands
  • 2. located on posterior of thyroid gland

27
VI. Parathyroid glands
  • Microscopic anatomy 21.16

28
VI. Parathyroid glands
  • B. Parenchyma
  • 1. oxyphil cells (21.24)
  • a. larger, polygonal cells
  • b. unknown function

29
VI. Parathyroid glands
  • 2. chief cells 21.23
  • a. pale, acidophilic cytoplasm b.
    secretes parathyroid hormone c. incr. blood
    Ca levels
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