1. Endocrine System How the body communicates with itself
Nervous system – impulses travel down nerves
Endocrine system – hormones released into the blood and travel to target organs.

2. Endocrine System Glands can be one of three types
Exocrine – release secretions that are carried within a duct or tube – sweat glands, salivary glands, sebaceous glands
Endocrine – release secretions directly into the blood – thyroid gland, adrenal gland, anterior pituitary gland
Heterocrine – contain both exocrine and endocrine components – pancreas, testis

3. Endocrine System
Endocrine system may consists of organs containing very specific concentrations of secretory cells (thyroid gland, pituitary gland, adrenal gland)
Organs that have dispersed areas of special secretory cells (pancreas), testis, ovary)
Dispersed cells within various organs (stomach, intestine, kidney)

4. Two kinds of secreting cells
Nitrogen-secreting cell
Steroid –secreting cell

5. Primary Endocrine Glands Addressed in this Unit
Hypophysis (Pituitary Gland)
Thyroid Gland
Parathyroid Gland
Adrenal Gland
Pancreas
*Testis and ovary will be covered in Reproductive System

6. Thyroid and Parathyroid Glands
Found at 2nd through 4th cartilages of the trachea
Small gland with four parathyroid glands attached to the posterior surface.
Follicles are the structural unit of the gland.
Follicle consists of a wall of simple cuboidal epithelium cells inclosing a space containing a jelly-like substance called colloid. If the colloid distends the follicles, the epithelial cells can become flattened almost like simple squamous. Colloid combines with iodine to form thyroid hormones – regulate body metabolism.
Isthmus thyroglobulin

8. Thyroid Gland Abnormalities
Hyperthyroid condition often result of tumor. Can produce disease called Graves syndrome
Hypothyroid condition – cretinism in children and myxedema in adults
Goggle-eyed
myxedema
Democratic Republic of the Congo Girl 15 with Cretinism
Democratic Republic of the Congo Girl 15 with Cretinism

9. Thyroid and Parathyroid Glands
Between the follicles are located small groups of parafollicular cells which secrete hormone thyrocalcitonin or often called just calcitonin.
Calcitonin functions to reduce calcium levels in the blood by actively reducing breakdown of bone and inhibiting re-absorption of calcium in digestive system.

10. Adrenal Gland Ectoderm;endoderm
Adrenal gland is located above each kidney
Divided on bases of outer region (cortex) and inner region (medulla)
The cortex is divided into three regions (glomerulosa, fasciculatus, and reticularis)
Ectoderm;endoderm

11. Adrenal Gland
Adrenal Cortex consists of three regions:
Outer region known as the zona glomerulosa. Theses cells are arranged in rounded clumps and secrete hormones known as mineralcorticoids.
The most common mineralcorticoid is aldosterone which helps to control electrolyte and water balance.
The next region is known as the zona fasciculata. It consists of columns of cells. It secretes hormone known as glucocorticoids including cortisone and hydrocortisone.
These hormones help to regulate glucose metabolism and important in inflammation reactions and stress management.

12. The inner region of the cortex is the zona reticularis
The inner region of the cortex is the zona reticularis. Cells of this region form and network of interlinking cells.
Secrete sex hormones mainly androgens or male sex hormones. Usually in small proportions if too many can cause bearded lady.
Adrenal Medulla
Consist of irregularly arranged groups of granular cells and connective tissue
Produces two products epinephrine and norepinephrine.
Part of the bodies response to an emergency or the fight or flight response.

13. Pituitary or Hypophysis
Small gland about size of large pea located under brain.
Often referred to as the “master gland”.
Secretes hormones that regulate other endocrine glands
Consists of two major lobes, anterior and posterior separated by intermediate lobe.
The larger anterior lobe referred to as the adenohypophysis. This is a highly glandular tissue that produces and secretes numerous hormones.
The second smaller posterior lobe is referred to as the neurohypophysis. This is neural tissue that secretes two hormones produced by hypothalmus.
posterior lobe
D = pars distalis, I= pars intermedia
N = pars nervosa, S = stem or stalk
T = pars tuberalis
Anterior lobe

14. Adenohypophysis Neurohypophysis Pituitary gland or Hypophysis
Pars distalis or anterior lobe
Pars nervosa
or posterior lobe
Intermedia between black lines

15. Adenohypothesis
Larger anterior lobe
Subdivided into the glandular pars distalis which is most of the lobe and is active in secretion
Also contains the pars tuberalis that forms covering for stalk
The pars intermedia separates the anterior lobe from the posterior lobe

16. lactation period Adenohypophysis
Cell types in the adenohypophysis are identified as to their staining characteristics
Chromophilic cells include the acidophils which stain with eosin stain and are thus reddish and the basophils which stain with hematoxylin and are thus dark blue/purple colored in hematoxylin/eosin staining.
Chromophobes do not stain with either stain
There are different types of Acidophils that can be separated with very special stains. These can not be separated with H & E stains. They include:
Somatrophs – secrete Growth Hormone
Mammotrophs – secrete prolactin
There are different types of Basophils that can be separated with very special stains. These can not be separated with H & E stains. They include:
Thyrotrophs – secrete Thyroid Stimulating Hormone
Gonadotrophs – secrete Luteinizing (LH) hormone and Follicle Stimulating Hormone (FSH).
ACTH-secrete adenocorticotrophic hormone regulates adrenal cortex
Chromophobes
lactation period

17. Young female dwarf standing next to a boy of normal stature.
Growth Hormone function
Young female dwarf standing next to a boy of normal stature.
gigantism

18. Posterior lobe or Neurohypophysis
Consists mostly of nervous tissue, pituitary cell, herring body
Does not produce any hormones but does secrete two hormones produced by the hypothalamus
Secretes oxytocin – regulates uterine muscle contraction and mammory glands stimulating milk flow
Secretes ADH – Antidiuretic hormone which increases water retention by the kidney