ENDOCRINE SYSTEM<br />Exerts chemical control over the human body<br />Maintains homeostasis <br />Acts with nervous system to coordinate the body's activities<br />Uses chemical messengers called hormones that are transported by the circulatory system (blood)<br />TYPES OF HORMONES<br /><ul><li>Steroid
Protein</li></ul>HYPOTHALAMUS<br /><ul><li>Inferior part of the diencephalon
Control center of all autonomic regulatory activities of the body
Main function of the hypothalamus is homeostasis
HOMEOSTASIS - maintaining the body’s internal environment</li></ul>Plays a major role in controlling the secretions from the Pituitary gland<br />Sends neural and chemical signals to the pituitary gland<br />CHEMICAL SIGNALS<br />Releasing Hormones<br /><ul><li>main purpose is to control the release of another hormone
Capillary bed, portal vein, receptors.</li></ul>Inhibitory Hormones<br /><ul><li>inhibits release of hormones from another structure
convey the hormones through the pituitary stalk into the anterior pituitary. </li></ul>*NEGATIVE FEEDBACK<br /><ul><li>when the particular level of concentration of a particular hormone reaches a certain level in the body, the endocrine gland that secreted the hormone in inhibited and the secretion of that hormone either ceases or decreases significantly
helps to control the concentrations of a number of hormones in the body</li></ul>PITUITARY GLAND (Hypophysis)<br />PITUITARY GLAND<br /><ul><li>a pea-sized, compound endocrine gland, centrally located at the base of the brain.
Sella turcica– saddle-shaped depression of the sphenoid bone where lies the pituitary gland
A short stalk, the infundibulum, and a vascular network connect the pituitary gland to the hypothalamus.
“master organs” of the ES (with the Hypothalamus) </li></ul>2 FUNCTIONAL COMPONENTS<br />Anterior Pituitary (Adenohypophysis)<br /><ul><li>The glandular epithelial tissue
The cells are organized in clumps and cords separated by fenestrated sinusoidal capillaries.
Regulates other endocrine glands and some non-endocrine tissues
Median Eminence</li></ul>*Hormones – See Hormones Page<br />THYROID GLAND <br /><ul><li>Located in the anterior neck region adjacent to the larynx and trachea
Consists of two lateral lobes united by an isthmus
Composed of connective tissue septa and follicles </li></ul>MAIN FUNCTION<br /><ul><li>Synthesize the thyroid hormones </li></ul>Thyroxine (Tetra – iodothyronine or T4)<br />Tri – iodothyronine (T3)<br />Calcitonin <br />STROMA <br /><ul><li>Thin loose areolar connective tissue capsule that forms connective tissue septa</li></ul>FOLLICULAR EPITHELIUM <br /><ul><li>Surrounds each follicle
Composed of reticular fibers and network of capillaries
Can be simple squamous, cuboidal, or low columnar epithelium</li></ul>THYROID FOLLICLE <br />Structural unit of thyroid gland <br />Roughly spherical cyst-like compartment<br />Wall formed by follicular epithelium<br />Central cavity contains a gelatinous substance called colloid<br /><ul><li>Surrounded by 2 types of cells
Less numerous than chief cells</li></ul>PARATHYROID HORMONE ( Parathormone)<br /><ul><li>Increases blood calcium</li></ul>*See Hormones Page for additional information<br />ADRENAL GLAND<br />Paired organs<br />Flattened structure with half – moon shape<br />Surrounded by dense irregular connective tissue – reticular fibers for support<br />Embedded in adipose tissue<br />2 concentric layers:<br /><ul><li>Adrenal cortex
Adrenal medulla</li></ul>Cells of both layers are grouped in cords along capillaries<br />Dense CT capsule sends thin septa to the interior of the gland – trabeculae<br />ADRENAL CORTEX<br />Cells contain numerous lipid droplets<br />Spongyocytes <br />Cells that secrete glucocorticoids, mineralocorticoids, and gonadocorticoids <br />Has 3 concentric layers with fenestrated capillaries<br /><ul><li>Zona Glomarulosa
Store norepinephrine </li></ul>*Hormones – See Hormones Page<br />FEMALE REPRODUCTIVE SYSTEM<br />OVARIES<br /><ul><li>Surface is covered by simple squamous or cuboidal epithelium called germinal epithelium
Under the covered surface is the tunica albuginea made of dense irregular connective tissue and responsible for whitish color of ovary
Below that tunica albuginea is the cortex of the ovary where there is predominance of ovarian follicles
Deep in the cortex is highly vascularized connective tissue core of ovary, medulla
Hormones: Estrogen and Progesterone</li></ul>ESTROGEN<br /><ul><li>Manufactured mostly in ovaries by developing egg follicles
In addition, produced by the corpus luteum, placenta, liver, breasts and adrenal glands in smaller quantities
Luteinizing hormone (LH) and Follicle stimulating hormone (FSH) help to control production of estrogen</li></ul>PROGESTERONE<br /><ul><li>Responsible for the changes in the endometrium in the second half of the menstrual cycle
Low progesterone hormones have negative influences on your body, fertility, pregnancy and can even lead to an expelling of a fertilized egg</li></ul>EGG CELL<br /><ul><li>The cell substance is known as the yolk or oöplasm
The nucleus as the germinal vesicle and the nucleolus as the germinal spot
The human ovum is surrounded by a number of egg envelopes:
An outer, thicker coat formed of radially elongated follicular cells.
Between the vitelline membrane and zona pellucida, there is a narrow space called perivitelline space </li></ul>MALE REPRODUCTIVE SYSTEM<br />TESTES<br />Located in the scrotum<br />Secrete hormone known as androgen; most important of which is testosterone <br />Have an exocrine part, Seminiferous tubules (tightly coiled) and endocrine part, intersitial or Leydig cells (clusters) Leydig cells<br />Synthesise and secrete testosterone<br />Testosterone increases sharply at puberty<br />Essential for the production of sperm<br />Production of testosterone is controlled by the release of luteinizing hormone (LH) <br />Located in the interstitial tissue between the convuluted seminiferous tubules<br />Occurs in clusters, which are variable in size and richly supplied by capillaries<br />Its cytoplasm is strongly acidophilic and finely granular<br />The nucleus is large, round and often located eccentric in the cell <br />GENERAL EFFECTS OF TESTOSTERONE<br /><ul><li>Anabolic</li></ul>Growth of muscle mass and strength<br />Increased bone density and strength<br />Linear growth<br />Bone maturation<br /><ul><li>Androgenic (Virilizing)
Growth of beard and axillary hair (sec. sex charac.)</li></ul>Hypothalamus<br />GnRH<br />Pituitary<br />LH<br />Testes<br />Testosterone<br />SERTOLI CELLS<br />‘Nurse’ cell of the testes<br />Part of the seminiferous tubule<br />Activated by follicle-stimulating hormone and has FSH-receptor on its membranes.<br />Estradiol and Inhibin – hormone secreted<br />Estradiol<br />Prevent apoptosis (death of cells) of germ cells <br />Inhibin<br />Inhibit production of FSH<br />PINEAL GLAND<br /><ul><li>Also called Epiphysis Cerebri
Functions as its capsule and which sends connective tissue septa into the pineal body, subdividing it into lobules.</li></ul>THYMUS GLAND<br /><ul><li>Enclosed in a capsule and divided internally by cross-walls into many lobules (full of T-lymphocytes).
Lymphocytes that have passed through the thymus are transformed into T cells.
Lymphocytes are white blood cells that function to fight infection. There are two kinds of lymphocytes: B cells and T cells. T cells participate in identifying and destroying body cells that are infected.</li></ul>HORMONES<br /><ul><li>Thymosin
Activates the immune system by activating the T-Cells (T-Killer Cells; T-Helper Cells; T-Memory Cells)