1. THE ENDOCRINE SYSTEM

2. Endocrine System Consists of a variety of glandular organs which act with the nervous system in controlling body activities and maintaining homeostasis. HORMONES-Are chemicals secreted by glands of the endocrine system and are transmitted in the blood to the tissue they affect. – The physiological effect of a particular hormone is restricted to a certain tissue called TARGET TISSUE. – Cells of target tissue possess specific receptor sites for the hormone molecules. – Endocrine- “ductless gland” They secrete their hormones directly into the blood. – The endocrine glands include the: pituitary gland, thyroid, parathyroid, adrenal, pancreas, pineal, thymus, and gonads, (testes) for males and (ovaries) for females.

3. Types of Hormones Proteins Steroids Amines Prostoglandins

4. Types of hormones Amines prostaglandins

5. Functions of the Endocrine System 1.Regulate metabolic processes 2.Control the rate of certain chemical reactions within the body 3.Aid in the transport of substances through the cell membranes 4.Play vital roles in cell growth, water and electrolyte balance 5.Control reproduction

6. Control of Hormone Secretions Negative Feedback System Gland A secretes Hormone A. Hormone A stimulates Gland B to secrete Hormone B Hormone B inhibits Gland A from secreting more Hormone A Gland A will not secrete more Hormone A until the levels of Hormone B drop to a certain level. The Hypothalamus controls the secretion of endocrine gland hormones 2 ways: 1. by secreting releasing or inhibitory factors 2. by nerve control

7. Endocrine Glands Pituitary Gland (hypophysis) “MASTER GLAND” Located on the inferior center of the brain below the hypothalamus Suspended beneath the brain on a stalk called the infundibulum Divided into 2 main parts: Anterior pituitary (adenohypophysis) Posterior pituitary (neurohypophysis)

8. Pituitary gland Ant. Pituitary is controlled by releasing factors from the hypothalamus Post. Pituitary is controlled by nerves from the hypothalamus. Anterior Pituitary secretes 6 different hormones: 1.Growth Hormone (GH) 2.Thyroid Stimulating Hormone (TSH) 3.Adrenocorticotrophic Hormone (ACTH) 4.Follicle Stimulating Hormone (FSH) 5.Lutenizing Hormone (LH) 6.Prolactin

9. Posterior Lobe Hormones The post. Pituitary does not synthesize hormones. They are synthesized in the hypothalamus. Post. Pituitary Hormones 1.Antidiuretic hormone 2.Oxytocin

10. Anterior Lobe Hormones 1. Growth Hormone (GH) (Somatotropin) Stimulates body cells to increase in size and undergo rapid cell division Conditions concerning GH Dwarfism-hypopituitary dwarf all body parts are proportional most are normal intellectually. Some need hormone therapy so they can develop sexually

11. GH conditions Giantism- hyperpituitary due to oversecretion of GH, usually due to a tumor. Acromegaly- Secretion of GH after growth plate closure of the long bones. These people are characterized by large hands and feet, protruding jaw, large tongue and nose

13. Ant. Lobe Hormones 2. Prolactin- milk production in the pregnant female breast. 3. Thyroid Stimulating Hormone (TSH) (thyrotropin) Controls the secretions of thyroid hormones. Some external features influence the release, extreme cold and emotional stress 4.Adrenocorticotrophic hormone (ACTH) Controls the manufacture and secretion of hormones by the adrenal cortex

14. Ant. Pit. Hormones cont. Follicle Stimulating Hormone ( FSH)- responsible for the growth and development of the egg containing follicle in the female ovary, also stimulates the follicle cells to secrete extrogen In males, stimulates the production of sperm cells in the testes Lutenizing Hormone (LH) Promotes the secretion of sex hormones in both male and female Essential for the release of the egg cells from the ovary

15. Posterior Lobe Hormones Posterior pituitary composed primarily of neuroglial cells (pituicytes). These cells seem to function as supporting cells for nerve fibers that run from the hypothalamus and synthesize the hormones. 1.ADH Antidiuretic Hormone – inhibits urine formation. It acts on the kidneys and reduces the amount of water they excrete. ADH is important in regulating the water concentration of the body.

16. ADH Diabetes insipidus- condition in which there is not enough ADH being secreted of total absence of ADH being secreted. Causes massive amounts of urine to be produced and intense thirst. As much as 45 liters of urine produced in a day. Treated with synthetic ADH.

17. Post. Pit. Hormones Oxytocin- causes contraction of the smooth muscle in the walls of the pregnant uterus. Released at the end of pregnancy and plays an important role in childbirth. Also causes milk to be ejected from the lactating breast after childbirth.

18. The Thyroid Vascular organ that consists of 2 large lobes connected by a broad isthmus. Located just inferior to the larynx on either side of the trachea. It has the ability to remove iodine from the blood. Composed of groups of secretory cells called follicles. They produce and secrete three hormones that effect the metabolic rate of most body cells and blood calcium levels.

19. Thyroid hormones Thyroxine & triiodothyrine They act to increase the rate of energy release from CHO’s and the rate of protein synthesis. Calcitonin Helps regulate the calcium level of the blood by inhibiting the rate at which calcium leaves the bones and enters the blood. Lowers the blood Ca++ level Decreases osteoclast activity of the bones as well as allows Ca++ to exit body thru the kidneys and large intestine.

20. Disorders of the Thyroid Hypothyroidism- not enough thyroxine or I-3 produced. Cretinism- infants and children, stunted growth, abnormal bone formation, retarded mental development, low body temperature. If not corrected within the first month of birth permanent mental retardation will occur. Myxedema- adults and teens, low metabolic rate, mentally slow, gain in a considerable amount of weight. Swollen tissues due to edema.

21. Hyperthyroidism Grave’s Disease – elevated metabolic rate, abnormal weight loss, excessive perspiration, muscle weakness and emotional instability. Eyes are likely to protrude due to edema behind the eyes. Thyroid is likely to enlarge (goiter)

22. Goiter Is an enlargement of the thyroid. Toxic goiter- due to the oversecretion of TSH from the ant. Pituitary Simple Goiter- due to lack of iodides in the diet.

23. Banjo Goiter

24. Parathyroid Gland Located on the posterior surface of the thyroid There are usually 4, 2 each on the lateral lobes of the thyroid. Yellowish brown structure covered with a thin layer of connective tissue Hormone secreted is called parathormone (PTH). Causes an increase in blood Ca++ levels and a decrease in phosphate levels. Does this by influencing the bones, intestines, and kidneys.

25. Parathormone Does this by: Activates bone reabsorbing osteoclasts Enhances the absorption of Ca++ rich food by the small intestine. Kidneys conserve blood Ca++ and increase the excretion of phosphates in the urine. Seems to be free of control by the hypothalamus.

26. Adrenal Glands Each sits atop the kidneys and are embedded in a mass of fat that encloses the kidneys. Pyramid shaped and very vascular divided into 2 parts: Adrenal medulla- inner portion Adrenal cortex- outer portion makes up the bulk of the gland. Hormones of the A. medulla Epinepherine & Norepinepherine Increases the rate of heart, elevates blood pressure, raises blood sugar, raises breathing rate, dialation of airways, lowers digestive activity. (FIGHT OR FLIGHT RESPONSE)

27. Hormones of the Adrenal Cortex All steroids, all are vital to life. 3 types of hormones secreted by different layers of the cortex. 1.Mineralocorticoids- regulate the concentration of extracellular electrolytes. 2.Glucocorticoids-influence the metabolism of carbs, proteins, and fats. 3.Sex hormones-effect sexual characteristics of both male and females.

28. Sex hormones

29. PANCREAS Flattened globular organ just posterior to stomach and small intestine. Islets of Langerhans are secretory cells. 2 types: 1.Alpha cells- glucagon which converts glycogen to glucose. Raising blood sugar levels. 2.Beta cells- insulin facilitates the transport of glucose into the cells of the body. lowering blood sugar levels.

30. Disorders of the Islets Diabetes Mellitus- severe upset of carbohydrate metabolism. 2 types: 1.Type I- childhood onset. Complete lack or severe shortage of insulin secretion 2.Type II – adult onset. Insulin receptors do not recognize insulin secreted Both cause elevated blood glucose levels. This can cause a great deal of side effects to all systems of the body. Hypoglycemia-too much insulin secreted. Resulting in low blood sugar after a spike in blood sugar levels.

31. Diabetes mellitus

34. Pineal Gland Located deep within the cerebral hemispheres of the brain Functions not entirely clear known to secrete at least 1 hormone. Melatonin-thought to stimulate the secretion of releasing factors from the hypothalamus. This affects the secretion of gonadotropins and ATCH. Thought to control the menstrual cycle in human females Controls the circadian rhythms- period of wakefulness and sleeping.

35. Thymus gland Located in the mediastinum between the lungs and heart. Relatively large in children but diminishes in size with age. Secretes a hormone called thymosin Thymosin- affects the production of certain white blood cells. (lymphocytes) Immune system function

36. The Gonads Female- Ovaries Secretes the hormones estrogen and progesterone. Estrogen-causes the maturation of the sexual organs and the development of secondary sexual characteristics. Causes menarche at puberty Male-Testes Secretes testosterone Causes maturation of the male sexual organs and the development of the secondary sexual characteristic Causes maturation of sperm cells

37. The Placenta Is a fetal-maternal capillary bed Sustains the fetus during pregnancy Secretes estrogen and progesterone during the first trimester of pregnancy Secretes HCG human chorionic gonadotropin which sustains the uterus during pregnancy.