1. The Endocrine System
Chapter 11

2. Introduction
The endocrine system is made up of the cells, tissues and organs that secrete hormones into body fluids.
The body has two types of glands:
Exocrine
Secretes products into ducts
Endocrine
Secretes products into body fluids

3. General Characteristics of Endocrine System
Endocrine glands and their hormones regulate a number of metabolic processes within cells, as well as reproduction, development and growth.
Endocrine glands include the pituitary gland, thyroid gland, parathyroid glands, adrenal glands, pancreas and other hormone-secreting glands and tissues.

4. Hormone Action
A hormone is a biochemical secreted by one cell that affects a specific target cell with appropriate cell surface receptors.
Prostaglandins are locally produced lipids that affect the organ in which they are produced.

5. Control of Hormonal Secretions
Hormone levels are very precisely regulated.
Negative Feedback Systems
Commonly control hormonal releases.
When the concentration of the regulated substance reaches a certain level (high or low), it inhibits the gland from secreting more hormone until the concentration returns to normal (if the level is too high), or releases more (if the level is too low).

6. Pituitary Gland
Is attached to the base of the brain and has an anterior lobe (anterior pituitary) and a posterior lobe (posterior pituitary)
The pituitary gland is controlled by the brain.
Releasing hormones from the hypothalamus control the secretions of the anterior pituitary.
The posterior pituitary releases hormones into the bloodstream in response to nerve impulses from the hypothalamus.

7. Pituitary Gland

8. Anterior Pituitary Hormones
Growth Hormone (GH)
Stimulates body cells to grow and reproduce and speeds the rate at which cells use carbohydrates and fats
Prolactin (PRL)
Promotes milk production following the birth of an infant.
Thyroid-Stimulating Hormone (TSH)
Controls the secretion of hormones from the thyroid gland.

9. Posterior Pituitary Hormones
Anti-Diuretic Hormone (ADH)
Causes the kidneys to conserve water (prevents dehydration)
Oxytocin
Plays a role in childbirth by contracting muscles in the uterine wall and in milk-letdown by forcing milk into ducts from the milk glands.

10. Thyroid Gland
Located below the larynx and consists of two broad lobes connected by an isthmus.

11. Hormones of the Thyroid Gland
Thyroid Hormones
Increase the rate at which cells release energy from carbohydrates, enhance protein synthesis, and stimulate the breakdown and mobilization of lipids.
These hormones are essential for normal growth and development.
The hypothalamus and pituitary gland control release of thyroid hormones.

12. Hormones of the Thyroid Gland
Calcitonin
Lowers blood levels of calcium and phosphate ions when they are too high.
Increases the rate at which calcium is stored in bones and excreted in the urine.

13. Parathyroid Glands
The four, tiny parathyroid glands are located on the posterior of the thyroid.

14. Hormones of the Parathyroid Gland
Parathyroid Hormone (PTH)
Increases blood calcium ion concentration and decreases phosphate ion concentration.
Stimulates bone breakdown by osteoclasts, which releases calcium into the blood.
Influences the kidneys to conserve calcium and causes increased absorption of calcium in the intestines.
Calcitonin and PTH have opposite effects in regulating calcium ion levels in the blood.

15. Adrenal Glands
Sit atop the kidneys enclosed in a layer of fat.

16. Hormones of the Adrenal Gland
Aldosterone
Causes the kidneys to conserve sodium ions and thus, water and to excrete potassium ions.
Cortisol
Influences the metabolism of glucose, protein and fat in response to conditions that stress the body and require a greater supply of energy in the bloodstream.
Adrenal Sex Hormones
Hormones that supplement those released by the gonads and may stimulate early development of reproductive organs.

17. Pancreas
Secretes hormones as an endocrine gland and digestive juices to the digestive tract as an exocrine gland.

18. Hormones of the Pancreas
Glucagon
Increases blood levels of glucose by stimulating the breakdown of glycogen and the conversion of non-carbohydrates into glucose.
Responds to low blood glucose levels
Insulin
Decreases blood levels of glucose by stimulating the liver to form glycogen, increasing protein synthesis and stimulating adipose cells to store fat.
Responds to high blood glucose levels.

19. Pineal Gland
Located near the upper portion of the thalamus of the brain

20. Hormones of the Pineal Gland
Melatonin
Involved in the regulation of the circadian rhythms of the body
Circadian rhythms regulate our sleep/awake cycle.

21. Thymus Gland
Located between the lungs, under the sternum

22. Hormones of the Thymus Gland
Thymosins
Affect production and differentiation of T-Lymphocytes that are important in immunity.

23. Reproductive Glands Ovaries Testes
Produce estrogen and progesterone in females
Testes
Produce testosterone in males

24. Disease Definitions
Pathology: the science of causes and effects of diseases
Hyper-: more than normal
Hypo-: less than normal

25. Adrenal Gland Disorders
Addison’s Disease
Pathology: hypersecretion of all adrenal cortex hormones
Symptoms: Bronze skin tone, muscles are weak, burnout, susceptibility to infection, hypoglycemia

26. Adrenal Gland Disorders
Cushing’s Syndrome
Pathology: tumor in adrenal gland; hypersecretion of adrenal cortex
Symptoms: extreme obesity, hirsutism (excessive hair growth), “moon face”, “buffalo hump”

27. Diseases of the Pituitary
Giantism
Pathology: hypersecretion of GH (growth hormone)
Symptoms: overgrowth of long bones leading to excessive tallness

28. Diseases of the Pituitary
Acromegaly
Pathology: hypersecretion of GH
Symptoms: Overdevelopment of bones in face, hands, and feet; cartilge is attacked; chin protudes, lips, nose, and extremities enlarge

29. Disease of the Pituitary
Dwarfism
Pathology: Hyposecretion of GH in childhood (genetic)
Symptoms: small size (body proportions and intellect are normal) sexual immaturity

30. Diseases of Thyroid Hyperthyroidism
Pathology: hypersecretion of thyroxine
Symptoms: consumption of large quantities of food but loss of body fat and weight; enlargement of the gland (GOITER) and bulging of the eyeballs (EXOPTHALMOS)

31. Diseases of the Thyroid
Hypothyroidism
Pathology: hyposecretion of thyroxine in adulthood
Symptoms: dry and itchy skin, dry and brittle hair, muscle cramps at night
Cretinism
Pathology: hyposecretion of thyroxine in childhood
Symptoms: dwarfism during childhood

33. Diseases of the Parathyroid Gland
Tetany
Pathology: hyposecretion of parathyroid hormone
Symptoms: development of convulsive twitching

34. Sex Related Endocrine Diseases
Central Hypogonadism
Pathology: hyposecretion of FH and LH from the pituitary gland
Females: (BEFORE PUBERTY) no menstruation or breast development; (AFTER PUBERTY) hot flashes, loss of body hair
Males: breast enlargement, decreased beard and body hair, muscle loss

35. Diseases of Pancreas Diabetes Mellitus Type 1 (“Juvenile Diabetes”)
Pathology: body’s immune system attacks and destroys cells in Islets of Langerhans
Effect: Pancreas unable to secrete enough insulin
Treatment: Insulin shots

36. Diseases of Pancreas Diabetes Mellitus Type 2
Pathology: muscle, fat, and liver cells become unable to respone to insulin properly (as a result of poor diet, low activity level, excess body weight around the waist)
Effect: Cells unable to use blood sugar for cellular respiration
Treatment: strict diet and exercise; doctor may prescribe medication that lowers blood sugar
Long term effects: blindness, infection needing amputation, nerve damage, damage to blood vessels and nerves

37. Disease of Pineal Gland
SADS (Seasonal Affective Disorder)
Pathology: hypersecretion of melatonin
Symptoms: cells prepare for winter, sleepy, sad, tired, gain weight, depression

38. Diseases of the Thymus Gland
Relatively rare and potentially serious
Mainly Genetic
Severe Combined Immunodeficiency disorder (SCID)
Pathology: mutation in a gene that affects the development of T cells and other immune cells
Symptoms: compromised immune system; inability to fight off infections