The Endocrine System PART B

Transcription

1 9 The Endocrine System PART B PowerPoint Lecture Slide Presentation by Jerry L. Cook, Sam Houston University ESSENTIALS OF HUMAN ANATOMY & PHYSIOLOGY EIGHTH EDITION ELAINE N. MARIEB

2 Thyroid Gland Found at the base of the throat Consists of two lobes and a connecting isthmus Produces two hormones Thyroid hormone Calcitonin

3 Thyroid Gland Figure 9.6

4 Thyroid Hormone Major metabolic hormone Composed of two active iodine-containing hormones Thyroxine (T 4 ) secreted by thyroid follicles Triiodothyronine (T 3 ) conversion of T 4 at target tissues

5 Calcitonin (Thyroid Gland) Decreases blood calcium levels by causing its deposition on bone Antagonistic to parathyroid hormone Produced by C (parafollicular) cells Figure 9.9

6 Parathyroid Glands Tiny masses on the posterior of the thyroid Secrete parathyroid hormone Stimulate osteoclasts to remove calcium from bone Stimulate the kidneys and intestine to absorb more calcium Raise calcium levels in the blood

7 Adrenal Glands Two glands Cortex outer glandular region in three layers Medulla inner neural tissue region Sits on top of the kidneys

8 Hormones of the Adrenal Cortex Mineralocorticoids (mainly aldosterone) Produced by outer adrenal cortex Regulate mineral, water, and electrolytes in blood to keep them in balance Cause the kidney tubules to reabsorb sodium and water Production stimulated by renin (which is made by the kidneys) when blood pressure is low

9 Hormones of the Adrenal Cortex Figure 9.10

10 Hormones of the Adrenal Cortex Glucocorticoids (including cortisone and cortisol) Produced in the middle layer of the adrenal cortex Help resist long-term stressors Suppress inflammation/decrease edema Increase blood glucose levels Released in response to increased blood levels of ACTH

11 Hormones of the Adrenal Cortex Figure 9.10

12 Hormones of the Adrenal Cortex Sex hormones Produced in the inner layer of the adrenal cortex Androgens (male) and some estrogen (female)

13 Hormones of the Adrenal Cortex Figure 9.10

14 Hormones of the Adrenal Medulla Produces two similar hormones (Catecholamines) Epinephrine Norepinephrine Prepare the body to deal with short-term stress

15 Roles of the Hypothalamus and Adrenal Glands in the Stress Response Figure 9.12

16 Pancreatic Islets The pancreas is a mixed gland The islets of the pancreas produce hormones Insulin allows glucose to cross plasma membranes into cells from beta cells Glucagon allows glucose to enter the blood from alpha cells These hormones are antagonists that maintain blood sugar homeostasis

17 Pancreatic Islets Figure 9.13

18 Pancreatic Hormones and Blood Sugar Figure 9.14

19 Pineal Gland Found on the third ventricle of the brain Secretes melatonin Helps establish the body s wake and sleep cycles May have other as-yet-unsubstantiated functions

20 Thymus Located posterior to the sternum Largest in infants and children Produces thymosin Matures some types of white blood cells Important in developing the immune system

21 Hormones of the Ovaries Estrogens Development of secondary female characteristics Prepares the uterus to receive a fertilized egg Stimulates menstruation

22 Hormones of the Ovaries (Corpus Luteum) Progesterone Helps bring about the menstrual cycle Helps maintain pregnancy Prepares breasts for milk production Small amount of estrogen made by the corpus luteum

23 Hormones of the Testes (Androgens) Interstitial cells make the hormones Androgens male hormones Testosterone is the most important androgen Adult male secondary sex characteristics Growth and maturation of male reproductive system Required for sperm cell production

24 Other Hormone-Producing Tissues and Organs Parts of the small intestine Parts of the stomach Kidneys Heart Many other areas have scattered endocrine cells

25 Endocrine Function of the Placenta Produces hormones that maintain the pregnancy Human chorionic gonadotropin (hcg) Estrogen Progesterone Relaxin relaxes mother s pelvic ligaments and pubic symphysis

26 Developmental Aspects of the Endocrine System Most endocrine organs operate smoothly until old age Menopause is brought about by lack of efficiency of the ovaries Problems associated with reduced estrogen are common Growth hormone production declines with age Many endocrine glands decrease output with age

27 Growth Hormone Hyposecretion-Dwarfism Slow bone growth Epiphyseal plates close before normal height is reached Treatment Growth Hormone therapy Hypersecretion- Gigantism long bones grow abnormally long during childhood and adolescence

28 Acromegaly Hypersecretion of Growth Hormone Happens after normal growth has stopped Bones of hands, feet, cheeks, and jaw thicken Soft tissues grow abnormally

29 Addison s Disease Hyposecretion of Adrenal Cortex hormones Bronze color to skin (hyperpigmentation) Symptoms include: Severe fatigue Unintentional weight loss Gastrointestinal problems, such as nausea, vomiting and abdominal pain Lightheadedness or fainting Salt cravings Muscle or joint pains

30 Cushing s Syndrome Hypersecretion of Adrenal Cortex hormones or administration of homrones Weight gain Obesity Moon face Buffalo hump) Stretch marks Bruise easily

31 Goiter Enlarged thyroid gland caused by iodine deficiency Iodine Deficiency causes thyroid to make nonfunctional thyroid hormones TSH keeps calling for more thyroxine Thyroid is overstimulated and enlarges, but still doesn t make functional thyroid hormones

32 Graves Disease Autoimmune disorder that causes growth of thyroid and hypersecretion of thyroid hormones, with no negative feedback Enlarged thyroid (2-3x larger) Bulging eyes Increased metabolic rate, heat intolerance, increased sweating, weight loss, insomnia, tremor, and nervousness. Treatment surgical removal of part of thyroid gland radioisotopes to destroy some of the thyroid anti-thyroid drugs to block synthesis of the hormones.

33 Cretinism Hyposecretion of T3/T4 during fetal life and infancy. Dwarfism and mental retardation Testing newborns can prevent the disease Treatment - oral thyroid therapy.

34 Myxedema Thyroid hyposecretion during adulthood Edema, slow heart rate, low body temp, dry hair and skin, muscular weakness, lethargy, weight gain Treatment - Oral thyroid hormones reduce symptoms

35 Parathyroid Hormone too Low Hyposecretion of parathyroid hormone results in low calcium levels If blood calcium levels fall too low, neurons become extremely irritable and overactive. Neurons deliver impulses to muscles so fast that they go into tetany and spasm Can lead to death

36 Diabetes Mellitus Symptoms : polyuria, polydypsia, polyphagia, acidosis. Two types: Type I absolute insulin deficiency, with insulin administration. Patients < 20 years; autoimmune disorder where β-cells are destroyed; Hyperglycemia results. Cells can't use glucose so fat is broken down, releasing ketone bodies, causing ketoacidosis, lowering blood ph, and causing death. Complications include Atherosclerosis, CV disease, IHD, PVD, gangrene, blindness due to cataracts (lens) and retinal vascular disease; renal failure. Treatments artificial pancreas that detects fall in glucose levels and automatically releases insulin; transplant of pancreas or Beta cells.

37 Diabetes Mellitus Symptoms : polyuria, polydypsia, polyphagia, acidosis. Two types: Type II Diabetes patients > 40 years, overweight, hypertension, Problem is usually with receptors on target cells; Controlled by diet, exercise, and weight loss;

38 Diabetes Mellitus

39 ADH Imbalances Diabetes Insipidus Hyposecretion of ADH from posterior pituitary Diuresis, dehydration, thirst Treatment - ADH in nasal spray