The Endocrine System/Hormones

Transcription

1 The Endocrine System/Hormones Controls many body functions exerts control by releasing special chemical substances into the blood called hormones Hormones affect other endocrine glands or body systems Derives its name from the fact that various glands release hormones directly into the blood, which in turn transports the hormones to target tissues via ducts.

2 The Endocrine System 2 Exocrine glands - transport their hormones to target tissues via ducts. Endocrine Emergencies: from common: Diabetes to the unusual: Thyrotoxicosis

3 The Endocrine System 3 Consists of several glands located in various parts of the body. Pituitary gland: a small gland located on a stalk hanging from the base of the brain - AKA The Master Gland Primary function is to control other glands. Produces many hormones. Secretion is controlled by the hypothalamus in the base of the brain.

4 The Endocrine System 4 The Pituitary Gland is divided into 2 areas, which differ structurally and functionally each area has separate types of hormone production. The two segments are: Posterior Pituitary: produces oxytocin and antidiuretic hormone (ADH) - Neurosecretory Anterior Pituitary: produces thyroid-stimulating hormone (TSH) growth hormone (GH) adrenocorticotropin (ACTH) follicle-stimulating hormone (FSH)

5 Overview of the endocrine system

6 Hypothalamus/pituitary gland

7 Posterior pituitary

8 Summary of pituitary activity

9 The Endocrine System 5 Posterior Pituitary ADH (Anti-diuretic hormone) Conserves body water by concentrating urine Alcohol inhibits this hormone can lead to dehydration Oxytocin (the natural form of pitocin) stimulates pregnant uterus causes let down of milk from the breast. ADH (vasopressin) causes the kidney to retain water.

10 The Endocrine System 6 Anterior Pituitary Primarily regulates other endocrine glands rarely a factor in endocrinological emergencies TSH stimulates the thyroid gland to release its hormones, thus metabolic rate Anterior Pituitary Growth hormone (GH) glucose usage consumption of fats as an energy source ACTH stimulates the adrenal cortex to release its hormones FSH & LH stimulates maturation & release of eggs from ovary.

11 The Thyroid Gland Thyroid Gland-1 lies in the anterior neck just below the larynyx. Two lobes, located on either side of the trachea, connected by a narrow band of tissue called the isthmus. Sacs inside the gland contain colloid Thyroid hormones contain IODINE which is in salt to maintain proper function Within the colloid are the thyroid hormones: thyroxine (T4) triiodothyronine (T3) When stimulated (by TSH or by cold), these are released into the circulatory system and the metabolic rate. C cells within the thyroid produce the hormone calcitonin.

12 The thyroid gland-2 Involved in metabolism, growth, & development Proper brain & nervous system development Calcitonin, when released, lowers the amount of calcium in the blood. Inadequate levels of thyroid hormones = hypothyroidism, or Myxedema. Myxedema symptoms: Facial bloating -altered mental status Weakness -oily skin and hair cold intolerance lethargy

13 Parathyroid Glands small, pea-shaped glands, located in the neck near the thyroid usually 4 - number can vary regulate the level of calcium in the body Regains calcium From bones Increased calcium absorption from intestines Decreases calcium excretion in urine Parathyroid Glands produce parathyroid hormone - level of calcium in blood Hypocalcemia can result if parathyroids are removed or destroyed.

14 Adrenal Glands Fight or Flight Adrenal Glands 2 small glands that sit atop both kidneys. Each has 2 divisions, each with different functions. the Adrenal Medulla secretes the catecholamine hormones norepinephrine and epinephrine (closely related to the sympathetic component of the autonomic nervous system).

15 The Adrenal Cortex-1 The Adrenal Cortex secretes 3 classes of hormones, all steroid hormones: gluticocorticoids mineralocorticoids androgenic hormones One at a time gluticocorticoids: accounts for 95% of adrenal cortex hormone production the level of glucose in the blood Released in response to stress, injury, or serious infection - like the hormones from the adrenal medulla.

16 Adrenal Cortex-2 Mineralocorticoids: work to regulate the concentration of potassium and sodium in the body. Prolonged in adrenal cortex hormone results in Cushing s Disease. Signs & Symptoms of Cushing s Disease: in blood sugar levels unusual body fat distribution rapid mood swings

17 Adrenal Cortex 3 And - if there is an in mineralocorticoids as well A serious electolyte imbalance will occur due to the potassium excretion by the kidney, which results in hypokalemia. Sodium can also be retained by the kidney, resulting in hyponatremia. Causes: dysrhythmias coma death usually results from a tumor.

18 Pancreas-1 Pancreas a key gland located in the folds of the duodenum has both endocrine and exocrine functions secretes several key digestive enzymes Islets of Langerhans specialized tissues in which the endocrine functions of the pancreas occurs include 3 types of cells: alpha ( ) beta ( ) delta ( ) each secretes an important hormone.

19 Pancreas-2-alpha Alpha ( ) cells release glucagon, essential for controlling blood glucose levels. When blood glucose levels fall, cells the amount of glucagon in the blood. The surge of glucagon stimulates the liver to release glucose stores (from glycogen and additional storage sites). Also, glucagon stimulates the liver to manufacture glucose - gluconeogenesis.

20 Pancreas 3-Beta/Delta Beta Cells ( ) release insulin (antagonistic to glucagon). Insulin the rate at which various body cells take up glucose. Thus, insulin lowers the blood glucose level. Insulin is rapidly broken down by the liver and must be secreted constantly. Delta Cells ( ) produce somatostatin, which inhibits both glucagon and insulin.

21 Diabetes Endocrine Emergencies: Diabetes Mellitus one of the most common diseases in North America. insulin secretion by the Beta ( ) cells of the islets of Langerhans in the pancreas. Complications of Diabetes: contributes to heart disease stroke kidney disease blindness

22 Diabetes-2 Pathophysiology of Diabetes: Glucose Metabolism Glucose (dextrose) is a simple sugar required by the body to produce energy. Sugars, or carbohydrates, are 1 of 3 major food sources used by the body. The other 2 major food sources are proteins fats Most sugars in the human diet are complex and must be broken down into simple sugars: glucose, galactose and fructose - before use.

23 Sex Hormones 3 types of Sex hormones: Estrogens, Progestins, and Androgens (Both Men & Women) Gonads and Ovaries: the endocrine glands associated with human reproduction. Female ovaries produce eggs Male gonads produce sperm both have endocrine functions. Ovaries: located in the abdominal cavity adjacent to the uterus. Under the control of LH and FSH from the anterior pituitary they manufacture estrogen protesterone

24 Sex Hormones-2 Females=Estrogen and Progesterone have several functions, including sexual development and preparation of the uterus for implantation of the egg. Breast development Fat storage=hips & thighs Male Testes: located in the scrotum produce sperm for reproduction manufacture testosterone (Androgen) promotes male growth and masculinization- (muscle mass & facial hair) Controlled by anterior pituitary hormones FSH and LH.

25 Pineal Gland Produces Melatonin Regulates our INTERNAL CLOCK Uses cues from our eyes Released during NIGHT hours Some people use Melatonin as Sleeping pills Adjustment pills when traveling Blind people need adjustment because they don t sense Day and Night

26 Table 19.1-a Endocrine Organ Hormone Effect Hypothalamus Regulated posterior & Anterior pituitary Anterior Pituitary Growth Hormone Regulates Growth Posterior Pituitary Prolactin Follicle Stimulating Hormone (FSH) Luteininzing Hormome (LH) Thyroid Stimulating Hormone (TSH) Adrenocorticotropic Hormone Antidiuretic Hormone (ADH) Oxytocin Milk Production Production of eggs & sperm Stimulates ovaries and testes Stimulates Thyroid Gland Stimulates adrenal secretion of glucorticoids Promotes H2O retention by kidneys Stimulates contraction of uterus Thyroid Gland Thryroid Hormones Stimulates/maintains metabolism, growth, dev. Calcitonin Lowers blood calcium levels

27 Table 19.1-b Endocrine Organ Hormone Effect Parathyroid Glands Parathyroid Hormone Raises blood calcium levels Adrenal Gland Epinephrine/Norepinephrine Fight or Flight response Glucocorticoids Mineralocorticoids Raise Blood Glucose Levels Control water and salt balance Pancreas Insulin Lowers Blood Sugar level Glucagon Raises Blood Glucose Levels Sex Organs-Testes Androgens Sperm formation, male secondary characterisitics Sex Organs-Ovaries Estrogen Uterine lining growth, female secondary characterisitics Progesterone Uterine Lining Growth Pineal Gland Melatonin Regulates Internal Clock