Endocrine System Ch. 51

Endocrine System Series of glands and organs that secrete hormones. Hormones function as chemical messengers in the blood stream affecting cells throughout the body.

Your body contains two types of glands: 1. Exocrine (sweat, mucous, salivary) 2. Endocrine (ductless, secrete directly into blood stream)

Your body has two general types of hormones: 1. Amino-Acid Based (epinephrine including proteins, peptides, amino acids, and other forms from amino acids) 2. Steroid (lipid based including estrogen and testosterone, come from cholesterol) Prostaglandins: group of hormone-like lipids that also regulate cell activities. Examples- relax smooth muscles, regulate blood pressure, contraction of the intestines and uterus, immune response)

Hypothalamus Links the Nervous System to the Endocrine System. Neurosecretory cells produce hormones that are either stored in the Pituitary Gland or control it. The Hypothalamus and the Pituitary Gland are the primary regulators of the Endocrine System

Pituitary gland Secretes hormones that affect other glands and organs. Regulated by the hypothalamus.

Pituitary Gland: Major Hormones ACTH: stimulates secretion of cortisol and aldosterone by the adrenal cortex. ADH: stimulates reabsorption of water by the kidneys. FSH: stimulates egg & sperm production. GH: regulates muscle and bone growth. LH: ovulation; stimulates estrogen, progesterone, and testosterone production. Oxytocin: uterine contractions; flow of milk during lactation. PRL: stimulates milk production for lactation. TSH: stimulates secretion of thyroid hormones.

Thyroid Gland TSH: regulates the thyroid gland. Hormones released: 1. Thyroxin- growth and metabolism. 2. Triiodothyronine- growth, body temp. and heart rate. 3. Calcitonin causes the bones to store calcium. Important for proper bone growth.

Illnesses Associated with the Thyroid Gland: Hypothyroidism: deficiency causing growth retardation, weight gain, lethargy, low heart rate and low body temp. Hyperthyroidism- overproduction causing overactivity, weight loss, high blood pressure, heart rate and body temp. Cretinism: mental retardation during fetal and childhood development. Goiter- iodine deficiency, swelling of the thyroid gland.

Adrenal Gland Epinephrine (adrenaline) and Norepinephrine – nervous system fight or flight response. ACTH- from the pituitary gland, stimulates production of cortisol and aldosterone. cortisol: metabolism of carbs and proteins. aldosterone: affects kidneys and salt/water balance.

Gonads

Sex Hormones regulate body changes that begin at puberty. LH & FSH: stimulate secretion of estrogen and progesterone. Estrogen and Progesterone: egg release, buildup of uterine lining; female sex characteristics. LH causes males to produce Androgens (testosterone): male sex characteristics and sperm production.

Pancreas Function: secretes two key hormones, insulin and glucagon. Islets of Langerhans- specialized cells Diseases: Diabetes and Hypoglycemia (excessive insulin)

Thymus Gland Located beneath the sternum, between the lungs. Function: proper development of the immune system Secretes thymosin: stimulates production of T-cells.

Pineal Gland Located near the base of the brain. Secretes melatonin: regulates sleep patterns.

Parathyroid Gland Four of them located on the thyroid. Secretes Parathyroid Hormone (PTH): controls the balance of calcium in the blood.

Gastrin: secreted in the lining of the stomach; stimulates other enzymes to be released. Secretin: secreted in the lining of the small intestine; stimulates other enzymes for digestion to be released