Endocrine SystemCh. 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

1. ACTH: stimulates secretion of cortisol and aldosterone by the adrenal cortex.

2. ADH: stimulates reabsorption of water by the kidneys.

3. FSH: stimulates egg & sperm production.

4. GH: regulates muscle and bone growth.

5. LH: ovulation; stimulates estrogen, progesterone, and testosterone production.

6. Oxytocin: uterine contractions; flow of milk during lactation.

7. PRL: stimulates milk production for lactation.

8. 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

1. Epinephrine (adrenaline) and Norepinephrine – nervous system fight or flight response.

2. 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.

1. LH & FSH: stimulate secretion of estrogen and progesterone.

2. Estrogen and Progesterone: egg release, buildup of uterine lining; female sex characteristics.

3. 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