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The Endocrine System? Major Glands?
- 1. Made up of glands that produce and secrete hormones (chemical mechanisms)
- 2. Regulation of growth, metabolism, and sexual development
- 3. Responses to stress and injury
- 4. Internal Balance of Body Systems
- Major Glands are:
- Pineal Body
- Reproductive Organs (ovaries and testes)
Hormones are chemical messengers that act on Target Cells and Target Organs.
Exocrine glands secrete outside the body through ducts and tubes (sweat, tear ducts [crying])
Steroids - Insoluble in water, carried in the blood and released near the vicinity of the target cell.
Nonsteroid hormones - Binding site, activity site (cylic AMP, cAMP=secondary messenger)
Prostoglandins - Act locally, affecting only the organ where they are products.
Control of Hormonal Secretions?
- Hypothalmus (releasing hormone) > Pituitary (stimulating horomone) > Target gland (secretes hormones)
- *Hormone levels rise and releasing hormone is shut down (Negative feedback)
- Location: base of the brain, pituitary stalk (infundibulum) attatches to the hypothalmus
- Consists of anterior pituitary and posterior pituitary
- *Often called the "master gland" because of its great influence on the body organs
Anterior Pituitary Gland?
Prolactin or PRL - PRL stimulates milk production from a woman's breasts after childbirth and can affect sex hormone levels from the ovaries in women and the testes in men.
Growth Hormone or GH - Stimulates growth in childhood and is important for maintaining a healthy body composition. In adults it is also important for maintaining muscle mass and bone mass. It can affect fat distribution in the body.
Adrenocorticotropin or ACTH - Stimulates production of cortiso by the adrenal galnds. Cortisol, a so-called "stress hormone," is vital to survival. It helps maintain blood pressure and blood glucose levels.
Thyroid-stimulating hormone or TSH - Stimulates the thyroid gland to make thyroid hormones, which, in turn, control (regulate) the body's metabolism, energy, growth, and development, and nervous system activity.
Lutenizing Hormone or LH - Regulates testosterone in men and estrogen in women. (gonadotropin)
Follicle-Stimulating hormone or FSH - promotes sperm production in men and stimulates the ovaries to release eggs (ovulates) in women. LH and FSH work together to allow normal function of the ovaries or testes. (gonadtropin)
Posterior Pituitary Hormone
Posterior Pituitary hormones?
Oxytocin - Oxytocin causes milk letdown in nursing mothers and contractions during childbirth.
- Antidiuretic hormone or ADH - also called vasopressin, is stored in the back of the pituitary gland and regulates water balance. If this hormone is not secreted properly, this can lead to problems of sodium (salt) and water balance and could also affect the kidneys.
- *diuretics - increase urine production
Thyroid Gland? Thyroid hormones? Thyroid disorders?
The thyroid gland is a small gland inside the neck, located in front of your breathing airway (trachea) and below your Adam's apple.
The thyroid hormones control your metabolism, which is the body's ability to break down food and store it as energy and the ability to break down food into waste products with a release or energy in the process.
- 1. Thyroxin (T4) and Tri-iodothyronine (T3) - both increase the rate at which cells release energy from carbohydrates.
- 2. Calcitonin - regulates the blood concentration of calcium.
- 3. BMR - basal metabolic rate; how many calories the body must consume to maintain life.
- Thyroid disorders:
- 1. Goiter - too little iodine in diet causes thyroid to swell
- 2. Hypothyroidism (cretinism in infants) - stunted growth, mental retardation, sluggishness, weight gain in adults.
- 3. Hyperthyroidism (Grave's disease) - restlessness, weight loss, anxiety; can cause goiter (enlarged thyroid)
Located behind the thyroid, four tiny glands that help maintain calcium and phosphorous levles.
Parathyroid hormone (PTH) - takes calcium from the bones to make it available in the blood.
Each adrenal gland is actually two endocrine organs located right above each kidney. The outer portion is called the adrenal cortex. The intter portion is called the adrenal medulla.
- Hormones of the Adrenal Medulla:
- 1. Epinepherine and Norepinephrine - increased hart rate, breathing rate, elevated blood pressure (fight or flight, response to stress)
- Hormones of the Adrenal Cortex:
- 1. Aldosterone - a mineralcoriticoid, helps kidneys conserve soidum and excrete potassium, maintaing blood pressure
- 2. Cortisol - gluccortoid, keeps blood glucose levels stable
- 3. Adrenal sex hormones - androgens (male) and estrogens (female)
- Cushing's Syndrome (hypersection of cortisol) - Blood glucose remains high, retains too much sodium, puffy skin, masculininzing effects effects in women.
Addisons Disease (hyposecretion) - decreased blood sodium, dehydration, low blood pressure, increased skin pigmentation
- The pancreas is a large gland behind your stomach that helps the body to maintain healthy blood sugar (glucose) levels.
- Contains islands of cells caled the Islets of Langerhans which secrete glucagon and insulin.
Glucagon - stimulates the liver to break down glycogen, raises blood sugar concentration.
Insulin - decreases blood sugar concentrations, affects the uptake of glucose by cells.
- Diabetes mellitus - results from an insulin deficency, blood sugar rises (hyperglycemia) and excess is excreted int he urine.
- Type 1 - Insulin dependent diabetes mellitu or juvenile onset diabetes, often caused by inherited immune disorder that destroys pancreatic cells.
- Type 2 - Mature onset diabetes (usually after the age of 40), often individualsd are overweight, can be controlled with diet and excercise
Hypoglycemia - Low blood sugar, can be caused by too much insulin.
Other endocrine glands?
Pineal gland - located between the cerebral hemispheres, secretes melatonin, important for maintaining Circadian rythems (light and dark activity)
Thymus Gland - large in young children, gradually shrinks the age, secretes thymosins, important to immune function
Reproductive glands - testes and ovaries - testosterone, proesterone, estrogen