© 2009 delmar, cengage learning endocrine system

© 2009 Delmar, Cengage Learning

ENDOCRINE SYSTEM


Endocrine System

• Consists of a group of ductless (without tubes) glands1. Pituitary

2. Thyroid

3. Parathyroid

4. Adrenal

5. Pancreas

6. Ovaries

7. Testes

8. Thymus

9. Pineal body

10. Placenta

• Secrete substances called hormones

• Hormones that are secreted directly into bloodstream


Hormones

• Chemical substances produced and secreted by the endocrine glands, and they are frequently called “chemical messengers”.

• Perform many functions:1. Stimulate endocrine glands to produce secretions

2. Stimulate other endocrine glands

3. Regulate metabolism

4. Maintain fluid and chemical balance

5. Control various sex processes


Pituitary Gland

• “Master gland” of the body because it produces many hormones that affect other glands

• Located at the base of the brain

• Divided into 2 lobes:– Anterior and posterior lobes

– Each lobe secretes certain hormones


Pituitary Gland – Diseases and Abnormal Conditions

• Acromegaly– Results from an over secretion of somatotropin (growth hormone) in an

adult (after normal bone growth has stopped)

– Usually caused by a benign tumor of the pituitary called an ademoma.

– Slow progression of signs over many years

– Signs & Symptoms:• Bone of the hands, feet, and face enlarge

• Skin and tongue thicken

• Slurred speech develops

– Treatment includes:• Medications that decrease growth hormone secretion

• Surgical removal and/or radiation of the tumor

• The disease eventually causes cardiovascular and respiratory diseases that shorten life expectancy



• Gigantism– Rare disorder

– Results from oversecretion of somatotropin before puberty

– Usually caused by a benign tumor of the pituitary gland

– Signs and Symptoms:• Excessive growth of long bones

• Extreme tallness

• Decreased sexual development

• Retarded mental development (at times)

– Treatment:• Medications to reduce growth hormone release and hormone levels

• Surgical removal and/or radiation of the tumor



• Diabetes Insipidus– Caused by a decreased secretion of vasopressin, or antidiuretic hormone (ADH)

– Risk factors include:• Pituitary surgery

• Trauma

• Encephalopathy

• Autoimmune disorders

– Low ADH levels prevents water from being reabsorbed in the kidneys

– Signs and Symptoms:• Polyuria (excessive urination)

• Polydipsia (excessive thirst)

• Dehydration

• Weakness

• Constipation

• Dry skin

– Treatment:• Administration of ADH



• Dwarfism– Results from an undersecretion of somatotropin.

– A random genetic mutation is the cause of most dwarfism

– Can also be caused by a tumor, infection, or injury

– Signs and Symptoms:• Adult height of less than 4ft 10inches

• Small body size

• Short extremities

• Lack of sexual development

• Mental development is usually normal

– Treatment:• If diagnosed early, it can be treated with somatotropic injections for 5 or

more years until long bone growth is complete


Thyroid Gland

• Regulates the body’s metabolism and controls the level of calcium in the blood

• Located in front of the upper trachea

• Has 2 lobes, one on either side of the larynx, connected by the isthmus

• Requires iodine from food intake to produce hormones


Thyroid Gland – Diseases and Abnormal Conditions

• Goiter– An enlargement of the thyroid gland

– Causes can include a hyperactive thyroid, an iodine deficiency, oversecretion of thyroid-stimulating hormones, or a tumor

– Signs and Symptoms:• Thyroid enlargement

• Dysphagia (difficulty swallowing)

• Dyspnea (difficulty breathing)

• Cough

• Choking sensation

– Treatment• Directed at eliminating the cause (giving iodine if there is a deficiency)

• Surgery for large or rapidly growing goiters



• Hyperthyroidism– Over activity of the thyroid gland – causes an increased production of thyroid

hormones and increased basal metabolic rate

– Signs and Symptoms:• Extreme nervousness Diarrhea

• Tremors Diaphoresis (excessive perspiration)

• Irritability Heat intolerance

• Rapid pulse Polydipsia (excessive thirst)

• Goiter formation Hypertension

– Excessive appetite with extreme weight loss is a classic symptom

– Treatment:• Antithyroid medications

• Can remove the thyroid, but must be given hormones for the duration of life



• Graves’ Disease– Severe form of hyperthyroidism more common in women

– Signs and Symptoms:• Strained and tense facial expression

• Exophthalmia (protruding eyeballs)

• Goiter

• Nervous irritability

• Emotional instability

• Tachycardia

• Tremendous appetite accompanied by weight loss

• Diarrhea

– Treatment:• Medications

• Thyroidectomy



• Hypothyroidism– Underactivity of the thyroid gland and a deficiency of thyroid

hormones

– Two main forms:1. Cretinism: develops in infancy or early childhood, and results in a lack

of mental and physical growth, leading to mental retardation and abnormal, dwarfed stature.

2. Myxedema: occurs later in childhood or adulthood. Symptoms include: course, dry skin, slow mental function, fatigue, weakness, intolerance of cold, weight gain, edema, puffy eyes, and slow pulse

– Treatment:• Oral thyroid hormones to restore normal metabolsim


Parathyroid Glands

• 4 small glands located behind and attached to the thyroid gland

• Parathormone (the hormone):– Regulates the calcium in the blood

– Stimulates bone cells to break down bone tissue and release calcium and phosphates into the blood

– Causes kidneys to conserve and reabsorb calcium

– Activates intestinal cells to absorb calcium from digested food

• Calcium in the blood is important for blood clotting, the tone of the heart muscle, and muscle contraction


Parathyroid Glands – Diseases and Abnormal Conditions

• Hyperparathyroidism– Over activity of the parathyroid gland resulting in an

overproduction of parathormone, this causes hypercalcemia

– Hypercalcemia – increased calcium in the blood which leads to renal calculi (kidney stones)

– Signs and Symptoms:• Kidney stones

• Lethargy

• Gastrointestinal disturbances

• Calcium deposits on the walls of blood vessels and organs

• Bones become weak, deformed, and likely to fracture

– Causes: adenoma

– Treatment: surgery (90% cure rate) and diuretics


Parathyroid Glands – Diseases and Abnormal Conditions

• Hypoparathyroidism– Under activity of the parathyroid gland

– Causes low level of calcium and a high level of phosphorus in the blood

– Causes include the surgical removal of or injury to the parathyroid and/or thyroid glands

– Signs and Symptoms:• Tetany (sustained muscle contraction)

• Hyperirritability of the nervous system

• Convulsive twitching

• Patchy hair loss

• Death can occur if the larynx and respiratory muscles are involved

– Treatment: vitamin D and parathormone


Adrenal Glands

• Frequently called the suprarenal glands because one is located above each kidney

• Each gland has 2 parts:– Cortex: secretes many steroid

hormones

– Medulla: secretes epinephrine and norepinephrine (cause the fight or flight response)


Adrenal Glands – Diseases and Abnormal Conditions

• Addison’s Disease– Caused by a decreased secretion of aldosterone on the

part of the adrenal cortex

– This interferes with the reabsorption of sodium and water and causes an increased level of potassium in the blood

– Signs and Symptoms:• Dehydration, diarrhea, fatigue, hypotension, anorexia,

weight loss, muscle weakness, edema, excessive pigmentation leading to a “bronzing” of the skin, hypoglycemia, mental lethargy, and in severe cases, coma or death

– Treatment:• Corticosteroid hormones, controlled intake of sodium, and

fluid regulation to combat dehydration.


Adrenal Glands – Diseases and Abnormal Conditions

• Cushing’s Syndrome– Caused from an over secretion of glucocorticoids due to a tumor, excessive

production of ACTH, or overuse of corticosteroids

– Signs and Symptoms:• Hyperglycemia, hypertension, muscle weakness, fatigue, hirsutism (excessive

growth and/or abnormal distribution of hair), poor wound healing, bruise easily, “moon face”, fatty hump between the shoulders, and obesity

– Treatment:• Surgical removal of the tumor (if that is the cause), then hormone therapy

• Gradually reduce corticosteroid usage if that is the cause


Pancreas

• A fish-shaped organ located behind the stomach

• Both an exocrine (secrete hormones via a duct) and endocrine (secrete hormones into the bloodstream) gland

• Produces insulin which is needed for the cells to absorb sugar from the blood and produces glucagon which increases the glucose level in the blood


Pancreas – Diseases and Abnormal Conditions

• Diabetes Mellitus– A chronic disease caused by decreased secretion of insulin

– 2 types of diabetes1. Type 1 (Insulin Dependent or Juvenile)

– Occurs early in life, is more severe, and requires insulin

2. Type 2 (Non-insulin Dependent or Adult-Onset)– Occurs in obese adults and is usually controlled by diet

– Signs and Symptoms:• Hyperglycemia, polyuria, polydipsia, polyphagia, glycosuria, weight

loss, fatigue, slow healing, and vision changes

– Treatment:• Regulated diet, regulated exercise, and hypoglycemic drugs or insulin

injections


Fasting blood glucose:1 Less than or equal to 100 milligrams per deciliter (mg/dL) (5.6 millimoles per liter, or mmol/L).

2 hours after eating (postprandial):2 Less than 140 mg/dL (7.8 mmol/L) for people age 50 and younger; less than 150 mg/dL (8.3 mmol/L) for people ages 50–60; less than 160 mg/dL (8.9 mmol/L) for people age 60 and older.

Random (casual):3 Levels vary depending on when and how much you ate at your last meal. In general: 80–120 mg/dL (4.4–6.6 mmol/L) before meals or when waking up; 100–140 mg/dL (5.5–7.7 mmol/L) at bedtime.


Other Endocrine Glands

• Ovaries: – female sex glands

– located in the pelvis

– secrete hormones that regulate menstruation

and secondary sexual characteristics

• Testes: – male sex glands,

– located in the scrotal sac

– produce hormones that regulate secondary

sexual characteristics



• Thymus– A mass of tissues located in the upper part of chest and under the

sternum

– Active in early life and activates cells in the immune system

– Atrophies (wastes away) during puberty

– Produces thymosin



• Pineal Body– Small structure located in the brain

– Exact function unknown

• Placenta– Temporary endocrine gland

produced during pregnancy

– Acts as a link between the mother and baby, provides nutrition for the developing baby, and promotes lactation

– Expelled after the birth of the child

© 2009 delmar, cengage learning endocrine system

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