The Endocrine System

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The Endocrine
System
Function of the Endocrine system is to produce hormones.
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Endocrine glands secrete chemicals (hormones) into the blood
Hormones perform general functions of communication and control but a slower, longer-lasting type of control than that provided by nerve impulses
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Cells acted on by hormones are called target organ cells
Non-steroid hormones
(first messenger) bind to receptors on the target cell membrane, triggering second messengers to affect the cell’s activities
Steroid hormones bind to receptors within the target cell nucleus and influence cell activity by acting on
DNA
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Hormone secretion is controlled by homeostatic feedback
Negative feedback — mechanisms that reverse the direction of a change in a physiologic system
Positive feedback —
(uncommon) mechanisms that amplify physiologic changes
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 Prostaglandins (PGs) are powerful substances found in a wide variety of body tissues
 PGs are often produced in a tissue and diffuse only a short distance to act on cells in that tissue
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Several classes of PGs include prostaglandin A (PGA), prostaglandin E (PGE), and prostaglandin F (PGF)
 PGs influence many body functions, including respiration, blood pressure, gastrointestinal secretions, and reproduction
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 Endocrinologist
(Physician who specializes in diseases of the endocrine system)
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Hypocrinism (Deficient secretion of any gland especially an endocrine gland)
Endocrinopathy (Disease to the disorder of the endocrine system)
 Hypercrinism (Excessive secretion of any gland especially an endocrine gland)
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 Nuclear Medicine
 Imaging Techniques
 Hormone levels are measured in the blood and/or urine
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Figure 18.1

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Primary Functions
Regulate electrolyte levels.
– Influence metabolism.
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Respond to stress.
Located on top of each kidney
Consists of the adrenal cortex & adrenal medulla
Related Combining Form
– adren/o
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Produce anti-immunity, antiallergy effect; bring about a decrease in the number of lymphocytes and plasma cells and therefore a decrease in the amount of antibodies formed
Secretion of glucocorticoid quickly increases when the body is thrown into a condition of stress; high blood concentration of glucocorticoids, in turn, brings about many other stress responses
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–
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Help maintain normal blood glucose concentration by increasing gluconeogenesis —the formation of “new” glucose from amino acids produced by the breakdown of proteins, mainly those in muscle tissue cells
The conversion to glucose of fatty acids produced by the breakdown of fats stored in adipose tissue cells play an essential part in maintaining normal blood pressure —make it possible for epinephrine and norepinephrine to maintain a normal degree of vasoconstriction , a condition necessary for maintaining normal blood pressure
Act with epinephrine and norepinephrine to produce an antiinflammatory effect, to bring about normal recovery from inflammation of various kinds
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Produce anti-immunity, anti-allergy effect; bring about a decrease in the number of lymphocytes and plasma cells and therefore a decrease in the amount of antibodies formed
Secretion of glucocorticoid quickly increases when the body is thrown into a condition of stress; high blood concentration of glucocorticoids, in turn, brings about many other stress responses
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Names of hormones
(corticoids)
Glucocorticoids (GCs) — chiefly cortisol (hydrocortisone)
Mineralocorticoids (MCs) — chiefly aldosterone. Increase blood sodium and decrease body potassium concentrations by accelerating kidney tubule reabsorption of sodium and excretion of potassium
Sex hormones —small amounts of male hormones
(androgens) secreted by adrenal cortex of both sexes
 Three cell layers
(zones)
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–
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Outer layer, secretes mineralocorticoids
Middle layer, secretes glucocorticoids
Inner layer, secretes sex hormones
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– Names of hormones — epinephrine (adrenaline) and norepinephrine
– Functions of hormones —help the body resist stress by intensifying and prolonging the effects of sympathetic stimulation; increased epinephrine secretion is the first endocrine response to stress
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Mineralcorticoids
(regulates mineral salts in the body)
Glucocrticoids (regulates the metabolism of carbohydrates, fats and proteins)
Gonadocorticoids
(hormones that influence sex-related characteristics)
 Adrenal medulla secretion
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Epinephrine (adrenaline)
Norepinephrine
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Adrenalitis
Addison’s Disease
(insufficient hormone production. Characterized by pain, fatigue, weight loss)
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Aldosteronism (abnormal electrolyte balance caused by excessive aldosterone)
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Primary hyperaldosteronism: Conn's syndrome is a disease of the adrenal glands involving excess production of a hormone, called aldosterone. Another name for the condition is primary hyperaldosteronism.
Secondary aldosteronism is increased adrenal production of aldosterone in response to nonpituitary, extra-adrenal stimuli, including renal artery stenosis and hypovolemia.
Symptoms are those of primary aldosteronism. Treatment involves correcting the cause.
Pheochromocytoma
(benign tumor of the adrenal medulla)
Cushing’s Syndrome
(hypercortisolism/hyperadrenalism) Caused by prolonged exposure to high levels of cortisol. “Moon face”

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Overview
Adrenal cancer is a rare disease that originates in the adrenal glands. The adrenal glands are located on top of the kidneys and consist of two parts that function separately: the outer layer (cortex) and the inner area (medulla).
The cortex produces three major hormones: cortisol (a glucocorticoid), aldosterone (a mineralocorticoid), and dehydroepiandrosterone (DHEA; an androgen). The medulla produces epinephrine (adrenaline), norepinephrine, and dopamine.
Adrenal tumors can increase hormone production (called functioning tumors).
Adrenal tumors that do not produce hormones are called nonfunctioning.
Symptoms of adrenal cancer and treatment for the condition depend on whether the tumor is functioning or nonfunctioning, and on which hormone is being overproduced.
Types
Most (99%) adrenal tumors are noncancerous (i.e., benign) adrenal cortical adenomas and do not require treatment. These tumors usually do not cause symptoms, are small, and are found incidentally during diagnostic imaging.
(metastasize) to the adrenal glands.
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The most common type of adrenal cancer develops in the adrenal cortex and is called adrenocortical carcinoma . Functioning adrenocortical carcinomas may produce symptoms related to increased hormone production.
Nonfunctioning tumors may cause pain from pressure on abdominal organs and a mass in the abdomen that is able to be felt with the fingers (palpable).
Cancers that develop in the adrenal medulla include neuroblastoma
(originates in undeveloped nerve cells) and pheochromocytoma (originates in cells that produce epinephrine and norephinephrine). Neuroblastoma usually occurs in infants and children and pheochromocytoma more commonly occurs in people who are in their 30s and 40s.
Other types of cancer (e.g., breast, lung) may spread
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Types
Most (99%) adrenal tumors are noncancerous (i.e., benign) adrenal cortical adenomas and do not require treatment. These tumors usually do not cause symptoms, are small, and are found incidentally during diagnostic imaging.
The most common type of adrenal cancer develops in the adrenal cortex and is called adrenocortical carcinoma .
Functioning adrenocortical carcinomas may produce symptoms related to increased hormone production.
Nonfunctioning tumors may cause pain from pressure on abdominal organs and a mass in the abdomen that is able to be felt with the fingers (palpable).
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Cancers that develop in the adrenal medulla include neuroblastoma (originates in undeveloped nerve cells) and pheochromocytoma (originates in cells that produce epinephrine and norephinephrine). Neuroblastoma usually occurs in infants and children and pheochromocytoma more commonly occurs in people who are in their 30s and 40s.
Other types of cancer (e.g., breast, lung) may spread
(metastasize) to the adrenal glands.
 Source: http://www.urologychannel.com/adrenalcancer
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 Laparoscopic adrenalectomy
 Hydrocortisone (immunosuppressant, suppress inflammation)
 Epinephrine ( vasoconstrictor causes the blood vessels to contract)
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adrenalectomy
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Adrenal gland
Laparoscopic adrenalectomy
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Actual production of ADH and oxytocin occurs in the hypothalamus
After production in the hypothalamus, hormones pass along axons into the pituitary gland
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The secretion and release of posterior pituitary hormones are controlled by nervous stimulation
The hypothalamus controls many body functions related to homeostasis
(temperature, appetite,
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Primary Functions
– Control blood sugar levels and glucose metabolism.
Related Combining Form
– pancreat/o
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 Functions of hormones
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Glucagon increases the blood glucose level by accelerating liver glycogenolysis (conversion of glycogen to glucose)
Insulin decreases the blood glucose by accelerating the movement of glucose out of the blood into cells, which increases glucose metabolism by cells
 Names of hormones
–
–
Glucagon —secreted by alpha cells
Insulin —secreted by beta cells
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Hyperglycemia
Polydipsia (excessive thirst)
Polyphagia (exccessive hunger)
Polyuria (excessive urination)
Hyperinsulinism
(excessive insulin secretion
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Hypoglycemia
Insulinoma (benign tumor of the pancreas caused by hypoglycemia)
Pancreatalgia (pain in the pancreas)
Pancreatitis
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 Diabetes mellitis (a group of metabolic disorders characterized by hyperglycemia)
 Type 1 Diabetes (insulin-dependant diabetes or juvenile diabetes)
 Type 2 Diabetes (non-insulin diabetes)
 Gestational Diabetes
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Diabetes Diagnostic
Procedures/Emergencies/Complications
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 Diagnostic Procedures
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Fasting Blood Sugar
Oral Glucose Tolerance
Test
Home blood glucose monitoring
Fructosamine test
(measures average glucose level over three weeks)
Hemoglobin
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Emergencies
Insulin Shock
Diabetic Coma
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Complications
Heart Disease
Kidney Disease
Neuropathy
Diabetes Retinopathy
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 Primary Function
– Influences the sleep-wakefulness cycle.
 Related Combining Form
– pineal/o
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 A small gland near the roof of the third ventricle of the brain
–
–
Glandular tissue predominates in children and young adults
Becomes fibrous and calcified with age
 Called third eye because its influence on secretory activity is related to the amount of light entering the eyes
 Secretes melatonin, which:
–
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Inhibits ovarian activity
Regulates the body’s internal clock
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Pathology & Treatment of the Pineal Gland
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Pinealopathy
Pinealectomy
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Primary Function
– Secretes hormones that control the activity of the other endocrine glands.
Related Combining
Forms
– pituit/o, pituitar/o
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Anterior pituitary gland
(adenohypophysis)
Names of major hormones
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Thyroid-stimulating hormone (TSH)
Adrenocorticotropic hormone (ACTH)
Follicle-stimulating hormone (FSH)
Luteinizing hormone
(LH)
Growth hormone (GH)
Prolactin hormone (PH)
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Pituitary GlandFunctions of major hormones
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 TSH
—stimulates growth of the thyroid gland; also stimulates it to secrete thyroid hormone (trophic hormone transmitter production)
 ACTH
—stimulates growth of the adrenal cortex and stimulates it to secrete glucocorticoids
 FSH —initiates growth of ovarian follicles each month in the ovary and stimulates one or more follicles to develop to the stage of maturity and ovulation;
 FSH also stimulates estrogen secretion by developing follicles; stimulates sperm production in the male
 LH —acts with FSH to stimulate estrogen secretion and follicle growth to maturity; causes ovulation; causes luteinization of the ruptured follicle and stimulates progesterone secretion by corpus luteum ; causes interstitial cells in the testes to secrete testosterone in the male
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GH —stimulates growth by accelerating protein anabolism; also accelerates fat catabolism and slows glucose catabolism; by slowing glucose catabolism, tends to increase blood glucose to higher than normal level (hyperglycemia)
Prolactin or lactogenic hormone — stimulates breast development during pregnancy and secretion of milk after the delivery of the baby
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 Posterior pituitary gland
(neurohypophysis)
– Names of hormones
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Antidiuretic hormone
(ADH) (Vasopressin)
Oxytocin
– Functions of hormones
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ADH —accelerates water absorption from urine in the kidney tubules into the blood, thereby decreasing urine secretion
Oxytocin —stimulates the pregnant uterus to contract; may initiate labor; causes glandular cells of the breast to release milk into ducts
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Acromegaly
Gigantism
Hyperpituitarism
Hypopituitarism
Puitarism
Pituitary Adenoma
Prolactin-producing adenoma
Diabetes Insipidus
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Human Growth
Hormone Therapy
(recombinant GH)
Synthetic version of the growth hormone.
Administered to stimulate growth when the natural supply of the hormone is insufficient.
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Primary Functions
– Stimulates metabolism, growth, and the activity of the nervous system.
Related Combining
Forms
– thyr/o, thyroid/o
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 Names of hormones (secretions)
– Thyroid hormone —thyroxine (T4) and triiodothyronine (T3)
– Calcitonin —decreases the blood calcium concentration by inhibiting breakdown of bone, which would release calcium into the blood
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Hashimoto’s (the immune system attacks thyroid tissue)
Hypothroidism
Cretinism (congenital hypothyroidism)
Myxedema (severe form of adult hypothyroidism)
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Hyperthyroidism
Thyrotoxicosis
(excessive release of thyroid hormones)
Grave’s disease
(autoimmune hyperthyroidism)
Goiter
Exopthalmos
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Thyroid Scan (Nuclear
Medicine)
Antithyroid Drug
(slows the thyroid)
Lobectomy (removal of one of the four thyroid lobes)
Synthetic thyroid hormones (given for lost thyroid function)
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 There are over 11,000 new cases of thyroid cancer each year in the United
States. Females are more likely to have thyroid cancer at a ratio of three to one. Thyroid cancer can occur in any age group, although it is most common after age 30 and its aggressiveness increases significantly in older patients.
The majority of patients present with a nodule on their thyroid which typically does not cause symptoms.
 Occasionally, symptoms such as hoarseness, neck pain, and enlarged lymph nodes do occur. Although as much as 10 % of the population will have thyroid nodules, the vast majority are benign. Only approximately 5% of all thyroid nodules are malignant. A nodule which is cold on scan (shown in photo outlined in red and yellow) is more likely to be malignant, nevertheless, the majority of these are benign as well.
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 Papillary and mixed papillary/follicular ~
78%
 Follicular and Hurthle cell ~ 15%
 Medullary ~ 5%
 Anaplastic ~ 2%
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 Most thyroid cancers are very curable. In fact, the most common types of thyroid cancer (papillary and follicular) are the most curable. In younger patients, both papillary and follicular cancers can be expected to have better than 95% cure rate if treated appropriately. Both papillary and follicular cancers are typically treated with complete removal of the lobe of the thyroid which harbors the cancer, PLUS, removal of most or all of the other side. The bottom line, most thyroid cancers are papillary thyroid cancer, and this is one of the most curable cancers of ALL cancers that humans get.
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 Medullary cancer of the thyroid is significantly less common, but has a worse prognosis. Medullary cancers tend to spread to large numbers of lymph nodes very early on, and therefore requires a much more aggressive operation than does the more localized cancers such as papillary and follicular.
This cancer requires complete thyroid removal PLUS a dissection to remove the lymph nodes of the front and sides of the neck.
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 The least common type of thyroid cancer is anaplastic which has a very poor prognosis...it tends to be found after it has spread and is not cured in most cases. Often an operation cannot remove all the tumor. These patients often require a tracheostomy during the treatment, and treatment is much more aggressive than for other types of thyroid cancer--because this cancer is much more aggressive.
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 Primary Function
– Plays a major role in the immune reaction.
 Related Combining Form
– thym/o
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Name of hormone — thymosin
Function of hormone — plays an important role in the development and function of the body’s immune system
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 Thymitis
 Thymoma
 Thymectomy
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Primary Function
– Regulate calcium levels throughout the body.
Related Combining
Form
– parathyroid/o
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

Name of hormone — parathyroid hormone
(PTH)
Function of hormone — increases blood calcium concentration by increasing the breakdown of bone with the release of calcium into the blood
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 Hypoparathyroidism
 Hypocalcemia
 Tetany (painful muscle spasms)
 Treatment of a diseased parathyroid gland(s) usually involves surgical treatment
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 Primary Function
– Regulate development and maintenance of secondary sex characteristics.
 Related Combining Form
– gonad/o
*Males: testicles (2)
*Females: ovaries (2)
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 The ovaries contain two structures that secrete hormones —the ovarian follicles and the corpus luteum
 Effects of estrogen (feminizing hormone)
– Development and maturation of breasts and external genitals
– Development of adult female body contours
– Initiation of menstrual cycle
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 Hypergonadism (excessive secretion of hormones)
 Hypogonadism
 Gynecomastia
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 The interstitial cells of the testes secrete the male hormone testosterone
 Effects of testosterone (masculinizing hormone)
–
–
–
–
Maturation of external genitals
Beard growth
Voice changes at puberty
Development of musculature and body contours typical of the male
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 Name of hormones —chorionic gonadotropins, estrogens, and progesterone
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 Functions of hormones —maintain the corpus luteum during pregnancy
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 Many organs (for example, the stomach, intestines, and kidneys) produce endocrine hormones
 The atrial wall of the heart secretes atrial natriuretic hormone (ANH), which stimulates sodium loss from the kidneys
 Fat-storing cells secrete leptin, which controls how full or hungry we feel
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