Chapter 12 The endocrine system

Pineal gland

A smaller 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 it's influence on secretory activity is related to the amount of light entering the eyes.

Adrenals

Abdominal cavity

Thyroid stimulating hormone (TSH)

Acts on the thyroid

Pituitary gland

Anterior pituitary gland, adenohypophysis

Names of hormones

Antidiuretic hormone ( ADH ) hyposecretion causes diabetes insipidus, characterized by excessive volume of urine. Accelerates water reabsorption from urine in the kidney tubules into the blood, thereby decreasing urine secretion

Hypothalamus

Appetite, body temperature, releasing hormones

Inhibiting hormones

Are produced by the hypothalamus, the actual production of ADH and oxytocin takes place in the hypothalamus

Names of the hormones

Calcitonin (CT), decreases the blood calcium concentration by inhibiting breakdown of bone, which would release calcium into the blood

Prostaglandins

Can be called tissue hormones

Pituitary giant

Can result when too much growth hormone is produced by the pituitary gland

Placenta

Chorionic gonadotropins, estrogens and progesterone are the hormones, maintain the corpus luteum during pregnancy

Pituitary

Cranial cavity

Effects of estrogen

Development and maturation of breasts and external genitals. Development of adult female body contours, and initiation of menstrual cycle

Exocrine glands

Discharge secretions into ducts

Mechanism of hormone action

Endocrine glands secrete hormones into the blood. Hormones perform general functions 9f communication and control but a slower, longer-lasting type of control than that provide by nerve impulses. Cells acted on by hormones are called target cells found within target organs. Nonsteroid hormones, first messengers, bind to receptors on the target cell membrane, triggering second messengers to affect the cell's activities

Functions of major hormones

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

Iodine

For the thyroxine to be produced in adequate amounts, the diet must contain sufficient iodine

Functions of major hormones

GH, stimulates growth by accelerating protein anabolism, also accelerates fat catabolism and slow glucose catabolism, by slowing glucose catabolism, tends to increase blood glucose to higher than normal level.

Names of hormones

Glucagon, secreted by alpha cells, increases the blood glucose level by accelerating glycogenolysis in liver, conversion of glycogen to glucose

Adrenal coretx, names of hormones, corticoids

Glucocorticoids (GCs) chiefly cortisol, hydrocortisone. Mineralocorticoids (MCs) chiefly aldosterone. Sex hormones, small amounts of male hormones, androgens, secreted by adrenal cortex of both sexes

Antidiuretic hormone ( ADH)

Hormone secreted by the posterior pituitary gland, serves the body by accelerating water reabsorption from urine into the blood. Diabetes insipidus is the disease cause by hyposecretion of adh. The actual production of adh and oxytocin takes place in the hypothalamus

Regulation of hormone secretion

Hormone secretion is controlled by homeostatic feedback. Negative feedback, mechanism that reverse the direction of a change in a physiological system. Positive feedback, uncommon, mechanisms that amplify physiological changes

Corticoids

Hormones secreted by the adrenal cortex

Adrenal Medulla

Hormones, epinephrine (Epi) or adrenaline and norepinephrine (NR). Helps the body resist stress by intensifying and prolonging the effects of sympathetic stimulation, increases epinephrine secretion is the first endocrine response to stress

Gh

Hypersecretion during childhood results in gigantism and during adulthood results in acromegaly. Hyposecretion during childhood results in pituitary dwarfism

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Hypersecretion of adrenal androgens may result from a virilizing tumor and cause masculinization of affected women

Adrenal abnormalities

Hypersecretion of glucocorticoid causes Cushing syndrome, moon face, hump on back, elevated blood sugar levels, frequent infections.

Hyperthyroidism

Hypersecretion of the thyroid hormones, increases metabolic rate. Characterized by restlessness and exophthalmos, protruding eyes. Graves disease is an inherited form of hyperthyroidism

Mechanisms of endocrine disease

Hypersecretion, secretion of an excess hormone. Hyposecretion, insufficient hormone secretion. Polyendocrine disorder, hyper or hyposecretion of more than one hormone. Target cell insensitivity produces results similar to hyposecretion. Endocrinologist have developed many different strategies for treatment

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Hyposecretion of cortical hormones may result in Addison disease, muscle weakness, reduced blood sugar, nausea, loss of appetite, and weigh loss

Hypothyroidism

Hyposecretion of thyroid hormones, may result from different conditions. Goiter, painless enlargement of thyroid caused by dietary deficiency of iodine. Hyposecretion during early development may result in cretinism, retardation, and during adulthood in myxedema characterized by edema and sluggishness

Growth hormone (GH)

Increases glucose catabolism, speeds up the movement of amino acids into cells from the bloodstream

Names of hormones

Insulin, secreted by beta cells. Decreases the blood glucose by accelerating the movement of glucose metabolism by cells

Pancreatic islets

Islands of endocrine tissue scattered within the exocrine tissue of the pancreas, a digestive gland near the junction of the stomach and small intestine

Antidiuretic hormone

It is released by the posterior lobe of the pituitary, it causes diabetes insipidus when produced in insufficient amounts, it decreases urine volume

Functions of major hormones

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

Thyroid gland

Lies below the larynx, secretes calcitonin.

Thyroid gland

Located in the neck, just inferior to the larynx

Adrenal glands

Located on the superior end of each kidney

Diabetes insipidus

Low antidiuretic hormone levels is the condition as the result of

Other endocrine structures

Many organs, the stomach, intestines, and kidneys produce endocrine hormones. Stomach lining produces ghrelin, which affects appetite and metabolism. The atrial wall of the heart secretes atrial natriuretic hormone (ANH), which stimulates sodium loss from the kidney. Fast storing cells secrete leptin, which controls how full or hungry we feel

Effects of testosterone

Maturation of external genitals, beard growth, voice changes at puberty, and development of musculature and body contours typical of the male

Thymus

Mediastinum

Three cell layers

Middle layer, secretes glucocorticoids. Glucocorticoids help maintain blood glucose concentration by increasing gluconeogenesis, the formation of new glucose from amino acids. Play an essential part in maintaining normal blood pressure, act with epinephrine and norepinephrine to produce an antiinflammatory effect, to bring about normal recovery from inflammations of various kinds. Produce antiimmunity, antialleregy effect, bring about a decrease in the number of lymphocytes and plasma cells.

Parathyroids

Neck

Posterior pituitary

Neurohypophysis, induced labor

Nonsteroid hormones

Nonsteroid hormones works according to the second messenger mechanism. According to this concept, a protein home on access our first messages, providing communication between endocrine glands and target cells. A second messenger such as cyclic amp, provides communication within a hormones target cell. Steroid abuse disrupt the normal negative feedback control of hormones throughout the body and maybe and may result in tissue damage,sterility, mental imbalance, and a host of life threatening metabolic problems

Three cell layers

Outer layer secretes Mineralocorticoids. Mineralocorticoids increase blood sodium and decrease body potassium concentrations by accelerating kidney tubule reabsorption of sodium and excretion of potassium

Names of hormones

Oxytocin (OT), stimulates the pregnant uterus to contract, may initiate labor, causes glandular cells of the breast to release milk into ducts

Prostaglandins

PGs are powerful substances found in a wide variety of body tissue. PGs are often produced in a tissue and diffuse only a short distance to act on cells in that tissue. Several classes of PGs include prostaglandin A, prostaglandin E, and prostaglandin F. PGs influence many body functions, including respiration, blood pressure, gastrointestinal secretions and reproduction

Islets of langerhans

Pancreas is the endocrine gland composed of cell clusters called the islets of langerhans

Ovaries

Pelvic cavity

Pituitary gland

Posterior pituitary gland, neurohypophysis

Hypothalamus

Produces posterior pituitary hormones, actual production of ADH and oxytocin occurs in the hypothalamus. After production in the hypothalamus, hormones pass along axons into the pituitary gland. The secretion and release of posterior pituitary hormones are controlled by nervous stimulation

Functions of major hormones

Prolactin (PRL) or lactogenic hormone, stimulates breast development during pregnancy and secretion of milk after the delivery of the baby. Prolactinoma, benign adenoma causing hypersecretion of PRL, occurs most frequently in females

Tissue hormones

Prostaglandins

Hypothalamus

Regulates anterior pituitary secretion, releasing hormones (RHs) and inhibiting hormones (IHs) control secretion by anterior pituitary. RHs and IHs reach pituitary through a direct capillary connection. The hypothalamus controls many body functions related to homeostatic, temperature, appetite and thirst

Target cells

Respond to a particular hormone

Polyendocrine disorders

Results from hyposecretion or hypersecretion of several hormones

Pineal gland

Secretes melatonin, which, inhibits ovarian activity, regulates the body's internal clock. Abnormal secretion of, or sensitivity to, melatonin may produce seasonal affective disorder (SAD), or winter depression, a form of depression that occurs when exposure to sunlight is low and melatonin levels are high

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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. Chronic stress can disturb the body's balance of metabolic and immune functions

Parathyroid glands

Several glands embedded on the posterior surface of the thyroid gland. Parathyroid hormone ( PTH) increases blood calcium concentration by increasing the breakdown of bone with the release of calcium into the blood

Negative feedback

Specialized homeostatic mechanism that regulates release of hormones

Mechanism of hormone action

Steroid hormones, primary effect produced by binding to receptors within the target cell nucleus and influence cell activity by acting on DNA- a slower process than nonsteroid action. Secondary effects may occur when steroid hormones bind to membrane receptors to rapidly trigger functional changes in the target cell

Functions of prolactin

Stimulates breast development during pregnancy, stimulates milk secretion after delivery

Luteinizing hormone (LH)

Stimulates maturation of a developing follicle, stimulates the production of estrogen, stimulates the formation of a corpus luteum, causes ovulation to occur

Adrenocorticotropic hormone (ACTH)

Stimulates the adrenal cortex

Follicle stimulating hormone (FSH)

Stimulates the growth of follicles, stimulates the production of estrogen and stimulates the growth of seminiferous tubules

Functions of major hormones

TSH, stimulates growth of the thyroid gland, also stimulates it to secrete thyroid hormone. ACTH, stimulates growth of the adrenal cortex and stimulates it to secrete glucocorticoids, mainly cortisol

Parathyroid hormone

Tends to increase the concentration of calcium in the blood,

A young child whose growth is stunted, metabolism is low, sexual development is delayed and mental development is retarded

The child suffers from cretinism, has an underactive thyroid and the child could suffer from a pituitary disorder

Male sex glands

The interstitial cells of testes secrete the male hormone testosterone

Mineralocorticoids

The outer zone of the adrenal cortex, the zona glomerulosa secretes

Female sex glands

The ovaries contain two structures that secrete hormones, the ovarian follicles, estrogen and the corpus luteum, progesterone.

Uterus

This structures will not be stimulated by a tropic hormone from the anterior pituitary

Thymus

Thymosin is the hormone, plays an important role in the development and function of the body's immune system

Names of the hormones

Thyroid hormones, thyroxine (T4) and triiodothyronine (T3), accelerate catabolism, increase the body's metabolic rate

Names of major hormones

Thyroid stimulating hormone ( TSH ), adrenocorticotropic hormone ( ACTH ), follicle stimulating hormone ( FSH ) luteinizing hormone ( LH ) growth hormone ( GH ) prolactin, lactogenic hormone

Glands regulated by the pituitary

Thyroid, ovaries and adrenals

Anterior pituitary gland secretes

Tropic hormones that stimulate other endocrine glands to grow and secrete

Diabetes mellitus

Type 1 results from hyposecretion of insulin. Type 2 results from target cell insensitivity to insulin. Glucose cannot enter cells and thus blood glucose levels rise, producing glycosuria, glucose in the urine

Sphenoid

Where the pituitary gland lies

Glucocorticoids

Would best treat a person suffering from severe allergies