chapter 18 Flashcards
the pineal gland
. Melatonin functions to support the
body’s “biologic clock” and is thought to induce sleep. The pineal gland has been linked
to a mental condition, seasonal affective disorder (SAD)
diologic landmark when x-rays of the brain are examined.
Hormones are also secreted by endocrine tissue in other organs apart from the major
endocrine glands.
erythropoietin (kidney), human chorionic gonadotropin
(placenta), and cholecystokinin (gallbladder
Prostaglandins
are hormone-like substances
that affect the body in many ways. First found in semen (produced by the prostate gland)
but now recognized in cells throughout the body, prostaglandins have three functions:
(1) stimulate the contraction of the uterus; (2) regulate body temperature, platelet
aggregation, and acid secretion in the stomach; and (3) have the ability to lower blood
pressure
isthmus
a narrow strip of glandular
tissue that connects the two lobes on the ventral (anterior) surface of the trachea
Two of the hormones secreted by the thyroid gland
thyroxine or tetraiodothyronine
(T4) and triiodothyronine (T3). These hormones are synthesized in the thyroid gland from
iodine, which is picked up from the blood circulating through the gland, and an amino
acid called tyrosine. T4 (containing four atoms of iodine) is much more concentrated in
the blood, whereas T3 (containing three atoms of iodine) is far more potent in affecting
the metabolism of cells. Most thyroid hormone is bound to protein molecules as it travels
in the bloodstream.
calcitonin
A more recently discovered hormone produced by the thyroid gland is calcitonin.
Calcitonin is secreted when calcium levels in the blood are high. It stimulates calcium to
leave the blood and enter the bones, thereby lowering blood calcium back to normal
Parathyroid hormone (PTH
) is secreted by the parathyroid glands. This hormone (also
known as parathormone) mobilizes calcium (a mineral substance) from bones into the
bloodstream, where calcium is necessary for proper functioning of body tissues, especially
muscles
The adrenal cortex secretes steroids or corticosteroids (complex chemicals derived from cholesterol);
; the adrenal medulla secretes catecholamines
chemicals derived from amino acids
The adrenal cortex secretes three types of corticosteroid
Glucocorticoids - Cortisol Increases blood glucose Mineralocorticoid - Aldosterone Increases sodium reabsorption; regulates blood pressure Sex hormones - Androgen Estrogen Sexual characteristics
The adrenal medulla secretes two types of catecholamine hormones:
- Epinephrine (adrenaline)—Increases heart rate and blood pressure, dilates bronchial
tubes, and releases glucose (sugars) from glycogen (storage substance) when the body
needs it for more energy. - Norepinephrine (noradrenaline)—Constricts blood vessels to raise blood pressure.
nd partly behind the stomach [2] at the level of
the first and second lumbar vertebrae. The endocrine tissue of the pancreas consists of
specialized hormone-producing cells called the islets of Langerhans [3] or islet cells
The islets of Langerhans produce insulin (produced by beta cells) and glucagon (produced
by alpha cells). Both play a role regulating blood glucose (sugar) levels.
insulin
Lowers blood sugar (glucose to glycogen)
Glucagon
Raises blood sugar
glycogen to glucose
The pituitary gland, also called the hypophysis
The pituitary consists of two distinct parts: an anterior lobe or adenohypophysis [1],
composed of glandular epithelial tissue, and a posterior lobe or neurohypophysis [2],
composed of nervous tissue. The hypothalamus [3] is a region of the brain under the
thalamus and above the pituitary gland
Special secretory neurons in the hypothalamus send
releasing and inhibiting factors (hormones) via capillaries to the anterior pituitary gland.
The hypothalamus also produces and secretes hormones directly to the
posterior lobe of the pituitary gland, where the hormones are stored and then released
anterior pituitary gland are:
- Growth hormone (GH), or somatotropin (STH)—Promotes protein synthesis that
results in the growth of bones, muscles, and other tissues. GH also stimulates the
liver to make insulin-like growth factor (also called IGF), which stimulates the growth
of bones. It increases blood glucose levels and is secreted during exercise, sleep, and
hypoglycemia. - Thyroid-stimulating hormone (TSH), or thyrotropin—Stimulates the growth of the
thyroid gland and secretion of thyroxine (T4) and triiodothyronine (T3). - Adrenocorticotropic hormone (ACTH), or adrenocorticotropin—Stimulates the
growth of the adrenal cortex and increases its secretion of steroid hormones (primarily
cortisol). - Gonadotropic hormones—Several gonadotropic hormones influence the growth and
hormone secretion of the ovaries in females and the testes in males.
In the female, follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
stimulate the growth of eggs in the ovaries, the production of hormones, and ovulation.
In the male, FSH influences the production of sperm, and LH (an interstitial cell–
stimulating hormone) stimulates the testes to produce testosterone. - Prolactin (PRL)—Stimulates breast development during pregnancy and sustains
milk production after birth.
The posterior pituitary gland stores and releases two important hormones that are
synthesized in the hypothalamus:
- Antidiuretic hormone (ADH), also called vasopressin—Stimulates the reabsorption
of water by the kidney tubules. In addition, ADH also increases blood pressure by
constricting arterioles. - Oxytocin (OT)—Stimulates the uterus to contract during childbirth and maintains
labor during childbirth. OT also is secreted during suckling and causes the production
of milk from the mammary glands
aden/o
gland
adrenal/o
adrenal gland
gonadotropin
Here, -tropin means to act on. Gonadotropins act on (stimulate)
gonads. Examples of gonadotropins are FSH and LH, secreted by
the pituitary gland.
dips/o
thirst
polydipsia
Poly- means many or increased. Uncontrolled diabetes (mellitus or
insipidus) causes increased thirst
myx/o
mucus
ster/o
solid structure
toc/o
childbirth
-agon
assemble, gather
together
-tropin
stimulating the
function of (to
turn or act on)
eu-
good, normal
hyperthyroidism
Overactivity of the thyroid gland; thyrotoxicosis.
The most common form of this condition is Graves disease (resulting from
autoimmune processes). Because metabolism is faster, the condition is marked by
an increase in heart rate (with irregular beats), higher body temperature,
hyperactivity, weight loss, and increased peristalsis (diarrhea occurs). In addition,
exophthalmos (protrusion of the eyeballs, or proptosis) occurs as a result of
swelling of tissue behind the eyeball, pushing it forward
hypothyroidism Underactivity of the thyroid gland.
Myxedema is advanced hypothyroidism in adulthood. Atrophy of the thyroid
gland occurs, and practically no hormone is produced. The skin becomes dry and
puffy (edema) because of the collection of mucus-like (myx/o = mucus) material
under the skin.
In cretinism, extreme hypothyroidism during infancy and childhood leads to a
lack of normal physical and mental growth
hyperparathyroidism
Excessive production of parathormone.
Hypercalcemia occurs as calcium leaves the bones and enters the bloodstream,
where it can produce damage to the kidneys and heart.
adrenal virilism
Excessive secretion of adrenal androgens.
Adrenal hyperplasia or more commonly adrenal adenomas or carcinomas can
cause virilization in adult women. Signs and symptoms include amenorrhea,
hirsutism (excessive hair on the face and body), acne, and deepening of the voice.
Cushing syndrome
Group of signs and symptoms produced by excess cortisol from the
adrenal cortex.
A number of signs and symptoms occur as a result of increased cortisol secretion,
including obesity, moon-like fullness of the face, excess deposition of fat in the
thoracic region of the back (so-called buffalo hump), hyperglycemia, hypernatremia,
hypokalemia, osteoporosis, virilization, and hypertension.
Addison disease
Hypofunctioning of the adrenal cortex.
The adrenal cortex is essential to life. When aldosterone and cortisol blood levels
are low, the patient experiences generalized malaise, weakness, muscle atrophy,
and severe loss of fluids and electrolytes (with hypoglycemia, low blood pressure,
and hyponatremia).
pheochromocytoma
Benign tumor of the adrenal medulla; tumor cells stain a dark or
dusky (phe/o) color (chrom/o).
hyperinsulinism
Excess secretion of insulin causing hypoglycemia.
panhypopituitarism
Deficiency of all pituitary hormones.
Tumors of the sella turcica as well as arterial aneurysms may be etiologic factors,
causing a failure of the pituitary to secrete hormones that stimulate major glands
in the body
syndrome of inappropriate ADH
SIADH
Excessive secretion of antidiuretic hormone.
Hypersecretion of ADH produces excess water retention in the body. Treatment
consists of dietary water restriction. Tumor, drug reactions, and head injury are
some of the possible causes.
diabetes insipidus (DI)
nsufficient secretion of antidiuretic hormone (vasopressin)
fasting plasma glucose (FPG)
Also known as fasting blood sugar test. Measures circulating glucose
level in a patient who has fasted at least 8 hours
thyroid scan
Scanner detects radioactivity and visualizes the thyroid gland
