Download Chapter 1 Goals

Page 749
Chapter 18 Goals
Students will be able to:
 Identify the endocrine glands & their hormones.
 Gain an understanding of the functions of these
hormones in the body
 Analyze medical terms related to the endocrine glands
& their hormones
 Identify the abnormal conditions resulting from
excessive & deficient secretions of the endocrine
glands.
 Describe laboratory tests & clinical procedures related
to endocrinology, & recognize relevant abbreviations.
Endocrine
System
Chapter 18
Pages 749 – 798
Page 750
Introduction
 The
endocrine system is an information signaling
system. Glands located in many regions of the
body release hormones into the bloodstream that
regulate many functions of the body.
 Each
hormone has its own receptor, & binding of
a receptor by a hormone is much like the
interaction of a key & a lock.
 The
receptors initiate specific biologic effects
when the hormones bind to them.
Page 750
Introduction: Cont.
•
Examples what hormones do:
 stimulates
the growth of bones
 causes
the maturation of sex
organs/reproductive cells
 controls
the metabolic rate within all the
individual cells
 one
powerful endocrine gland regulates the
activities of other endocrine glands
Page 750
Introduction: Cont.




The pineal gland is included as an endocrine gland
because it is ductless, although less is known about
its endocrine function.
Located in the central portion of the brain, the
pineal secretes melatonin.
The pineal gland has been linked to mental
condition, seasonal affective disorder (SAD), in
which the person suffers from depression in winter
months.
Melatonin secretion increases with deprivation of
light & is inhibited by sunlight.
Page 750
Introduction: Cont.
Endocrine Tissue (apart from major glands)
Location
Secretion
Action
Aggregation of
platelets; Contract
Body cells
Prostaglandins uterus; Lower acid
secretion in stomach;
lower blood pressure
Contracts
gallbladder;
Gastrointestinal Cholecystokinin,
stimulates gastric
tract
Gastrin, Secretin
secretion; stimulates
pancreatic enzymes
Page 750
Introduction: Cont.
Endocrine Tissue (apart from major glands)
Location Secretion
Action
Kidney
Stimulates erythrocyte
Erythropoietin
production
Placenta
Human
Chorionic
Sustains pregnancy
Gonadotropin
Skin
Vitamin D
Affects absorption of
calcium
Page 752
Thyroid Gland
Location & Structure
 Thyroid gland = composed of a right & left lobe
on either side of the trachea, just below the
thyroid cartilage.
• Isthmus = a narrow strip of glandular tissue
that connects the two lobes on the ventral
(anterior) surface of the trachea.
Pages 752 – 753
Thyroid Gland: Cont.
Function
 Hormones
secreted by the thyroid gland are:
•
thyroxine or tetraiodothyronine (T4) &
triiodothyronine (T3) – These hormones are
synthesized in the thyroid gland from iodine &
tyrosine. T4 & T3 are necessary in the body to
maintain a normal level of metabolism in the cells.
•
Calcitonin – secreted when calcium levels in the
blood is high. It stimulates calcium to leave the
blood & enter the bones, thereby lowering blood
calcium back to normal.
Page 753
Parathyroid Glands
Location & Structure
 The parathyroid glands are four small oval bodies
located on the dorsal aspect of the thyroid gland.
Page 754
Parathyroid Glands: Cont.
Function
 Parathyroid hormone (PTH) is secreted by the
parathyroid glands. This hormone mobilizes
calcium from bones into the bloodstream, where
calcium is necessary for proper functioning of the
body tissues, especially muscles.
 If blood calcium decreases (as in pregnancy or
with vitamin D deficiency), parathyroid hormone
secretion increases, causing calcium to leave
bones & enter the bloodstream. In this way, blood
calcium levels are brought back to normal.
Page 754
Adrenal Glands
Location & Structure
 The adrenal glands are two small glands, one on
top of each kidney. Each gland consists of two
parts: an outer portion, the adrenal cortex, & an
inner portion, the adrenal medulla.
• The adrenal cortex & the adrenal medulla are
two glands in one, secreting different
hormones.
 The adrenal cortex secrets steroids or
corticosteroids
 The adrenal medulla secretes catecholamines
Page 755
Adrenal Glands: Cont.
Function
 The adrenal cortex secretes three types of
corticosteroids
1. Cortisol – influence the metabolism of sugar, fats,
& proteins within all body cells & have a powerful
anti-inflammatory effect.
2. Aldosterone – regulate blood volume, blood
pressure & electrolyte concentration
3. (Androgens & estrogens) Sex hormones –
secreted in small amounts & influence secondary
sex characteristics.
Page 755
Adrenal Glands: Cont.
The adrenal medulla secretes two types of
cateholamine hormones:
1. Epinephrine (adrenaline) – Increases heart rate
& blood pressure, dilates bronchial tubes, &
releases glucose from glycogen when the body
needs it for more energy.
2. Norepinephrine (noradrenaline) – Constricts
blood vessels to raise blood pressure.
 Both epinephrine & norepinephrine are
sympathomimetic agents because they mimic, or
copy, the actions of the sympathetic nervous system.

Page 756
Pancreas
Location & Structure
 The pancreas is located near & partly behind the
stomach at the level of the first & second lumbar
vertebrae. The endocrine tissue of the pancreas
consists of specialized hormone-producing cells
called the islets of Langerhans or islet cells.
 More than 98% of the pancreas consists of
exocrine cells (glands & ducts). These cells
secrete digestive enzymes into the gastrointestinal
tract.
Page 756
Pancreas: Cont.
Function
 The islets of Langerhans produce insulin (produced
by beta cells) & glucagon (produced by alpha cells).
Both play a role regulating blood glucose levels.
 When blood glucose rises, insulin lowers blood sugar
by helping it enter body cells. If blood glucose levels
fall too low, glucagon raises blood sugar by acting on
liver cells to promote conversion of glycogen back to
glucose.
 Thus, the endocrine function of the pancreas is
another example of homeostasis.
Page 758
Pituitary Gland
Location & Structure
 The pituitary gland is a small pea-sized gland
located at the base of the brain in a small pocketlike depression of the skull call the sella turcica. It
is a well-protected gland, with the entire mass of
the brain above it & the nasal cavity below. It
consists of two distinct parts: an anterior lobe
composed of glandular epithelial tissue, & a
posterior lobe composed of nervous tissue.
Pages 757 – 758

Pituitary
Gland
The hypothalamus is a region of the brain under the
thalamus & above the pituitary gland. Signals
transmitted from the hypothalamus control secretions
by the pituitary gland. Special secretory neurons in
the hypothalamus send releasing & inhibiting factors
(hormones) via capillaries to the anterior pituitary
gland.
 These factors stimulate or inhibit secretion of
hormones from the anterior lobe of the pituitary
gland. The hypothalamus also produces & secretes
hormones directly to the posterior lobe of the pituitary
gland, where the hormones are stored & then released.
Page 758
Pituitary Gland: Cont.
Function
 The major hormones of the anterior pituitary
gland are:
• Growth hormone (GH) – promotes protein
synthesis that results in the growth of bones,
muscles, & other tissues.
• Thyroid-stimulating hormone (TSH) –
stimulates the growth of the thyroid gland &
secretion of thyroxine (T4) &
triioodothyronine (T3)
Page 758
Pituitary Gland: Cont.
•
Adrenocorticotropic hormone (ACTH) –
Stimulates the growth of the adrenal cortex &
increases it secretion of steroid hormones
•
Gonoadotropic hormones – Several
gonadotropic hormones influence the growth &
hormone secretion of the ovaries in females &
testes in males.
•
Prolactin (PRL) – Stimulates breast
development during pregnancy & sustains milk
production after birth.
Page 758
Pituitary Gland: Cont.
 The
posterior pituitary gland stores & releases
two important hormones that are synthesized in
the hypothalamus:
•
Antidiuretic hormone (ADH) – Stimulates
the reabsorption of water by the kidney
tubules.
•
Oxytocin (OT) – Stimulates the uterus to
contract during childbirth & maintains labor
during childbirth. OT also is secreted during
suckling & causes the production of milk from
the mammary glands.
Page 759
Ovaries
Location & Structure
 The ovaries are two small glands located in the
lower abdominal region of the female.
 The ovaries produce the female gamete, the ovum,
as well as hormones that are responsible for
female sex characteristics & regulation of the
menstrual cycle.
Page 759
Ovaries: Cont.
Function
 The
ovarian hormones are estrogens (estradiol &
estrone) & progesterone.
•
Estrogens stimulate development of ova (eggs)
& development of female secondary sex
characteristics.
•
Progesterone is responsible for the preparation
& maintenance of the uterus in pregnancy.
Page 760
Testes
Location & Structure
 The testes are two small ovoid glands glands
suspended from the inguinal region of the male by
the spermatic cord & surrounded by the scrotal
sac.
 The testes produce the male gametes,
spermatozoa, as well as the male hormone called
testosterone.
Page 760
Testes: Cont.
Function
 Testosterone is an androgen (male steroid
hormone) that stimulates development of sperm &
secondary sex characteristics in the male
(deepening of the voice & development of beard
& pubic hair)
Page 768
Pathology
Thyroid Gland
 Enlargement of the thyroid gland is goiter.
• Endemic goiter occurs in certain regions where
there is a lack of iodine in the diet.
• Nodular or adenomatous goiter, in hyperplasia
occurs as well as formation of nodules &
adenomas. Some patients with nodular goiter
develop hyperthyroidism with clinical signs &
symptoms such as rapid pulse, tremors,
nervousness, & excessive sweating.
Pages 768 – 769
Pathology: Cont.
Thyroid Gland – Hypersecretion
Over-activity of the thyroid
hyperthyroidism
gland; thyrotoxicosis.
Thyroid Gland – Hyposecretion
hypothyroidism Under-activity of the thyroid gland
Thyroid Gland – Neoplasms
thyroid
carcinoma
Cancer of the thyroid gland
Pages 769 – 770
Pathology: Cont.
Parathyroid Glands – Hypersecretion
Excessive production of
hyperparathyroidism
parathormone
Parathyroid Gland – Hyposecretion
Deficient production of
hypoparathyroidism
parathyroid hormone
Pages 770 – 771
Pathology: Cont.
Adrenal Cortex – Hypersecretion
Adrenal
Excessive secretion of adrenal androgens
virllism
Cushing Group of signs & symptoms produced by
syndrome excess cortisol from the adrenal cortex.
Adrenal Cortex – Hyposecretion
Addison disease
Hypofunctioning of the adrenal
cortex
Adrenal Medulla – Hypersecretion
Benign tumor of the adrenal
pheochromocytoma
medulla
Pages 772 – 774
Pathology: Cont.
Pancreas – Hypersecretion
Excess secretion of insulin
hyperinsulinism
causing hypoglycemia
Pancreas – Hyposecretion
Lack of insulin secretion or resistance of
diabetes insulin in promoting sugar, starch, & fat
mellitus metabolism in cells.
(DM) Type 1 diabetes - autoimmune disease
Type 2 diabetes - insulin resistance
Pages 775 – 776
Pathology: Cont.
Pituitary Gland: Anterior Lobe– Hypersecretion
acromegaly
gigantism
Hypersecretion of growth hormone from the
anterior pituitary after puberty, leading to
enlargement of extremities
Hypersecretion of growth hormone from the
anterior pituitary before puberty, leading to
abnormal overgrowth of body tissues.
Pituitary Gland: Anterior Lobe– Hyposecretion
Congenital hyposecretion of growth
dwarfism
hormone; hypopitutary dwarfism
panhypopituitarism Deficiency of all pituitary hormones.
Page 777
Pathology: Cont.
Pituitary Gland: Posterior Lobe –
Hypersecretion
syndrome of
Excessive secretion of
inappropriate ADH
antidiuretic hormone
(SIADH)
Pituitary Gland: Posterior Lobe–
Hyposecretion
diabetes insipidus
(DI)
Insufficient secretion of
antidiuretic hormones
(vasopressin).
Page 778
Laboratory Tests
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.
Measurement of hormones, electrolytes,
serum &
glucose, & other substances in serum
urine
(blood) & urine as indicators of endocrine
tests
function
thyroid
Measurement of T3, T4, & TSH in the
function
bloodstream.
tests
Page 778
Clinical Procedures
Measurement of eyeball
protrusion (as in Graves
exophthalmometry
disease) with an
exophthalmometer
computed
tomography (CT)
scan
X-ray imaging of endocrine
glands in cross section &
other views, to assess size &
infiltration by tumor.
Page 778
Clinical Procedures: Cont.
magnetic
resonance
imaging
(MRI)
Magnetic waves produce images of
the hypothalamus & pituitary gland to
locate abnormalities
Scanner detects radioactivity &
thyroid scan
visualizes the thyroid gland
ultrasound Sound waves show images of
examination endocrine organs