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Endocrine System
CHAPTER 13
2
Endocrine System Overview
• Endocrine system– Consists of ductless glands
• Secrete hormones directly into bloodstream
– Affect the function of specific body organs• Regulates many intricate body functions
3
Pituitary Gland
• Referred to as “master gland”– Secretes hormones that control functions of
other glands– Known as hypophysis– Has two distinct lobes with specific functions
4
Pituitary Gland • Anterior Pituitary Gland = Adenohypophysis
– Secretes Growth Hormone (GH) • Also called Somatotropic Hormone (STH)• Regulates growth of bone, muscle, and other body
tissues
– Secretes Adrenocorticotropic Hormone (ACTH)• Stimulates normal growth and development of
adrenal cortex and secretion of corticosteroids
5
Pituitary Gland• Anterior Pituitary Gland
– Secretes Thyroid-Stimulating Hormone (TSH)• Promotes and maintains normal growth and
development of the thyroid gland• Stimulates secretions of the thyroid hormones
– Secretes Lactogenic Hormone (LTH) • Also called Prolactin• Promotes development of breasts during
pregnancy• Stimulates secretion of milk from breasts after
delivery of baby
6
Pituitary Gland• Anterior Pituitary Gland
– Secretes Follicle-Stimulating Hormone (FSH)• Stimulates secretion of estrogen and production of
eggs in the female ovaries• Stimulates production of sperm in the male testes
– Secretes Luteinizing Hormone (LH)• Stimulates female ovulation and the secretion of
testosterone in the male– Melanocyte-Stimulating Hormone (MSH)
• Controls intensity of pigmentation in pigmented cells of the skin
7
Pituitary Gland• Posterior Pituitary Gland = Neurohypophysis
– Secretes Antidiuretic Hormone (ADH)• Decreases excretion of large amounts of urine • Increases reabsorption of water by the renal tubules
– Secretes Oxytocin (OT) • Stimulates contraction of the uterus during childbirth• Stimulates release of milk from the breasts of lactating
women in response to the suckling reflex of the infant
8
Pineal Gland• Tiny, pinecone-shaped gland
– Located behind dorsal aspect of midbrain region
– Plays a part in supporting body’s biological clock• Regulation of patterns of eating, sleeping, and
reproduction
– Secretes melatonin• Induces sleep
9
Thyroid Gland
• Located in front of the neck just below the larynx, on either side of the trachea– Consists of a right and left lobe
10
Thyroid Gland• Secretes Triiodothyronine (T3)
– Helps regulate growth and development of body
– Helps control metabolism and temperature– Secretes Thyroxine (T4)
• Helps maintain normal body metabolism
– Secretes Calcitonin• Helps regulate the level of calcium in the blood
11
Parathyroid Glands
• Four tiny rounded bodies located on dorsal aspect of thyroid gland– Secrete Parathyroid Hormone (PTH)
• Also known as parathormone• Regulates level of calcium in blood
12
Thymus
• Single gland located in mediastinum near the middle of the chest, just beneath sternum– Large in fetus and infants, shrinks with age– Secretes thymosin and thymopoietin
• Stimulates production of T cells that are involved in the immune response
13
Adrenal Glands
• Two small glands, one positioned atop each kidney
• Also known as suprarenal glands– Consists of an adrenal cortex and an adrenal
medulla• Each has independent functions
14
Adrenal Glands• Adrenal cortex secretes corticosteroids
– Mineralocorticoids• Regulate how mineral salts (electrolytes) are
processed in the body– Glucocorticoids
• Influence metabolism of carbohydrates, fats, and proteins in the body
• Necessary for maintaining normal blood pressure• Have an anti-inflammatory effect on the body• Increase glucose available during “fight-or-flight”
responses by the body
15
Adrenal Glands
• Adrenal cortex secretes – Gonadocorticoids
• Sex hormones secreted in small amounts• Contribute to secondary sex characteristics in
males and females
16
Adrenal Glands• Adrenal medulla secretes catecholamines
– Epinephrine = adrenaline• Sympathiomimetic agent• Increases heart rate and force of heart muscle
contraction• Dilates bronchioles in the lungs• Decreases peristalsis in the intestines• Raises blood glucose levels by causing the liver to
convert glycogen into glucose
17
Adrenal Glands
• Adrenal medulla secretes – Norepinephrine = noradrenaline
• Known as a sympathomimetic agent• Produces a vasoconstrictor effect on the blood
vessels, thereby raising blood pressure
18
Pancreas
• Elongated gland located in upper left quadrant of the abdomen– Behind the stomach
• Extends horizontally across the body– Beginning at first part of small intestines and
ending at edge of spleen
19
Pancreas• Islets of Langerhans secrete:
– Glucagon• Increases blood glucose levels by stimulating liver
to convert glycogen into glucose when blood sugar is extremely low
– Insulin• Makes it possible for glucose to pass from blood
through cell membranes to be used for energy• Promotes conversion of excess glucose into
glycogen for storage in the liver for later use
20
Ovaries
• Female sex glands = female gonads– Pair of almond shaped glands
• Located in upper pelvic cavity, on either side of lateral wall of uterus
• Near fimbriated ends of the fallopian tubes
– Responsible for producing mature ova and releasing them at monthly intervals during ovulation
21
Ovaries• Hormones secreted by the ovaries
– Estrogen• Promotes maturation of ovum in the ovary• Stimulates vascularization of uterine lining each
month to prepare for implantation of a fertilized egg• Contributes to secondary sex characteristic
changes in female with onset of puberty– Progesterone
• Primarily responsible for changes within the uterus in anticipation of a fertilized ovum
• Responsible for development of maternal placenta after implantation of a fertilized ovum
22
Testes• Testes = male gonads = testicles
– Two small ovoid glands located in scrotum– Primary organs of male reproductive system– Responsible for production of sperm and
secretion of androgens (male steroid hormones)
– Secrete testosterone• Responsible for secondary sex characteristic
changes that occur in male with onset of puberty• Responsible for maturation of sperm
PATHOLOGICAL CONDITIONS
Pituitary Gland
24
Acromegaly
• Pronounced– (ak-roh-MEG-ah-lee)
• Defined– Chronic metabolic condition characterized by
the gradual, noticeable enlargement and elongation of the bones of the face, jaw, and extremities, due to hypersecretion of the human growth hormone after puberty
25
Diabetes Insipidus
• Pronounced– (dye-ah-BEE-teez in-SIP-ih-dus)
• Defined– Deficiency in secretion of antidiuretic hormone
(ADH) by posterior pituitary gland• Characterized by large amounts of urine and
sodium being excreted from the body
26
Dwarfism• Pronounced
– (DWARF-ism)• Defined
– Generalized growth retardation of body due to deficiency of human growth hormone
– Also known as congenital hypopituitarism or hypopituitarism
27
Gigantism
• Pronounced– (JYE-gan-tizm)
• Defined – Proportional overgrowth of body’s tissue due
to hypersecretion of human growth hormone before puberty
28
Hypopituitarism
• Pronounced– (high-poh-pih-TOO-ih-tah-rizm)
• Defined – Complex syndrome resulting from absence or
deficiency of pituitary hormone(s)
PATHOLOGICAL CONDITIONS
Thyroid Gland
30
Cancer, Thyroid Gland
• Pronounced– (CAN-sir, THIGH-royd gland)
• Defined– Malignant tumor of the thyroid gland– Leads to dysfunction of gland and inadequate
or excessive secretion of thyroid hormone
31
Goiter, Simple; Nontoxic
• Pronounced– (GOY-ter simple; nontoxic)
• Defined– Hyperplasia of thyroid gland
• Results from a deficient amount of iodine in diet, required for synthesis of T3 and T4, thyroid hormones produced by the thyroid gland
32
• Pronounced– (high-per-THIGH-royd-izm)
• Defined– Hypertrophy of thyroid gland resulting in
excessive secretion of thyroid hormone• Causes extremely high body metabolism, thus
creating multisystem changes
Graves’ Disease (Hyperthyroidism)
33
Graves’ DiseaseHyperthyroidism
• Three distinguishing characteristics– Hyperthyroidism– Thyroid gland enlargement (goiter)– Exophthalmia
• Unnatural protruding of the eyes
34
Hypothyroidism• Pronounced
– (high-poh-THIGH-royd-izm)• Defined
– Condition in which there is a shortage of thyroid hormone causing an extremely low body metabolism due to a reduced usage of oxygen
35
Hypothyroidism
• Most severe form known as myxedema– Water retention all over body in connective
tissues– Person has puffy appearance and thick
tongue– Reduced metabolic rate
36
Thyroiditis(Hashimoto’s)
• Pronounced– (thigh-royd-EYE-tis)– (HASH-ee-moh-TOZ)
• Defined– Chronic inflammation of the thyroid gland,
leading to enlargement of the thyroid gland
37
Thyrotoxicosis(Thyroid Storm)
• Pronounced– (thigh-roh-toks-ih-KOH-sis)
• Defined– Acute, sometimes fatal, incident of
overactivity of the thyroid gland resulting in excessive secretion of thyroid hormone
PATHOLOGICAL CONDITIONS
Parathyroid Gland
39
Hyperparathyroidism(Hypercalcemia)
• Pronounced– (high-per-pair-ah-THIGH-royd-izm)– (high-per-kal-SEE-mee-ah)
• Defined– Overactivity of any one of the parathyroid
glands– Leads to high levels of calcium in blood and
low levels of calcium in bones
40
Hypoparathyroidism
• Pronounced– (high-poh-pair-ah-THIGH-royd-izm)
• Defined– Decreased production of parathyroid hormone
resulting in hypocalcemia– Characterized by nerve and muscle weakness
with muscle spasms or tetany
PATHOLOGICAL CONDITIONS
Adrenal Glands
42
Addison’s Disease• Pronounced
– (AD-ih-sons dih-ZEEZ)• Defined
– Life-threatening disease process due to failure of the adrenal cortex to secrete adequate mineralocorticoids and glucocorticoids • Resulting from an autoimmune process, a
neoplasm, an infection, or a hemorrhage in the gland
43
• Pronounced– (PRYE-mary al-doss-STAIR-ohn-izm)
• Defined– Condition characterized by excretion of
excessive amounts of aldosterone• Leads to an increased volume of blood and
hypertension• Causes body to retain extra sodium and excrete
extra potassium
Conn’s Disease(Primary Aldosteronism)
44
Cushing’s Syndrome
• Pronounced– (CUSH-ings SIN-drom)
• Defined– Cluster of symptoms in the adrenal gland as a
result of an excessive amount of cortisol or ACTH circulating in blood
45
Cushing’s Syndrome• Cushing’s Syndrome
– Symptoms• Central obesity• Round “moon” face• Edema• Hypertension• Supraclavicular fat pads (buffalo hump)• Muscular weakness and wasting• Skin infection• Poor wound healing• Low potassium level• Emotional changes
46
Pheochromocytoma• Pronounced
– (fee-oh-kroh-moh-sigh-TOH-mah)• Defined
– Vascular tumor of adrenal medulla– Produces extra epinephrine and
norepinephrine– Leads to persistent or intermittent
hypertension and heart palpitations
47
Virilism
• Pronounced– (VEER-il-izm)
• Defined– Development of male secondary sex
characteristics in the female due to the excessive secretion of adrenocortical androgens from the adrenal cortex
48
Virilism• Virilism
– Symptoms• Excessive hair on the body and face (hirsutism)• Absence of menstruation• Deepening of the voice• Acne• Oily skin• Muscular hypertrophy• Atrophy of the breasts and uterus• Ovarian changes
PATHOLOGICAL CONDITIONS
Pancreas
50
Diabetes Mellitus• Pronounced
– (dye-ah-BEE-teez MELL-ih-tus)• Defined
– Disorder of pancreas in which beta cells of islets of Langerhans of the pancreas fail to produce an adequate amount of insulin• Results in body’s inability to appropriately
metabolize carbohydrates, fats, and proteins
51
Diabetes Mellitus• Classifications
– Type I Diabetes – Formerly known as Insulin-Dependent
Diabetes Mellitus (IDDM)• Usually occurs before age of 30• Sudden onset• Controlled with insulin injections • Individuals are prone to developing ketosis
52
Diabetes Mellitus• Classifications
– Type II Diabetes – Formerly known as Non-Insulin-Dependent
Diabetes Mellitus (NIDDM)• Usually appears in adults after age of 40• Majority of these individuals are obese• Usually controlled through diet and exercise
53
Diabetic Retinopathy• Pronunciation
– (dye-ah-BET-ik ret-in-OP-ah-thee)• Defined
– Disorder of blood vessels of retina in which capillaries of the retina undergo localized areas of bulging (microaneurysms), hemorrhages, leakage, and scarring• Consequence of 8-10 year duration of diabetes
mellitus
54
Gestational Diabetes• Pronounced
– (jess-TAY-shun-al dye-ah-BEE-teez)• Defined
– Disorder in which women who are not diabetic before pregnancy develop diabetes during the pregnancy• Inability to metabolize carbohydrates• Results in hyperglycemia
55
Pancreatic Cancer
• Pronounced– (pan-kree-AT-ik CAN-sir)
• Defined– Life-threatening primary malignant neoplasm
typically found in head of pancreas
56
Pancreatitis• Pronounced
– (pan-kree-ah-TYE-tis)• Defined
– Acute or chronic destructive inflammatory condition of the pancreas• Creates symptoms that vary from mild self-limiting
pancreatic edema to massive necrotizing hemorrhagic pancreatitis
Diagnostic Techniques, Treatments, and Procedures
Endocrine System
58
• Thyroid function tests– Tests that measure blood levels of hormones
T3, T4, and TSH• Thyroid-Stimulating Hormone (TSH) Blood
Test – Measures concentration of TSH in blood
• Used to differentiate primary hypothyroidism from secondary hypothyroidism
Diagnostic Techniques, Treatments, and Procedures
59
• Fasting Blood Sugar (FBS)– Blood glucose sample taken usually early in
the morning after the person has been without food or drink since midnight
Diagnostic Techniques, Treatments, and Procedures
60
• Glucose Tolerance Test (GTT)– Test that evaluates person’s ability to tolerate
a concentrated oral glucose load by measuring glucose levels:• Prior to glucose administration• 30 minutes after glucose administration• 1, 2, and 3 hours after glucose administration
Diagnostic Techniques, Treatments, and Procedures
61
• Radioactive Iodine Uptake (RAIU) Test– Thyroid function test – Evaluates function of thyroid gland– Administers radioactive iodine – Places gamma ray detector over thyroid
gland – Determines percentage of radioactive iodine
absorbed by gland over specific time periods
Diagnostic Techniques, Treatments, and Procedures
62
• Serum Glucose Tests– Tests that measure amount of glucose in
blood at time sample was drawn• Thyroid Echogram (Ultrasound)
– Examination to distinguish solid thyroid nodules from cystic nodules
Diagnostic Techniques,Treatments, and Procedures
63
• Thyroid scan– Examination to determine position, size,
shape, and physiological function of thyroid gland through use of radionuclear scanning
Diagnostic Techniques, Treatments, and Procedures