Download Chapter 11: Endocrine System Theory Lecture Outline

Chapter 11: Endocrine System
Theory Lecture Outline
Objectives
1. List the glands that make up the endocrine system
2. Describe negative feedback hormonal control
3. Name the hormones of the endocrine system and their function
4. Describe the role of prostaglandins
5. Describe some disorders of the endocrine system
6. Define key words that relate to this chapter
Introduction
The organs that make up the endocrine system are the endocrine glands that secrete hormones into the
blood. Unlike the organs in other systems, endocrine glands are scattered throughout the body. In
addition, they are small and unimpressive; however, as you study this chapter, you will discover that they
are extremely important. The study of endocrine glands and hormones is called endocrinology.
Endocrine Glands
• Glands produce secretions
• Endocrine glands make hormones
a. Pituitary
b. Thyroid and parathyroid
c. Thymus
d. Adrenal
e. Gonads
f. Pancreas
g. Pineal
• Hormones use the circulatory system to reach their target
• Do not confuse with exocrine glands which has secretions that go through a duct
a. Examples of exocrine glands include sweat, salivary, lacrimal (tears) and pancreas
b. Pancreas performs both as an exocrine gland and an endocrine gland
1. Produces pancreatic juices through a duct into the small intestine
2. Produces insulin secreted into the bloodstream
Function of the Endocrine System
• Coordinate and integrate functions to maintain homeostasis
o The endocrine system, along with the nervous system, function in the regulation of body
activities
• Nervous system acts through electrical impulses and neurotransmitters to cause muscle
contraction and glandular secretions
o The secretion of the hormones operates on a negative feedback system or under the
control of the nervous system
• Negative feedback system
o Occurs when there is a drop in the level of a hormone; this drop triggers a chain reaction
of responses to increase the amount of hormone in the blood
Pituitary Gland
• Also known as the master gland
• It’s About the size of a grape
• And is Located at the base of the brain
• Connected to the hypothalamus
o Hormones of the pituitary are controlled by the releasing chemicals of the hypothalamus
• Divided into an anterior lobe and posterior lobe
Ann Senisi Scott & Elizabeth Fong: Body Structures & Functions 11th Edition
Anterior Lobe – Pituitary
The larger anterior pituitary lobe produces six hormones
• Growth hormone (GH) or somatotropin
o Responsible for growth and development
• Prolactin hormone (PRL)
a. Develops breast tissue and stimulates milk production after childbirth
b. Function unknown in males
• Thyroid-stimulating hormone (TSH)
o Stimulates the growth and secretion of the thyroid gland
• Adrenocorticotropic hormone (ACTH)
o Stimulates the growth and secretion of the adrenal cortex
• Follicle-stimulating hormone (FSH)
a. Follicle (immature egg) maturation and estrogen secretion in females
b. Spermatogenesis in males
• Luteinizing hormone (LH)
a. Ovulation and progesterone production in females
b. Called interstitial cell-stimulating hormone (ICSH) in males
o Testosterone production
Posterior Lobe – Pituitary
Smaller posterior pituitary lobe consists primarily of nerve fibers and neuroglial cells
• Vasopressin converts to antidiuretic hormone (ADH) in the bloodstream
o ADH maintains water balance by increasing the absorption of water in the kidneys
• Oxytocin
a. Released during childbirth, causing strong contractions of the uterus
b. Stimulates ejection of milk form mammary gland
Thyroid Glands
• The thyroid and parathyroid glands are Located in the neck close to the cricoid cartilage (Adam’s
apple)
o Consists of two lobes, one on each side of the trachea, just below the larynx or voice box
• Regulates body metabolism and secretes three hormones
Iodides combine with the amino acid tyrosine to form the hormones triiodothyronine (T3) and
thyroxine (T4)
a. Thyroxine (T4)
1. Controls the rate of metabolism, heat production and oxidation of all cells
2. Stimulates protein synthesis
3. Stimulates breakdown of liver glycogen to glucose
b. Triiodothyronine (T3)
1. Controls metabolic rate
2. Stimulates protein synthesis
3. Stimulates breakdown of liver glycogen to glucose
c. Calcitonin
o Controls the calcium ion concentration in the body by maintaining a proper
calcium level in the bloodstream
Parathyroid Glands
• Four glands the size of grains of rice
• Attached to the posterior surface of the thyroid gland
• Maintains calcium-phosphorus balance
• Secretes the hormone Parathormone
Ann Senisi Scott & Elizabeth Fong: Body Structures & Functions 11th Edition
•
Parathormone and calcitonin
o Antagonistic effects
1. Calcitonin decreases blood calcium
2. Parathormone increases blood calcium
Thymus Gland
• Both an endocrine gland and lymphatic organ
• Located under the sternum
• Decreases in size with aging
• Secrets the hormone Thymosin
o Stimulates the lymphoid cells responsible for production of T cells which fight certain
diseases
o Critical to the development of the immune system
Adrenal Glands
• Located on top of each kidney
• Gland has two parts – the cortex and the medulla
a. Cortex
1. ACTH from the pituitary gland stimulated activity of the cortex
2. Hormones secreted by the adrenal cortex are known as corticoids (effective as
anti-inflammatory drugs)
3 groups of corticoids
o Mineralocorticoids – mainly aldosterone which speeds up reabsorption
in the kidneys
o Glucocorticoids – namely cortisone and cortisol, increase the amount of
glucose in the blood
o Sex hormones for both males and females (androgens and some
estrogen) – androgens are male sex hormones which together with
similar hormones form the gonads
b. Medulla
1. Secretes the hormones epinephrine and norepinephrine
2. Epinephrine (adrenalin) is a powerful cardiac stimulant
o Bronchial relaxation
o Increased cardiac output and venous return
3. Responds to the sympathetic nervous system triggering the fight-or-flight
hormones
Gonads
• Also called sex glands
• Ovaries in females
o Ovaries are responsible for producing the ova or egg and the hormones estrogen and
progesterone
1. Estrogen stimulates the development of the reproductive organs
2. Progesterone works with estrogen to prepare uterus for pregnancy
• Testes in Males
a. Responsible for producing sperm and the hormone testosterone
b. Testosterone is responsible for the development of the male reproductive organs and
secondary sex characteristics
Ann Senisi Scott & Elizabeth Fong: Body Structures & Functions 11th Edition
Pancreas
• Located behind stomach
• Exocrine and endocrine functions
• Islets of Langerhans
a. B (Beta) cells produce Insulin
o Decreases blood glucose
b. A (Alpha) cells produce Glucagon
o Increases blood glucose
Pineal Gland
• Located on the roof of the third ventricle in the brain
• Hormone produced by the pineal gland is called Melatonin
• Function is unclear but melatonin causes body temperature to drop
o Melatonin production is influenced by the amount of light entering the eye
Effects of Aging
• Affects nearly every gland
• Blood levels of some hormones increase while others decrease
• Affects the homeostasis of the body
Endocrine System Disorders
• A number of factors can cause problems
a. Disease of the gland
b. Autoimmune causes
c. Infections
d. Dietary deficiencies
• Signs and symptoms usually do to hyper- or hypoactivity of the glands
Disorders – Pituitary
• Hyperfunction
a. Gigantism
o Overgrowth of the long bones leading to excessive tallness
b. Acromegaly
o Overdevelopment of the bones of the face, hands and feet
• Hypofunction
o Dwarfism – long bones are abnormally decreased due to inadequate production of growth
hormone
Disorders – Thyroid
Because the thyroid gland controls metabolic activity, any disorder will affect other structures besides the
gland itself
• Hyperthyroidism
o Overactivity of the thyroid gland leads to loss of body fat and weight, increased blood
pressure, enlargement of the thyroid gland among other symptoms
• Hypothyroidism
Condition where not enough thyroxin is secreted possibly because of iodine deficiency
a. Myxedema
o Face becomes swollen, weight increases and initiative and memory fail
b. Cretinism
o Lack of mental and physical growth, resulting in mental retardation and
malformation
Ann Senisi Scott & Elizabeth Fong: Body Structures & Functions 11th Edition
Disorders – Adrenal Cortex
• Hyperfunction
o Cushing’s syndrome – results from hypersecretion of the glucocorticoid hormones from
the adrenal cortex leading to high blood pressure, muscular weakness, obesity, poor
healing of skin lesions, a tendency to bruise easily, excessive hair growth, menstrual
disorders in women and hyperglycemia
• Hypofunction
o Addison’s disease – symptoms include excessive pigmentation, decreased levels of blood
glucose, hypoglycemia, low blood pressure, pronounced muscular weakness and fatigue,
diarrhea, weight loss, vomiting and imbalance of electrolytes
Diabetes Mellitus
• Pancreatic disorder
• Decreased secretion of insulin from the islets of Langerhans cells or by the ineffective use of
insulin
• Diabetes is divided into two main types: Type I and Type II diabetes
a. Type I
1. Must take insulin and monitor daily blood glucose levels
2. Symptoms include: polyuria, polydypsia, polyphagia, weight loss, blurred vision
and possible diabetic coma
b. Type II
1. Treat with oral hypoglycemic agents and some may need insulin
2. Symptoms may gradually onset, occur in adults over 45, have feelings of
tiredness or illness, frequent urination, unusual thirst and frequent infections
Ann Senisi Scott & Elizabeth Fong: Body Structures & Functions 11th Edition