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ELAINE N. MARIEB
EIGHTH EDITION
9
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
PowerPoint® Lecture Slide Presentation by Jerry L. Cook, Sam Houston University
ESSENTIALS
OF HUMAN
ANATOMY
& PHYSIOLOGY
PART B
The Endocrine System
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Thyroid Gland
▪ Found at the base of the throat
▪ Consists of two lobes and a connecting
isthmus
▪ Produces two hormones
▪ Thyroid hormone
▪ Calcitonin
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Thyroid Gland
Figure 9.6
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Thyroid Hormone
▪ Major metabolic hormone
▪ Composed of two active iodine-containing
hormones
▪ Thyroxine (T4) – secreted by thyroid
follicles
▪ Triiodothyronine (T3) – conversion of T4
at target tissues
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Calcitonin (Thyroid Gland)
▪ Decreases blood
calcium levels by
causing its
deposition on bone
▪ Antagonistic to
parathyroid hormone
▪ Produced by C
(parafollicular) cells
Figure 9.9
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Parathyroid Glands
▪ Tiny masses on the posterior of the thyroid
▪ Secrete parathyroid hormone
▪ Stimulate osteoclasts to remove calcium
from bone
▪ Stimulate the kidneys and intestine to
absorb more calcium
▪ Raise calcium levels in the blood
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Adrenal Glands
▪ Two glands
▪ Cortex – outer glandular region in three
layers
▪ Medulla – inner neural tissue region
▪ Sits on top of the kidneys
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Hormones of the Adrenal Cortex
▪ Mineralocorticoids (mainly aldosterone)
▪ Produced by outer adrenal cortex
▪ Regulate mineral, water, and electrolytes in blood to keep them in balance
▪ Cause the kidney tubules to reabsorb sodium and water
▪ Production stimulated by the enzyme, renin(which is made by the kidneys) when blood pressure is low, stimulating the production of aldosterone to reabsorb sodium and water in an effort to raise blood pressure
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Hormones of the Adrenal Cortex
Figure 9.10
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Hormones of the Adrenal Cortex
▪ Glucocorticoids (including cortisone and cortisol)
▪ Produced in the middle layer of the adrenal
cortex
▪ Help resist long-term stressors
▪ Suppress inflammation/decrease edema
▪ Increase blood glucose levels
▪ Released in response to increased blood levels of
ACTH
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Hormones of the Adrenal Cortex
Figure 9.10
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Hormones of the Adrenal Cortex
▪ Sex hormones
▪ Produced in the inner layer of the adrenal
cortex
▪ Androgens (male) and some estrogen
(female)
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Hormones of the Adrenal Cortex
Figure 9.10
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Hormones of the Adrenal Medulla
▪ Produces two similar hormones (Catecholamines)
▪ Epinephrine
▪ Norepinephrine
▪ Prepare the body to deal with short-term stress
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 9.12
Roles of the Hypothalamus and Adrenal
Glands in the Stress Response
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Pancreatic Islets
▪ The pancreas is a mixed gland
▪ The beta cells in the islets of the pancreas
produce hormones
▪ Insulin – allows glucose to cross plasma
membranes into cells from beta cells
▪ Glucagon – allows glucose to enter the
blood from alpha cells
▪ These hormones are antagonists that
maintain blood sugar homeostasis
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Pancreatic Islets
Figure 9.13
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Pancreatic Hormones and Blood Sugar
Figure 9.14
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Pineal Gland
▪ Found on the third ventricle of the brain
▪ Secretes melatonin
▪ Helps establish the body’s wake and sleep
cycles
▪ May have other as-yet-unsubstantiated
functions
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Thymus
▪ Located posterior to the sternum
▪ Largest in infants and children
▪ Produces thymosin
▪ Matures some types of white blood cells
▪ Important in developing the immune
system
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Hormones of the Ovaries
▪ Estrogens
▪ Development of secondary female characteristics
▪ Prepares the uterus to receive a fertilized egg
▪ Stimulates menstruation
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Hormones of the Ovaries (Corpus
Luteum)
▪ Progesterone
▪ Helps bring about the menstrual cycle
▪ Helps maintain pregnancy
▪ Prepares breasts for milk production
▪ Small amount of estrogen made by the corpus
luteum
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Hormones of the Testes (Androgens)
▪ Interstitial cells make the hormones
▪ Androgens – male hormones
▪ Testosterone is the most important androgen
▪ Adult male secondary sex characteristics
▪ Growth and maturation of male reproductive system
▪ Required for sperm cell production
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Other Hormone-Producing Tissues and
Organs
▪ Parts of the small intestine
▪ Parts of the stomach
▪ Kidneys (renin)
▪ Heart
▪ Many other areas have scattered endocrine
cells
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Endocrine Function of the Placenta
▪ Produces hormones that maintain the
pregnancy
▪ Human chorionic gonadotropin (hCG)
▪ Estrogen
▪ Progesterone
▪ Relaxin – relaxes mother’s pelvic ligaments
and pubic symphysis
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Developmental Aspects of the Endocrine
System▪ Most endocrine organs operate smoothly until old
age
▪ Menopause is brought about by lack of
efficiency of the ovaries
▪ Problems associated with reduced estrogen are
common
▪ Growth hormone production declines with age
▪ Many endocrine glands decrease output with age
Growth Hormone
Hypersecretion- Gigantismlong bones grow abnormally long
during childhood and adolescence
Hyposecretion-Dwarfism• Slow bone growth
• Epiphyseal plates close
before normal height is
reached
• Treatment – Growth
Hormone therapy
• Hypersecretion of Growth
Hormone
• Happens after normal growth
has stopped
• Bones of hands, feet, cheeks,
and jaw thicken
• Soft tissues grow abnormally
Acromegaly
Addison’s Disease
• Hyposecretion of Adrenal Cortex hormones
• Bronze color to skin (hyperpigmentation)
• Symptoms include:• Severe fatigue
•Unintentional weight loss
•Gastrointestinal problems, such
as nausea, vomiting and abdominal pain
•Lightheadedness or fainting
• Salt cravings
•Muscle or joint pains
Cushing’s Syndrome
Hypersecretion of Adrenal
Cortex hormones or
administration of homrones•Weight gain
•Obesity
•“Moon face”
•Buffalo hump)
•Stretch marks
•Bruise easily
Goiter• Enlarged thyroid gland caused by iodine deficiency
• Iodine Deficiency causes thyroid to make nonfunctional thyroid hormones
• TSH keeps “calling for” more thyroxine
• Thyroid is overstimulated and enlarges, but still doesn’t make functional thyroid hormones
Graves DiseaseAutoimmune disorder that causes growth of thyroid and hypersecretion of thyroid hormones, with no negative feedback
• Enlarged thyroid (2-3x larger)
• Bulging eyes
• Increased metabolic rate, heat intolerance, increased sweating, weight loss, insomnia, tremor, and nervousness.
• Treatment
• surgical removal of part of thyroid gland
• radioisotopes to destroy some of the thyroid
• anti-thyroid drugs to block synthesis of the hormones.
CretinismHyposecretion of T3/T4 during fetal life and infancy.
•Dwarfism and mental retardation
•Testing newborns can prevent the disease
•Treatment - oral thyroid therapy.
Myxedema
Thyroid hyposecretion during adulthood
•Edema, slow heart rate, low body temp, dry hair and
skin, muscular weakness, lethargy, weight gain
•Treatment - Oral thyroid hormones reduce symptoms
Parathyroid Hormone too Low• Hyposecretion of parathyroid hormone results in low calcium levels
• If blood calcium levels fall too low, neurons become extremely irritable and overactive.
• Neurons deliver impulses to muscles so fast that they go into tetany and spasm
• Can lead to death
• Symptoms : polyuria, polydypsia, polyphagia, acidosis.
• Two types:Type I
• absolute insulin deficiency, with insulin administration.
• Patients < 20 years;
• autoimmune disorder where β-cells are destroyed;
• Hyperglycemia results.
• Cells can't use glucose so fat is broken down, releasing ketone bodies, causing ketoacidosis, lowering blood pH, and causing death.
• Complications include Atherosclerosis, CV disease, IHD, PVD, gangrene, blindness due to cataracts (lens) and retinal vascular disease; renal failure.
• Treatments• artificial pancreas that detects fall in glucose levels and automatically releases
insulin;
• transplant of pancreas or Beta cells.
Diabetes Mellitus
Diabetes Mellitus
•Symptoms : polyuria, polydypsia, polyphagia, acidosis.
•Two types:
Type II Diabetes• patients > 40 years, • overweight, • hypertension,• Problem is usually with receptors on target cells; • Controlled by diet, exercise, and weight loss;
ADH Imbalances
•Diabetes Insipidus
•Hyposecretion of ADH from posterior pituitary•Diuresis, dehydration, thirst
• Treatment - ADH in nasal spray