Anatomy and Physiology The Endocrine System Chapter 12

1
Anatomy and PhysiologyThe Endocrine
SystemChapter 12

• Community Education
• Mr. Kestner

2
Introduction

• Exerts chemical control over the human body
• Control includes growth, maturation,
  reproduction, metabolism, human behavior
• Shared partnership with nervous system
• Hypothalamus sends signals to pituitary gland
• Pituitary gland is historically referred to as
  the master gland

3
Introduction

• The endocrine system consists of a group of
  ductless glands that secrete hormones directly
  into the bloodstream
• Help regulate metabolism, water electrolyte
  concentrations, growth, and reproduction
• System consists of pituitary gland, thyroid
  gland, parathyroid gland, adrenal glands,
  pancreas, testes, ovaries, thymus, pineal body

4
Hormones

• Control internal environment of body
• Control cellular respiration, growth,
  reproduction
• Control fluids in body
• Control secretion of other hormones
• Control behavior patterns
• Play vital role in reproductive cycles of ? and ?
• Regulate growth and development cycles

5
Hormones

• Three classes of hormones
• Modified amino acids
• Epinephrine, norepinephrine, oxytocin,
  vasopressin
• Protein hormones
• Insulin, gonad-stimulating hormones, growth
  hormone
• Steroid (lipid) hormones
• Cortisol, estrogen, testosterone

6
Negative Feedback Loop

• In homes furnace and thermostat operate as
  negative feedback loop
• Set thermostat to temp, when ?, furnace turns on
  once temp reaches set temp, furnace shuts off
• Hormones function same way
• When concentration of particular hormone reaches
  certain level endocrine gland that secretes that
  hormone is inhibited and hormone decreases
• As concentration drops, inhibition ceases and
  gland secretes more hormone

7
Negative Feedback Loop
8
Hypothalamus

• Unique role with endocrine system
• Sends neural and chemical signals to pituitary
  gland
• Chemical signals called
• Releasing hormones
• Releasing inhibitory hormones
• Due to negative feedback, endocrine hormones can
  influence the hypothalamus

9
Pituitary Gland

• Often called the master gland
• Produces many hormones that affect other glands
• Located at base of brain in the bony depression
  of the sphenoid bone
• Divided into two sections, or lobes
• Anterior lobe
• Posterior lobe

10
Anterior Pituitary Lobe

• Produces 7 hormones
• Growth Hormone (GH) or Somatotropin
• Thyroid-Stimulating Hormone (TSH)
• Adrenocorticotropic Hormone (ACTH)
• Melanocyte-Stimulating Hormone (MSH)
• Follicle-Stimulating Hormone (FSH)
• Luteinizing Hormone (LH)
• Lactogenic Hormone (LTH) or Prolactin

11
Growth Hormone

• Stimulates cell metabolism in most tissues
• Causes cells to divide and increase in size
• Stimulates growth of bones and muscles
• Too little
• Pituitary dwarfism
• Excess during childhood
• Gigantism
• Excess after childhood when bones stop growing
• Acromegaly

12
Other Hormones of Anterior Pituitary Lobe

• Thyroid-Stimulating Hormone (TSH)
• Stimulates thyroid to produce thyroxine
• Adrenocorticotropic Hormone (ACTH)
• Stimulates adrenal cortex to secrete cortisol
• Melanocyte-Stimulating Hormone (MSH)
• Increases melanin production in melanocytes
• Follicle-Stimulating Hormone (FSH)
• Stimulates development of follicles in ovaries
• Stimulates production of sperm cells in testes
• Luteinizing Hormone (LH)
• Stimulates ovulation in ovary and production of
  progesterone
• Stimulates synthesis of testosterone in testes
• Lactogenic Hormone (LTH) or Prolactin
• Stimulates milk production in mammary glands
• May cause decrease in sex hormones in males

13
Posterior Pituitary Lobe

• Antidiuretic Hormone (ADH) or Vasopressin
• Maintains bodys water balance by promoting
  increased water reabsorption in the tubles of the
  nephrons of kidneys, resulting in less water in
  urine
• A deficiency can result in Diabetes Insipidus,
  which can lead to a production of 20-30 liters of
  urine/day may produce a loss of electrolytes
  resulting in death
• Oxytocin
• Stimulates contraction of smooth muscles of
  uterus
• Stretching of uterus and vagina in pregnancy
  stimulates production of oxytocin causing
  contraction and labor

14
Thyroid Gland

• Synthesizes hormones that regulate bodys
  metabolism
• Controls level of calcium in blood
• Located in front of upper part of trachea
• Two lobes, located on either side of larynx
• Requires iodine to produce hormones, which is
  obtained from certain foods and iodized salt
• Hormones called thyroxine (T4) and T3

15
Diseases and Abnormal Conditions

• Goiter
• Enlargement of thyroid caused by hyperthyroidism,
  iodine deficiency, oversecretion of TSH from
  pituitary, or tumor
• Hyperthyroidism
• Overactivity of thyroid gland, which causes
  increased production of thyroid hormones and
  increased BMR
• Graves Disease
• Severe form of hyperthyroidism and more common in
  women
• Hypothyroidism
• Underactivity of thyroid gland and a deficiency
  of thyroid hormones

16
Parathyroid Glands

• Four small glands located behind and attached to
  the thyroid gland
• Their hormone regulates amount of calcium in
  blood
• Stimulates bone cells to break down bone tissue
  and release calcium and phosphates into blood

17
Diseases and Abnormal Conditions

• Hyperparathyroidism
• Overactivity of parathyroid glands, resulting in
  an overproduction of hormones and hypercalcemia
• Causes brittle bones
• Hypoparathyroidism
• Underactivity of parathyroid gland, which causes
  a low level of calcium in the blood
• Causes muscles to be easily excitable

18
Adrenal Glands

• Frequently calld the suprarenal glands
• Each gland has two parts the outer portion
  called the cortex, and the inner portion called
  the medulla
• The cortex secretes many steroid hormones
• The adrenal medulla secretes two main hormones
• Epinephrine
• Norepinephrine

19
Diseases and Abnormal Conditions

• Addisons Disease
• Caused by decreased secretion of aldosterone
• Interferes with reabsorption of Na and H2O,
  causes increased level of K
• Treatment includes steroids
• Cushings Syndrome
• Results from oversecretion of glucocorticoids
  from adrenal cortex
• Symptoms include moon face and obesity, muscle
  weakness, and poor wound healing
• Hormonal therapy is required if glands are removed

20
Pancreas

• Fish-shaped organ located behind stomach
• Both endocrine and exocrine gland
• Secretes pancreatic juices exocrine
• Produces hormone glucogon and hormone insulin in
  the islets of Langerhans endocrine

21
Diabetes Mellitus

• Chronic disease caused by decrease in insulin
• Two main types IDDM, Type I NIDDM, Type II
• Main symptoms include
• Hyperglycemia, polyuria, polydypsia, polyphagia,
  glycosuria, weight loss, fatigue, slow healing,
  and vision changes
• Treatment includes
• Regulated diet control, regular exercise, and
  insulin

22
Other Endocrine Glands

• Ovaries
• Female sex glands
• Testes
• Male sex glands
• Thymus
• Gland containing lymph atrophies at puberty
  (lymph)
• Pineal body
• Small structure in brain secretes melatonin and
  serotonin