Endocrine Quiz 2

• Pituitary Gland is also called the Hypophysis. It is a small gland about the size of a pea. It rests in a depression of the sphenoid bone inferior to the hypothalamus called the Sella Turcica.
• The pituitary gland lies posterior to the optic chiasm and is connected to the hypothalamus by a stalk called the infundibulum.
• The Optic Chiasm, the point where the two optic

  nerves cross each other.
• The infundibulum, where the pituitary gland connects with the hypothalamus.
• The pituitary gland is divided into two parts:

  Anterior Pituitary Gland

  Posterior Pituitary Gland
• Hormones of the Posterior Pituitary Gland:

  Antidiuretic Hormone (ADH)

  Oxytocin
• Hormones of the Anterior Pituitary Gland:

  Growth Hormone

  Adrenocorticotropic Hormone

  Thyroid-Stimulating Hormone

  Gonadotropic Hormones

  Melanocyte- Stimulating Hormones

  Prolactin
• GROWTH HORMONE

  Stimulates the growth of bones, muscles, and other organs by increasing gene expression.

  It favors lipid breakdown, resists protein breakdown, and increases blood sugar level.
• Pituitary Dwarfism results from a deficiency of growth hormone, which can be treated with Growth Hormone supplementation. It is characterized by proportionate dwarfism. On the other hand, characterized by disproportionate dwarfism.
• Acromegaly occurs when there is an excess of growth hormone secretion during adulthood, resulting in enlargement of hands, feet, nose, lips, tongue, etc.
• GIANTISM occurs if there is excess of growth hormone before the bones finish growing in length. There is excessive growth in length of bones. The person becomes abnormally tall.
• ACROMEGALY occurs if there is an excess of growth hormones after bone growth is complete.

  There is excessive growth in diameter of bones

  The facial features and hands become abnormally large.
• The secretion of growth hormone is controlled by TWO hormones from the hypothalamus:

  1.A releasing hormone that stimulates the release of growth hormone,

  2. An inhibiting hormone that inhibits the release of growth hormone.
• Daily peak level of growth hormone secretion is during DEEP SLEEP.
• THYROID-STIMULATING HORMONE

  Binds to receptors in the Thyroid Gland and causes the thyroid gland to release thyroid hormones.

  When too much TSH is secreted, the thyroid gland enlarges and secretes too much thyroid hormone.

  When too little TSH is secreted, the thyroid gland decreases in size and secretes too little thyroid hormone.
• Adrenocorticotropic hormone (ACTH)

  Binds in the cells in the cortex of the adrenal glands.

  ACTH increases the secretion of a hormone from the adrenal cortex called the CORTISOL (Hydrocortisone)
• Gonadotropins

  Hormones that bind to receptors on the cells of the gonads (ovaries or testes) They regulate the growth, development, and functions of the gonads.
• Luteinizing Hormones in females cause the OVULATION of oocytes and the secretion of the sex hormones ESTROGEN and PROGESTERONE. Luteinizing Hormones in males stimulates the interstitial cells of the testes to secrete the sex hormone TESTOSTERONE, and thus is sometimes referred to as Interstitial Cell- Stimulating Hormone (ICSH).
• Follicle Hormones stimulates the DEVELOPMENT of follicles in the ovaries and sperm cells in the testes.
• Prolactin

  “pro” – precursor “lact” – milk. It binds to receptors in cells of the breast, where it helps to promote development of the breast during pregnancy and stimulates the production of milk after pregnancy.
• Melanocyte-stimulating hormone

  Binds to receptors on melanocytes and causes them to synthesize melanin. Over-secretion of this hormone causes darkening of the skin.
• Antidiuretic hormone (ADH)

  “anti” – against “uresis” – urine volume

  Binds to receptors and increases water reabsorption by kidney tubules. Water reabsorption decreases water volume in urine. It can also cause blood vessels to constrict (vasoconstriction) when released in large amounts.
• DIABETES INSIPIDUS occurs when there is a lack of ADH secretion, leading to production of large amount of dilute urine.
• Oxytocin

  Binds to receptors and causes contraction of the smooth muscle cells of the uterus, as well as milk letdown from the breasts in lactating women.
• Prolactin – production of milk

  Oxytocin – milk letdown (milk “flows” from the breast)
• Thyroid gland

  Made up of two lobes connected by a narrow band called the ISTHMUS (“constriction”). The lobes are located on each side of the trachea, just inferior to the larynx. It appears more red than the surrounding tissues because it is highly vascular. The main FUNCTION of the thyroid gland is to secrete the THYROID HORMONES.
• Thyroid Follicles is a small spheres in the thyroid gland where the thyroid hormones are synthesized.
• Thyroglobulins are glycoprotein molecules which contain the thyroid hormones. They are found within the thyroid follicles.
• 93% - Thyroxine (14); more abundant

  %7 - Triodothyronine (T3); more potent
• Iodine is needed for the synthesis of thyroid hormones.

  It binds with the thyroqlobulin for the synthesis of Thyroid Hormones. Without lodine, thyroid hormones are not synthesized.
• Thyroid Hormones promote growth and development of the brain during fetal life and for the first few years of postnatal life. Babies with les thyroid hormones (hypothyroidism) may have delayed brain development leading ot mental retardation.
• CRETINISM

  Otherwise known as Congenital Hypothyroidism.

  This is a condition of decreased thyroid hormones at birth, leading ot underdevelopment of brain, leading to mental retardation. This can be treated with thyroid hormone supplementation if detected earlier, and can be treated.
• Efects of Thyroid Hormones ni Metabolism:

  Increased numbers of mitochondria (more ATP si produced)

  Increased oxygen consumption

  Increased glucose absorption

  Increased gluconeogenesis

  Increased glycogenolysis

  Increased lipolysis

  Increased protein synthesis

  Increased Basal Metabolic Rate
• Thyroid hormones are regulated by the hypothalamus and the anterior pituitary gland
• CA

  
  

  Released by the parafolicular cells or C cells. It is secreted if the blood concentration of calcium ions became too high. It binds to osteoclasts and reduces breakdown of the bone by inhibiting osteoclast activity.
• PTH is secreted in response to low calcium level in the blood. Calcitonin is secreted ni response to high calcium level in the blood.
• Adrenal glands are two small glands located superior on each kidney. Each adrenal gland has an inner part called the ADRENAL MEDULLA ("marow "or middle) and an outer part called the ADRENAL CORTEX ("bark "or outer)
• The principal hormone released si EPINEPHRINE (“epi"- upon, “nephros"- kidney)

  Epinephrine is also called ADRENALINE

  Small amount of NOREPINEPHRINE is also released.
• Epinephrine and Norepinephrine are referred to as the

  FIGHT-OR-FLIGHT hormones because of their role ni

  preparing the body for vigorous physical activity.
• Three Classes of Hormones in the Adrenal Cortex:

  MINERALOCORTICOIDS

  GLUCOCORTICOIDS

  ANDROGENS