endocrine

• • Second messenger system of the body is the endocrine system
• Primary messenger  is nervous system (brain)
• • Uses chemical messages (hormones) that are released into the blood
• • Amino acid-based hormones
  • Proteins
  • Peptides
  • Amines
• • Steroids – made from cholesterol
• Prostaglandins – made from highly active lipids
• Steroid Hormone Action

  • Diffuse through the plasma membrane of target cells, bins
• Nonsteroid Hormone Action

  • Hormone binds to a membrane receptor
  • Hormone does not enter the cell
• Hormone levels in the blood are maintained by negative feedback
• Pituitary Gland

  • Size of a grape
  • Hangs by a stalk from the hypothalamus
• Anterior pituitary – glandular tissue (linalabas ng glands)
• • Posterior pituitary – nervous tissue (need stimulus)
• Growth Hormone (GH)

  • General metabolic hormone
  • Major effects are directed to growth of skeletal muscles and long bones
• • Prolactin (PRL)
  • Stimulates and maintains milk production following childbirth
• • Adrenocorticotropic hormone (ACTH)

  Regulates endocrine activity of the adrenal cortex
• • Thyroid-stimulating hormone (TSH)
  • Influences growth and activity of the thyroid
• Gonadotropic hormones (FSH, & LH)

  • Regulate hormonal activity of the gonads
• • Follicle-stimulating hormone (FSH)
  • Stimulates follicle development in ovaries
• • Luteinizing hormone (LH)
  • Triggers ovulation
• Pituitary - Hypothalamus Relationship

  • Release of hormones is controlled by releasing and inhibiting hormones produced by the hypothalamus
• Hormones of the Posterior Pituitary

  • Oxytocin
  • Stimulates contractions of the uterus during labor
  • Causes milk ejection
• Hormones of the Posterior Pituitary

  Thyroid Gland

  • Found at the base of the throath
• 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
• Calcitonin

  • Decreases blood calcium levels
• Parathyroid Glands

  -increase calcium
• Adrenal Glands

  • Two glands
  • Cortex – outer glandular region in three layers
  • Medulla – inner neural tissue region
  • Sits on top of the kidneys
• sex hormone: Androgens (male) and some estrogen (female)
• Pancreatic Islets

  • The pancreas is a mixed gland
  • The islets of the pancreas produce hormones
• • Insulin – allows glucose to cross plasma (allow sugar to low)
• • Glucagon – allows glucose to enter the blood from alpha cells (allow sugars to high)
• Pineal Gland

  • Found on the third ventricle of the brain
  • Secretes melatonin
• Thymus

  • Located posterior to the sternum in upper thorax
  • Largest in infants and children
  • Produces thymosin
• Hormones of the Ovaries

  • Estrogens
  • Helps maintain pregnancy
  • Prepares the breasts to produce milk
• Hormones of the Ovaries

  progesterone

  • Produced by the corpus luteum
  • Acts with estrogen to bring about the menstrual cycle
• • Testosterone is the most important androgen
  • Responsible for adult male secondary sex characteristics