HISTO FINALS

• Endocrine System

  The endocrine system is composed of glands that synthesize and secrete products, called hormones.

  A network of glands of internal secretions that is considered the body’s regulatory system.

  Each of which secretes a type of hormone into the bloodstream to regulate the body

  • Either Endocrine or Exocrine
• Endocrine

  Secreted without a duct, secreted through the bloodstream
• Exocrine

  Secreted within a duct
• HORMONES

  Are chemical signals/messenger produced by specialized cells secreted into the bloodstream and carries to a target tissue.

  To maintain the constancy of chemical composition of extracellular and intracellular fluid.
• Characteristics of Hormones

  Each hormone is produced by a specific gland.

  Directly released from the tissue into the bloodstream and carried to the site.

  Each hormone act on a specific site or target to induce certain characteristic biochemical changes.
• Hormones can be

  Proteins/Peptides

  Lipid derivatives

  Amino Acid derivatives
• Proteins/Peptides


  (e.g., insulin, growth hormone)
• Lipid derivatives

  Derived from cholesterol of fatty acids

  (e.g., steroids, eicosanoids)
• Amino Acid derivatives

  Derived from tyrosine or tryptophan

  (e.g., epinephrine, melatonin, thyroid hormones)
• Hormone effects are described as:

  Endocrine

  Paracrine

  Autocrine
• Endocrine

  Released into blood and act at long distances
• Paracrine

  Diffuse a short distance through tissue fluids to nearby cells
• Autocrine

  Act on the same cell that produced the hormone
• 8 GLANDS

  Pituitary gland

  Hypothalamus

  Thyroid gland

  Parathyroid gland

  Adrenal gland

  Pancreas

  Ovaries

  Testes
• 2 parts Pituitary gland

  Anterior Pituitary gland

  Posterior Pituitary gland
• Endocrine glands

  are highly vascular and often fenestrated capillaries to facilitate the diffusion of hormones into blood.
• Pineal gland

  One of the glands that are present in the brain
• .PITUITARY GLAND

  Often called the “master gland” of the body

  Because it produces hormones that regulate other endocrine glands, as well as, have direct effects on target tissues.

  POSTERIOR PITUITARY GLAND

  • (ADH) Antidiuretic hormone , Oxytocin
• ANTERIOR PITUITARY GLAND

  (ACTH) - adrenocorticotropic hormone

  (FSH) - follicle-stimulating hormone

  (LH) - luteinizing hormone

  (TSH) -thyroid-stimulating hormone

  (GH) – growth hormone

  Prolactin
• ANTERIOR PITUITARY GLAND

  Aka Adenohypophysis

  Secretes six hormones
• ACTH (Adrenocorticotropic hormone)


  Stimulates the adrenal cortex to produce steroids

  Mineralocorticoids (e.g., aldosterone)

  - act on the kidney to regulate ion balance and increase blood pressure

  Glucocorticoids (e.g., cortisol)

  - stimulate gluconeogenesis suppresses immune responses and modulates CNS functions
• TSH (Thyroid-stimulating hormone)


  stimulates the thyroid to produce thyroid hormones which influence the basal metabolic rate and protein synthesis.
• FSH (Follicle-stimulating hormone)

  Testis

  • stimulates spermatogenesis and inhibin production.

  Ovary

  • stimulates development of ovarian follicles and estrogen production.
• LH (Luteinizing hormone)


  Testis

  • Stimulates the secretion of testosterone.

  Ovary

  • Stimulates ovulation and progesterone production.
• GH (Growth hormone)


  Effects by direct action of GH and indirect actions through GH - induced proportion of insulin-like growth factor - 1 by the liver

  Major promoter of body growth
• Prolactin

  Stimulates milk production in mammary glands
• POSTERIOR PITUITARY GLAND •

  Aka Neurohypophysis

  Secretes two hormones.

  Each hormone is synthesized in cell bodies of neurons in the hypothalamus and released from axon terminals in the posterior pituitary.
• ADH (Antidiuretic hormone)


  increases water reabsorption in the kidney.
• Oxytocin

  stimulates contraction of smooth muscle in the uterus during childbirth, stimulates ejection of milk by the mammary gland.
• Hypothalamus

  the one the produces the ADH and Oxytocin
• Function of anterior

  both produces and secretes hormone
• While the function posterior

  is to secrete only
• HYPOTHALAMUS

  Two sets of nerve cells in the hypothalamus that produce hormones

  • Posterior and Anterior

  The other set of nerve cells produces stimulating and inhibiting hormones that reach the anterior lobe

  • Corticotropin-releasing hormone
  • GH-releasing hormone
  • Gonadotropin-releasing hormone
  • Thyrotropin-releasing hormone
• THYROID GLAND

  Is a bilobed endocrine gland.

  It is unique in that it stores it hormones bound to an extracellular pool of protein (colloid)

  Produces hormones

  - triiodothyronine (T3) and thyroxine (T4)
• triiodothyronine (T3) and thyroxine (T4)

  that primarily influence the basal metabolic rate and protein synthesis
• Parenchyma

  secretory follicles constitute the functional units of the gland.

  • Follicular cells are lined by a simple cuboidal to columnar epithelium depending on functional activity. Secrete thyroid hormones when active.
• Stroma

  Capsule

  Enclosed by a thin layer of connective tissue.

  Trabeculae

  Connective tissue extends inwards from the capsule to partially outline irregular lobes and lobules
• .PARATHYROID GLAND

  The glands are located on the four poles of the thyroid.

  Secrete PTH in response to low blood levels of Calcium.
• PTH secretion

  causes the release of calcium from bones by stimulating osteoblasts, and increased reabsorption of calcium in the kidney.
• Calcitonin

  a hormone that your thyroid gland makes and releases to help regulate calcium levels in your blood by decreasing it