endocrine & lymphatic system

• Chemical messengers


  Hormones that allow cells to communicate with each other to regulate body activities
• Four classes of chemical messengers

  • Autocrine
  • Paracrine
  • Neurotransmitter
  • Endocrine
• Autocrine


  Secreted by cells in local effect area and influences the activity of the same cell
• Autocrine


  • eicosanoids
• Paracrine


  Produced by a wide variety of tissues and secreted in ECF
• Paracrine


  • somatostatin, histamine
• Neurotransmitter


  Produced by neuron, secreted in the synaptic cleft that activate adjacent cell
• Neurotransmitter


  • Acethycholine
• Endocrine


  Secreted into blood and bind to receptor sites
• Endocrine


  • Epinephrine and Insulin, estrogen, GH, testosterone, and estrogen
• Endocrine system functions


  • Metabolism
  • Control of food intake and digestion
  • Tissue development
  • Ion regulation
  • Water balance
  • Heart rate and blood pressure regulation
  • Control of blood glucose and other nutrients
  • Controls of Reproductive functions
  • Uterine contraction and milk release
  • Immune System regulation
• Endocrine system


  Composed of endocrine glands and specialized endocrine cells located throughout the body

  
• Types of hormones


  • Water-soluble hormones (proteins, peptides, amino acids)
  • Lipid-soluble hormones (steroids and eicosanoids)
• Water-soluble hormones


  • growth hormone, antidiuretic, prolactin
• Lipid-soluble hormones


  • LH, FSH, androgens
• Negative feedback mechanism


  The hormone's secretion is inhibited by the hormone itself once blood levels have reached a certain point
• Positive feedback mechanism


  The response to the stimulus does not stop or reverse the stimulus, but instead keeps the sequence of event going
• Classification of hormones


  • Amines
  • Proteins
  • Steroids
• Hypothalamus


  Superior to the pituitary gland and inferior to the thalamus, regulates the secretions of the hormones of the pituitary gland

  
• Pituitary gland


  Small gland in brain, controlled by hypothalamus, divided into two regions: Anterior and Posterior, secretes at least 8 hormones

  
• Anterior pituitary hormones


  • Growth Hormone
  • Prolactin
  • Thyroid-Stimulating Hormone (TSH)
  • Gonadotrophin Hormone (LH, FSH)
  • Melanocyte Stimulating Hormone
  • Adrenocorticotrophic Hormone (ACTH)

  
• Growth Hormone


  Stimulates growth of bones, muscles, and organs, stimulates cells to produce insulin like growth factors, increases the rate of CHON synthesis, increases the use of fats as energy metabolism, increases blood glucose levels by reducing glucose utilization (insulin antagonist)
• Too much GH causes giantism, too little GH causes pituitary dwarfism
• Prolactin


  Necessary for breast development and lactation, Prolactin Releasing Hormone (PRH) stimulate the secretion from the hypothalamus, Prolactin Inhibiting Hormone inhibits the secretion from the hypothalamus
• Thyroid-Stimulating Hormone (TSH)


  Regulates thyroid gland secretions, Thyroxine (T4) and thriodothyronine T3 by the TG, Thyrotropin releasing hormone- triggers the pituitary gland to release TSH

  
• Too much TSH, thyroid gland enlarges, too little TSH, Thyroid glands shrinks

  
• Gonadotrophin Hormone (LH)


  For females: promotes ovulation and progesterone production, for males: sperm production and testosterone

  
• Gonadotrophin Hormone (FSH)


  For females: follicle maturation and estrogen secretion, for males: sperm production

  
• Melanocyte Stimulating Hormone (MSH)


  Stimulate melanin production in melanocytes to make skin darker
• Adrenocorticotrophic Hormone (ACTH)


  Stimulate production of certain corticosteroids

  
• Posterior pituitary


  Synthesizes and releases hormones produced by neuroendocrine cells in the hypothalamus, Antidiuretic hormone (ADH) and Oxytocin

  
• Antidiuretic Hormone (ADH)


  Conserve water, decreases sweating, urinary output is decrease, causes vasoconstriction in arterioles to raise or maintain BP

  
• Abnormalities: Diabetes Insipidus - low ADH production, kidneys produce large amounts of dilute (watery) urine, can lead to dehydration and thirst
• Oxytocin


  Causes contraction of myometrium of the uterus during labor, stimulus: nerve impulses from the hypothalamus as cervix is stretched and as infants suck the nipple
• Thyroid gland


  One of the largest glands, located in front and on the side of the trachea just below the larynx, requires iodine to function, secretes Thyroid hormones and Calcitonin

  
• Thyroid hormones


  Secreted by follicular cells, produces T3 and T4, regulates metabolic rates and is needed for growth, regulate CHON, CHO and fat metabolism, necessary for normal physical, mental and sexual development, act as insulin antagonist

  
• Calcitonin


  Secreted or produced by parafollcular cells, reduces blood calcium level when high, inhibits osteoclastic activity, lowers phosphate levels, helps maintain stable and strong bone matrix
• Thyroid hormone disorders


  • Hypothyroidism (decreased metabolism, weight gain, reduced appetite, fatigue, low temp. and pulse, dry, cold skin, myxedema in adults, cretinism in infants)
  • Hyperthyroidism (increased metabolism, weight loss, increased appetite, nervousness, higher temp. and pulse, warm, flushed skin, Graves' disease leading to goiter)

  
• Parathyroid Hormone (PTH)


  Regulates blood Ca2+ levels (more that calcitonin), if Ca2+ is low then osteoclasts break down bone matrix and less Ca2+ is lost in urine, if Ca2+ is high then osteoclasts don't break down bone matrix and more Ca2+ is lost in urine

  
• Adrenal glands


  Two small glands located superior to each kidney, each has an inner part called the adrenal medulla, and an outer part called the adrenal cortex, function as separate endocrine glands