endocrine system

• Coordinate all the body systems

  nervous and endocrine
• Nervous system


  coordinates body systems through the action potentials traveling on neurons, and the neurotransmitters they secrete
• Endocrine system


  coordinates body systems by using hormones produced by endocrine structures to produce their effects
• Hormones


  mediator molecules that have effects on cells in the local area, or more distant part of the body
• autocrine hormones


  secreted and bind to the same cell
• paracrine hormones


  secreted into interstitial fluid and act on nearby cells
• endocrine hormones


  are secreted into interstitial fluid and then absorbed into the bloodstream to be carried systemically to any cell that displays the appropriate type of receptor
• lipid soluble hormones


  bind to receptors in the cytoplasm or nucleus of the cell
• water soluble hormones


  bind to receptors on the surface of the cell
• water soluble hormones are most chemically similar to

  proteins
• distance is an important factor for

  paracine hormones: they move through interstitial fluids to get to nearby cells. also the further the distance, the weaker the signal (like a TV signal)
• endocrine hormones travel through the ___ and signal cells that have___

  bloodstream; receptors
• lipid soluble hormones 


  consist of steroid hormones, thyroid hormones, and gas nitric oxide
• steroid hormones are most chemically similar to


  lipids
• steroid hormones


  derived from cholesterol
• thyroid hormones


  (T3 and T4) are synthesized by attaching iodine to the amino acid tyrosine
• steroid hormones are able to freely pass through___ so they work___

  plasma membrane; inside the cell
• water soluble hormones include

  peptide and protein hormones
• cAMP


  second messenger that allows hormone stimulated responses to take place in the cell
• exocrine glands


  secrete their products into ducts
• negative feedback system


  hormone output reverses a particular stimulus
• low blood Ca2+


  parathyroid glands release more PTH which causes the body to increase blood Ca2+ until back to normal
• high blood Ca2+


  the body will cease PTH production and secrete calcitonin causing the body to lower the Ca2+ levels
• positive feedback system


  hormone output reinforces and encourages the stimulus
• during childbirth the hormone oxytocin stimulates contractions of the uterus. uterine contractions stimulate more oxytocin release

  positive feedback effect
• endocrine system organs


  pituitary, thyroid, parathyroid, adrenal and pineals glands. hypothalamus, thymus, pancreas, ovaries and testes
• secondary endocrine organs

  kidney, stomach, liver, small intestine, skin, heart, placenta etc.
• hypothalamus


  major link between the nervous and endocrine system; receives input from several regions in the brain. mainly controls pituitary gland
• pituitary gland


  aka hypophysis, mainly controlled by hypothalamus. 2 parts: anterior adenohypophysis and posterior neurohypophysis
• anterior pituitary (adenohypophysis)


  connected by the hypothalamus by the hypophyseal portal system
• anterior pituitary releases hormones under the effect of

  releasing hormones
• growth hormone relating hormone (GHRH) in hypothalamus causes

  human growth hormone (hGH) to be released from adenohypophysis
• thyrotropin releasing hormone (TRH) in hypothalamus causes

  thyroid stimulating hormone (TSH) to be released from adenohypophysis
• prolactin releasing hormone (PRH) in hypothalamus causes


  prolactin (PRL) to be released from adenohypophysis
• gonadotropic releasing hormone (GnRH) in hypothalamus causes


  follicle stimulating hormone (FSH) and luteinizing hormone (LH) to be released from adenohypophysis
• corticotropin releasing hormone (CRH) in hypothalamus causes


  adrenocorticotropic hormone (ACTH) and melanocyte stimulating hormone (MSH) to be released from adenohypophysis
• portal system carriers blod to organs (or other parts of the body) before going to the


  heart
• T/F: tropic hormones stimulate other glands 


  true- secreted by the anterior pituitary, target other endocrine glands
• posterior pituitary (neurohypophysis)


  releases but does NOT synthesize any hormones, hormones are produced in neurosecretory hypothalamus cells then travel down the axon and released when stimulated. include oxytocin and ADH
• oxytocin


  causes uterine contractions and “milk letdown”