Block 1

• change in blood pressure is detected by arterial and juxtaglomerular baroreceptors activating sympathetic nervous system and RAAS
• heart uses B1 receptor
• lung uses B2 receptor
• blood vessels uses a1 receptor
• sympathetic nervous system and RAAS work together to maintain blood pressure
• Vasoconstriction in response to drop in blood pressure, what kind of feedback?

  Negative
• How does lymphatic flow increase in a burn patient?

  Increased capillary permeability
• Release of neurotransmitter onto the neuromuscular junction causes

  increased Na+ permeability
• hemorrhage shock is what kind of feedback loop?

  positive feedback
• positive feedback due to hemorrhage shock

  1. severe hemorrhage
  2. decrease venous return
  3. decrease cardiac output
  4. decrease blood pressure
  5. decrease coronary blood flow
  6. decrease cardiac contractility
  7. decrease cardiac output more
• What causes the release of Ca2+ from sarcoplasmic reticulum during muscular contraction?

  Physical interactions that change conformation of ryanodine receptors
• hemorrhage is what kind of feedback?

  positive feedback
• maintaining homeostasis with low BP is what kind of feedback?

  negative feedback
• step of negative feedback of blood pressure in a hemorrhage

  1. hemorrhage
  2. decrease in blood pressure
  3. baroreceptor detects change in BP
  4. baroreceptor sends information to brain
  5. brain tells autonomic to release NE
  6. increase HR and respiratory rate to try to correct for decrease in BP
  7. Still bleeding
  8. decrease cardiac output and decrease venous return
• A1 pathway – causes contraction of smooth muscles
• B2 pathway – causes relaxation of smooth muscles
• Extracellular fluid is made of Plasma and Interstitial fluid
• Interstitial fluid is Fluid outside of body ‘s cell (extracellular fluid) and outside of blood vessels - Contain water and solutes (electrolytes)
• Lymphatics connects plasma and interstitial fluid
• Capillary membrane separates plasma and interstitial fluid
• Isotonic – solution having the same amount of solute concentration
• Isosmotic – two solutions having the same osmotic pressure.  
• Hypotonic solution – has a lower concentration of solute – water will flow out of it
• Hypertonic solution – has higher concentration of solute – water will flow into it                                                                                 
• Effective osmotic pressure

  • 1 = impermeable – can’t pay through the membrane
  • 0 = freely permeable – can pass through freely
• isotonic solution can be isosmotic (can have same amount of solute and same osmotic pressure) but isosmotic solution doesn’t have to be isotonic, since some solution can freely cross the membrane – like urea
• high salt concentration in the body causes blood pressure to increase, increasing cardiac output and increasing baroreceptor response
• Loss of isotonic fluid loss - losing both water and solute
• Loss of isotonic fluid loss example

  • Bleeding
  • Vomiting
  • Diarrhea
  • Burns* - burn skin – pt will loose a large amount of water by evaporation
  • Loop diuretics  
• isotonic fluid loss result in iso-osmotic volume contraction

  
• Loss of hypotonic fluid - loss more water than salt, losing just water
• Loss of hypotonic fluid example

  • Excessive sweating
  • Diabetes insipidus
  • Alcohol abuse
  • injection of 5% dextrose or glucose
• hypotonic fluid loss result in hyper-osmotic volume contraction

  
• Loss of electrolytes - *loss of salt only*
• Loss of electrolytes example

  • Adrenal insufficiency – lack of mineralocorticoid (aldosterone) – cause excessive loss of Na+ - can’t retain salt
• Loss of electrolytes result in hypo-osmotic volume contraction

  
• Hypotonic fluid gain - *drinks too much water*
• Hypotonic fluid gain example

  • Water intoxication, pathologic primary polydipsia

  Inappropriate secretion of SIADH – retain too much water
• hypotonic fluid gain result in hypo-osmotic volume expansion

  
• Macula densa of the kidney regulate glomerular filtration which help maintain blood pressure by regulating salt and water balance