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Chpt. 31.1-31.4 (blood vessels (capillaries (structure (smallest diameter,…

- - - - present as a net in body tissue and organs, coming in close proximity to every cell in the body
      - facilitates molecule diffusion between blood and interstitial fluid
    - - smallest diameter
      - very thin walls that are optimal for diffusion
      - endothelium: 1 layer of endothelial cells + basal lamina
  - - - carries blood away from the heart
    - - endothelium + thick layer of smooth muscle + thick layer of connective tissue
      - hormones and nervous system signal act on arteries to dilate or constrict arteries to control blood flow to different body parts
  - - - carries blood toward the heart
    - - endothelium + thin layer of smooth muscle + thin layer of connective tissue
      - also contain valves to maintain unidirectional blood flow even with low blood pressure
- - - - relaxed/relaxed blood flows in
    - - atrial systole and ventricular diastole
        
        atria contract, ventricle relaxed, blood forced from atria to ventricle
      - step 3:
        
        ventricular systole and atrial diastole
        
        atria relaxed, ventricle contract - blood forced from ventricle to arteries
- - - - bundle branches pass signals to the heart apex
        
        signals spread throughout ventricles
- - - - lower hydro static pressure makes them less energetically costly
      - in some organisms, it can serve for additional functions, spiders use it to extend their legs
  - - - relatively high blood pressure enables effective delivery of oxygen and nutrients in large, active animals
      - well suited for regulating blood distribution to different organs
- - - - 2 fluid control mechanisms
        
        blood pressure/ hydrostatic pressure: drives fluid out of capillaries into tissue
        
        blood pressure is greatest force, so there is a net loss of fluid out of capillaries, net loss is greatest at arterial end of vessels, where blood pressure is highest
        
        blood proteins/ osmotic pressure: their presence pull fluid back into capillaries. (fluid moves from tissue --> capillaries
        
        proteins are responsible for bloods osmotic pressure
        
        osmotic pressure (opposes movement out of capillaries
      - diffusion is very slow for long distance journeys
        
        solution 1
        
        body size and shape place many or all cells in direct contact with environment
        
        solution 2
        
        circulatory system moves fluid between cells immediate surroundings and the body tissue where exchange with the environment occurs, lungs or skin
  - - - vessels have valves to prevent back flow + rhythmic contractions to move fluid into smaller vessels
      - along vessels are organs called lymoh nodes, which filter lymph and house immune system cells that protect against bacteria and viruses
      - fluid inside = lymph
    - - improper function can lead to edema
    - - joining allows lipids to be transferred from the small intestine to the blood
- - - - right ventricle
        
        pulmonary semilunar valve
        
        pulmonary artery
        
        lungs
        
        pulmonary veins
        
        left atrium
        
        1 more item...
        
        un-oxygenated blood enters lungs, gas exchange occurs, getting rid of co2, obtaining o2, blood continues back to heart