Cardiovascular system

Cardiovascular system

1. Location & general features of heart

   • Located in the mediastinum, between the lungs, within the thoracic cavity, rests on diaphragm.
   • Wide part at top = the base, narrow, cone shape at bottom = the apex
   • 2/3 on left side of body
   • Chordae tendineae (kor-die ten-dinny-eye), attached to papillary muscles
   • Coronary sulcus (atrioventricular groove)

2. Structure & function of pericardium

   • 1. barrier against infection, 2. hold heart in place, 3. prevent overexpansion, 4. provide friction-free movement
   • Parietal pericardium - outer layer, pericardial cavity - inbetween, visceral pericardium/epicardium - inner layer
   • parietal = lines the dense irregular connective tissue
   • visceral = simple squamous epithelium (mesothelium), loose connective (areolar) tissue (often infiltrated with fat)
   • Fibrous pericardium - tough, superficial

3. flow of blood through the heart, name vessels, chambers and heart valves

   • venae cavae - R atrium - Tricuspid - R ventricle - P semilunar - pulmonary arteries (2) - lungs - pulmonary veins (4) - L atrium - bicuspid - L ventricle - A semilunar - aorta
   • Bicuspid valve/Mitral valve (bishop's hat - Miter)

4. Layers of heart wall

   • Endocardium, myocardium, epicardium/visceral pericardium, pericardial cavity & pericardial fluid, parietal pericardium, fibrous pericardium

5. Process of vascular supply to heart

   • oxygenated blood leaves aorta just above semilunar valves - coronary arteries
     • Deox. blood back to R atrium via coronary sinus (& through wall)

6. relationship between exercise and heart

   • heart beats faster, myocardium is strengthened, can perform better at rest

7. aging effects on cardiovascular system

   • Heart attack (myocardial infarction) can cause myocytes to die & impair function in those areas of the heart
   • Elasticity reduced with age, blood vessel ability to expand & contract impaired
   • Baroreceptors less effective
   • Arterial walls thicken

8. Pulmonary circulation

   • Deoxygenated blood sent to lungs to be oxygenated - sent back to heart to be used in systemic circulation

9. Systemic circulation

   • Heart - body - heart

10. structure & function of arteries, arterioles, capillaries, venules & veins

    • Arteries carry oxygenated blood away from heart
      • (exception of pulmonary artery)
      • Arteries thicker, higher pressure
    • Both artery & vein walls have:
      • Tunica externa - collagen fibres (for strength)
        • Tunica media - smooth muscle & elastic fibres
          • Tunica intima - simple squamous epithelium (endothelium), continuous
    • All are linked: heart - body - heart
      • Heart - elastic arteries - muscular arteries - arterioles - capillaries - venules - veins - heart
    • Arteries:
      • Elastic (largest)
        • Large amounts of elastic fibres allow for expansion and contraction, allowing blood to flow smoothly
        • Muscular
          • Distributes blood to different parts of the body, muscular walls allow blood flow control
          • Arterioles
            • Mostly smooth muscle around an endothelium, held together by collagen fibres. Smooth muscle allows regular blood flow to capillaries. Ability to contract and relax for vasoconstriction and vasodilation
    • Capillaries:
      • Continuous capillary (regular)
        • Fenestrated capillary
          • Cells have pores, found in kidneys, small intestine
          • Sinusoidal capillary
            • Most permeable cell wall, found in liver, bone marrow & spleen
    • Precapillary sphincters
      • valves (?) which can open and close to either bypass or supply capillaries with blood depending on the body's needs
    • Veins formed by venules joining together

11. factors influencing blood flow

    • Pressure - high to low
      • Measured in mmHg - millimetres of mercury
      • Systole & diastole
      • Blood always moves from high to low pressure
    • Pacemaker - contractions
    • Physical activity/demand on heart

12. factors influencing blood flow back to heart

    • Muscular contraction
      • Veins squeezed, blood moved along
    • Respiratory pump
      • Breathing in drops thoracic cavity blood pressure
        • Blood drawn toward cavity
          • Breathing out pressure increases, large veins squeezed, blood pushed toward heart
    • Valves in veins
      • Blood can't move backward

13. How does blood flow contribute to homeostasis?

    • elimination of wastes
    • Blood can be directed to body parts of need - or redistributed from less important processes
    • Provision of oxygen & nutrients to all areas of body