Heart

Heart

1. Anatomy

   • Endocardium
     • One epithelial layer on the inner lining
       • Endocarditis- Infection preventing efficient valve functioning
   • Myocardium
     • Cardiac muscle with blood supply and conducing fibers
   • Pericardium
     • Double layered Protective bag to prevent movement
       • Pericarditis- Infection causing pain similar to heart attack
   • Tricuspid Valve- Three flaps into the right ventricle
   • Mitral Valve- Two flaps into the left ventricle
   • Coronary Arteries
     • Left Coronary Artery
       • Left anterior descending
         • supplies the septum and left and right ventricle
       • Left circumflex artery
         • Supplies The left atrium and Left ventricle
     • Right coronary artery
       • Supplies the right atrium
     • Penetrate into the muscle to supply O2 blood which is then removed via cardiac veins into the right atrium via the coronary sinus

2. ECG

   • P wave
     • atrial depolarisation
   • QRS wave
     • Ventricular depolarisation
   • T wave
     • Ventricular repolarisation
   • U wave
     • Repolarization of the muscle fibers in the myocardium

3. Action Potential Transmission

   • SA node
     • AV node
       • His- Purkinje Fibers
         • Ventricle walls muscle fibers

4. Heart contraction

   • AV valves open to allow ventricle filling
     • Atrium contraction to increase pressure in the ventricles
       • Ventricle contraction to close AV nodes and allow pressure increase
         • Semi Luna valves open and blood ejection
           • Decreasing pressure causing retrograde flow and closing of the semi Luna valves
             • When pressure in ventricles falls below atrium the cycle continues.

5. Blood Vessels

   • Aorta/ Artery
     • Adventita
       • Collagen for support and overexpansion prevention
       • Vaso vasorum
       • Nerves to control dilation and constriction
       • Lymphatics
     • Media
       • Thick smooth muscular walls to maintain pressures
         • Elastic arteries- Spirals
         • Muscular arteries- Rings/ helices
       • Elastic Fibers to allow stretch an recoil pressure changes
     • Intima
       • Endothelium cells and the basement membrane
     • SMALL LUMEN FOR HIGH PRESSURES
   • Vena Cava/ Vein
     • Adventita- THICKER
     • Media- LITTLE ELASTIC AND MUSCLE
     • Intima
       • Pocket valves present to prevent backflow of blood
   • Arterioles
     • Smooth muscle for complete constriction and control of flow
   • Capillaries
     • similar to INTIMA with fenestrations/ gaps

6. Blood Pressure

   • Larger on left due to thicker muscle walls to pump round the body
     • 120/ 75
       • Systematic- Whooshing sound
       • Diastolic - Silence
   • Baroreceptor detection of pressure signals to medulla
     • -ive feedback controlling pacemaker, muscle fibers and vessel diameter
   • Drugs to control!
     • Vasoconstriction
       • Angiotensin formed by renin from kidneys. AT2 formed in the lungs.
       • alpha-1 agonists (blood vessels)
       • beta- 1 agonists (heart)
     • Vasodilation
       • AT2 antagonist
       • alpha-1 antagonist
       • beta-1 antagonist
         • beta- blockers- can cause hypoglycemia
       • Ca2+ channel blockers- decrease heart activity!
   • Exercise increase BP!
     • Stronger heart therefore more blood pumper per beat
       • resting BP decrease