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Anatomy of the heart (Major Heart models (OTHER) (Papillary muscles…

- - - - composed of irregular connective tissue containing both elastic and collagen fibers
      - layer helps to hold the blood vessels in place.
    - - differs between the blood vessels
      - composed of both smooth muscle and connective tissue with elastic and collagen fibers
      - smooth muscle allows it to stretch a bit but the collagen fibers help to keep the integrity of the vessels
      - contains a lot of smooth muscle
    - - an endothelial lining made up of squamous epithelial tissue that is of single-cell thickness
  - - - Valves are present inside of veins
        
        help to keep the blood from flowing backwards as it moves on its way to the heart
      - Skeletal muscle also helps move the blood
      - The diaphragm helps move blood in the veins
        
        contracts and relaxes aiding in the flow by breathing
- - - - supplies blood to the right atrium and the right ventricle of the heart.
    - - supplies blood to the left atrium but then branches off into two sections:
        
        anterior interventricular branch
        
        left circumflex artery.
    - - ischemia
        
        when tissue is lacking a supply of blood
        
        can cause a heart attack to where tissue is dead
        
        can interconnect (called collaterals) to help prevent ischemia.
    - - great cardiac vein drains blood from anterior surface of the heart
      - middle cardiac vein drains blood from posterior surface of heart
      - these veins empty into a coronary sinus which returns blood to right atrium
  - - - tough fibrous layer that doesn't allow much stretch so the heart doesn't overfill
      - continuous with a tendon from the diaphragm and is composed of dense connective tissue
    - - Parietal pericardium
        
        lines the fibrous pericardium and is a thin layer of epithelial cells
      - Visceral pericardium
        
        internal visceral layer of the pericardium but is also the outer layer of the heart, the epicardium
        
        composed of a thin layer of epithelial cells
        
        inner layer of the pericardium= the visceral pericardium
        
        outer layer of the hear= the epicardium
      - pericardial cavity between two
        
        narrow space that contains small amount of serous fluid for lubrication; helps reduce friction between two layers as heart beats.
- - - - thickest layer and the amount varies when comparing the right to the left side
      - collagenous fibers to give it strength, blood vessels to supply heart itself and nerve fibers to help regulate the heart
      - contraction of the myocardium pumps blood through the heart and into major arteries
      - ventricles of heart pump same amount of blood per contraction, however, the muscle of the left ventricle is thicker and stronger in order to pump blood to entire body
      - left ventricle has to generate a large amount of pressure to overcome pressure
      - right side of the heart only has to pump blood to the lungs
      - Cardiac muscle differs from skeletal muscle as it branches and it contains intercalated discs
      - Cardiac muscle cells only found in heart
      - utilize mostly oxygen for energy and contain a lot of mitochondria and myoglobin
      - action of myofibrils and sarcomeres so cardiac muscle still exhibits striations of skeletal muscle.
      - cells are connected together closely through gap junctions and desmosomes at the intercalated discs
      - gap junctions allow ions to move from one cell to another creating an electrical charge so that an action potential can move quickly from one cell to another
      - desmosomes help to hold the cells together: can pull together as one mass of cells, so the tissue is called a syncytium
    - - made of simple squamous epithelium called endothelium that is continuous with the blood vessels
      - also lines the chambers where blood circulates and also covers the heart valves.
- - - - Left atrium- this chamber receives blood from the pulmonary circulation
        
        4 pulmonary veins that empty into the left atrium and they are the right and left pulmonary veins
        
        blood comes from the lungs and has dropped off carbon dioxide for exhalation and picked up oxygen
        
        blood going into the left atrium then is oxygenated.
      - Right atrium - This chamber receives blood from the systemic circulation
        
        3 major veins that empty into this chamber: inferior vena cava, the superior vena cava, and the large cardiac vein
        
        blood arriving into the right atrium is said to be deoxygenated (low in oxygen content).
    - - Right ventricle
        
        blood flows from the right atrium into the right ventricle through a valve called the tricuspid valve
      - Left ventricle
        
        The blood flows from the left atrium into the left ventricle through a valve called the bicuspid valve
  - - - Right AV valve - is known as the tricuspid valve.
        
        Each cusp of valve is attached to strong strands of connective tissue called chordae tendineae: composed of 80% collagenous fibers which accounts for their strength
        
        These strands connect each of the 'cusps' to a papillary muscle at the bottom of the right ventricle
        
        purpose of chordae tendinae to stop any backflow when the flap closes
      - Left AV valve - known as bicuspid valve or mitral valve.
        
        cusps of this valve are connected to papillary muscles via chordae tendinae
    - - Pulmonary SL valve
        
        Deoxygenated blood from the right ventricle leaves the heart through this valve to go to the lungs
        
        made up of three cusps that close from the pressure of blood after it leaves the ventricle
        
        There are no chordae tendinae or papillary muscles that attach to the SL valves.
      - Aortic SL valve
        
        Oxygenated blood from the left ventricle leaves the heart through this valve to go to the body
        
        made up of three cusps which close from the pressure of blood after it leaves the ventricle