Chapter 11 The Cardiovascular System

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Chapter 11The Cardiovascular System
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• The Cardiovascular System

• A closed system of the heart and blood vessels
• -heart pumps blood
• -blood vessels - circulate to all parts of body
• Deliver oxygens nutrients and to remove carbon
  dioxide waste products

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• The Heart

• In thorax between lungs
• Pointed apex toward left hip
• Size of fist

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• Heart Coverings Wall Layers

• Pericardium double serous membrane
• Visceral - next to heart
• Parietal - outside layer
• Serous fluid fills space between the layers

• Three layers
• 1.Epicardium- Outside
• parietal pericardium
• Connective tissue
• 2.Myocardium- Middle
• Mostly cardiac muscle
• 3.Endocardium - Inner
• Endothelium

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• External Heart Anatomy

Figure 11.2a
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• The Heart Chambers

• Right and left act as separate pumps
• Four chambers
• 2 Atria - Receiving
• - Right atrium
• - Left atrium
• 2 Ventricles - Discharging
• - Right ventricle
• - Left ventricle

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• The Heart Valves

• Allow blood to flow in only one direction
• Four valves
• 2 Atrioventricular valves between atria
  ventricles
• Bicuspid valve (left)
• Tricuspid valve (right)
• 2 Semilunar valves - between ventricle artery
• Pulmonary semilunar valve
• Aortic semilunar valve

• Held in place by chordae tendineae (heart
  strings)

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• Operation of Heart Valves

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• The Heart Associated Great Vessels

• Aorta - Leaves left ventricle
• Pulmonary arteries - Leave right ventricle
• Vena cava - Enters right atrium
• Pulmonary veins (four) - Enter left atrium

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• Coronary Circulation

• Blood in heart doesnt nourish the heart
• Hearts nourishing circulatory system
• - Coronary arteries
• - Cardiac veins
• - Blood empties into the right atrium via the
  coronary sinus

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• The Heart Conduction System

• Intrinsic conduction system (nodal system)
• Heart muscle cells contract, without nerve
  impulses, in a regular, continuous way

• Sinoatrial node Pacemaker initiates contraction
• Sequential stimulation occurs at other
  autorhythmic cells
• Atrioventricular node
• Atrioventricular bundle
• Bundle branches
• Purkinje fibers

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• The Heart Cardiac Cycle

• Cardiac cycle events of one heart beat
• Terms Systole contraction Diastole
  relaxation
• Atria contract simultaneously
• Atria relax, then ventricles contract

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• The Heart Cardiac Output

• Cardiac output (CO)
• Amount of blood pumped by each side of the heart
  in one minute
• CO (heart rate HR) x (stroke volume SV)
• Stroke volume SV
• Volume of blood pumped by each ventricle in one
  contraction

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• Cardiac Output Regulation

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• The Heart Regulation of Heart Rate

• Stroke volume usually remains relatively constant
• - Starlings law of the heart the more that the
  cardiac muscle is stretched, the stronger the
  contraction
• Changing heart rate is the most common way to
  change cardiac output

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• Regulation of Heart Rate

Decreased Heart Rate 1. Parasympathetic nervous
system 2. High blood pressure or blood volume 3.
Decreased venous return

• Increased Heart Rate
• 1. Sympathetic nervous system
• Crisis
• Low blood pressure
• 2. Hormones
• Epinephrine
• Thyroxine
• 3. Exercise
• 4. Decreased blood volume