The Circulatory System

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The Circulatory System

• The Heart, Blood Vessels, Blood Types

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The Closed Circulatory System

• Humans have a closed circulatory system, typical
  of all vertebrates, in which blood is confined to
  vessels and is distinct from the interstitial
  fluid.
• The heart pumps blood into large vessels that
  branch into smaller ones leading into the organs.
• Materials are exchanged by diffusion between the
  blood and the interstitial fluid bathing the
  cells.

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The Cardiovascular System

• Three Major Elements Heart, Blood Vessels,
  Blood
• 1. The Heart- cardiac muscle tissue
• highly interconnected cells
• four chambers
• Right atrium
• Right ventricle
• Left atrium
• Left ventricle

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Pathway of the blood

• Superior Vena Cava
• Right Atrium
• Tricuspid Valve
• Right Ventricle
• Pulmonary Semilunar Valve
• Lungs
• Pulmonary Vein
• Bicuspid Valve
• Left Ventricle
• Aortic Semilunar Valve
• Aorta
• To the bodies organs cells

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Circuits

• Pulmonary circuit
• The blood pathway between the right side of the
  heart, to the lungs, and back to the left side of
  the heart.
• Systemic circuit
• The pathway between the left and right sides of
  the heart.

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The Cardiovascular System

• 2. Blood Vessels -A network of tubes
• Arteries?arterioles move away from the heart
• Elastic Fibers
• Circular Smooth Muscle
• Capillaries where gas exchange takes place.
• One cell thick
• Serves the Respiratory System
• Veins?Venules moves towards the heart
• Skeletal Muscles contract to force blood back
  from legs
• One way values
• When they break - varicose veins form

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The Cardiovascular System

• 3. The Blood
• Plasma
• Liquid portion of the blood. Contains clotting
  factors, hormones, antibodies, dissolved gases,
  nutrients and waste

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The Cardiovascular System

• The Blood
• B. Erythrocytes - Red Blood Cells
• Carry hemoglobin and oxygen. Do not have a
  nucleus and live only about 120 days.
• Can not repair themselves.

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The Cardiovascular System

• The Blood
• C. Leukocytes White Blood cells
• Fight infection and are formed in the bone marrow
• Five types neutrophils, lymphocytes,
  eosinophils, basophils, and monocytes.

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The Cardiovascular System

• The Blood
• D. Thrombocytes Platelets.
• These are cell fragment that are formed in the
  bone marrow from magakaryocytes.
• Clot Blood by sticking together via protein
  fibers called fibrin.

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Disorders of the Circulatory System

• Anemia - lack of iron in the blood, low RBC
  count
• Leukemia - white blood cells proliferate wildly,
  causing anemia
• Hemophilia - bleeders disease, due to lack of
  fibrinogen in thrombocytes
• Heart Murmur - abnormal heart beat, caused by
  valve problems
• Heart attack - blood vessels around the heart
  become blocked with plaque, also called
  myocardial infarction

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Unit 9 The Heart

• Cardiovascular System
• The Heart

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Functions of the Heart

• Generating blood pressure
• Routing blood
• Heart separates pulmonary and systemic
  circulations
• Ensuring one-way blood flow
• Heart valves ensure one-way flow
• Regulating blood supply
• Changes in contraction rate and force match blood
  delivery to changing metabolic needs

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Size, Shape, Location of the Heart

• Size of a closed fist
• Shape
• Apex Blunt rounded point of cone
• Base Flat part at opposite of end of cone
• Located in thoracic cavity in mediastinum

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Heart Cross Section
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Pericardium
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Heart Wall

• Three layers of tissue
• Epicardium This serous membrane of smooth outer
  surface of heart
• Myocardium Middle layer composed of cardiac
  muscle cell and responsibility for heart
  contracting
• Endocardium Smooth inner surface of heart
  chambers

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Heart Wall
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External Anatomy

• Four chambers
• 2 atria
• 2 ventricles
• Auricles
• Major veins
• Superior vena cava
• Pulmonary veins
• Major arteries
• Aorta
• Pulmonary trunk

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External Anatomy
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Coronary Circulation
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Heart Valves

• Atrioventricular
• Tricuspid
• Bicuspid or mitral
• Semilunar
• Aortic
• Pulmonary
• Prevent blood from flowing back

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Heart Valves
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Function of the Heart Valves
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Blood Flow Through Heart
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Systemic and PulmonaryCirculation
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Heart Skeleton

• Consists of plate of fibrous connective tissue
  between atria and ventricles
• Fibrous rings around valves to support
• Serves as electrical insulation between atria and
  ventricles
• Provides site for muscle attachment

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Cardiac Muscle

• Elongated, branching cells containing 1-2
  centrally located nuclei
• Contains actin and myosin myofilaments
• Intercalated disks Specialized cell-cell
  contacts
• Desmosomes hold cells together and gap junctions
  allow action potentials
• Electrically, cardiac muscle behaves as single
  unit

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Conducting System of Heart
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Cardiac Conduction

• Electrical impulses generate action potentials.
• Depolarization of muscle fibers contraction of
  muscles
• Polarization of muscle fibers relaxation of
  muscles
• The SA node receives electrical impulses. This
  SA node is located on the upper right atrium.
• This node serves as the hearts pacemaker,
  regulating the pace and initiating the beat
  sequence.
• Electrical impulses from the SA node spread
  throughout both atria and the muscle fibers
  depolarize , causing them to contract (pushing
  blood into the ventricles) (Atrial Systole)

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Cardiac Conductionhttps//www.youtube.com/watch?v
RYZ4daFwMa8
The AV node is located on other side of right
atrium . The AV node Serves as the gateway to the
ventricles. It delays the passage of electrical
impulses to the ventricles. So that the atria
have ejected all the blood into the ventricles
before ventricles contract. AV node receives
signals from the SA node and passes them onto
the atrioventricular bundle, the bundle of HIS.
This bundle is divided into right and left
branches and conducts the impulses towards the
apex of the heart. The signals are then passed
onto Purjinje fibers, turning upward, spreading
throughout the ventricular myocardium. As the
signal spreads through the ventricles, muscle
fibers depolarize and contract, pushing blood to
lungs and aorta.
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• https//www.youtube.com/watch?vv3b-YhZmQu8
• Another good video

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Electrical stimuluses of the heart can be
recorded in the form of an ECG, electrocardiogram
or EKG.

• Action potentials through myocardium during
  cardiac cycle produces electric currents than can
  be measured
• Pattern
• P wave
• Atria depolarization
• QRS complex
• Ventricle depolarization
• Atria repolarization
• T wave
• Ventricle repolarization

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What does the ECC show about the Heart?

• When the atria are full of blood the SA node
  fires, electrical signals spread throughout the
  atria and cause them to depolarize. This is
  represented by the P wave on the ECG. Atrial
  contraction (systole ) starts about 100ms after
  the P wave begins.

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Cardiac Arrhythmias

• Tachycardia Heart rate in excess of 100bpm
• Bradycardia Heart rate less than 60 bpm
• Sinus arrhythmia Heart rate varies 5 during
  respiratory cycle and up to 30 during deep
  respiration
• Premature atrial contractions Occasional
  shortened intervals between one contraction and
  succeeding, frequently occurs in healthy people

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• The PQ segment represents the time the signals
  travel from the SA node to the AV node.
• The QRS complex marks the firing of the AV node
  and represents ventiricular depolarization
  (contraction) ( systole)
• Q corresponds to the depolarization of the
  interventricuoar septum.

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• . R wave is produced by depolarization of the
  main mass of the ventricles.
• S wave represents the last phase of ventricular
  depolarization at the base of the heart.
• During the QRS wave the Atrial repolarization
  occurs but cant be seen due to the big QRS wave.

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• ST complex represents the myocardial action
  potential. This is when the ventricles contract
  and pump blood.
• The T wave represents ventricular repolarization
  immediately before ventricular relaxation
  (diastole)
•  
• The cycle repeats itself with every heartbeat.

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Alterations in Electrocardiogram
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Cardiac Cycle

• Heart is two pumps that work together, right and
  left half
• Repetitive contraction (systole) and relaxation
  (diastole) of heart chambers
• Blood moves through circulatory system from areas
  of higher to lower pressure.
• Contraction of heart produces the pressure

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Cardiac Cycle
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Heart Sounds

• First heart sound or lubb
• Atrioventricular valves and surrounding fluid
  vibrations as valves close at beginning of
  ventricular systole
• Second heart sound or dupp
• Results from closure of aortic and pulmonary
  semilunar valves at beginning of ventricular
  diastole, lasts longer
• Third heart sound (occasional)
• Caused by turbulent blood flow into ventricles
  and detected near end of first one-third of
  diastole

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Location of Heart Valves
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Mean Arterial Pressure (MAP)

• Average blood pressure in aorta
• MAPCO x PR
• CO is amount of blood pumped by heart per minute
• COSV x HR
• SV Stroke volume of blood pumped during each
  heart beat
• HR Heart rate or number of times heart beats per
  minute
• Cardiac reserve Difference between CO at rest
  and maximum CO
• PR is total resistance against which blood must
  be pumped

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Factors Affecting MAP
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Regulation of the Heart

• Intrinsic regulation Results from normal
  functional characteristics, not on neural or
  hormonal regulation
• Starlings law of the heart
• Extrinsic regulation Involves neural and
  hormonal control
• Parasympathetic stimulation
• Supplied by vagus nerve, decreases heart rate,
  acetylcholine secreted
• Sympathetic stimulation
• Supplied by cardiac nerves, increases heart rate
  and force of contraction, epinephrine and
  norepinephrine released

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Heart Homeostasis

• Effect of blood pressure
• Baroreceptors monitor blood pressure
• Effect of pH, carbon dioxide, oxygen
• Chemoreceptors monitor
• Effect of extracellular ion concentration
• Increase or decrease in extracellular K
  decreases heart rate
• Effect of body temperature
• Heart rate increases when body temperature
  increases, heart rate decreases when body
  temperature decreases

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Baroreceptor and ChemoreceptorReflexes
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Baroreceptor Reflex
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Chemoreceptor Reflex-pH
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Effects of Aging on the Heart

• Gradual changes in heart function, minor under
  resting condition, more significant during
  exercise
• Hypertrophy of left ventricle
• Maximum heart rate decreases
• Increased tendency for valves to function
  abnormally and arrhythmias to occur
• Increased oxygen consumption required to pump
  same amount of blood