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Heart Valves

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increases systemic blood pressure and routes more blood to the working muscles. ... Diastolic (pressure at the moment your heart relaxes to permit blood flow into ... – PowerPoint PPT presentation

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Title: Heart Valves


1
Heart Valves
  • Atrioventricular valves
  • Tricuspid and Bicuspid
  • Prevent backflow into the atria when ventricles
    are contracting
  • Semilunar valves
  • Pulmonary and Aortic semilunar valves
  • Prevent backflow into the ventricles when they
    are relaxing

2
Mechanisms to aid in return of blood to heart
  • One way Valves
  • Open to allow blood through then close to prevent
    backflow
  • Skeletal muscle contractions
  • Help to pump blood through by constricting veins
    and squeezing blood
  • Breathing
  • Help to pump blood through by constricting veins
    and squeezing blood

3
Problems with blood return
  • Fainting
  • Standing still too long without moving
    particularly your lower body
  • less blood circulating because of accumulation in
    veins already have low blood pressure
  • Varicose veins
  • stretching of veins caused by accumulation of
    blood
  • weak valves (allowed pooling of blood), standing
    too much
  • Light headedness from lifting
  • improper breathing

4
Heart sounds
  • Heart valves closing during each heartbeat create
    stereotypical sound lub-dup
  • LUB two atroventricular valves close during
    ventricular contraction
  • DUP two semilunar valves close during
    ventricular relaxation

5
Heartbeat conduction
  • Myogenic
  • The ability of the heart to contract is a
    property of the heart muscle itself it is not
    dependent on the body's nervous system
  • But brain does control the rate

6
Heartbeat
7
Conduction of heartbeat 0.85 sec
8
Electrical and Contractile Sequence of the Heart
Beat
  • SA node fires, initiating an impulse that rapidly
    travels across the atria
  • Atria contract almost simultaneously (as a unit)
    forcing blood across the valves and into the
    ventricles
  • Signal passes on to the septum separating right
    and left halves of the heart Atrioventricular
    node
  • AV node delays conduction of impulses from the
    atria to the ventricle (to ensure complete atrial
    contraction before ventricles begin contraction)

9
  • AV node transfers signal to rapid conduction
    pathway called the bundle of His
  • Bundle branches divide into right and left halves
    going to right and left ventricles respectively
  • Bundle of His accelerates the impulse and passes
    it down the interventricular septum to the
    Purkinje fibers
  • Purkinje fibers carry the impulse deep into the
    ventricular myocardial walls
  • Ventricles contract simultaneously (as a unit),
    forcing the AV valves shut, and pumping the blood
    into the aorta on the left and the pulmonary
    arteries on the right

10
Extrinsic control of heartbeat
  • Nervous Control of Heartbeat
  • Cardiac center in medulla oblongata can alter
    heartbeat through autonomic nervous system
  • Parasympathetic system promotes normal responses
    including slowing down heartbeat
  • Sympathetic system promotes stress responses
    including speeding up heartbeat
  • Need for oxygen, increase in blood pressure, etc.
    may activate systems

11
Hormones in heartbeat
  • Chemical messengers (hormones) called
    catecholamines, which consist of adrenaline
    (epinephrine) and noradrenaline (norepinephrine)
    help to speed up heart rate
  • Acetylcholine, has the opposite effect, causing
    the heart rate to slow

12
Heart rate (72 beats/min)
  • Factors age, gender, exercise, body temp.
  • fetus 140-160 beats per min (FYI)
  • faster in women
  • Exercise raises heart rate
  • increases systemic blood pressure and routes more
    blood to the working muscles.
  • Trained athletes may be as low as 40-60 beats per
    min.

13
Blood Pressure
  • The pressure the blood exerts against any unit
    area of the blood vessel walls
  • Systolic (heart contracting) Less than 120mm Hg
  • Diastolic (pressure at the moment your heart
    relaxes to permit blood flow into its chambers)
    Less than 80mm Hg
  • Normal blood pressure written as 120/80mmHg

14
Measured in the arteries
15
Sounds of Korotkoff
  • Cuff tightens it cuts off the blood flow to your
    arm. As pressure is released, a thump is heard
    (Systolic). This is what we hear as the LUB
    sound
  • As the cuff is loosened further, the pressure
    continues to fall and the lighter thumps are
    heard as the blood finds it easy to push pass the
    cuff. Thumping stops (Diastolic). This is what we
    hear as the DUP sound

16
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17
ECG (Electrocardiogram)
  • Recording of electrical changes during a cardiac
    cycle

18
ECG
  • Normal heartbeat
  • Is the result of an electrical impulse
  • Originates in a specialized area in the wall of
    the right atrium called the SinoAtrial node
  • SinoAtrial node (a.k.a) SA node (a.k.a) Pace Maker

19
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20
ECG
  • P wave-electrical activity initiated by SA node
    causing atria to contract
  • QRS wave-impulses to stimulate ventricle to
    contract
  • T wave- electrical recovery of ventricles

21
Arrhythmia (Irregular heart beat)
  • Problems that affect the electrical system of the
    heart muscle
  • Irregularities in initiation or conduction of
    impulses
  • Results in abnormal heart beat
  • Cause the heart to pump less effectively
  • Occurs due to
  • coronary artery disease, high blood pressure,
    diabetes, smoking, excessive use of alcohol, drug
    abuse and stress

22
Irregular heart beats Too slow
  • Bradycardia
  • heart rate slower than 60 beats per minute
  • Result
  • low body temp, certain drugs, brain edema after
    head trauma
  • In endurance type athletes, heart rate can lower
    and still provide the same cardiac output

23
Irregular heart beats Too fast
  • Tachycardia
  • abnormally fast heart rate, over 100 beats per
    minute
  • Due to
  • stress, elevated body temp, stress, certain drugs
    or heart disease. Can promote fibrillation
  • Rapid and irregular or out of phase contractions
  • Defibrillation - strong electrical shock

24
Heart Murmur
  • Small deformity in valve blood passes back into
    the atria after the valves have closed
  • Produces a swishing noise
  • Reduce efficiency of blood flow
  • Can hinder persons ability to sustain normal
    activity levels

25
Emergency Defibrillation
  • Heart attack induces ventricular fibrillation
  • Regain normal rhythm
  • CPR (Cardio-Pulmonary Resuscitation)
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