Biology 20 - Circulation Beat Still My Heart

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Biology 20 - Circulation Beat Still My Heart

• Heart Innervation, ECG, Sounds Blood
  Pressure

http//science.nhmccd.edu/biol/ap2int.htm HEART
CENTER ONLINEhttp//www.heartcenteronline.com/my
heartdr/common/articles.cfm?ARTID187
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How the Heart holds a Beat!

• Basic Anatomy
• Draw Label ?

Label the right and left side, also the SA AV
too
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How the Heart holds a Beat

• The heart has a pacemaker called the SINOATRIAL
  Node (SA Node)
• SA is located in the upper right atrium
• Sends out a signal for atria to contract
• A 2nd node, ATRIOVENTRICULAR, (AV-Node) is
  triggered by the SA Node
• AV is located at the top of the septum

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How the Heart holds a Beat

• As atria contract blood moves ______?
• AV node sends a signal down the septum (via
  Bundle of His) to the apex
• Ventricles now contract from bottom-up
• The Bundle of His acts as a time delay between
  atrial ventricular contraction

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Heart Beat terms

• Tachycardia SA signals speed up
• Bradycardia SA signals slow down
• Pacemaker device to help set the rate

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Nervous System Control of the Heart Beat.

• Heart rate can be altered by two nerves coming
  from the medulla oblongata of the brain to the SA
  node.
• i. Vagus nerve more impulses slows heart
  rate. Part of the parasympathetic nervous
  system.
• ii. Sympathetic Nerve more impulses
  increase heart rate. Part of the sympathetic
  nervous system.

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• Heart rate can also be increased by the release
  of epinephrine (adrenaline) by the adrenal gland
  into the blood.

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Reading an ECG electrocardiogram.

• 5 parts to read
• P-wave atria contract
• QRS-wave ventricles contract
• P-Q apex receives signal
• R-S rapid contraction of heart relaxation
• T-wave rest period

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Cardiac Cycle! - see handout
TOP HALF DIASTOLE Period of relaxation I.e.
when heart is resting!
DIASTOLE MEANS TO?
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Cardiac Cycle! - see handout
BOTTOM HALF SYSTOLE Period of contraction
SYSTOLE MEANS TO?
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Heart Sounds see handout

• The lubb-dup sound comes from the heart valves
  slapping to a close
• First Heart Sound
• When ventricles contract
• Tri Bicuspid valves slap ? LUBB
• Sometimes called A-V valve flaps
• Second Heart Sound
• When ventricles relax
• Semi-lunar valves slap ? DUP

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Heart Sounds

• MURMUR - valves do not close properly
• Blood leaks backwards
• Causes
• Inherited
• Disease (viral)
• Not flossing teeth

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Blood Pressure See Handout!

• How is blood under pressure?
• Any fluid confined in a vessel (hose or vein)
  exerts a push against the walls that contains it
• If the blood vessel narrows what happens to the
  pressure of the fluid?
• If the blood vessel expands in diameter what
  happens to the pressure inside it?
• If the volume of blood goes up ? pressure will
  ____
• If you lose blood volume (bleeding) ? pressure
  will ____

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Blood Pressure See Handout!

• BP Facts
• BP is highest at the heart decreases from there
  on
• That is why your carotid pulse is stronger than
  your wrist!
• Any factor that speeds your heart will increase
  BP! WHY?
• Your arteries can control BP by changing diameter
  according to your bodies need

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Blood Pressure See Handout!

• Low BP reduces your capacity to transport blood,
  O2 in tissues go down.
• High BP over time weakens the arteries and
  capillaries which may rupture.
• Sphygmomanometer
• measures blood pressure ? 120/80
• gauge that measures the pressure that blood
  exerts during ventricular contraction (systolic
  blood pressure) 120 mm Hg
• also measures pressure during ventricular
  relaxing (diastolic blood pressure) 80 mm Hg

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Blood Pressure Lab Investigation!
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Blood Pressure

• 2 factor affecting blood pressure
• 1. Cardiac output
• ? C.O. ? B.P
• 2. Arteriolar Resistance
• ? diameter ? B.P
• ? diameter ? B.P

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Cardiac Output

• Cardiac output - the amount of blood that flows
  from each side of the heart / minute
• Two Factors
• stroke volume
• heart rate

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Cardiac Output
Cardiac Output Heart Rate x Stroke Volume
70 beat/min x 70 ml/beat 4900 ml/min

• Stroke Volume
• the quantity of blood pumped with each beat
  70ml
• Heart Rate
• is the number of times the heart beats per minute

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Cardiac Output

• Problem
• Dusty has just finished exercising and in order
  for his heart to keep up with the increased
  oxygen demands it is pumping at 150 beats per
  minute. Dustys heart can deliver 70ml of blood
  per beat. What is Dustys cardiac output?

Heart rate X Stroke volume 150 beats/min X
70ml/beat 10500ml/min or 10.5L/min
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While waiting to complete lab

• Read p 319 334
• Complete Case study on page 324, 1 10 on p
  327 and 1 12 on p 335