Transcript Beat Still My Heart

Biology 20 - Circulation
Beat Still My Heart
Heart Innervation, ECG, Sounds
& Blood Pressure
http://science.nhmccd.edu/biol/ap2int.htm
HEART CENTER ONLINE:
http://www.heartcenteronline.com/myheartdr/comm
on/articles.cfm?ARTID=187
How the Heart holds a Beat!
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Basic Anatomy
Draw & Label 
Septum with Bundle of
His (nerve tissue)
Purkintje Fibers
Apex
Label the right and left side,
also the SA & AV too
How the Heart holds a Beat…
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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
How the Heart holds a Beat…
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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
Heart
Beat terms…
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Tachycardia – SA signals speed up
Bradycardia – SA signals slow down
Pacemaker – device to help set the rate
Nervous System Control of the
Heart Beat.
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Heart rate can be altered by two nerves coming from the
medulla oblongata of the brain to the SA node.
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i.
Vagus nerve – more impulses slows
heart rate. Part of the parasympathetic nervous system.
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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.
Reading an ECG –
electrocardiogram.
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1)
2)
3)
4)
5)
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
T
Cardiac Cycle! -
see handout
TOP HALF – DIASTOLE [Period of relaxation]
– I.e. when heart is resting!
DIASTOLE MEANS TO?
Cardiac Cycle! -
see handout
BOTTOM HALF – SYSTOLE [Period of contraction]
SYSTOLE MEANS TO?
Heart Sounds – see handout
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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
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Second Heart Sound:
– When ventricles relax
– Semi-lunar valves slap  DUP
Heart
Sounds…
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MURMUR valves do not
close properly
Blood leaks
backwards
Causes:
– Inherited
– Disease (viral)
– Not flossing teeth
Blood Pressure – See Handout!
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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 ____
Blood Pressure – See Handout!
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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
Blood Pressure – See Handout!
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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
Blood Pressure Lab
Investigation!
Blood Pressure
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2 factor affecting
blood pressure
1. Cardiac output
–  C.O.  B.P
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2. Arteriolar
Resistance
–  diameter  B.P
–  diameter  B.P
Cardiac Output
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Cardiac output - the amount of blood
that flows from each side of the heart /
minute
Two Factors
– stroke volume
– heart rate
Cardiac Output
Cardiac Output =
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Stroke Volume
– the quantity of blood
pumped with each
beat ~ 70ml
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Heart Rate
– is the number of
times the heart beats
per minute
Heart Rate x Stroke Volume
= 70 beat/min x 70 ml/beat
= 4900 ml/min
Cardiac Output
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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. Dusty’s heart can
deliver 70ml of blood per beat. What is
Dusty’s cardiac output?
Heart rate X Stroke volume
150 beats/min X 70ml/beat
10500ml/min or 10.5L/min
While waiting to complete lab:
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Read p 319 – 334
Complete: Case study on page 324, #1
– 10 on p 327 and #1 – 12 on p 335