Transcript Resting heart rate

Cardiovascular System: The Heart
Essential Terms
Cardiology
apex of heartbase of heart
Ventricles
atria
Introduction

heart beats about _____times every
day or about ______beats per year

left side pumps to ______ circuit
right side pumps to ______ circuit

Location & Heart Anatomy
Heart Anatomy

size ~ 12cm long, 9cm wide at broadest part
(5” x 3.5”)

average mass 250g (8 oz) in females

average mass 300g (10 oz) in males
PERICARDIUM
Heart Wall
1.
Epicardium
2.
Myocardium
3.
endocardium
Concept 19.2
Heart Chambers
Right Atrium (RA)- upper chamber

receives blood from:

anterior wall is rough with _________
divided from left atrium by thin partition
called _________

oval depression in septum called _______



remnant of foramen ovale
blood leaves RA through ________
Figure 19.4a
Figure 19.4b
Figure 19.4c
Right Ventricle (RV)




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
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receives blood from______
forms
Contains:
cusps of tricuspid valve connected to
chordae tendineae
chordae tendineae connected to ______
divided from left ventricle by:
blood ejected to pulmonary valve to
pulmonary trunk en route to lungs for gas
exchange
Figure 19.3a
Figure 19.3b
Figure 19.3c
Left Atrium (LA)
receives blood from:


through 4 pulmonary veins

structurally similar to:

blood passes to left ventricle through
the____________
Left Ventricle (LV)
receives blood from _______ through
_______ valve
internal structures similar to RV





chordae tendineae
papillary muscles
interventricular septum

blood ejected into:

some aortic blood travels to coronary arteries

remainder passes to arch of aorta
Figure 19.4a
Figure 19.4b
Figure 19.4c
Figure 19.1a
Figure 19.1b
Myocardium

atrial walls are thinnest

right ventricle thinner than left ventricle

Why?

left ventricle walls are thickest

right and left ventricles pump same volume of
blood with each beat
Figure 19.4a
Figure 19.4b
Figure 19.4c
Concept 19.3
Heart Valves
Valves Of The Heart
Ensure one way flow through the heart

Atrioventricular Valves



between the atria & the ventricle
Names:
Semilunar Valves




at the beginning of the arteries that leave the heart
3 cusps per valve
Names:
Videos: http://www.youtube.com/watch?v=4Go0hhBP_aw
and http://www.youtube.com/watch?v=rkW1smPoXKA

Valve Stenosis-valve is scarred and does not
work well-requires valve surgery:

http://www.youtube.com/watch?v=rkW1smPo
XKA (old way) or
http://my.clevelandclinic.org/heart/disorders/va
lve/valve_videos.aspx
Concept 19.4
Circulation
Systemic and Pulmonary Circulation

systemic circulation:

pulmonary circulation:
Figure 19.6
Coronary Circulation

functional blood supply of the heart

arteries arise from base of aorta and encircle heart
in atrioventricular groove

Left coronary artery
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Right coronary artery

Heart attack
animation:http://www.youtube.com/watch?v=Yc
NYxegDXa8
Figure 19.7a
Figure 19.7b
Figure 19.7c
Coronary Veins

AKA coronary sinus
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great cardiac vein (anterior)
middle cardiac vein (posterior)
small cardiac vein
anterior cardiac veins
Figure 19.7a
Figure 19.7b
Figure 19.7c
Cardiac Conduction
nobel prize.org: EKG activity
Anatomy of Cardiac Conduction System
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Autorhythmic Cells:
excitation begins at________
arrives at __________ located in
_________
Action Potential flows to _______
then enters right and left _________
traveling ________
final Action Potential arrives at
___________ contracting ventricular
myocardium from apex up ejecting blood
through semilunar valves
Cardiac Conduction

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SA node initiates action potentials about
____ times per minute
Sets the rhythm of the heart
Called the ___________________
Autonomic Nervous SystemHormones-
Figure 19.8
Carotid artery disease video
• http://mdvideocenter.brighamandwomen
s.org/specialties/cardiovascular/endova
scular-treatment-of-carotid-arterydisease
Figure 10.17c
Figure 10.17b
Figure 10.17a
Concept 19.6
Electrocardiogram
ECG or EKG
Electrocardiography


recording of _______
electrodes placed on body surface


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arms and legs and six positions on chest
graphed as series of up and down waves
produced during each heartbeat
instrument called ________ that produces 12
different tracings
ECG Waves
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P wave
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QRS complex
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-
T wave
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-
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atrial repolarization usually not visible
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masked by larger QRS complex
Figure 19.9
ECG Waves & Heart Activity
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Systole


contraction
Diastole

relaxation
Figure 19.10
Concept 19.7
Cardiac Cycle
CARDIAC CYCLE

All events associated with one heartbeat

two atria contract

while two ventricles relax

two ventricles contract

while two atria relax
Animations

http://www.youtube.com/watch?v=SMXBR_Y
Focs

http://www.youtube.com/watch?NR=1&featur
e=fvwp&v=WNN4Fw2EWxI
Pressure & Volume Changes
Resting heart rate - about 75 beats/min.

each beat approximately 0.8 seconds
0.4 seconds relaxation period

greatest variation in timing is here
0.1 seconds atria contract
0.3 seconds atria relax & ventricles contract
Figure 19.11
Atrial Systole
SA node depolarization
causes atrial systole forcing blood through AV
valves into ventricles
Ventricles fill
1.
2.
3.
EDV measure just prior to ventricle contraction
•

approximately 130mL
Ventricular Systole
ventricles contract as atria relax
pushes blood against AV valves forcing them
shut
4.
5.
•
all valves shut for an instant
when pressure in ventricles exceed pressure
in arteries both SL valves open and blood is
ejected from ventricles
resting body volume of blood ejected is about
70mL (just over half of EDV)
6.
7.
•
ESV is about 60mL
Relaxation Period
ventricular repolarization
8.
T wave in ECG
•
causes ventricular diastole
9.
ventricles relax
chamber pressure drops
blood flows from pulmonary trunk and aorta back toward
ventricles SL valves close
isovolmetric relaxation
1.
2.
3.
4.
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when ventricular pressure less than atrial pressure
AV valves open & ventricle fill
10.
•
11.
all four valves closed
occurs without atrial systole
another cardiac cycle begins at atrial depolarization
(P wave)
Heart Sounds
AuscultationSound of heart valves closing
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four sounds but only two loud enough to hear by
stethoscope (S1 and S2)
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S1 = lubb = long, booming sound AV valves closing
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S2 = dupp = short, sharp sound SL valves closing
Figure 19.12a
Figure 19.12b
Concept 19.8
Cardiac Output
Cardiac Output

Cardiac output equals ________



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CO = SV x HR
difference between resting and maximal
cardiac output is called ________
Stroke volume equals the amount of blood in
ventricle during diastole (EDV) minus the
amount of blood in ventricle after it has
contracted (ESV)
SV = EDV - ESV
Regulation of Stroke Volume
Preload
1.
degree of stretch of ventricles before
contracting
Frank-Starling law of the heart




the greater the stretch - the greater the
contraction (within limits)
stretch is due to blood in the ventricles at the end
of diastole
Regulation of Stroke Volume
Contractility
2.
forcefulness of contraction of individual fibers
increased contractility (positive inotropic)



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direct consequence of greater Ca2+ influx
Glucagon, thyroxine, epinephrine
decrease contractility (negative inotropic)

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acidosis
rising extracellular potassium
calcium channel blockers
Afterload
3.

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pressure that must be exceeded before ejection begins
pressure at semilunar valves of large arteries
Control of Heart Rate


cardiovascular center of medulla oblongata
sensory inputs:



movement as monitored by proprioceptors
increase input to cardiovascular center
chemical changes in the blood, monitored by
chemoreceptors
blood pressure changes , monitored by
baroreceptors
Control of Heart Rate
sympathetic effect

cardiac accelerator nerves

Release of NOR that bind to beta 1 receptors
1.
increases spontaneous firing of SA & AV nodes
2.
increases Ca++ to contractile fibers
parasympathetic effect

vagus nerve

1.
2.
3.
Release of acetylecholine
causes hyperpolarization (open K+ channels)
slows spontaneous depolarization of intrinsic fibers
PNS activation may be persistent in some grief and
depression conditions
Chemical Regulation of Heart Rate
Hormonal effects
1.
EPI & NOR, and thyroid hormones

all increase heart activity
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Cations
2.
Na+

high levels block Ca2+ inflow
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K+

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high levels block AP generation
Ca2+
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high blood levels increase heart rate and activity
low levels depress heart activity
Other Factors
Resting Heart rate influenced by:
 age
 gender
 physical fitness



bradycardia may be exhibited
strong effective slow beats under 60bpm
body temperature
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increased temperature increases rate
decreased temperature decreases rate