chapter 18 anatomy part 2
DESCRIPTION
Part two of chapter 18 for anatomyTRANSCRIPT
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Chapter 18 The heart (Part 2)
• Microscopic Anatomy of Cardiac Muscle
• Heart cells
• Electrocardiography (ECG)
• Stroke volume and cardiac output
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Microscopic Anatomy of Cardiac Muscle:
Characteristics
Intercalated discs (unique)BranchesStriationUninucleate
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Microscopic Anatomy of Cardiac Muscle:
Characteristics
Intercalated discs (unique)BranchesStriationUninucleate
![Page 4: Chapter 18 Anatomy Part 2](https://reader035.vdocuments.net/reader035/viewer/2022062221/563dbaf5550346aa9aa90d1a/html5/thumbnails/4.jpg)
Microscopic Anatomy of Cardiac Muscle
Gap junctions
Microscopic Anatomy of Cardiac Muscle:Intercalated discs
Desmosomes
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Microscopic Anatomy of Cardiac Muscle:Intercalated discs
• Junctions between cells
Gap junctions: allow ions to pass from cell to cell, which makes heart to be functional syncytium
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Microscopic Anatomy of Cardiac Muscle:Intercalated discs
• Junctions between cells
Gap junctions: allow ions to pass from cell to cell, which makes heart to be functional syncytium
Desmosomes: prevent cells from separating during contraction
![Page 7: Chapter 18 Anatomy Part 2](https://reader035.vdocuments.net/reader035/viewer/2022062221/563dbaf5550346aa9aa90d1a/html5/thumbnails/7.jpg)
Microscopic Anatomy of Cardiac Muscle:
Characteristics
Intercalated discs (unique)BranchesStriationUninucleate
![Page 8: Chapter 18 Anatomy Part 2](https://reader035.vdocuments.net/reader035/viewer/2022062221/563dbaf5550346aa9aa90d1a/html5/thumbnails/8.jpg)
Microscopic Anatomy of Cardiac Muscle:Striation
A band
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Chapter 18 The heart (Part 2)
• Microscopic Anatomy of Cardiac Muscle
• Heart cells
• Electrocardiography (ECG)
• Stroke volume and cardiac output
![Page 10: Chapter 18 Anatomy Part 2](https://reader035.vdocuments.net/reader035/viewer/2022062221/563dbaf5550346aa9aa90d1a/html5/thumbnails/10.jpg)
Heart cells
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Heart cells
• Pace maker cells (1%)
• Cardiac muscle cells (99%)
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Heart cells
• Pace maker cells (1%)
• Cardiac muscle cells (99%)
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Pace maker cells
Sinoatrial (SA) node
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Pace maker cells: SA node
1% of cells: modified cardiomyocytes
Only exist in right atrium of heart
Automaticity (sinus rythm):
Do not need nervous system stimulation
Can depolarize entire heart
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Intrinsic cardiac conduction system
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Intrinsic cardiac conduction system
1, SA node in right atrium2, AV node3, AV bundle4, Bundle of His5, Purkinje fibers
Modified cardiomyocytesArrhythmia
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Intrinsic cardiac conduction system
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Chapter 18 The heart (Part 2)
• Microscopic Anatomy of Cardiac Muscle
• Heart cells
• Electrocardiography (ECG)
• Stroke volume and cardiac output
![Page 19: Chapter 18 Anatomy Part 2](https://reader035.vdocuments.net/reader035/viewer/2022062221/563dbaf5550346aa9aa90d1a/html5/thumbnails/19.jpg)
ECG
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Electrocardiography (ECG)
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Electrocardiography (ECG)
P
QRS complex
T
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ECG waves
P wave – Atrial depolarization
QRS complex - ventricular depolarization and atrial repolarization
T wave - ventricular repolarization
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ECG intervals and segments
P-R interval
S-T segment
Q-T interval
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ECG intervals and segments
P-R interval
S-T segment
Q-T interval
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ECG intervals: P-R interval
Beginning of atrial excitation to beginning of ventricular excitation
P-R
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ECG intervals and segments
P-R interval
S-T segment
Q-T interval
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ECG intervals: S-T segment
Entire ventricular myocardium depolarized
S-T
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ECG intervals and segments
P-R interval
S-T segment
Q-T interval
![Page 29: Chapter 18 Anatomy Part 2](https://reader035.vdocuments.net/reader035/viewer/2022062221/563dbaf5550346aa9aa90d1a/html5/thumbnails/29.jpg)
ECG intervals: Q-T interval
Beginning of ventricular depolarization through ventricular repolarization
Q - T
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Normal sinus rhythm.
Junctional rhythm. The SA node is nonfunctional, P waves areabsent, and the AV node paces the heart at 40 –60 beats/min.
Second-degree heart block. Some P waves are not conductedthrough the AV node; hence more P than QRS waves are seen. Inthis tracing, the ratio of P waves to QRS waves is mostly 2:1.
Ventricular fibrillation. These chaotic, grossly irregular ECGdeflections are seen in acute heart attack and electrical shock.
ECG
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31
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Chapter 18 The heart (Part 2)
• Microscopic Anatomy of Cardiac Muscle
• Heart cells
• Electrocardiography (ECG)
• Stroke volume and cardiac output
![Page 33: Chapter 18 Anatomy Part 2](https://reader035.vdocuments.net/reader035/viewer/2022062221/563dbaf5550346aa9aa90d1a/html5/thumbnails/33.jpg)
Stroke volume (SV)
• volume of blood pumped out by one ventricle with each beat.
• 70ml/beat
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Cardiac Output (CO)
• Volume of blood pumped by each ventricle in one minute
• CO (ml/min) = HR (75 beats/min) SV (70 ml/beat) = 5.25 L/min
• Normal – 5.25 L/min
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Regulation of SV and CO
Sympathetic
Parasympathetic
SA node
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Regulation of SV and CO
By autonomic nervous system via medulla oblongata
Sympathetic rate and force
Parasympathetic rate and force