cardiovascular physiology 2014.pdf
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Dewi Irawati MD, MS Dept.of Physiology
FMUI
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Everyday Activities
Sedentary Life
White collar
Heavy physical work
High concentration work
Routine activities
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Special conditions
Pregnancy Obesity
Exercise
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Extreme conditions
Starvation
Deep-sea diving High-altitude
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What the .........
Stressful situation
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Cardiovascular Adjustment
To meet Oxygen demand
Maintain Homeostasis
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Transport System
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Cardiovascular Function Rapid convective transport of O2, glucose, amino
acids, fatty acids, vitamin, drugs and water. Rapid washout of waste products Part of a control system distribution/secretion
of hormones Temperature regulation Role in reproduction hydraulic mechanism for
penile erection
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How does the Heart function?
Contraction - Relaxation
Act as a pump
Excitable tissue Electrical event
Mechanical event
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Life style
Coffee & alcohol Food Smoking
Influences the cardiovascular response
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Case illustration: Wake-up Call (part 1)
It was 4:30 a.m. She was in cold sweat and having difficulties breathing. She felt as though she had run a marathon. Fear swept through her-something terrible was going to happen. Panic-stricken, she woke up her husband, Jeremy. Denise, what is it? Is it a nightmare? No, its like Im having an asthma attack. I feel lightheaded and I cant catch my breath. My heart feels like its beating irregularly a thousand times a minute.
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Questions 1. How likely is this to be a heart problem? Asthma?
Panic attack? 2. What are the symptoms that are consistent with
your preliminary diagnosis? 3. What are the underlying mechanisms of those
symptoms?
Keywords: lightheaded, difficulty in breathing, increased heart rate, irregular heart beat
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Knowledge needed: How is the normal heart beat conducted?
Electrical events of the heart Action potential of autorhythmic cells Action potential of contractile cells Spread of action potential throughout the heart
What influences frequency of the heart beat? Neural regulation of the heart Others.......??
What are the consequences of irregular heart beat? Regulation of normal cardiac output
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Knowledge needed: Distribution of normal blood flow
Hemodynamic laws Characteristics/properties of various blood vessels Vascular regulation:
Central regulation Local/peripheral regulation
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HEART ANATOMY & HISTOLOGY
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Functional Anatomy of the Heart Chambers
4 chambers 2 Atria 2 Ventricles
2 systems Pulmonary Systemic
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Functional Anatomy of the Heart Valves
Function is to prevent backflow Atrioventricular Valves
Prevent backflow to the atria Prolapse is prevented by the chordae
tendinae Tensioned by the papillary muscles
Semilunar Valves Prevent backflow into ventricles
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Functional Anatomy of the Heart Intrinsic Conduction System
Consists of pacemaker cells and conduction pathways Coordinate the
contraction of the atria and ventricles
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Conduction System of the Heart
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Coordinating the pump: Electrical signal flow
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Myocardial Physiology Autorhythmic Cells (Pacemaker Cells) Characteristics of Pacemaker Cells
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Myocardial Physiology Autorhythmic Cells (Pacemaker Cells) Altering Activity of Pacemaker Cells
Sympathetic activity NE and E increase If channel activity
Binds to 1 adrenergic receptors which activate cAMP and increase If channel open time
Causes more rapid pacemaker potential and faster rate of action potentials
Sympathetic Activity Summary:
increased chronotropic effects heart rate
increased dromotropic effects conduction of APs
increased inotropic effects contractility
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Myocardial Physiology Autorhythmic Cells (Pacemaker Cells) Altering Activity of Pacemaker Cells
Parasympathetic activity ACh binds to muscarinic receptors
Increases K+ permeability and decreases Ca2+ permeability = hyperpolarizing the membrane Longer time to threshold = slower rate of action potentials
Parasympathetic Activity Summary:
decreased chronotropic effects heart rate
decreased dromotropic effects conduction of APs
decreased inotropic effects contractility
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Myocardial Physiology Contractile Cells Skeletal Action Potential vs Contractile Myocardial
Action Potential
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Myocardial Physiology Contractile Cells Plateau phase prevents summation due to the
elongated refractory period No summation capacity = no tetanus
Which would be fatal
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Summary of Action Potentials Skeletal Muscle vs Cardiac Muscle
YOUR TASK
MAKE COMPARISON OF ACTION POTENTIAL BETWEEN SKELETAL AND CARDIAC MUSCLE
(CONTRACTILE AND AUTORHYTHMIC MYOCARDIUM)
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Excitation-Contraction Coupling
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The Cardiac Cycle Coordinating the activity
Seven phases
The sequence of events as blood enters the atria, leaves the ventricles and then starts over
Synchronized by the Intrinsic Electrical Conduction System
Influenced by the sympathetic and parasympathetic divisions of the ANS
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Electrical Conduction Pathway
The Cardiac Cycle Coordinating the activity
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The electrical system gives rise to electrical changes (depolarization/repolarization) that is transmitted through isotonic body fluids and is recordable The ECG!
A recording of electrical activity
Can be mapped to the cardiac cycle
The Cardiac Cycle Coordinating the activity
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Systole = period of contraction Diastole = period of relaxation Cardiac Cycle is alternating periods of systole and
diastole Phases of the cardiac cycle
1. Atrial filling (Rapid and Late phase), both atrium and ventricle are relaxed (diastole)
2. Atrial Systole 3. Isovolumetric Ventricular Contraction 4. Ventricular ejection (Rapid and Late phase) 5. Isovolumetric Ventricular Relaxation
Back to Atrial & Ventricular Diastole
The Cardiac Cycle Phases
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Wiggers Curve
Correlation between: Electrical events Mechanical events Heart sounds Ventricular volume During One Cycle
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Autonomic innervation of the heart
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Characteristic of various blood vessels
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Regulation of blood vessels
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No, Denise thought to herself. Theres no way this was a sign of heart troubles. I didnt have any pain in my chest, Im physically fit, and I have no family history. Theres just no way.
After assuring herself of this, Denise immediately stood up to get a glass of water. Suddenly Denise felt faint and passed out on the floor. Her face was as pale as a ghost.
Case illustration: Wake-up Call (part 2)
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Questions Why didnt Denise feel any pain? What causes Denise to faint upon standing up? Why was her face pale?
Keywords: Suddenly stood up, felt faint, passed out, pale
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Knowledge needed: Coronary circulation normal, disturbances Parameters of the cardiovascular system
Heart rate Stroke volume Cardiac output Cardiac index Blood-pressure
Factors influencing cardiac output and blood pressure Factors influencing blood flow abnormalities of the
blood vessels Compensation mechanism of the cardiovascular system
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Denise was in the early stages of menopause. She had been on a strict diet since she gained weight, and doing exercise as well. She only ate apples and water melon, and drank nothing but water. Jeremy, 48 years old, was diagnosed with coronary artery disease. The scare had encouraged him to gradually end years of chain smoking and adopt a healthier lifestyle. He was currently working on giving up the occasional cigarette for good. I think you its about time you consult a doctor Jeremy said.
Case illustration: Wake-up Call (part 3)
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Questions What are the characteristics of Denises lifestyle/risk
factors that might lead to a heart problem? What laboratory & supplementary diagnostic
examination should be conducted?
Keywords: menopause, strict diet, exercise, chain smoking husband, cardiovascular examination
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Knowledge needed: Factors influencing cardiovascular regulation
Hormonal Dietary Other
Cardiovascular risk factor Exposure to harmful conditions
Cardiovascular examination Non-invasive Invasive
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The Heart Sound
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Electrocardiogram
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Summary What should be studied: Electrical events of the heart Mechanical events of the heart Special properties of the heart Regulation of the cardiovascular system Parameters of the cardiovascular system Laboratory & supplementary diagnostic examination
of the cardiovascular system
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Websites http://www.gwc.maricopa.edu/class/bio202/
cyberheart/cardio.htm http://www.mic.ki.se/MEDIMAGES.html
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ELECTROCARDIOGRAPH Recording of electrical activity of the heart
(depolarization and repolarization of the myocardial cells) through special electrodes
Human body: volume conductor ability to conduct electrical activity in all direction
Significancy: Overview of spread of action potential (action
potential summation of active cells), variates with time, spread of impulse during one cycle.
Recording of electrical potential (voltage) difference between two electrodes
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ECG Recorder Galvanometer, sensitive to electrical potential
changes Active/recording electrode at 2 different points/site Amplification of electrical potential difference Recording apparatus - speed Specific curve: amplitude (mV) and duration
(seconds)
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Technique of recording an ECG Special Graphic Paper:
Distance between 2 thin lines = 1 mm Distance between 2 thick lines = 5 mm Paper speed 25 mm/sec. ( 1 mm = 0.04 sec.)
Sensitivity: , 1 and 2 (1 mV = 5, 10 or 20 cm)
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ECG Leads Bipolar:
Potential difference between 2 active electrodes Einthoven: I, II and III
Unipolar: Potential diference between 1 active electrode and
indifferent electrode Augmented extremity leads GOLDBERGER: aVR,
aVL and aVF Precordial leads WILSON: V1, V2, V3, V4, V5 dan V6
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ECG Curve
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ECG Analysis Normal rhythm: sinus rhythm
Every P wave is followed by QRS complex and T wave All 12 lead
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Heart rate: 60 P-P (R-R) interval (mm) X 0.04
ECG Analysis
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P wave Lead II Amplitude: < 0.25 mV Duration: < 0.11 sec.
ECG Analysis
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ECG Analysis P-R interval Lead II
Amplitude: < 0.25 mV Duration: < 0.2 sec.
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QRS complex Lead V2 V3 Duration: < 0.12 sec.
QRS configuration: V1 V6 rS Rs Transitional zone
ECG Analysis
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QRS electrical heart axis QRS T angle: < 70
I
III
Lead I: - 1 + 8 = +7
Lead III: - 2 + 12 = +10
ECG Analysis
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S-T segment all leads Iso-electric Important clinical significance
ECG Analysis
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T wave configuration all leads Positive deflection except aVR and sometimes
V1
ECG Analysis
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U wave Late Purkinje cells depolarization Unknown significance
ECG Analysis
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