Dewi Irawati MD, MS Dept.of Physiology

FMUI

Everyday Activities

Sedentary Life

White collar

Heavy physical work

High concentration work

Routine activities

Special conditions

Pregnancy Obesity

Exercise

Extreme conditions

Starvation

Deep-sea diving High-altitude

What the .........

Stressful situation

Cardiovascular Adjustment

To meet Oxygen demand

Maintain Homeostasis

Transport System

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

How does the Heart function?

Contraction - Relaxation

Act as a pump

Excitable tissue Electrical event

Mechanical event

Life style

Coffee & alcohol Food Smoking

Influences the cardiovascular response

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.

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

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

Knowledge needed: Distribution of normal blood flow

Hemodynamic laws Characteristics/properties of various blood vessels Vascular regulation:

Central regulation Local/peripheral regulation

HEART ANATOMY & HISTOLOGY

Functional Anatomy of the Heart Chambers

4 chambers 2 Atria 2 Ventricles

2 systems Pulmonary Systemic

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

Functional Anatomy of the Heart Intrinsic Conduction System

Consists of pacemaker cells and conduction pathways Coordinate the

contraction of the atria and ventricles

Conduction System of the Heart

Coordinating the pump: Electrical signal flow

Myocardial Physiology Autorhythmic Cells (Pacemaker Cells) Characteristics of Pacemaker Cells

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

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

Myocardial Physiology Contractile Cells Skeletal Action Potential vs Contractile Myocardial

Action Potential

Myocardial Physiology Contractile Cells Plateau phase prevents summation due to the

elongated refractory period No summation capacity = no tetanus

Which would be fatal

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)

Excitation-Contraction Coupling

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

Electrical Conduction Pathway

The Cardiac Cycle Coordinating the activity

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

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

Wiggers Curve

Correlation between: Electrical events Mechanical events Heart sounds Ventricular volume During One Cycle

Autonomic innervation of the heart

Characteristic of various blood vessels

Regulation of blood vessels

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)

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

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

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)

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

Knowledge needed: Factors influencing cardiovascular regulation

Hormonal Dietary Other

Cardiovascular risk factor Exposure to harmful conditions

Cardiovascular examination Non-invasive Invasive

The Heart Sound

Electrocardiogram

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

Websites http://www.gwc.maricopa.edu/class/bio202/

cyberheart/cardio.htm http://www.mic.ki.se/MEDIMAGES.html

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

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)

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)

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

ECG Curve

ECG Analysis Normal rhythm: sinus rhythm

Every P wave is followed by QRS complex and T wave All 12 lead

Heart rate: 60 P-P (R-R) interval (mm) X 0.04

ECG Analysis

P wave Lead II Amplitude: < 0.25 mV Duration: < 0.11 sec.

ECG Analysis

ECG Analysis P-R interval Lead II

Amplitude: < 0.25 mV Duration: < 0.2 sec.

QRS complex Lead V2 V3 Duration: < 0.12 sec.

QRS configuration: V1 V6 rS Rs Transitional zone

ECG Analysis

QRS electrical heart axis QRS T angle: < 70

I

III

Lead I: - 1 + 8 = +7

Lead III: - 2 + 12 = +10

ECG Analysis

S-T segment all leads Iso-electric Important clinical significance

ECG Analysis

T wave configuration all leads Positive deflection except aVR and sometimes

V1

ECG Analysis

U wave Late Purkinje cells depolarization Unknown significance

ECG Analysis