7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
1/68
AKTIVITAS MEKANIK
JANTUNG
Rahmatina B. Herman
Bagian FisiologiFakultas Kedokteran - Unand
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
2/68
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
3/68
Position of Heart in Thoracic Cavity
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
4/68
Structure of Heart
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
5/68
Structure of Heart..
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
6/68
Anatomy - Physiology of Heart
Two separate parts: left and rightRespectively:
- left atrium and ventricle
- right atrium and ventricle
Atrial function: primary pumps for ventricular
Ventricular function: pumping blood to all parts of
body and to the lungs
Ventricles pump more powerful than the atria
Atria contract prior to ventricles
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
7/68
Anatomy - Physiology of Heart..
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
8/68
Function of Valves and Papillary Muscles
The valves open and close passivelyAV valves (tricuspid and mitral):- Prevent backflow of blood from the ventricles into
atria during systole
Semilunar valves (aortic and pulmonary):- Prevent backflow of blood from aorta and pulmonary
arteries into ventricles during diastole
Papillary muscles:- Papillary muscles contract when the ventricular walls
contract
- They pull the vanes of valves inward toward the
ventricles to prevent their bulging too far backward
toward the atria during ventricular contraction
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
9/68
AnatomyPhysiology of Cardiac Muscles
Myocardium:- Atrial muscles
- Ventricular muscles
- Specialized excitatory and conductive system
of the heart
Involuntary muscles
Similar manner to skeletal muscle contraction
Syncytium
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
10/68
Structure of Cardiac Muscle Fibers
Sarcolemma
Myofibril
Filaments: - Actin
- Myosin
Sarcoplasma
Sarcoplasmic reticulum
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
11/68
Structure of Cardiac Muscle Fibers..
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
12/68
Structure of Cardiac Muscle Fibers..
Intercalate Disc
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
13/68
Structure of Cardiac Muscle Fibers..
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
14/68
Electrical Activity of Cardiac Muscle Fibers
Polarization
Depolarization: - Plateau
- Rhythmicity
Repolarization
Conductivity
Refractory period
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
15/68
Electrical Activity of Cardiac Muscle Fibers..
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
16/68
Electrical Activity of Cardiac Muscle Fibers..
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
17/68
Electrical Activity of Cardiac Muscle Fibers..
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
18/68
Electrical Activity of Cardiac Muscle Fibers..
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
19/68
Electrical Activity of Cardiac Muscle Fibers..
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
20/68
Rhythmicity of Cardiac Action Potential
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
21/68
Rhythmicity of Cardiac Action Potential..
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
22/68
Refractory Period
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
23/68
Conductivity of Cardiac Action Potential
Conduction velocity in atrial and ventricular musclefibers:
0,30,5 m/second
= 1/250 conduction velocity of action
potential in large nerve fibers
= 1/10 conduction velocity of action potential in
skeletal muscle fibers
Conduction velocity in Purkinye system
0,024 m/second depend on location
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
24/68
Mechanism of Contraction
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
25/68
Duration of Contraction
Duration of contraction = duration of action potential:- In atrial: 0,2 second
- In ventricular 0.3 second
Greatly influenced by frequency of heart rate (HR)
- The faster the frequency of HR, the shorter the
duration of contraction, especially diastolic period
- HR 72x/sec syst period : diast period = 40:60- HR increased 3x syst period : diast period = 65:35
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
26/68
Oxygen Consumption By Heart
Basal O2 consumption is 2 ml/100g/minConsiderably higher than that of resting skeletal
muscle
O2 consumption by beating heart is 9 ml/100g/minat rest
Increases during exercise and in a number of different
states
Cardiac venous O2 tension is low, and little additional
O2 can be extracted from the blood in the coronaries
blood flow, so increases in O2 consumption require
increases in coronary blood flow
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
27/68
SIKLUS JANTUNG
(CARDIAC CYCLE)
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
28/68
The Cardiac Cycle
Definition:The cardiac events that occur from the beginning
of one heartbeat to the beginning of the next
The cardiac cycle consists of:
- Diastole : period of relaxation, during which the
heart fills with blood
- Systole : period of contraction, during whichthe heart ejects blood from its
chambers
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
29/68
Conductive System of Heart
SA Node (sinoatrial node)/ sinus node :- located in the superior lateral wall of right atrium,immediately below and slightly lateral to theopening of the superior vena cava
Internodal pathways:- conductive system from SA node to AV node
AV node (atrioventricular node):- located in the posterior septal wall of right atrium,
immediately behind tricuspid valve and adjacent tothe opening of coronary sinus
AV bundle/ His bundle
Purkinje System
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
30/68
Conductive System of Heart..
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
31/68
Conductive System of Heart..
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
32/68
Organization of AV node
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
33/68
Transmission of Cardiac Impulse
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
34/68
Events of Cardiac Cycle
Generating and transmission of cardiac impulses:1. Generating rhythmical impulses in SA node
2. Conducting the impulses rapidly throughout atria
atria contract3. Conducting impulses to AV node (delay 0,13 sec)
4. Conducting impulses through AV/ His bundle
5. Finally transmission impulses rapidly throughoutventricles through Purkinye systemventricle
contract
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
35/68
Events of Cardiac Cycle..
Because of impulses generate in SA node and delay intransmission to ventricles atria contract (atrial
systole) prior to ventricles
Ventricles still in relaxation period (ventricular
diastole), called diastole
AV valves open and allow blood to flow into ventricles
filling of ventricles
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
36/68
Filling of the ventricles during diastoleRapid filling:
- A-V nodes closed large amount of blood accumulate in
atria immediately push AV valves open blood flow
rapidly into ventricles; lasts for the first third of diastole
Diastasis:
- During the middle third of diastole, only a small amount
of blood that continues to empty into atria from veins and
passes directly into ventricles
Atrial systole:
- During the last third of diastole, atria contract and
give additional thrust to inflow of blood into ventricles
Events of Cardiac Cycle..
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
37/68
Emptying of the ventricles during systolePeriod of isovolemic (isometric) contraction:- Ventricular contraction intraventricular pressures
AV valves close
- But not sufficient to push semilunar valves open noemptying of blood from ventricles
Period of ejection:- Semilunar valves opened blood pour out of ventricles
Period of isovolemic (isometric) relaxation:- Ventricular relaxation intraventricular pressures
semilunar valves close- But not sufficient to cause AV valves open no blood
flow into ventricles
Events of Cardiac Cycle..
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
38/68
During ventricular contraction:- Period of ejection
- Ventricular pressure blood pour from ventricles
into arterial system (aorta and pulmonary trunks)
> cardiac output (volume / minute)
> stroke volume (volume/ contraction)
During atrial relaxation:
- Atrial pressure blood flow from veins into atria
venous return (volume/ minute)
Events of Cardiac Cycle..
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
39/68
The greater venous return, the greater theheart muscle is stretched, the greater will be
the force of contraction and the greater stroke
volume
Within physiological limits, the heart pumps all
the blood that comes to it without allowingexcessive damming of blood in the veins
Events of Cardiac Cycle..
(Frank-Starling Law)
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
40/68
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
41/68
Events of Cardiac Cycle..
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
42/68
Ventricular Volume
End diastolic volume (EDV): 110120 cc,- Can be increased to 150180 cc
Stroke volume (SV): 70 cc
- SV = EDVESV (110 cc40 cc)
Ejection fraction: 60 %
- SV/EDV x 100%
End systolic volume (ESV): 4050 cc,- Can be decreased to 1020 cc
- SV can be increased to 140 - 160 cc
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
43/68
Relationship between left ventricular volume and intraventricular pressure duringdiastole and systole. The heavy red lines is volume-pressure diagram.
EW, net external work
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
44/68
Concepts of Preload and Afterload
Preload:In assessing the contractile properties of muscle, it is
important to specify the degree of tension on muscle
when it begins to contract
After load:
To specify the load against which the muscle exerts
its contractile force
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
45/68
Concepts of Preload and Afterload..
The importance of the concepts of preload andafterload:
Many abnormal function states of the heart or
circulation, the pressure during filling ofventricle (the preload), the arterial pressure
against which the ventricle must contract (the
afterload), or both are severely altered fromthe normal
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
46/68
BUNYI JANTUNG
(HEART SOUNDS)
l d
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
47/68
Normal Heart Sounds
Using a stethoscope, one hears a sound usuallydescribed as lub, dub, lub, dub
- The lub is 1stheart sound, associated with closure
of atrioventricular (A-V) valves at the beginning ofsystole
- The dub is 2ndheart sound, associated with closure
of semilunar (aortic and pulmonary) valves at theend of systole
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
48/68
Normal Heart Sounds..
1stheart sound:- Duration: 0.14 seconds- Low pitch
2ndheart sound :- Duration: 0.11 detik seconds
- High pitch3rdheart sound :- heard at the beginning of the middle third of diastole- blood oscillation in ventricles initiated by inrushing blood from
atria- weak, rumbling- can often be recorded in the phonocardiogram
4thheart sound (atrial heart sound):- blood oscillation in ventricles when atria contract
- sometimes can be recorded in the phonocardiogram
l d
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
49/68
Normal Heart Sounds..
Phonocardiogram from normal heart
C f H S d
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
50/68
Causes of Heart Sounds
Vibration of the taut valves immediately after closure,along with vibration of adjacent walls of the heart andmajor vessels around the heart
Vibrating is caused by turbulencesin blood
1stheart sound:
Contraction of ventricles sudden backflow of bloodagainst A-V valves closing of valves and bulging towardatria vibrating turbulence in blood vibrations
2ndheart sound:Semilunar valves close rapidly at the end of systole bulge backward toward ventricles vibrating turbulencein blood vibrations
C f H S d
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
51/68
Causes of Heart Sounds..
3rd
heart sound:Oscillation of blood back and forth between the walls of
ventricles initiated by inrushing from the atria
vibrations of the walls
This sound does not occur until the middle third ofdiastole because the ventricles are not filled sufficiently
to create elastic tension necessary for reverberation
4thheart sound (atrial heart sound):
Atria contract inrush of blood into ventricles vibrations
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
52/68
Mitral and aortic valves (left ventricular valves)
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
53/68
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
54/68
Chest areas from which sound from each valve is best heard
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
55/68
CURAH JANTUNG
(CARDIAC OUTPUT)
D fi iti
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
56/68
Definition
Cardiac output (COP):- is the quantity of blood pumped into the aorta each
minute by heart
- is also the quantity of blood that flows through circulation
The volume of cardiac output is equal with strokevolume (SV)multiplied by heart rate (HR) per minute
Venous return:- is the sum of all the local blood flows through all
individual tissue segments of peripheral circulation
COP = SV x HR
N l V l f C di O t t
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
57/68
Normal Values for Cardiac Output
COP varies widely with the level of activity of body
Factors that directly affect COP:
1. Venous return (Frank-Starling Law)
2. Basic level of body metabolism
3. Body activity4. Age
5. Body size
Resting COP: the average 5 L/min for resting adult
- 5.6 L/min for young healthy men
- 4.9 L/min for young healthy women (10-20% lower)
With increasing age, body activity and metabolism
diminishes COP
C di I d
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
58/68
Cardiac Index
Cardiac index is COP per square meter of bodysurface area (COP/surface area)
COP increases approximately in proportion to the
body surface area
The normal human being weighing 70 kg has body
surface area of 1,7 m2, COP 5 L/min.
cardiac index : 5 L/min/1,7 m2 = 3 L/min/m2of
body surface area
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
59/68
Cardiac index for the human being
Cardiac Reser e
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
60/68
Cardiac Reserve
Cardiac reserve is:- Ratio between maximum COP and resting COP
- Average: 4-5 times
- Athlete: may increase 7-8 times
- In severe heart disease: cardiac reserve 0
not be able to perform physical activity
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
61/68
PENGATURAN
POMPA JANTUNG
(REGULATION
OF HEART PUMPING)
I Intrinsic Regulation
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
62/68
I. Intrinsic Regulation
Intrinsic Regulation by Frank-Starlingmechanism
The amount of blood pumped by heart is
determined by the rate of blood flow into
the heart from veins (venous return)
Within physiology limits, heart pumps allblood that comes to it
II Control by Autonomic Nervous System
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
63/68
II. Control by Autonomic Nervous System
Excitation of heart by sympathetic nerves:- Increasingheart rate (to 180200 bpm)
- Increasingthe force of myocardial contraction
stroke volume COP
Parasympathetic(vagal) stimulation:- DecreasingHR and force of contraction
- Vagal fibers are distributed mainly to atria, but not
much to ventricles- Strong vagal stimulation can stop heart beats, but
then usually escapes and beats at rate 20-40 bpm
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
64/68
Cardiac sympathetic and parasympathetic nerves
The vagus nerves are parasympathetic nerves
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
65/68
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
66/68
Control of Heart Rate
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
67/68
Control of Heart Rate
Effects of strain on right atrial wallStrain on right atrial wall strain on SA
node increasing SA node rhythmicity
increasing heart rate
Strain on right atrial wall Bainbridge
reflect: increasing heart rate
7/24/2019 Kp 1.3.2.1 Aktivitas Mekanik Jantung (2 Jam)
68/68