basic physiology of cvs

1. H A R I T H A . M 1 S T Y R P G
CARDIOVASCULAR SYSTEM – CARDIAC
MUSCLE , CONDUCTING SYSTEM OF HEART
, CARDIAC CYCLE ,HEART SOUND

2. TABLE OF CONTENT
 Cardiovascular System
 Functional Anatomy of the Heart
 Cardiac muscle
 Conducting system of heart
 Cardiac Cycle
 Heart sound

3. Cardiovascular System
 Functional components of the cardiovascular system:
 Heart
 Blood Vessels
 Blood

4. FUNCTIONS
 Primary functions :
1. Distribution of nutrients and oxygen (O2) to all
body cells
2. Collection of waste products and CO2 from different
body cells, and to carry them to excretory organs for
excretion.
 Secondary functions :
1. Thermoregulation,
2. Distribution of hormones to the target tissues
3. Delivery of antibodies, platelets and leucocytes to
aid body defense mechanism

5. Cardiovascular System Function
 To create the “pump” we have to examine the
Functional Anatomy
Cardiac muscle
Chambers
Valves
Intrinsic Conduction System

6. FUNCTIONAL ANATOMY OF HEART
 Chambers of heart
 Valves of heart
 Structure of walls
PHYSIOLOGY OF CARDIAC MUSCLE
 Structural organization
 Structure of cardiac muscle fibre
 Sarcotubular system.
 Properties of cardiac muscle.

7. FUNCTIONAL ANATOMY
 Muscular pump
 Wt – 300 gms
 2 halves
 Right – pumps blood to
lungs for oxygenation
 Left – Pump blood to
systemic circulation.

8. Functional Anatomy of the Heart
Chambers
 4 chambers
 2 Atria
 2 Ventricles
 2 systems
 Pulmonary
 Systemic

9. 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
 Semilunar Valves
Prevent backflow into ventricles

10. STRUCTURE OF WALLS
 Pericardium
 Myocardium
 Endocardium.

12. PERICARDIUM
 Heart & root of great vessels enclosed by fibro -
serous sac
 Has 2 layers
 Fibrous
 Serous – has parietal & visceral layers.
 Between this is pericardial cavity filled with
pericardial fluid.

13. PIC

14. MYOCARDIUM
 Main tissue constituting walls
3 types
Cardiac muscle –
 forming walls of atria & ventricles
 Pacemakers
 Conducting system

15.  Thin, smooth &
glistening membrane
lining myocardium
internally.
 The endocardium
continues as the
endothelium of great
vessels opening in the
heart
ENDOCARDIUM

16. PHYSIOLOGY OF CARDIAC MUSCLE
 STRUCTURAL ORGANIZATION
 Fibers are striated & involuntary
 Ribbon-like & branched & at junction 2 fibres are
fused & form Intercalated disc – important during
contraction.

17.  Along the sides fibers
connected through Gap
juctions which provide
low resistance bridges &
acts as a functional
syncytium.
 Fibres are richly supplied
by the capillaries (one
capillary/fibre).
PHYSIOLOGY OF CARDIAC MUSCLE

18.  80–100 μm long and 15
μm broad.
 Cell membrane –
sarcolemma & cytoplasm
called sarcoplasm.
 Myofibril – each muscle
fibre ( 2µm diameter)
 Made up of thick & thin
filaments.
STRUCTURE OF CARDIAC MUSCLE FIBER

19. SARCOTUBULAR SYSTEM
Well developed like that of the skeletal muscle
The tubules of the T-system penetrate the sarcomere at
Z-line.
So in cardiac muscles, there is only one triad per
sarcomere as compared to two in skeletal muscle

20. PROPERTIES OF CARDIAC MUSCLE
 EXCITABILITY
 RHYTHMICITY
 CONDUCTIVITY
 CONTRACTILITY

21. PROCESS OF EXCITABILITY &
CONTRACTILITY
 The events which link the electrical phenomenon
with mechanical phenomenon constitute the
Excitation– Contraction Coupling phenomenon.

22. ELECTRIC POTENTIAL IN CARDIAC MUSCLE
 Resting membrane potential
 Is −85 to −95 mV (negative interior with reference to
exterior).

23.  Action potential.
 Divided into five distinct phases.
 Phase 0: Rapid depolarization
 Phase 1: Initial rapid repolarization
 Phase 2: Plateau
 Phase 3: Repolarization
 Phase 4: Resting potential

24. SPREAD OF AP THROUGH CARDIAC MUSCLE
 The cardiac muscle acts as a
physiological syncytium due to
the presence of gap junctions
amongst the cardiac muscle
fibres.

25. Summary of Action Potentials
Skeletal Muscle vs Cardiac Muscle

26. CONDUCTION SYSTEM OF HEART
 Consists of
“pacemaker” cells and
conduction pathways
 Coordinate the contraction
of the atria and ventricles

29. Cardiac Cycle
Coordinating the activity
 Cardiac cycle is the sequence of events as blood
enters the atria, leaves the ventricles and then starts
over
 Synchronizing this is the Intrinsic Electrical
Conduction System
 Influencing the rate (chronotropy & dromotropy) is
done by the sympathetic and parasympathetic
divisions of the ANS

30. Cardiac Cycle
Phases
 Systole = period of contraction
 Diastole = period of relaxation
 Cardiac Cycle is alternating periods of systole and diastole
 Phases of the cardiac cycle
1. Rest
 Both atria and ventricles in diastole
 Blood is filling both atria and ventricles due to low pressure conditions
2. Atrial Systole
 Completes ventricular filling
3. Isovolumetric Ventricular Contraction
 Increased pressure in the ventricles causes the AV valves to close
 Creates the first heart sound (lub)
 Atria go back to diastole
 No blood flow as semilunar valves are closed as well

31. Cardiac Cycle
Phases
 Phases of the cardiac cycle
4. Ventricular Ejection
 Intraventricular pressure overcomes aortic pressure
 Semilunar valves open
 Blood is ejected
5. Isovolumetric Ventricular Relaxation
 Intraventricular pressure drops below aortic pressure
 Semilunar valves close = second heart sound (dup)
 Pressure still hasn’t dropped enough to open AV valves so volume
remains same (isovolumetric)
Back to Atrial & Ventricular Diastole

32. Cardiac Cycle
Phases

33. HEART SOUNDS
 Produce by the mechanical activities of the heart during
each cardiac cycle
 FLOW OF BLOOD THROUGH CHAMBERS
 CONTRACTION
 CLOSURE OF VALVES
1. S1 – LUB
2. S2 – DUB
3. S3
4. S4

34. HEART SOUNDS

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