CARDIOVASCULAR SYSTEM - ANATOMY & PHYSIOLOGY for B.Pharm & Pharm.D

1. Cardiovascular System
ANATOMY & PHYSIOLOGY
-By-DR.S.Kameshwaran

2. Cardiovascular System
• Also known as circulatory system
• Consists of: the heart, arteries, veins,
capillaries

3. Functions of the cardio vascular system:
• Distribution of oxygen and nutrients to
all the body parts
• Transportation of CO2 and metabolic
waste products from tissues to lungs
and other excretory organs
• Distribution of water electrolytes and
hormones through out the body
• Part of immune system
• Thermoregulation

4. Heart
• Blood pumped through the muscular
organ called heart
• It is composed of strong cardiac muscle
tissue
• Shows rhythmic contraction and
relaxation
• Due to this blood pumped to the entire
body along with nutrients and oxygen

5. ANATOMY OF HEART:
• Heart is a muscular organ
• Size is about closed fist
• Average weight –
female – 250-300gms, Male – 300-350gms
• Average human heart beats 70-72 times per
minute
• Situated in the thoracic cavity – in the
mediastinum space, just above the diaphragm
• Present at the level of thoracic vertebrae T5-T8
• Present in the midline just tilted towards the left
• It is a rounded cone shaped structure

6. Heart

7. Walls of the Heart
• Pericardium – loose fitting sac surrounding the
heart
• EPICARDIUM
• MYOCARDIUM
• ENDOCARDIUM

8. Epicardium: outer layer of heart
Consist of 2 layers
– Fibrous pericardium – tough, loose-
fitting, inelastic
– Serous pericardium
• Parietal layer: lines the inside of the
fibrous pericardium
• Visceral layer: adheres to outside of
the heart
– Pericardial space: between parietal
and visceral layer
• Filled with 10-15mL of pericardial fluid
• Decreases friction

10. Myocardium:
• It is the thickest layer
• contractile layer composed of cardiac muscle
cells
• Cardiac muscle is striated, involuntary, and
branched
• Heart contracts by contraction of myocardial
membrane
Endocardium:
• – inner most and third layer of heart wall
– Consist thin layer of specialized epithelial tissue
(Endothelium)
– Covers inner layers of heart and provides smooth
flow of blood inside the heart

11. Chambers of the Heart
• Heart is a hollow chamber
• Divided in to 4 different chambers
Atria – two superior chambers
– “Receiving chambers”
– Thin walled low pressure chambers
– Blood from superior vena cava & Inferior vena
cava enters atria
Ventricles – two inferior chambers
– “pumping chambers”
– Thick walled high pressure chamber
– Thick muscular walls to increase force of
pumping action
– Left & right venticles Separated by
interventricular septum

12. Valves of the Heart
“Permit blood flow in one direction
during circulation”
• Atrioventricular valves (AV valves)
– Also cuspid valves
– Between atria and ventricles
• Semilunar (SL valves)
– Between R ventricle and pulmonary
arteries and L ventricle and aorta

13. Atrioventricular Valves
Tricuspid valve
– Between R atrium and ventricle
– 3 flaps of endocardium
– Connected to ventricular papillary muscle
via chordae tendinea
Bicuspid valve
– Between L atrium and ventricle
– Also called mitral valve
– Two flaps of endocardium
– Connected to ventricular papillary muscle
via chordae tendinea

15. Semilunar Valves
• Pulmonary semilunar valve
– Btwn R ventricle and pulmonary trunk
• Aorta semilunar valve
– Btwn L ventricle and aorta

16. Chambers & Valves
Trace the blood flow through the heart

17. Blood Supply to the Heart
• To work efficiently the heart needs a continues
blood supply
• Needs to supply oxygen and nutrients and to
remove the waste materials
• Heart has its own system of circulation – coronary
circulation
• Left and right coronary arteries arises at the base
of aorta
• From there they supply the blood to right and left
side of heart
• Coronary artery provides – pure blood
• Coronary vein – remove waste products
• Coronary sinus – empties the deoxygenated blood in
to the right atrium

19. CONDUCTION SYSTEM OF THE HEART
Conduction system of heart includes 6 components
• SINOATRIL (SA) NODE
• INTERNODAL PATHWAYS
• ATRIOVENTRICULAAR (AV) NODE
• BUNDLE OF HIS
• BUNDLE BRANCHES
• PURKINJIE FIBRES

21. • Sinoatrial Node (SA Node)
– It is located it right atrium – near the
opening of superior vena cava.
– It is 1.5cm length & 0.5cm width
– It is also known as Pacemaker of the heart
– It comprises of pacemaker cells (P) & some
myofilaments
– Impulse is generated by the P cells and
transmitted with in the conducting system
for the excitation and contraction of heart
muscles

22. INTERNODAL PATHWAYS:
• They connect SA node and AV node
• They are
– Anterior internodal pathway
– Middle internodal pathway
– Posterior internodal pathway

23. ATRIOVENTRICULAAR (AV) NODE
• It is located in the lower part of the right atrium
• Close to the interatrial septum
• It is 2.2cm long 10mm wide and 3 mm thick
• The pacemaker (P) cells are also present in the AV node
• Impulse formation is slower in AV node than SA node

24. BUNDLE OF HIS:
• A small fibre bundle arising from the AV node
and terminating in the purkinje system
- Bundle of His
 It is located beneath the AV node and passes
towards the interventricular septum
 It is about 1 cm in length
 Left branch bundle & Right branch bundle
 In case of non functioning SA & AV node
impulse generated by Bundle of His

26. BUNDLE BRANCHES:
“The branches of bundle fibres enters the walls
of the ventricle to further branch out in to very
small fibre bundles – further branch in to very
small fibre“ – Purkinje fibres
The bundle branches also have ability to
generate impulses
2 types:
Right bundle branch &
Left Bundle branch

27. PURKINJE FIBRES:
• The fibres forms a network of small
bundle of conducting fibres
• They are located all over the sub
endocardial regions of R&L ventricles

28. PATHWAY OF NERVE IMPULSE
SA NODE
↓
INTERNODAL PATHWAY
↓
AV NODE
↓
BUNDLE OF HIS
↓
RIGHT AND LEFT BUNDLE BRANCHES
↓
PURKINJE FIBRES
↓
VENTRICULAR MYOCYTES

29. REGULATION OF HEART BY ANS
 The centre for regulation of the heart is
CARDIOVASCULAR CENTRE
 Which is present in the medulla oblongata
 It receives input from
Sensory receptor
Higher centre of brain
 The cardiac output is maintained either by
increasing or decreasing the frequency of
nerve impulses in the ANS – increase or
decrease cardiac output.

30. • Sympathetic Neurons (thoracic region of spinal
cord) – release - Nor-Epinephrine – acts on -
muscle fiber of heart – produces 2 effects
• Increases heart rate – by increasing the rate of
spontaneous depolarization in SA node, AV
Node & cardiac muscle fibers
• Increases contractility – by increasing entry of
Ca2+ ions through voltage gated calcium
channels present in the contractile fibers
• Maximum synthetic stimulation can be
200pulse per min

31. PARA SYMPATHETIC NEURONS:
• Reaches heart via Xth cranial nerve
(vagus)
• Releases acetylcholine – act on muscle
fibers of heart – decreases HR by
decreasing the rate of spontaneous
depolarization in cardiac muscle fibres
• The heart can slow to 20-30 beats/Min

34. PHYSIOLOGY OF HEART:
• The heart has four separate chambers.
• The upper chamber on each side of the heart, which is
called an atrium - receives and collects the blood
coming to the heart.
• The atrium then delivers blood to the powerful lower
chamber, called a ventricle - which pumps blood away
from the heart through powerful, rhythmic contractions.

35. • The human heart doing two pumps in
one.
• The right side receives oxygen-poor
blood from the various regions of the
body and delivers it to the lungs.
• In the lungs - oxygen is absorbed in the
blood.
• The left side of the heart receives the
oxygen-rich blood from the lungs and
delivers it to the rest of the body.

36. Cardiac cells
• Cardiac cells are cylindrical in shape
• It is arranged such if one cell is stimulated it
stimulates the adjacent cell
Two types of cardiac cells
• Electrical cells & Myocardial cells
Electrical cells - Specialized cell
• This cell cannot able to contract but can
conduct the nerve impulse
• Electrical impulse – produced in SA Node –
forwarded to rest of the heart – force of
contraction is generated – pumps the blood.

37. ACTION POTENTIAL
• Resting membrane potential at the heart
is – 90mV
• Sudden influx of Na+ Ions in cardiac
membrane – initiates action potential in
myocardial cell
- Phase 0/ Upstroke of action potential
• outward movement of K+ ions – initial
phase of repolarization – 1st phase of
action potential

38.  Increase in the Inward movement of Ca2+
ions and outward movement of K+ ions
- 2nd Phase/ plateau phase
 Inward movement of calcium ions
(decreasing)& outward movement of
potassium ions (increasing)
- 3rd phase/ phase of repolarization
 The potassium ions concentration becomes
equilibrium by the outward conduction of
potassium ions in the third phase
-4th Phase/ Phase of repolarization

41. CARDIAC CYCLE
“Rhythmic Pumping of Heart”
Contraction and relaxation occurring during the
one heart beat – cardiac cycle
Phases of Cardiac Cycle
1. Systole – contraction
2. Diastole – relaxation
• At a normal heart rate, one cardiac cycle last for 0.8
seconds!

42. • “One contraction (systole) and one
relaxation (diastole) of auricles and
ventricles resulting in one heart beat”
» - known as CARDIAC CYCLE
SYSTOLE:
• A significant pumping of blood from the
cardiac chamber
DIASTOLE:
• Significant entry of blood in to the cardiac
chamber

43. Stages of cardiac cycle:
4 stages:
• ATRIAL SYSTOLE
• VENTRICULAR SYSTOLE
• VENTRICULAR DIASTOLE
• JOINT DIASTOLE
ATRIAL SYSTOLE:
 This is marked by stimulation of SA node
 A wave of contraction spreads through atria and
bicuspide and tricuspid valves open up
 Which pumps blood from atria in to ventricles

44. VENTRICULAR SYSTOLE:
• Contraction of ventricles occurs as the
wave of contraction spreads through
both the ventricles
• This is stimulated by AV node stimulation
• The bi & tri cuspid valves close and
produce the first heart sound – LUB
• The sound lasting for 0.16-0.90 sec
• As the ventricle contracts blood flows
into dorsal aorta from left ventricle &
pulmonary artery from right ventricle

45. VENTRICULAR DIASTOLE:
• As ventricles relax both semilunar valves
closes with a sound of – DUB
• Pressure with in the ventricles decreases
continuously
• When the pressure falls below the
pressure of atrium both bicuspid and
tricuspid valves open and the blood again
flows in to the ventricles

46. JOINT DIASTOLE:
• Before the cycle starts again, both the atria and
ventricles are relaxed
- JOINT DIASTOLE
During this state blood flows from superior and
inferior vena cava into the atria & atria to ventricles
Duration of cardiac cycle: 0.88 Sec
Which can be divided as
Auricular systole - 0.18 Sec
Auricular diastole - 0.08 sec
Ventricular systole - 0.30 sec
Ventricular diastole - 0.32 sec

47. CARDIAC OUTPUT:
“The amount of blood flowing from the heart ( from left
ventricle in to aorta) in one heart beat”
Cardiac output = stroke volume x Heart rate
= 70ml x 72/min
= 5040 ml/min
= about 5 liters/ min
Stroke volume = volume of blood pumped by heart per
heart beat
Heart rate = ventricular systole / min

48. PULSE:
“A wave of distension felt in the arteries with
each heartbeat “
 It is counted from radial artery of the wrist
 Pulse rate normally is the same as the heart
rate
 Tachycardia – increase in the pulse/ heart rate
over 100 beats/min
 Bradycardia – decrease in the heart/pulse rate
under 50 beats/ min
 Normal pulse rate – 70-90 per minute
 Men – 72/min, women – 80/min

49.  ELECTRO CARDIOGRAM (ECG)
 Electrical current generated in the heart by the
propagation of action potential can be detected
on the surface of the body as electrical signals
 These changing signals are recorded by an
instrument – Electrocardigram (ECG)
 ECG – composite record of action potentials
produced by the heart muscles
 Recording done by using electrodes – helps in
detection of cardiac abnormalities

51. There are 3 recognizable waves
– P wave
– QRS complex
– T wave
P WAVE:
This is first wave spreading from SA node
through contractile fibres in both atria
Representing atrial depolarisation
It is seen as a small upward deflection on
ECG

52. QRS COMPLEX
• this is the second wave
• Occurs due to action potential spreadds
through ventricular contractile fibres
• Representing rapid ventricular
depolarisation
• It continues as large upright, triangular
wave
• Beginning as downward deflection and
ending as downward wave

53. T WAVE:
• This is the third wave
• Its seen when ventricle relax
• Indicating ventricular repolarisation
• Appear as dome shaped upward
deflection
• Smaller and wider than QRS complex
• This is due to the slower repolarisation
than the depolarisation

54. • Size of each wave appearing on ECG helps
in interpreting any abnormality
• Larger P wave – Enlarged atrium
• Large Q wave – possible myocardial infarction
• Large R wave – Enlargement of ventricles
• Flatter T wave – insufficient O2 supply to cardiac
muscles
• Elevated T wave – high level of K+ in the blood

55. Analysis of ECG:
• Intervals or segments are the time spans
present between the waves
• This helps in analyzing an ECG
• P-Q INTERVAL
• S-T SEGMENT
• Q-T INTERVALS

56. BLOOD PRESSURE
“BLOOD PRESSURE (BP) IS THE PRESSURE OF
CIRCULATING BLOOD ON THE WALLS OF BLOOD
VESSELS”
Normal blood pressure has high systolic value and low
diastole value 120mm Hg/ 80mm Hg in arteries
The blood pressure is measured by sphygmomanometer

57. Types of blood pressure:
Arterial blood pressure may be of 4 types
Systolic pressure :
 maximum pressure exerted during systole of the heart
when LV contact & pump blood to aorta),
 Normal value: 120mm Hg
 Occurs in the beginning of the cardiac cycle
Diastolic pressure:
 it is the minimum pressure on the arteries
 Normal value: 90mm Hg
 It occurs at the end of the cardiac cycle
 When V is in resting phase after pumping blood
Pulse pressure: it is differential pressure of systolic and
diastolic pressure – 40mm Hg
Mean atrial pressure – average pressure on the arteries

58. REGULATION OF BLOOD PRESSURE:
SHORT TERM REGULATION OF BLOOD PRESSURE:
• BARORECEPTOR REFLEXES
• CHEMORECEPTOR REFLEXES
• CNS ISHCHAEMIC RESPONSE
• SHIFT OF CAPILLARY FLUID
LONG TERM REGULATION OF BLOOD PRESSURE
• REGULATION OF VOLUME OF EXTRACELLULAR
FLUID
• RENIN- ANGIOTENSIN MECHANISM
HORMONAL CONTROL

59. Baroreceptors reflex:
 Baroreceptors are receptors found in carotid
sinus & aortic arch.
 They are stimulated by changes in BP.
 BP
+ Baroreceptors
Stimulate
Para Sympathetic nerve
Stimulate
Sympathetic nerve
 Heart contractility &
vasoconstriction
Heart contractility &
vasoconstriction
Decrease in blood pressure
Increase in blood pressure

60. Chemoreceptors reflex:
■ Chemoreceptors are receptors found in carotid &
aortic bodies.
■ they are stimulated by chemical changes in blood
mainly - hypoxia ( O2), hypercapnia ( CO2), & pH
changes.
Chemoreceptors
Vasomotor centre
in heart rate & stroke volume
Decreased partial pressure of oxygen
Increase in the blood pressure
Increased partial pressure of oxygen

61. CNS ISHCHAEMIC RESPONSE
If the blood pressure reduces to less than 50mm Hg &
Increased partial pressure of CO2
Vasomotor centre stimulated by this
Increase in the sympathetic activity
Increases heart rate
BP turns to normal

62. Shift of capillary fluid:
• Capillary pressure is directly
proportional to arterial pressure
• When arterial pressure is more the fluid
present in the capillaries start passing
out to the capillary
• Automatically blood pressure comes to
normal

63. LONG TERM REGULATION OF BLOOD
• Regulation of volume of extracellular fluid:
Increase in volume of extra cellular fluid
↓
Which increases blood volume
↓
Thus increases arterial blood pressure
↓
The kidney excrete excess amount of water and salt
↓
There by reducing the ECF volume
↓
Brings the blood pressure to the normal

64. RENIN – ANGIOTENSIN MECHANISM:
Hypotension
↓
Low blood flow to the kidney
↓
Secretes renin
↓
Renin converts Angiotensinogen to Angiotensin-I
↓
ACE- converts Angiotensin-I to Angiotensin-II
↓
Angiotensin-II is potent vasoconstrictor
↓
Increase Blood Pressure

65. HORMONAL CONTROL
 Hormones may increase or decrease blood
pressure
THYROXIN:
 increases systolic blood pressure
 Reduces diastolic blood pressure
ANGIOTENSIN & SERATONIN:
 Increases blood pressure by vasoconstriction
BRADYKININ & ACETYLCHOLINE:
 Reduces BP by vasodilatation

66. DISORDERS OF HEART:
• Coronary heart disease – affect coronary blood vessel
• Rhuematic heart disease – damage to heart muscle & valve
• Congenital heart disease – due to genetic factor deformities of heart
structure
• Stroke: interruption of blood supply to brain
• Peripheral artery disease (PAD) – Plaque in peripheral artery ( supply
blood to limbs & heart)
• Deep vein thrombosis - blood clots in the vein – carried to the heart
• pulmonary embolism – blood clots in the vein – carried to the lungs
 Hypertension – High blood pressure > 140/90mm Hg
 Hypotension – Low blood pressure < 90/60 mm Hg
• Angina pectoris – chest pain - decreased blood supply to heart
• Myocardial ischemia – imbalance btn supply and demand of oxygen
• Myocardial infarction – due to loss of blood supply – death of heart cell
• Congestive heart failure – heart fails to pump blood from ventricle
• Cardiac arrhythmia – irregularities in cardiac rhytham
• Arteriosclerosis – formation of fibrofatty plaques in tunica intima layer
of arteries

67. THANK YOU