The document provides information about the circulatory system and its key components. It discusses the heart, blood vessels (arteries, veins, capillaries), blood flow, and disorders that can affect the circulatory system. The heart is described as a hollow muscular organ that pumps blood through the network of blood vessels. The circulatory system consists of the heart, blood vessels and blood, and serves to transport gases, nutrients, wastes and hormones throughout the body.

1. The Circulatory System
Mr. Rahat Ali
Lecturer
PCNMS, Haldwani

2. Cardiovascular System
• Heart, vessels,
blood
• Function:
transport
gases,
nutrients,
wastes,
hormones

3. The Heart
• The heart is a cone-shaped, hallow
muscular organ about the size of a fist,
located just behind and slightly left of
the breastbone.
• The heart pumps blood through the
network of arteries and veins called the
cardiovascular system.

4. Contd…
• Size: The heart is large as
a enclosed fist, being
approximately 14 cm (5.5
Inches) long & 9 cm (3.5
Inches) wide
• It weights about 300-350
gm.

5. Relations
• Interiorly: The sternum, ribs & intercostals
muscles.
• Posteriorly: The esophagus, trachea, left & right
bronchus, descending aorta, inferior vena cava
and thoracic vertebrae.
• Laterally: The lungs, left lung overlaps the left
side of the heart
• Superiorly: The great blood vessels, the aorta,
pulmonary artery, superior vena cava and inferior
vena cava

6. Contd…
• Inferiorly: The apex rests on the central
tendon of the diaphragm

7. Structure of the walls of heart
• The heart has made up of 3 layers-
 Pericardium
 Myocardium
 Endocardium

8. Pericardium
• Confines heart to
the mediastinum
• Allows sufficient
freedom of
movement.
• Consists of two
parts: the fibrous
and serous.

9. Contd…
• Fibrous: Thin inelastic, dense irregular
connective tissue
---Helps in protection, anchors heart to
mediastinum
• Serous: Thinner, more delicate divided into
parietal and visceral

10. Pericarditis
• Decrease in fluid
causes layers to
cling & rub against
each other resulting
in pain & decreased
efficiency of heart

11. Pericardial Tamponade
• Bleeding into
pericardial space
after chest trauma
• Excess blood
restricts expansion
of heart during
pumping
• Causes shock or
death if not corrected

12. Myocardium
• The myocardium is
the main tissue
constituting the wall
of the heart.
• The actual cardiac
muscle that
contracts

13. It consists of three types of
muscle fibres:
• Cardiac muscles forming the wall of the
atria & ventricles
• Muscle fibres forming the pacemaker which
is the site of origin of cardiac impulse.
• Muscle fibres forming the conducting
system which transmits the impulse to the
various part of the heart.

14. Endocardium
• Endocardium is the thin
smooth & glistening
membrane lining the
myocardium internally.
It consists of a single
layers of the endothelial
cells. The Endocardium
continues as the
endothelial of great
vessels opening in the
heart.

15. Heart Chambers
Four chambers:
• 2 atria: top of
heart – receive
blood from
veins
• 2 ventricles:
bottom of heart
– pump blood
through arteries

16. • Septum: divides
left from right
heart
• Valves: keep blood
flowing in one
direction
• Four valves:
– 2 AV valves,
– 2 semilunar valves
Contd…

17. Atrioventricular Valves
AV valves: between atria
and ventricles
• Bicuspid (mitral) valve:
on the left
• Tricuspid valve: on the
right
• When valves are open blood drains from atria into
ventricle
• When ventricle contract, valve flaps are forced
shut, blocking blood from reentering atria

18. Semi lunar Valves
• Located in arteries leaving
ventricles
• Pulmonic valve: at base of
pulmonary artery
• Aortic valve: at base of aorta
• When ventricles contract, valves are forced open &
let blood flow
• When ventricle relaxes, backflow of blood fills flaps
of valve & forces them to shut

20. Structure of Blood Vessels
• Histologically, walls
of most of blood
vessels accept the
capillaries consist
of three layers.
 Tunica adventitia
 Tunica media
 Tunica intima

21. Contd…

22. Contd…
• Tunica adventitia: It is outermost layer of the
blood vessel wall. It made up of connective tissue
in which collagen fibres are prominent. This layer
prevent undue stretching or distension of blood
vessel.
• Tunica media: it is middle, thickest layer of the
blood vessel wall. It consist of smooth muscle &
elastic tissue. Depending on body’s needs – lumen
is narrowed (vasoconstriction) or widened
(vasodilatation)

23. Contd…
• Tunica intima: It is the innermost layer of blood
vessel wall. In large arteries, from inside-outside
consists of:
• Endothelial lining which is very smooth & silky &
consist of single layer of cell. It lies in contract
with blood.
• Basal lamina is the thin layer of glycoprotein with
lines the external aspect of endothelium.
• Subendothelial connective tissue is a delicate layer
of CT wthich lies outside the basal lamina
• Internal elastic lamina is a thin membrane formed
by elastic fibres.

24. Blood Vessels
• Arteries: carry
blood away from
the heart
• Veins: carry
blood to the
heart
• Capillaries:
connect arteries
to veins &
exchange gases
with tissues

25. Arteries
• Carry blood at high
pressure
• Very thick, stretchy
walls that expand in
size
• Most carry oxygenated
blood (red)
• Damaged arteries
spurt in time to heart
beat

26. Contd…
• Aorta: largest
vessel (diameter of
a garden hose) –
receives blood from
left ventricle
• Arteriole: smaller
vessels connecting
arteries to
capillaries

27. Veins
• Carry blood at low
pressure
• Have valves to
prevent backflow of
blood against gravity
• Most carry de-
oxygenated blood
(purple)
• Damaged veins ooze
blood

28. Contd…
• Vena Cava: Dump all
blood from the body into
the right atria
 Superior vena cava:
receives blood from
upper body
 Inferior vena cava:
receives blood from
lower body
• Venules: smaller vessels
connecting veins to
capillaries

30. Capillaries
• Connect arteries and
veins
• Walls are one cell thick
• Allow exchange of gases
through thin walls
 Drop off oxygen
delivered from heart
by arteries
 Pick up CO2 and send it
to the heart through
veins

31. How Blood Travels through
Vessels
heart artery arteriole capillary venule vein

32. • Narrowing of vessel
lumen due to
plaque/fat formation
on inside of walls
• Causes: diet high in
fat, cholesterol, salt;
inactive lifestyle;
smoking
• Risks: high BP,
enlarged heart,
embolus blocking
circulation; stroke
Atherosclerosis

33. Coronary Artery Disease
• When Atherosclerosis
affects the arteries that
supply the heart muscle
• Symptoms: short of
breath after simple
exertion, angina (chest
pain)
• Risk: MI, cardiac arrest,
death

34. Treatment
• Medication
• Angioplasty (balloon
surgery) – balloon is
inserted and inflated in
blocked vessel to
compress fatty mass
against the artery wall
• Stent
• Coronary Artery
Bypass Graft

35. Contd…

36. Vessel Disorders
Varicose Veins:
Twisted, dilated
veins resulting
from pooling of
blood due to long
periods of
standing, obesity,
or inactivity

37. Contd…
Thrombophlebitis:
Inflammation of a
vessel due to clot
formation & poor
circulation. Clot
can become an
embolus if freed.

38. • Aneurysm: Weakling
in the wall of a vessel,
causing it to balloon
outwards.
• Rupture of the site
causes
– Stroke (if in the
brain)
– Death (in a large
artery – aorta).

39. Pulmonary Circulation
• Right ventricle pumps
deoxygenated blood
through pulmonary
artery to the lungs
• The blood picks up O2
from the lungs and
dumps CO2 into the
lungs
• Oxygenated blood is
returned to the left
atrium through the
pulmonary vein

40. Systemic Circulation
• Oxygenated blood is
pumped from left
ventricle thru aorta to
the body
• Blood dumps oxygen
into tissues and picks
up CO2
• Deoxygenated blood
travels from body to
vena cava to the right
atrium

42. Flow chart

44. Congestive Heart Failure
• Heart is ‘worn out’ from hypertension,
multiple MI, atherosclerosis, or age
• Heart pumps too weakly to meet tissue needs
• If one side is weaker than the other, blood will
back up in system

45. • Left ventricle is failing:
– Pulmonary congestion
– Pulmonary edema (blood
in lungs) causes
suffocation
• Right ventricle is failing:
– Peripheral congestion
– Edema in distal body parts
(ankles, feet)
Contd…

46. Pulmonary Edema
• Peripheral edema:
Swelling of feet and
ankles due to CHF

47. Conduction System of the
Heart
• These are some specialized Neuro-muscular
in the myocardium, which initiate and
conduct impulses of contraction through the
muscle of heart

48. Contd…
Heart is under two types of control:
• Autonomic Nervous system
– Sympathetic: speeds up contractions
– Parasympathetic: the “brakes” that slows down
contractions
• Intrinsic Conduction System
– Also called “nodal system”
– Heart determines its own rate of contractions

49. Intrinsic Conduction System
• Nodes are heart tissue that stimulate heart
muscle to depolarize (contract)
• Depolarization moves from base to apex
• Different areas of the heart have different
nodes, each with a different rate
• Node rate gets slower as it moves
downwards
• Faster nodes will override slower nodes

51. Nodes

52. Stages
• SA node fires, atria contract (depolarize)
• Impulse travels to AV node, then travels thru
bundle of His, bundle branches, & Purkinje fibers
– ventricles contract (depolarize)
• Contraction of ventricles has ‘wringing’ action,
pushing blood upward and out through large
arteries
• Heart muscle repolarizes

53. Conduction pathway
SA node:
• “The Heart’s Pacemaker”
• In atria
• Normally sets the pace of 60 –
70
• SA can increase rate when
stimulated by drugs, fever, or
sympathetic NS (exercise,
stress, emotion)

54. Contd…
AV Node:
• Between atria & ventricles
• Special tissues transmit signal from SA to AV node
• Intrinsic rate: 40 – 60
Bundle of His:
• Transmits impulse to ventricles
• Rate: 30 – 40 beats/min

55. Bundle Branches:
• Within ventricular
muscles
• Rate: 20 – 30
beats/min
Purkinje fibers:
• Terminal end of
branches
Contd…

56.  If heart is unable to
generate impulse, or
pace is too slow,
mechanical
pacemaker is
surgically implanted
to provide artificial
impulses
Pacemaker

57. Video

58. Electrocardiogram
• Electrical impulses in
heart are measured
with ECG
• Electrical activity is
translated into waves

59. Irregular Heart Rhythms
• Tachycardia: heart is beating too fast
• Bradycardia: heart is beating too slow
• Heart Block: no connection between atria
& ventricles – ventricles beat at their own
rate
• Ventricular Fibrillation: heart is
‘shivering’ – no contractions or pulse
(cardiac arrest)
• Asystole: dead heart – no electrical activity

60. Comparing Rates
• Normal Sinus Rhythm
• Sinus Bradycardia
• Sinus Tachycardia

61. Heart Sounds
• Cardiac cycle heard with a stethoscope
• Two sounds: “lub dup” (pause) “lub dup” (pause)
…..
– Lub = closing of AV valves (ventricular systole)
– Dup = Closing of semilunar valves (between
ventricular systole & diastole)
• Murmurs: abnormal heart sounds that usually
indicate valve problems

62. Cardiac Output
• Cardiac Output: The amount of blood
pumped by each side of the heart per
minute
• Cardiac output = heart rate X stroke volume
• Stroke volume = the amount of blood
pumped with each contraction

63. Example
Cardiac output=Stroke volume X Heart rate
CO = 70mL/beat x75beats/min
= 5250 mL/min
= 5.25 L/min

64. Contd…
• Contractility: Contractility is the intrinsic
ability of cardiac muscle to develop force
for a given muscle length.

65. Preload
• Preload is the muscle length prior to
contractility, and it is dependent of
ventricular filling (or end diastolic
volume…EDV)
• This value is related to right atrial pressure.
• The most important determining factor for
preload is venous return.

66. Afterload
• Afterload is the tension (or the arterial
pressure) against which the ventricle must
contract.
• If arterial pressure increases, afterload also
increases.
• After load for the left ventricle is determined
by aortic pressure
• After load for the right ventricle is
determined by pulmonary artery pressure.

67. What affects Stroke Volume?
Increase in Stroke volume:
• Increased venous blood return
– exercise (muscles force blood into heart)
– Slow hr (more time to fill ventricles)
Decrease in stroke volume
• Decreased venous return
– Hemorrhage (less blood volume)
– Tachycardia (not enough time to fill)

68. Vitals Sign
• Blood Pressure
• Heart rate
• Temperature
• Pulse

69. Thank You