2. Heart
The central blood pumping organ that
receives & pumps out blood to the whole
body.
Position: In middle mediastinum in between
the two lungs, behind body of sternum,
about 1/3rd of it is on the right side &2/3rd are
on the left side of the body
5. Superficial Anatomy of the Heart
Inside heart there are
Four chambers
Four openings, guarded by
Four valves
Right & Left Atrium are receiving chambers
Right & Left Ventricle are distributing chambers
6.
7. Openings of Heart
1.
1.
2.
3.
4.
Right atrio-ventricular
opening
Right atrio-ventricular opening
Left atrio-ventricularLeft atrio-ventricular
2. opening
opening
Aortic opening
Pulmonary opening
3. Aortic opening
4. Pulmonary opening
8. Valves of Heart
There are four valves:
1. Right atrioventricular
valve
(tricuspid valve)
2. Left atrioventricular valve
(mitral valve)
3. Pulmonary valve
4. Aoritc valve
9. Heart valves ensure unidirectional blood flow through the
heart.
Atrio-ventricular (AV) valves lie between the atria and the
ventricles.
AV valves prevent backflow into the atria when ventricles
contract.
Aortic semilunar valve lies between the left ventricle and
the aorta .
Pulmonary semilunar valve lies between the right ventricle
and pulmonary trunk.
Semilunar valves prevent backflow of blood into the
ventricles
14. Heart Muscle:
Syncytium
• Cardiac muscle fibers are striated –
sarcomere is the functional unit
• Fibers are branched; connect to one
another at intercalated discs. The
discs contain several gap junctions
• Nuclei are centrally located
• Abundant mitochondria
• SR is less abundant than in skeletal
muscle, but greater in density than
smooth muscle
• Sarcolemma has specialized ion
channels that skeletal muscle does
not – voltage-gated Ca2+ channels
• Fibers are not anchored at ends;
allows for greater sarcomere
shortening and lengthening
15. Major Types of Cardiac Muscle
• Atrial Muscle
• Ventricular Muscle
• Specialized excitatory and conductive muscle
fibers
SA Node
Inter-nodal pathway
AV Node
The AV Bundle
The left & right bundles of purkinje fibers
16. Heart Muscle: Cardiac Conduction System
• Specialized muscle cells “pace” the
rest of the heart; cells contain less
actin and myosin, are thin and pale
microscopically
• Sinoatrial (SA) node; pace of about
65 bpm
• Internodal pathways connect SA
node to atrioventricular (AV) node
• AV node could act as a secondary
pacemaker; autorhythmic at about
55 bpm
• Bundle of His
• Left and right bundle branches
• Purkinje fibers; also autorhythmic at
about 45 bpm
17. Properties of Heart Muscle
Autorhythmicity
Conductivity
Excitability & Contractility
All or none law
Frank Starling Law
Refractory Period
Absolute
Relative
Tonicity
18. Blood Vessel
Hollow tubes, which carry blood along with
oxygen, nutrients & metabolic waste
products within the body.
Types:
• Artery
• Vein
• Capillary
26. Coronary Circulation
• Coronary circulation is the functional blood
supply to the heart muscle itself
• Collateral routes ensure blood delivery to heart
even if major vessels are occluded
27. Coronary Circulation: Arterial Supply
Arteries include:
1. the right and left
coronary arteries
2. marginal arteries
3. anterior and
posterior
interventricular
arteries and
4. the circumflex
artery
28. Coronary Circulation: Venous Supply
Veins include:
• the great cardiac
vein
• anterior and
posterior cardiac
veins
• the middle
cardiac vein and
• the small cardiac
vein
30. Importance of Circulation
• Supply oxygen, nutrients to tissue
• Carry away CO2 & waste products
• Prevent intravascular coagulation
• Thermal balance
31. Important Terms
• Cardiac output: The amount of blood that is
ejected by heart per minute.
• Stroke Volume: The amount of blood pumped out
by ventricles in each beat/contraction. It is about
70-80 ml.
• Heart rate: The number of contractions of heart
per minute.
• Cardiac Output = Stroke Volume Heart rate
32. Abnormalities of Heart Rate
Tachycardia: Increased heart rate above the
upper normal physiological limit
Bradycardia: Decreased heart rate below
normal physiological limit
33. Pulse
The rhythmic dilatation & elongation of arterial
wall by intermittent ejection of blood from heart
transmitted as a wave to the periphery.
Importance:
• Heart rate is counted
• Few clinical condition can be recognized:
Hypertrophy, arrhythmia, Fibrillation etc.
34. Some Diseases
• Myocardial Infarction: Acute ischaemic necrosis
of an area of heart muscle.
• Heart Block: Transmission of impulse through the
heart is blocked.
• Shock: Widespread hypo perfusion of tissue due to
reduction of blood volume or cardiac output is
called shock.
• Angina Pectoris: Cardiac pain due to impaired
coronary blood flow.
36. Blood Pressure
It is the lateral pressure exerted by
blood on the vessel wall while
flowing through it.
BP is expressed as
systolic (during systole) and
diastolic (during diastole) blood pressure.
Normal BP in healthy adult:
Systolic: 120 ± 15 mm Hg
Dialstolic: 80 ±10 mm Hg
37. Blood pressure
Blood pressure =
Cardiarc output × Peripheral resistance
• Peripheral resistance is the resistance of the
vessels to blood while passing within it.
39. Hypertension
Persistent rise of blood pressure above normal
range in respect of age & sex.
Types:
• Essential Hypertension: 85 to 90%
Unknown cause.
• Secondary Hypertension: 10 to 15%
Causes are:
–
–
–
–
Kidney diseases
Endocrine diseases
Stricture of Aorta
Drugs like oral contraceptives, steroids etc.
40. Receptors & Neurotransmitters
•
Receptors are substances, lipoprotein in nature,
present in the cell membrane or inside the cell, with
which neurotransmitters and drugs combine in
order to produce various effects.
•
Neurotransmitters are chemical substances
released from nerve terminals and acts on various
receptors to produce physiological effects.
41. Adrenergic receptors
The receptors of the sympathetic nervous systems
are called adrenergic receptors. Sympathetic
neurotransmitters like adrenaline and noradrenaline
stimulates these receptors.
There are mainly two types of adrenergic receptors:
α (alpha) and β (beta) receptors. They are further
subdivided into α1, α2, β1 and β2 receptors.
These receptors are found in heart, blood vessels,
kidney, pancreas, uterus and some other organs.
45. Antihypertensive Drugs
Drugs that are used to control hypertension are called
antihypertensive drugs.
Antihypertensives are mainly of following groups:
• Diuretic
• Alpha Blocker
• Beta Blocker
• Calcium Channel Blocker
• ACE inhibitor
• Angiotensin II antagonist
46. Diuretics
Diuretics promote the excretion of water
and electrolytes by the kidneys.These are
used either alone or in combination to
reduce blood pressure.
Classification of Diuretics:
1. Loop diuretics (high efficacy)
2. Thiazides (moderate efficacy)
3. K+ sparing diuretics (low efficacy)
48. Alpha Blocking drugs
Alpha (α) blockers block the α1 & α2 adrenoceptors.
Blockade of α1 receptor results in vasodilatation
leading to fall of blood pressure due to decrease in
peripheral resistance.
Drugs are:
• Prazosin
• Doxazosin
• Terazosin
49. Beta Blockers
Beta blockers block beta adrenergic receptor
and are used in the management of
cardiovascular disorder like hypertension,
angina pectoris , cardiac arrhythmia and
myocardial infarction.
51. Calcium Channel Blockers
Calcium Channel Blockers inhibit the influx
of calcium in vascular smooth muscle and
myocardial cells. This results in dilatation
of coronary and peripheral arteries &
arterioles.
CCB have no effect in venous tone.
52. Drugs used as calcium channel blockers are
• Amlodipine
• Nifedipine
• Diltiazem
• Verapamil
• Lacidipine
• Lercanidipine etc.
53. ACE Inhibitors
Angiotensin II is a very potent vasoconstrictor.
ACE Inhibitors inhibit angiotensin converting
enzyme (ACE) thus preventing conversion of
Angiotensin I to Angiotensin II . This results in
vasodilation and fall of blood pressure.
54. Drugs used as ACE Inhibitors are:
•
•
•
•
Captopril
Enalapril
Lisinopril
Ramipril
55. Angiotensin II Receptor
Antagonists
These act mainly by selective blockade of
Angiotensin II receptors resulting in vasodilation
and fall of BP
Drugs are:
» Losartan
» Irbesartan
» Valsartan
59. Grading of Hypertension
Hypertension can be graded on the basis of
diastolic blood pressure.
Mild :
90 to 105 mm Hg
Moderate:
105-120 mm Hg
Severe:
>120 mm Hg
Malignant:
rising rapidly over 140 mm Hg
60. Treatment of Mild & Moderate
Hypertension
First line treatment (any one drug)
1. Diuretics
–
–
Particularly in the elderly
Thiazides are the drug of choice
2. Beta blockers
3. ACE inhibitors or Angiotensin II antagonists
can be used as alternative first line therapy, if the
above drugs are not tolerated
61. Sencond line treatment (addition of a 2nd drug)
• If first line therapy fails
• To minimize side effects
Logical combination of drugs:
First line drug
+
Additional drug
ACE inhibitor
+
CCB
Diuretics
Beta blocker
+
Diuretics
Diuretics
+
ACE inhibitor
Beta blocker
62. Treatment of Severe Hypertension
In case of severe hypertension or despite second
line therapy hypertension is not controlled, a third
drug, especially, Vasodilators is added with second
line therapy.
64. If hypertension is associated with other disease:
Associated with
Choice of drugs
Diabetes
Hyperlipidemia
ACE inhibitor
CCB
Asthma
Diuretics
CCB
Angina pectoris
Beta blocker
CCB
Heart failure
Diuretics
ACE inhibitor
Previous MI
Beta blocker
ACE inhibitor
Drugs avoided
Beta blocker
Verapamil
Notas do Editor
Mediastinum: pl. Mediastina 1. A septum or cavity between two principal portions of an organ. 2. The mass of organs and tissues separating the lungs. It contains the heart and its large vessels, trachea, esophagus, thymus, lymph nodes, and connective tissue.
Right atrium tricuspid valve right ventricle
Right ventricle pulmonary semilunar valve pulmonary arteries lungs
Lungs pulmonary veins left atrium
Left atrium bicuspid valve left ventricle
Left ventricle aortic semilunar valve aorta
Aorta systemic circulation
