Unit 2 applied anatomy and physiology - 2.1.1

UNIT 2 APPLIED ANATOMY AND
PHYSIOLOGY

2.1 CARDIOVASCULAR SYSTEM :
2.1.1 ANATOMY OF THE HEART

LEARNING OUTCOMES

• State the anatomy of the heart
❑Surface anatomy
❑Internal anatomy

• Describe the position of the heart in relation to the thorax
• Describe the significance of the pericardium
• Describe the features within each cardiac chambers: atria and ventricles
• Describe the valves structures and function: mitral, aortic, tricuspid, pulmonary
• State the coronary blood supply

❑Arterial system
❑Venous drainage

POSITION

• Lies within the pericardium in middle mediastinum
• Behind the sternum and the 2nd to 6 th costal cartilages
• In front of 5th to 8th thoracic vertebrae
• A third of it lies to the right of median plane and 2/3 to the left
• Anterior to the vertebral column, posterior to the sternum



HEART ANATOMY

EXTERNAL CHARACTERISTICS

• A hollow muscular organ, pyramidal shape
• Consists of 4 chambers
• Cardiac apex directed downward and forward to the left .

Lies at level 5th left intercostal spaces ( 1-2 cm medial to left
midclavicular line or 9cm from midline)

EXTERNAL CHARACTERISTICS

• Approximately the size of your fist

• Wt.: 250-300gm ( male: female : ) Length
12cm, wide 9cm thickness -6cm

• Cardiac Base – formed by left atrium and to a small
extent by the right atrium) , it faces backward, upward
and to the right.

EXTERNAL CHARACTERISTICS

• Two surfaces
- sternocostal surface: formed by right atrium and

right ventricle , directed forward and upward
- Diaphragmatic surface: formed by the ventricles(

chiefly left side) directed backward and downward .
Rest upon the central tendon of the diaphragm

EXTERNAL CHARACTERISTICS

• Three borders

1. Right – Vertical ; is formed entirely by Rt atrium

2. Left – round; mainly by left ventricle , partly by
left auricle

3. Inferior – horizontal; is formed by right ventricle and
cardiac apex

EXTERNAL CHARACTERISTICS

• FOUR GROOVES

1. Coronary sulcus (circular sulcus), which marks division between atria
and ventricles. Contains the trunks of the coronary vessels and
completely encircles the heart

2. Interatrial groove: separates the two atria and is hidden by
pulmonary trunk and aorta in front

3. Interventricular grooves : anterior & posterior longitudinal sulcus, :
the division between ventricular (which separate RV &LV) . The two
grooves extend from the base of the ventricular portion to a notch
called – the cardiac apical incisure.

COVERING OF THE HEART

• Pericardium – a double-walled sac around the heart.
• Composed of

❑- superficial fibrous pericardium
❑ a deep two layer serous pericardium – parietal layer line and

visceral layer. Separated by fluid in the pericardial cavity
• Protect and anchors the heart
• Prevent overfilling of the heart with blood
• Allows for the heart to work in a relatively friction – free environment

• Interatrial septum
❑Located between right and left atria
❑Contains fossa ovalis ( foramen ovale closes becomes
fossa ovalis)

• Interventricular septum
❑Located left and right ventricles
❑Upper membranous part
❑Thick lower muscular part

PERICARDIAL LAYER

LAYERS OF THE HEART WALL

• Epicardium – visceral pericardium
• Myocardium – cardiac muscle layer forming the bulk

of the heart
• Endocardium – endothelial layer of the inner

myocardial surface

FRONTAL SECTION

ATRIA OF THE HEART

• Atria- receiving chambers od the heart
• Receive venous blood returning to heart
• Separated by an interatrial septum
• Foramen ovale- opening interatrial septum in fetus
• Fossa avails – remnant of foramen ovale
• Each atrium has protruding auricle

• Pectinate muscle mark atrial walls
• Pump blood into ventricles
• Blood enters right atria from superior and inferior
venae cavae and coronary sinus
• Blood enters left atria from pulmonary veins

• Left auricle (LAA-Left atria appendage)- projecting to the
right (increase the power of contracting without increase
heart mass substantially

• Four inlets- four orifice of pulmonary veins open through the
posterior wall

• One outlet – left atrioventricular orifice , blood leaves
through left AV orifice to left ventricle



VENTRICLE OF THE HEART

• Ventricles are the discharging chambers of the heart.
• Papillary muscle and trabeculae carneae muscle mark ventricular

walls
• Separated by an interventricular septum
• Contains components of the conduction system
• Right ventricle pumps blood into the pulmonary trunk
• Left ventricle pumps blood into the aorta

• Thicker myocardium due to greater workload
• Pulmonary circulation ( low pressure)
• Systemic circulation ( high pressure )
• One outlet- left atrioventricular orifice
• One outlet – aortic orifice
• Two parts – divided by anterior cusps of mitral valve
• Inflow tract – rough walls
• Outflow tract – aortic vestibule smooth area leading to aortic orifice

SEPTUMS/FIBROUS SKELETON

• Interatrial septum
❑Located between left and right atria
❑Contains fossa avale

• Interventricular septum
❑Located between left and right ventricles
❑Upper membrous part
❑Thick lower muscular part

• Fibrous skeleton
❑Fibrous ring surround the AV , pulmonary and aorta orifice

ANTERIOR VIEW OF THE HEART

HEART VALVES

• Two major types
1. Atrioventricular valves(AV)
2. Semilunar valves (SV)

• AV lie between the atria and ventricle
❑ tricuspid valve – Right AV
❑ bicuspid or mitral valve – Left AV

• Chordae tendineae anchor AV to papillary muscles of
ventricle wall ( prevent prolapse of valve back to atrium

THE HEART VALVES

SEMILUNAR HEART VALVES

• SV prevent backflow of the bld into the ventricles
• Have no chordae tendineae attachments
• Aortic SV lies between the ventricle and the aorta
• Pulmonary SV lies between the right ventricle and pulmonary trunk
• Heart sounds due to valves closing.

❑“lub” – closing of AV
❑“Dub” – closing of SV

• Tricuspid valve
❑ guard right AV orifice
❑Three triangular cusps ; anterior, posterior , septal the base of cusps are
attached to fibrous ring
❑Chordae tendineae – attach margin of cusps to papillary muscles

• Mitral valve
❑Guard left AV orifice
❑Two triangular cusps- anterior and posterior

• Valve of pulmonary trunk
❑Guards the orifice of pulmonary trunk
❑Has 3 semilunar cusps – each with free border

POSTERIOR VIEW

CONDUCTING SYSTEM OF THE HEART

• Cardiac muscle tissue has intrinsic ability to :
❑Generate & conduct impulses
❑Signal these cells to contract rhymthmically

• Conducting system
❑A series of specialized cardiac muscle cells
❑Sinoatrial (SA) node sets the inherent rate of contraction

CONDUCTING SYSTEM OF THE HEART

INNERVATION

• Heart rate is altered by external controls
• Nerves to the heart include :

❑Visceral sensory fibers
❑Parasympathetic branches of vagus

nerve
• Sympathetic fibers- from cervical and

upper thoracic chain ganglia

• SA node
➢ called the pacemaker cell ( P cell )
➢Located at the junction of Rt atrium and superior vena cava,
upper part of sulcus terminalis ,under the epicardium

▪ Atrioventricular (AV) node
➢Located in the lower part of interatrial septum just above the
orifice of coronary sinus, under the endocardium
➢Lower part related to membranous part of interventricular
septum

AV bundle
➢Passes forward through Rt
fibrous trigon to reach inferior
border of membranous part
➢Divide into Rt and Lt branches
at upper border of muscular part
of interventricular septum

The right fibrous trigone is the connective tissue
bridge between the aortic valve and the right
atrioventricular (tricuspid) valve rings

MAJOR VESSELS OF THE HEART

Vessels returning blood to the heart include:

• SVC , IVC (Inferior superior venae cavae)
➢Open into the Rt atrium
➢Return deoxygenated blood from body cells

• Coronary sinus
➢Opens into the Rt atrium
➢Returns deoxygenated blood from heart muscle (coronary veins)

• Rt and Lt pulmonary veins
➢Open into Lt atrium
➢Return oxygenated blood from lungs

Vessels conveying blood away from the heart includes:

• Pulmonary trunk
➢Carries deoxygenated blood from right ventricle to lungs
➢Splits into Rt and Lt pulmonary arteries

• Ascending aorta
➢Carries oxygenated blood away from Lt ventricle to body organ
➢Three major branches
❑Brachiocephalic
❑Lt common carotid
❑Lt subclavian artery

BLOOD FLOW THROUGH THE HEART

PATHWAY OF BLOOD THROUGH THE HEART

CARDIAC CYCLE

PHASES OF CARDIAC CYCLE

• A short simultaneous contraction of both atria , termed the atrial
systole, followed , lowed, after a slight pause , by

• A simultaneous, but more prolonged, contraction of both ventricles,
named the ventricular systole, and

• A period of rest, during which the whole heart relaxed.





THE DURATION OF A CARDIAC CYCLE

ATRIAL SYSTOLE : 1/10
ATRIAL DIASTOLE : 7/10
VENTRICULAR SYSTOLE : 3/10
VENTRICULAR DIASTOLE : 5/10
TOTAL SYSTOLE : 4/10
COMPLETE DIASTOLE : 4/10

QUESTIONS

• The right ventricle is the chamber of the heart that pumps blood for the pulmonary circulation.
Based on this information, blood from the right ventricle is on its way to the __________.

• Lungs
• Liver
• appendages

• Which of the following is correct regarding blood flow in reference to the right side of the heart?

• Blood flows from right atrium through the pulmonary semilunar valve, into the right ventricle,
through the tricuspid valve, into the pulmonary trunk and then into the pulmonary arteries.

• Blood flows from right atrium through the tricuspid valve, into the right ventricle, through the
pulmonary semilunar valve into the pulmonary trunk and then into the pulmonary arteries.

• Blood flows from right atrium through the tricuspid valve, into the right ventricle into the pulmonary
trunk through the pulmonary semilunar valve and then into the pulmonary arteries.

• Which of the following is correct regarding the flow of blood in reference to the left side of the
heart?

• Blood flows from left atrium , through the bicuspid valve, into the left ventricle through the aortic
semilunar valve, and the into the aortic arch

• Blood flows from left atrium through the aortic semilunar valve, into the left ventricle through the
bicuspid valve and the into the aortic arch

• Blood flows from left atrium , through the bicuspid valve into the left ventricle into the aortic arch
through the aortic semilunar valve, and then into the systemic arterial system.

• Which of the following is also known as the mitral valve?

• Bicuspid

• Tricuspid
• pulmonic