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Anatomy Dissections 6 Cardiovascular System, Aortic Arch ends at the T4…
Anatomy Dissections 6 Cardiovascular System
The Cardiovascular System
List the Components of the Cardiovascular System
The Components of the Cardiovascular system are as follows:
Heart
Blood Vessels
Blood
Outline the Functions of the Heart
Transport
Heart is responsible for the transportation of Nutrients, Hormones, Gases and Waste Products
Immune Response
Thermoregulation
Vasoconstriction and Vasodilation
Anatomical Location of the Heart
Describe the Anatomical Location of the Heart
The Heart is an inverted Cone Shape
Apex is situated Inferior
Base is situated Superior
It is enclosed in a Pericardial Sac
And surrounded by Pericardial Fluid
Heart is located Antero-posteriorly
The Heart is found between the Pleural Cavities (Lungs)
In the Middle Mediastinum
Anterior to the Vertebral Colum
Posterior to the Sternum
Medial to the Lungs
Describe the Anatomical Location of the Heart relative to the Thoracic Cage
Heart is located between the following points:
Lower Edge of the 2nd Left Coastal Cartilage, 2cm from the Sternum
Upper Edge of the 3rd Right Coastal Cartilage, 2cm from the Sternum
Lower Edge of the 6th Right Coastal Cartilage, 2cm from the Sternum
Apex beat is 7cm from the Midline in the 5th Left Intercostal Space
Functions of the Heart
Outline the functions of the Heart
Heart is responsible for the following
Generates Pressure in the Cardiovascular System
Separates Pulmonary and Systemic circulation
Ensures Unidirectional flow of blood
Regulates blood supply
alters contraction rate and contraction force according to the metabolic needs of the body
Pericardium
Outline the structure of the Pericardium
Pericardium is made up of 3 layers of Connective Tissue
Visceral Pericardium
Attached to the Heart
Parietal Pericardium
Lines inside of Fibrous Pericardium
NOTE: The Parietal and Visceral pericardium are separated by a serous cavity containing serous fluid
Fibrous Pericardium/ Pericardial Sac
It is the thickest layer encapsulating the heart
Pericardium has Pericardial Cavity which is found between the Parietal and Visceral pericardial layers
It contains Pericardial Fluid to provide friction reduction during heart contraction and relaxation
Heart Wall
Outline the Anatomy of the Heart Wall
The Heart wall is made up of 3 layers:
Epicardium
Epicardium is the outermost layer covering the external surface of the heart
Epicardium is made up of the Visceral pericardium
Structure: Loose Areolar Connective tissue and Mesothelium
Myocardium
Myocardium is the middle layer of the heart
It is the muscular wall of the heart
Structure: Concentric layers of Cardiac Muscle, Connective Tissue and Cardiac Muscle Cells
Endocardium
Endocardium is the inner layer heart, covering the inner surface of the heart including the Valves
Structure: Simple Squamous Epithelium and Areola Tissue
Internal Anatomy of the Heart
Outline the Internal anatomy of the heart
The heart is made up of 4 Chambers
2 Atria (Singular: Atrium)
2 Ventricles
The Heart is completely separated into the Left and Right sides by the following structures:
Interatrial Septum: separates the Left and Right atrium
Interventricular Septum: separates the Left and Right ventricle
Right side of the heart carries Deoxygenated Blood
Left Side of the heart carries Oxygenated blood
Atrioventricular valves that separates the Atria and Ventricles
Anatomical Features of the Atria
Describe the anatomical features of BOTH the Left and Right Atria
Atria are thin walled and contain the following distinct structures:
Musculi Pectinati/ Pectinate Muscles
Pectinate muscles allow for stronger contraction with minimum muscle mass
Auricle
Auricle faces anteriorly
It increases the capacity of the atrium
Christa Terminalis
Christa Terminalis are crescent shaped smooth muscle ridges at the opening of the Auricles
Outline the distinct anatomical features of the Right Atrium
Fossa Ovalis
Before birth, the opening connecting the 2 Atria is known as the Foramen Ovale
After birth, the Foramen Ovale seals off and becomes the Fossa Ovalis
Fossa Ovalis is an indentation
Failure to close of the Foramen Ovale is known as Patent Foramen Ovale
Three Vessels carrying Deoxygenated Blood entering the Right Atrium
Superior Vena Cava: which caries blood from the Head, Neck, Upper Limbs and Chest
Inferior Vena Cava: which carries blood from the Trunk, Viscera and Lower Limbs
Coronary Sinus: which is the main drainage of the Coronary Veins
Found on the posterior surface of the heart
Valves of Inferior and Superior Vena Cava
Valve of Coronary Sinus
Anatomical Features of the Left Atrium
Describe the distinct anatomical features of the Left Atrium
Fossa Ovalis
Fossa Ovalis is visible in the Interventricular Septum
Four vessels carrying Oxygenated blood entering into the Left Atrium
Pulmonary Veins, 2 from each Lung, carrying Oxygenated Blood
Anatomical Features of the Ventricles
Describe the Anatomical Features of BOTH the Left and Right Ventricles
Ventricles are thicker walled than Atria
Trabeculae Carneae
Trabeculae Carneae are muscular ridges on the internal surface of the Ventricles
Atrioventricular (AV) valves
AV valves are made up of:
Cusps
Chordae Tendineae
Chordae Tendineae connect the Cusps to the Papillary Muscles
Papillary Muscles
nm
Right Ventricle
Outline the Anatomical Features of the Right Ventricle
Right Ventricle has the following distinct structures
Right ventricle is thinner walled that the Left ventricle
Tricuspid Valve
Tricuspid valve is the right AV valve
It has 3 Cusps
And prevents a backflow of blood into the Right Atrium
Moderator Band
Moderator Band forms part of the Trabeculae Carneae
It is responsible for carrying conduction from the Interventricular Septum to the Anterior Papillary Muscle
Moderator Band creates a short cut across the ventricle
Facilitates conduction times so that ALL Papillary muscles contract at the same time
Pulmonary Trunk/Artery
Blood exists the Right Ventricle via the Pulmonary Trunk through the Pulmonary Semilunar valve
the Pulmonary trunk then splits into a Left and Right Pulmonary Artery
And arrives at the Lungs via the Pulmonary Artery
Left Ventricle
Outline the Anatomical Features of the Left Ventricle
Left Ventricle is thicker walled than the Right Ventricle
No Moderator Band
Bicuspid Valve
Bicuspid Valve is the left AV valve
Has 2 Cusps
Blood exists via the:
Aorta through the Aortic Semi-lunar Valves
Heart Valves
Outline the Cardiac valves
There are two types of Cardiac Valves:
Atrioventricular (AV) Valves
Semilunar Valves
AV Valves
AV Valves are located at the interface between the Atria and Ventricles
Tricuspid Valve is found on the Right
Bicuspid/ Mitral Valve is found on the Left
Semilunar Valves
Semilunar valves are located at the base of the Aorta and Pulmonary Trunk
Aortic Semilunar Valve
Pulmonary Semilunar Valve
These 2 great arteries of the heart regulate passage of blood from the ventricles to the Aorta and Pulmonary Trunk
Cardiac Skeleton
Outline the cardiac skeleton
Cardiac skeleton is formed by dense fibrous connective tissue
Fibrous anuli (rings) and Intervening trigones separate the Atria from the Ventricles
List the functions of the Cardiac Skeleton
Cardiac skeleton provides:
Mechanical stability
Electrical insulation
Attachment point for the cardiac muscles and valve cusps
Cardiac Valves
Describe the Position and Auscultation Site of the Cardiac Valves
Aortic Semilunar valve
Anatomical Position: Left Sternal Border, at the level of the 3rd Rib
Auscultation Site: Right 2nd Intercoastal Space at Sternal Margin
Pulmonary Semilunar valve
Anatomical Position: Left Sternal Border at the level of the 3rd Costal Cartilage
Auscultation Site: Left 2nd Intercoastal Space at sternal margin
Bicuspid Valve
Anatomical Position: Left 4th/5th Coastal Cartilage
Auscultation Site: Left 5th Intercoastal Space (at midclavicular line) or Cardiac Apex
Tricuspid Valve
Anatomical Position: Sternum at level of 5th Costal Cartilage
Auscultation Site: Left 5th Intercoastal Space at Sternal Margin
Atrioventricular Muscles
Explain the application to function of the AV Valves
When the Atrium contracts, blood pushes the cuspid leaflets aside and flows into the Ventricle
The Ventricle will contract and pushes the blood into the space between the AV valve cuspid leaflets and the Ventricle wall
Resulting in the AV valves being pushed closed by the blood
The Papillary Muscles which form part of the ventricle wall contract at the same time as the ventricle contracts
Papillary muscle contraction prevents the cuspid leaflets from being forced into the Atrium by the high pressure from the Ventricular Contraction
Papillary Muscles can ONLY pull and NOT push
To prevent a backflow of blood
Semilunar Valves
Outline the Characteristics of Semilunar Valves
Semilunar valves are found at the entrance of the
Pulmonary Trunk: Pulmonary Semilunar Valve
Aorta: Aortic Semilunar Valve
Semilunar Valves are 3 half-moon shaped cusps
Semilunar valves have NO muscular control
Therefore, backflow of blood closes the valves
Provide a brief explanation of the Semilunar valve functional action
When the ventricle contracts, the blood pushes the semilunar valve leaflets up against the wall of the Aorta or Pulmonary Trunk
As the ventricle relaxes and the pressure in the ventricle decreases, the backflow of blood from the Aorta or Pulmonary Trunk fills the Semilunar Valve cusps
Forcing the cusps to close the semilunar valve
This prevents the backflow of blood
Major Blood Vessels
List the Major Blood Vessels of the Heart
Arteries
Aorta
Pulmonary Trunk which splits into a Left and Right Pulmonary Artery
Veins
Superior Vena Cava
Inferior Vena Cava
4 Pulmonary Veins
Circulation of the body
There are 2 types of circulation in the body:
Systemic Circulation
Is the Transport of oxygenated blood between the Lungs, Heart and Organ Systems
Pulmonary Circulation
Is the Transport of Deoxygenated blood between the Heart and Lungs
Blood Supply to the heart: Coronary Vessels
Transportation of Oxygenated Blood to the Cardiac Muscles is via the Coronary Arteries
Describe the blood supply to the Heart
Coronary arteries originate at the base of the Aorta
There is a Left Coronary Artery and Right Coronary Artery
Elastic rebound forces blood through coronary arteries during contraction
Each coronary artery has branches
List the Branches and the position of the branches of the Left and Right Coronary Arteries
Left Coronary Artery
Anterior interventricular artery (Left Anterior Descending Artery): Anterior
Left Circumflex Artery: Anterior & Posterior
Left Marginal Artery: Posterior
Right Coronary Artery
Right Marginal Artery: Anterior
Posterior Interventricular artery: Posterior
Blood supply to the Heart: Coronary Vessels
List the regions of the Heart supplied by each Coronary Artery and its Branches
Right Coronary Artery provides blood to the:
Right atrium
Left and Right Ventricles
Conducting System: SA (Sinoatrial) node and AV (Atrioventricular) Node
Left Coronary Artery provides blood to the:
Left Atrium
Left Ventricle
Interventricular Septum Anteriorly
Transportation of blood from the heart: Cardiac Veins
Transportation of Deoxygenated Blood from the Heart Muscles is via the Cardiac Veins
Outline the types of Cardiac Veins and their position on the Heart
Great Cardiac vein
Left Anterior side of the heart and descends into Right Anterior Side of the heart
Middle Cardiac vein
Middle Posterior side of the heart
Small Cardiac vein
Right Anterior/Marginal side of the heart
List the regions of the heart drained by the Cardiac Veins
ALL the Cardiac veins drain deoxygenated blood produced by the heart.
Great Cardiac Vein
Drains blood from the area around the Anterior Interventricular Artery
Middle Cardiac vein
Drains blood from the area around Posterior Interventricular Artery
Small Cardiac Vein
Drain blood from area of the Right Atrium and Right Ventricle
ALL the Cardiac Vines empty into the Coronary Sinus
Coronary sinus drains into the Right Atrium
Circulation of the Blood
Outline the Circulation of Blood and start with blood returning from the body
Pulmonary Circulation
Deoxygenated blood enters the Right Atrium from the Coronary Sinus, Superior Vena Cava and Inferior Vena cava
After the Right Atrium contracts deoxygenated blood passes into the Right Ventricle via the Tricuspid Valves
As the Right Ventricle contracts deoxygenated blood in the Right Ventricle leaves the Right Ventricle
And enters into the Pulmonary Trunk via the Pulmonary semilunar valves
Pulmonary trunk then splits into a Left and Right Pulmonary Artery that enter the Left and Right Lungs, respectively.
Systemic Circulation
Oxygenated blood then returns from the Lungs into the left atrium via the 4 Pulmonary Veins
After the Left Atrium contracts oxygenated blood then leaves the Left Atrium and enters into the Left Ventricle via the Bicuspid/Mitral valve
As the Left Ventricle contracts, the oxygenated blood in the Left Ventricle is then forced into the Aorta via the Aortic Semilunar valves
From the Aorta the oxygenated blood is taken to different parts of the body
Systemic & Pulmonary Circulations: Venous Supply
Pulmonary Veins
Pulmonary veins carry oxygenated blood from the Lungs to the Heart
There are 4 Pulmonary veins in total
2 for each Lung
And they ALL open into the Left Atrium
Systemic Veins
Systemic veins carry deoxygenated blood from the Body to the Heart
The major veins are:
Superior Vena cava
Bring blood from the Head, Neck, Thorax and Upper Limbs
Inferior Vena cava
Brings blood from the Abdomen, Pelvis, Lower Limbs
Coronary Sinus (Cardiac veins)
Brings deoxygenated blood from the heart via the cardiac veins
Systemic and Pulmonary Circulations: Arterial
Pulmonary Arteries
Carry deoxygenated blood from the Heart to the Lungs for oxygenation
Via the Pulmonary trunk from the Right ventricle
Pulmonary trunk splits into a Right and Left Pulmonary artery to the Lungs
Systemic Arteries
Carry oxygenated blood from the Heart to the Organ systems
Aorta is a systemic artery which is has the following parts:
Ascending Aorta, Aortic Arch, Descending Aorta which opens into the Thoracic and Abdominal area
Aorta gives rise to ALL arteries, directly or indirectly
Coronary Arteries supply the heart
The Cardiac Cycle and Conducting System
Outline the Cardiac Cycle
Cardiac cycle is a single cardiac contraction
Heart chambers contract in series:
Atria contract first
And then the Ventricles contract after the atria
Outline the Conducting System
Conducting system is made up of 2 types of cardiac muscle cells
Autorhythmic Cells
Autorhythmic Cells control and coordinate the heartbeat
They initiate and distribute electrical impulses that stimulate contractions
Examples are: Sinoatrial Node and Atrioventricular Node
Contractile Cells
Contractile cells form the bulk of the Atrial and Ventricular Walls
They receive stimulus from the Purkinje Fibres
And produce contractions that propel blood
Intercalated discs connect cardiac contractile cells
Components of the Conducting System
List the Components of the Conduction system
Pacemaker cells found in the:
SA Node in the Right Atrium Wall
AV Node at the junction between the Atria and Ventricles
Conducting cells are found in the:
Internodal Pathways of the Atria
AV Bundle
Bundle Brunches
Purkinje Fibres of the Ventricle
The Cardiac Cycle and Conducting System: Impulse conduction through the Heart
Explain the Conduction of an Impulse through the Heart
Sino Atrial (SA) Node activity and Atrial Activation begin
Stimulus spreads across the Atria to the Atrioventricular (AV) Nodes
Atrial contraction begins
Impulse is delayed for 100 msec at the AV Node by the Cardiac Skeleton
This is to give appropriate time for Atrial contraction to occur before Ventricle contraction occurs
Impulses travel in the AV Bundle to the Left and Right Bundle Branches in the Interventricular septum to the Purkinje Fibres
Purkinje fibres distribute impulse to ventricular myocardium
Atrial contraction is completed and ventricular contraction begins
Conducting System Pathologies
Outline disturbances in Heart Rhythm
Bradycardia
Abnormally slow heart rate
Tachycardia
Abnormally fast heart rate
Ectopic Pacemaker
Abnormal cells generate high rate of action potentials
Bypassing conducting system
This disrupts timing of ventricular contraction
Aortic Arch ends at the T4 Vertebrae
Mitral stenosis results in an enlarged left Atrium
