1 - Heart Flashcards
What is the rough overview of the structure of the heart?
Four Chambers
Atria - Receive Venous Blood
Ventricles - Pump d blood to body/lungs
Right Side A/V = Pulmonary Circuit
Left Side A/V = Systemic Circuit
What is the main objective of the Right and Left sides of the heart?
Right: Right Atrium/Right Ventricle
Forms Pulmonary Circuit
R-Atrium: Deoxygenated blood from body from superior vena cava and inferior vena cava
R-Ventricle: Pumps to lungs via pulmonary trunk
Left: Left Atrium/Left Ventricle
Forms Systemic Circuit
L-Atrium: Oxygenated blood from four pulmonary veins.
L-Ventricle: Pumps oxygenated blood to body via ascending aorta
Shape of the heart and divisional landmarks
Pyramid
Right Side mostly anterior
Left Side mostly posterior
- - -
Atrioventricular Sulcus - Separates atria from ventricles
Anterior and Posterior interventricular Sulci - Separates Right and Left Ventricles
Surface of the Heart:
Anterior (Sternocostal)
Inferior (Diaphragmatic)
Posterior (Base)
Anterior (Sternocostal) - mostly right ventricle
Inferior (Diaphragmatic) - right and left ventricles
Posterior (Base) - left atrium (Base of Pyramid)
Right Atrium: Divisions
Can be divided into two division by vertical ridge: Crista Terminalis
Right Atrium: Anterior Part
Has pectinate muscles
“pectinate = comb-like”
Right Atrium: Posterior Part
Smooth walled, receives superior and inferior vena cava, and the coronary sinus
Posterior Wall:
- forms part of the septum dividing L/R Atria
- Has fossa ovalis
- Has Limbus of the Fossa Ovalis (upper margin of fossa)
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Clinical: Foramen Ovale Fetal Defect
Atrial Septal Defect (ASD)
Foramen Ovale allowed blood from right atrium to flow to left atrium (bypassing pulmonary circuit)
At birth, this is closed
- - -
ASD - Congenital malformation; minor, defect called Probe-Patent Forman Ovale
Right Atrium: Right Auricle
“ear”
Small blind pouch like appendange of atrium
Lined by Musculi Pectinati
Right Ventricle: Overall Summary
Thick-walled, muscular pump
Trabeculae Carneae
Infundibulum (Conus Arteriosis)
Posterior Wall of Right Ventricle
Tricuspid Valve
Pulmonary Valve
Right Ventricle: Trabeculae Carneae
“fleshy beams”
Irregular ridges of muscle that line ventricular lumen
Right Ventricle: Infindibulum (Conus Arteriosus)
Superior, cone-shaped part of ventricle
Smooth
Right Ventricle: Posterior Wall
Forms part of interventricular septum separating ventricles
Right Ventricle: Tricuspid Valve
Cusps
Chordae Tendineae
Located at right atrioventricular orifice; prevents blood from flowing back into Right Atrium following ventricular contraction.
Cusps = thick valve coverings preventing backflow; Anterior, Posterior, Septal
Chordae Tendineae:
Small cords which attach free margins and ventricular surface of each cusp to papillary muscle on ventricular walls
Attaches two adjacent cusps
*The Chordae Tendineae connect Papillary Muscles to the Cusps; giving tension to the system. Force of ventricular blood closes the valve*
Right Ventricle: Anulus Fibrosis
Ring of fibrous tissue surrounding the orifice that serves as attachmnt site for valve cusps
Right Ventricle: Pulmonary Valve
Located at pulmonary orifice at superior end of conus arteriosus; blood takes L-shaped path from right atrioventricular orifice to its outflow through pulmonary orifice
Right Ventricle: Pulmonary Valve - Cusp Type?
Three Semilunar cusps
Right Ventricle: Pulmonary Valve
Three semilunar cusps; sinus on each cusp
Once contraction is complete (systole), blood flows back into sinuses behind cusps, closing pulmonary orifice
Clinical: Pulmonic Valvular Incompetence
Volve does not close properly
Due to thickened and inflexible free margins of cusps
Results in backflow of blood into right ventricle from pulmonary trunk, heart as a heart murmur (turbulent blood flow)
Fibrous Skeleton of the Heart
Rings of connective tissues which surround orifice of pulmonary trunk and right atrioventricular orifice on right side and orifice of ascending aorta and left atrioventricular orifice on left side
1. Attachment for Valves
2. Attachment for Cardiac Fibers
3. Separates Atrial/Ventricular Muscles
4. Gives Rigidity to orifices
Left Atrium: Organization
Mostly Smooth Walled–lining of left auricle contains pectinate muscles
Receives FOUR pulmonary veins
Forms most of posterior heart
Contains valve for foramen ovale
Left Ventricle: Overview
Walls 3x Thicker bc SYSTEMIC CIRCULATION
Biscuspid (Mitral) Valve
Aortic Valve
Left Ventricle: Lining of Ventricular Cavity
Well developed trabeculae carneae except for smooth-walled aortic vestibule
Left Ventricle: Interventricular Septum
Two Parts:
1. Muscular Part: Thick, Most of septum
2. Membranous Part: Thin, Site of Ventricular Septal Defects (VSD); upper part of septum and inferior to the right and posterior cusps of aortic valve
Left Ventricle: Biscuspid (Mitral) Valve
Two cusps
Commonly affected by calcium deposits in Rheumatic Fever, can be “stuck” together which is audible as heart murmur
Left Ventricle: Aortic Valve
- Similar to pulmonary valve
- Aortic Sinus (3x) = Right/Left Open to Coronary Arteries
During diastole (relaxation) blood backflows, flipping down valve and flowing out Coronary Arteries
Clinical: Stenosis of Aortic Orifice
Narrowing of the aortic orifice due to adherence of “free” margins of cusps as a result of disease
Valves in Systole and Diastole
Diastole:
Atria Contract, Ventricles Relax
Tricuspid / Mitral OPEN
Aortic / Pulmonary CLOSED
Systole:
Atria Relax, Ventricles Contract
Tricuspid / Mitral CLOSED
Aortic / Pulmonary OPEN
Coronary Vessels: Overview
Blood within chambers does not provide oxygen/nutrients to muscles of hear; Coronary Vessels on exterior of hear provide this.
Coronary Vessels: Right Coronary Artery
Arises from Right Aortic Sinus
Descends Atrioventricular Sulcus (b/t R Atrium & R Ventricle) on anterior surface of the heart, continuing to posterior surface
Supplies:
R Atrium
R Ventricle
Sinoatrial Node
Atrioventricular Node
Posterior 1/3 of Interventricular Septum
Small portions of left Atrium and Ventricle
Coronary Vessels: Right Coronary - Sinu-Atrial Nodal Brance
Supplies Sinu-atrial Node
Always ends up in Right Atrium
Coronary Vessels: Right Coronary - AV (atrio-ventricular) Nodal Artery
Supplies AV Node
Coronary Vessels: Right Coronary - Posterior Interventricular Branch (Posterior Descending Artery)
Located on Sulcus of same name, suplied right and left ventricles and posterior 1/3 of interventricular septum
Can anastoose with Anterior Interventricular Branch of Left Coronary
Coronary Vessels: Left Coronary Artery
Originates from Aortic Sinus of Left Cusp of Aortic Valve
Supplies:
Mostly Left Side of Heart
Left Atrium
Left Ventricle
Anterior 2/3 of Interventricular Septum
Atrioventricular Bundles
Left Anterior Descending (LAD) [Anterior Interventricular Branch]
Branch of Left Coronary Artery
Runs inferior in Anterior Interventricular Sulcus towards apex
Can anastomose with the Posterior Interventricular Branch of the Right Coronry Artery
- Supplies both ventricles and anterior 2/3 of Interventricular Septum
Coronary Branching Variation
Right vs Left Dominance
Right: Posterior Interventricular Artery is branch of Right Coronary Artery
Left: Posterior Interventricular Artery is branch of the circumflex branch of the left coronary artery
Clinical: Coronary Arterial Dominance
Left Dominant: Blockage of left coronary will result in ischemia of interventricular septum = less chance of survival from blockage in Left Dominant Heart
Right Dominant: Blockage of left coronary will result in decreased blood flow, but collateral circulation can develop via Posterior Interventricular Artery of Right Coronary = better chance of survival
Clinical: Atherosclerotic Plaque in Coronary Arteries
Vessel lumens narrowed, risk b/c branches are functionally end arteries.
Anastomoses often small, insufficient to supply enough blood if suddenly stopped.
Results in Myocardial Infarction (heart attack)
Clinical: Coronary Artery By-Pass Graft
- Vein
- Arterial Source
- Occuluded Artery can be replaced by vein (usually Great Saphenous from leg)
Graft from aorta to end beneath occlusion
- Internal Thoracic (branch of Subclavian) attached directly beneath occlusion
Clinical: Angioplasty
Balloon catheter inserted into ascending aorta, and into occluded artery.
Balloon expanted to clear blockage.
Coronary Veins: Coronary Sinus
Large vein in posterior part of atrioventricular sulcus
Receives most of blood of the heart via its tributaries
Opens into the right atrium (superior to opening of the inf. vena cava)
Coronary Veins: Coronary Sinus Tributaries
(For locations, prepare via practical)
Great Cardiac Vein:
Drains area supplied by left coronary artery
Middle Cardiac Vein:
Drains area supplied by Posterior Interventricular Artery
Small Cardiac Vein:
Drains area suuplied by Marginal Artery
Coronary Veins: Anterior Cardiac Veins
Drain directly into the right atrium
Coronary Veins: Smallest Cardiac Veins
Tiny vessels within heart wall that open directly into chambers of heart
Electrical Conduction System of Heart: Sinuatrial (SA) Node
Pacemaker of the Heart
Right Atrium, Superior Crista Terminalis (base of Superior Vena Cava)
Generates electrical impulses, spread throughout the atrial muscles of both right and left sides.
Causes Atrial CONTRACTION
Waves does NOT reach ventricles directly due to Fibrous Skeleton (rings) of heart
Electrical Conduction System of Heart: Atrioventricular (AV) Node
Located Inferior Part of the Interatrial Septum
Receives impulse from Atrial Muscles
Relays via AV Bundles (ONLY electrical connection between atria/ventricles)
DELAY BUILT IN TO ALLOW ATRIA TO CONTRACT FULLY BEFORE VENTRICLES CONTRACT
What is the only electrical connection between the Atria and the Ventricles?
AV Node
Delay intented to allow atria to fully empty before ventricle contraction
Electrical Conduction System of Heart: Atrioventricular (AV) Bundles
Pierces fibrous rings separating atria from ventricles and passes through membranous part of interventricular septum
Divides into:
1. Right - Courses via Moderator Band; bridges lower portion of septum and anterior wall at Base of the Anterior Papillary Muscle
2. Left - Runs down left side of septum to supply ventricle and papillary muscles
Clinical: Artificial Pacemaker
Damage to conduction system can cause abnormal ventricular contraction
Pacemaker attached to chest wall, electrical field fed through Cephalic or Subclavian Vein
Implanted in right ventricle
Innervation of Heart: Autonomic Nervous System
Vagus Nerve
Sympathetics
Sensory
Vagus - Parasympathetic nerve, decreases heart rate and force; constricts coronary arteries
Sympathetics - Incrase heart rate and force of the beat; dilates coronary arteries
Sensory - Heart insensitive to touch, temperature; Pain sensitive to ischemia; course in cardiac branches and mid/inf br. of sympathetic trunk
Enter at T1-T4 on Left Side
Clinical: Referred Pain in Heart
Sensory enter Spinal T1-T4 on Left Side
Intercostobrachial Nerve - T2
Chest/Arm Pain, T1 - T4 dermatomes
Surface Markings of Heart (Borders)
Right
Inferior
Left
Superior
Right - 3rd - 6th R Costal Cart
Inferior - L 5th Intercostal Space
Left - L 2nd Intercostal Space
Superior - 2nd L - 3rd R Costal Cart
Clinical: Heart Sound Locations
Tricuspid - Left Lower Sternum near 5th intercostal space
Mitral - Left 5th intercostal, mid clavicular
Pulmonary - Medial Left 2nd Intercostal Space
Aortic - Medial Right 2nd Intercostal Space
