Heart Flashcards
What is the Mediastinum?
Middle portion of the thorax that incases the heart
Contents of the Superior Mediastinum
Thymus
Great vessels
Nerves: Vagus, phrenic, cardiac plexus
Veins: Brachiocephalic, SVC
Arteries: Aortic arch Brachiocephalic trunk, Left common carotid, left subclavian
Cervical Viscera: Trachea, esophagus
Contents of the Posterior Mediastinum
Thoracic aorta
Thoracic duct
lymphatic trunks
Lymph nodes
Azygos & Hemi-Azygos veins
Esophagus
Contents of Middle Mediastium
Pericardium
Heart
Roots of great vessels: Ascending aorta, pulmonary trunk, SVC
List the contents of the Superior Mediastinum in order from anterior to posterior
Thymus
Veins: Brachiocephalic, SVC
Arteries: Aortic arch, Brachiocephalic trunk, left common carotid, left subclavian
Trachea
Alimentary tract: esophagus
Lymphatics: Lymphatic trunks & Thoracic duct
Branches (in-order) from the Aorta
Ascending->Arch->Descending (thoracic)
Ascending-> coronary arteries
Arch -> Brachiocephalic trunk (splits into RIght common carotid & Right subclavian arteries) -> Left common carotid artery -> Left subclavian
Descending (supplies in 3 separate planes) -> Anterior, midline plane -> Lateral plane -> Posterolateral plane
What do the right and left Brachiocephalic merge to become?
Superior Vena Cava
What does the Vagus nerve innervate?
R/L pulmonary plexuses
Esophageal plexuses
cardiac plexuses
What do the Recurrent Laryngeal Nerves innervate?
R/L intrinsic muscles of the larynx
What do the phrenic nerves innervate?
Most of the diaphragm
Mediastinal parietal pleura
pericardium
What are the 2 major lymph structures in the mediastinum?
Thoracic duct (drains from rest of the body) & right lymphatic duct (drains from upper right quadrant of the body)
What is the Pericardium?
fibrous membrane that covers the heart and the beginning of its great vessels
What are the parts of the pericardium?
Tough external layer (fibrous pericardium)
Serous pericardium (parietal & visceral)
Different between Parietal and visceral pericardium
Parietal: internal surface touching the fibrous pericardium
Visceral: layer touching the heart and its great vessels
Function of the pericaridum
protects the heart from overfilling because it is unyielding & allows for reduced friction between heart and surrounding structures
List the sequence of blood flow through the heart
Right atrium -> tricuspid valve -> right ventricle -> semilunar valve (pulmonary valve) -> pulmonary arteries -> lungs -> pulmonary veins -> left atrium -> mitral valve -> left ventricle -> semilunar valve (aortic valve) -> aorta -> Rest of the body
Diastole
ventricular filling (relaxation)
Systole
ventricular emptying (contraction)
What makes the “lub” sound?
The blood slamming on the shut atrioventricular valves (tricuspid & mitral)
What makes the “dub” sound?
The blood slamming on the semilunar valves (aortic & pulmonary)
Describe the endocardium
Thin internal layer
Lining membrane that covers valves
Epithelium & subendothelial connective tissue
Describe the Myocardium
Thick middle layer
Cardiac muscle
Wringing motion w/ contraction because of helical orientation of fibers
Describe the Epicardium
Thin external layer
Visceral pericardium
What makes the pulmonary veins & arteries different from normal veins and arteries?
Pulmonary arteries carry de-oxygenated blood to the lungs
Pulmonary veins carry oxygenated blood to the left atria
Normally arteries take oxygenated blood to the rest of the body and veins take de-oxygenated blood back to the heart
Characteristics of Right Atrium
Receives low oxygen blood from SVC, IVC, & Coronary sinus
Oval Fossa is remnant of oval foramen in fetus
Contracts using Pectinate muscles
Right AV orifice where blood dumps into right ventricle
Characteristics of Right Ventricle
Receives low oxygen blood from right atrium
Tricuspid valve present with Chordae Tendinae and Papillary muscles that all help to prevent the back flow of blood
Pushes blood to pulmonary valve & artery
*Interventricular septum separates R & L Ventricles
Characteristics of Left Atrium
Receives oxygenated blood from pulmonary veins
Thicker than right atrium
Left AV orifice that leads oxygenated blood to left ventricle
Smaller pectinate muscles
Characteristics of Left Ventricle
Receives oxygenated blood from left atrium
Thicker than right ventricle
Mitral valve (2 cusps) with chordae Tendinae (more numerous) and papillary muscles (larger) to prevent back flow
Aortic semilunar valve
Longer cavity
List the sequence of conduction throughout the heart
Sino-atrial node initiates impulse -> conducted to cardiac muscle fibers in atria causing them to contract -> myogenic conduction of impulse from SA node to atrioventricular node -> AV node distributes signal to ventricles through AV bundle & right and left bundle branches -> Impulses pass to subendocardial branches (purkinje fibers) to supply papillary muscles & walls of ventricles
Branches of the Coronary arteries
Coronary artery off of the ascending aorta -> 1) Right coronary artery & 2) left coronary artery ->
1) Sinu-atrial nodal branch, Right marginal branch, Atrioventricular nodal branch, posterior interventricular branch
2) Anterior IV Branch -> Lateral branch of anterior IV branch
Circumflex branch -> (40% have SA nodal branch coming from here), Left marginal branch
What do the Right Coronary arteries supply?
Right atrium
Most of Right ventricle
Part of left ventricle
part of IV septum (posterior aspect)
SA node
AV node
What do the left coronary arteries supply?
Left atrium
Most of left ventricle
Part of right ventricle
Most of IV Septum (AV Bundle)
(40% SA node)
Explain Sympathetic innervation of the heart
Increases HR, force of contraction, and blood flow through coronary vessels
Explain Parasympathetic innervation of the heart
Decreases HR, force of contraction, and constricts coronary arteries
Explain Pericarditis
Inflammation of pericardium
Symptoms: chest pain, makes pericardium rough so it sounds like rustling silk
Explain Pericardial Effusion
The passage of fluid from pericardial capillaries into pericardial cavity or the accumulation of pus
Results in: heart compressed and can’t expand fully and fill completely; ineffective pump
Explain Congestive Heart Failure (CHF)
Blood returns to heart at rate that exceeds cardiac output
Results in: cardiac hypertension which is elevated pressure on right side of the heart; often occurs in non-inflammatory pericardial effusions
What are the consequences of an Atrial Septal Defect (ASD)?
Congenital anomaly (happens at birth)
incomplete closure of oval foramen
Left-to-right shunt of blood overloads pulmonary vascular system
What are the consequences of a Ventricular Septal Defect (VSD)?
25% of congenital heart disease
holes between walls of the ventricles
left-to-right shunt of blood causes pulmonary disease and CARDIAC FAILURE
What happens when the mitral valve prolapses?
Usually results in a heart murmur (1 in 20 people)
allows blood to flow back into the previous chamber
1 or both leaflets are enlarged of floppy
usually has chest pain & fatigue
Why is a mitral valve prolapse an issue?
this increases the workload on the heart
How does coronary artery disease (CAD) develop?
An embolus breaks off & occludes a coronary artery leading to an infarction
Which are the most common arterial sites for Coronary Artery disease?
Anterior IV Branch (LAD - 40%) - widow maker
Right coronary artery (RCA - 30-40%)
Circumflex branch (15-20%)
What is a myocardial infarction and what are the potential consequences?
Localized tissue death in the muscles of the heart
This causes death
How does atherosclerosis develop?
Lipids build up in the arteries and form plaque which eventually occludes arteries
This results in stenosis - hardening of the vessels
What is Angina Pectoris?
Pain that occurs in the heart
Usually results from narrowing of arteries & ischemia of the myocardium
Necrosis DOES NOT occur
How can you tell Angina Pectoris from a Myocardial Infarction?
pain usually worsens with exercise (especially after a heavy meal) but gets better after 1-2 minutes of rest
A MI does NOT get better with rest
*Sublingual nitroglycerin could help by dilating the blood vessels
Explain the procedure for a Coronary Artery Bypass Graft (CABG)
Take either the Great saphenous vein or Radial artery and connect it to the ascending aorta and to the other side of the occluded artery to bypass the occlusion
Describe a pacemaker
Subcutaneous
Acts as an SA node for the heart
It is an electrode that is fixed to trabeculae carneae in ventricular wall
Describe cardio pulmonary resuscitation (CPR)
Force’s blood out of the hear when compressing the sternum
Heart fills back up with blood after the sternum is decompressed
Used when heart stops beating
Describe Atrial Fibrillation (A-Fib)
ventricles respond at irregular intervals compared to the atrium
circulation is okay
Describe Ventricular Fibrillation
Can NOT pump blood sufficiently
NO cardiac output
Fatal if allowed to continue
Describe Defibrillation
Electrical shock given to the heart to essentially reset the heart
stops the heart beat and hopes that normal heart rhythm continues once it begins beating again
How can the heart refer pain to other parts of the body?
Usually the spinal nerves that supply the coronary arteries are shared by the visceral afferent terminations for the referred parts of the body
The afferent fibers receive signals at the same posterior roots of these dermatomes
