Day 1 - Cardiac Flashcards
Anatomy and Physiology
What are the layers of the pericardium?
and their significance to cardiac tamponade and pericarditis.
Fibrous pericardium - tough layer, stops vibrations from getting into the thoracic cavity
Serous pericardium
* Parietal layer
* Pericardial fluid (sac) in between - brings nutrients and coshin to the layers
* Visceral layer pericardium
Pericarditis - inflammation of pericardium
* layers stick together = heart is unable to stretch and fill with blood
* therefore decreased CO
Cardiac Tamponade - ++ fluid collection in the pericardial sac = increased pressure
* decreased CO
Effusion may cause tamponade
What are the cardiac landmarks?
A PET Monkey
Aortic
Pulmonic
Erbs point
Tricuspid
Mitral
Cardiac tamponade
vs. pericardial effusion
Pericardial effusion is extra fluid in the pericardial space, normal pressure
Tamponade is when this fluid increases pressure on the heart, decreasing its size
* causes decreased CO
Symptoms
* hypotension (unable to get blood out efficiently)
What is pericarditis?
Inflammation within the pericardium caused by infection, trauma (MI), post cardiac surgery.
Symptoms
* sharp stabbing pain NOT affected by breathing
* worsens with activity
What are the 3 layers of the heart?
Epicardium - outer
Myocardium - middle
Endocardium - inner
Pericardium (protective layer)
What are the 3 layers of blood vessels?
Tunicas
* adventitia - outer
* media - middle, thickest
* intima - inner
What is the difference between arteries, veins, and capillaries?
- Less smooth muscle (media tunica) in veins than arteries
- Veins have valves
- Capillaries connect arteries and veins
Describe flow of blood through the heart
- Blood enters RA through superior / inferior vena cava
- Tricuspid valve to RV
- Pulmonic valve into lung capillaries, gas exchange
- Pulmonary veins into the LA
- Mitral valve into LV
- Aortic valve into aorta then throughout the body
Identify the coronary arteries and the areas of the myocardium that each supply
Right coronary artery - RA, RV, AV node, SA node
Left coronary artery / main stem - Left atrioventricular groove
Left anterior descending artery - anterior LA, LV, some RV, 2/3 septum, apex, RBB, part of LBB
Circumflex - lateral LA and LV, Posterior / inferior walls of LV
Arteries perfuse during diastole
What are the four properties of cardiac cells?
Automaticity - initiate an impulse on its own, electrical
Excitability - responds to an impulse, electrical
Conductivity - transmits impulses to other areas, electrical
Contractility - responds to electrical impulses with contraction
Identify and describe the key structures of the electro-conduction system
SA node - best pacemaker
* sends impulses through RA
Intra-atrial tracts - transmits from SA node in RA to LA at the same time
Atrial internodal tracts - electrical pathway between SA node and AV node
AV node - near septum of RA
* The 2nd pacemaker, 40-60 BPM
* sends impulses to bundle of his
Bundle of His - divides into RBB / LBB to respective ventricles
HIS purkinje system - carries impulses throughout the ventricles myocardium
* 20-40 BPM backup
What are the key events of the cardiac cycle?
Systole and diastole
atrial kick, preload, stroke volume, cardiac output
CO = HR x stroke volume
What are the 4 factors that affect cardiac output?
Heart rate +
Stroke volume
* Preload - volume entering the heart, the greater the stretch the greater the force of contraction. CVP measures it. Blood left in ventricles after diastole
* Contractility - pumping ability. FOC = strength of cardiac muscles
* Afterload - resistance the ventricle meets during contraction. Affected by condition of valves, diameter of vessels, viscosity/thickness of blood
What are 3 effects of tachycardia?
- Decrease ventricular filling = decreased preload & cardiac output
- Decrease coronary artery perfusion = decreased myocardial oxygen supply
- Increase workload = increase myocardial oxygen demand
Describe the role of baroreceptors in the regulation of BP
Stretch receptors in aortic arch / carotid
* Detect changes in BP
* ^ BP: PSNS will decrease HR to correct CO
* v BP: SNS will increase HR / vasoconstrict to correct CO
* Glossopharyngeal, vagus nerve
