Porth- Cardio phys Flashcards
Pulmonary circulation consists of the _____ side of the heart
Right
Systemic circulation consists of the ____ side of the heart
Left
Low pressure system designed to collect and return blood to the heart…contains about 2/3 of the blood
Venous system
High pressure distributive system that contains about 1/6 of the blood
Arterial system
Refers to the ability of a blood vessel to be stretched and accommodate an increased volume of blood
Distensibility
Refers to the total quantity of blood that can stored in a given portion of the circulation for each millimeter of mercury rise in pressure
Vascular compliance
____ _____ is determined largely by the pressure difference between the 2 ends of a vessel or group of vessels and the resistance that blood must overcome as it moves through the vessel(s)
Blood flow
Layers of heart (from outside to inside)
Pericardium (sac around heart)
Epicardium
Myocardium
Endocardium
contain gap junctions that serve as low resistance pathways for passage of ions and electrical impulses from one cardiac cell to another
Intercalated disks
Because of intercalated disks, myocardium behaves in..
Syncytium (as a single unit)
Which phase…
Na channels open, influx of Na
Phase 0
Which phase…
Peak of AP
Inactivation of fast Na channel with an abrupt decrease in Na permeability
Phase 1
Which phase…
Plateau caused by slow opening Ca channels
Ca enters cell..this plateau phase causes the AP of cardiac cells to last 3-15 times longer than skeletal muscle
*longer period of contraction
Phase 2
Which phase... Final rapid repolarization -Slow Ca channels close -Influx of Ca and Na stop -Sharp rise in K permeability, contributing to rapid outward movement of K and reeestblishment of resting membrane potential
Phase 3
Which phase…
Resting membrane potential
Na moving out
K moving in
Phase 4
Maximum force of contraction when the muscle fibers are stretched about _____ times their resting length
Two and a half
Which class of arrhythmias are most serious
Ventricular arrhythmias
During this arrhythmia, the ventricles quiver but do not contract. Thus, there is no cardiac output and there are no palpable or audible pulses
Ventricular fibrillation
Ventricular fibrillation is fatal unless treated with immediate..
Defibrillation
Can you see atrial repolarization on an EKG?
No, it is hidden in the QRS complex
Six limb leads view the heart on the..
Frontal or vertical plane
Chest electrodes view the heart on the
Horizontal plane
What stage do the ventricles fill will blood?
Diastole..when the ventricles are relaxed!
The first heart sound is initiated at the onset of systole and reflect the closure of..
AV valves
The second heart sound occurs at the end of systole with abrupt closure of the..
Semilunar valves
2 periods of ventricular systole..
- isovolumetric contraction period
2. ejection period
Immediately after the closure of the AV valves, there is a 0.02 to 0.03 second period during which the pulmonic and aortic valves remain closed. During this time, THE VENTRICULAR VOLUME REMAINS THE SAME WHILE THE VENTRICLES CONTRACT, PRODUCING AN ABRUPT INCREASE IN PRESSURE**
Isovolumetric contraction period
Ventricles will contract until left ventricular pressure is slightly higher than aortic pressure and right ventricular pressure is higher than pulmonary artery pressure. At this point…
The aortic and pulmonic valves open
onset of ejection period
Approx ____% of stroke volume is ejected during the first quarter of systole
60
At the end of systole, the ventricles relax, causing a fall in intraventricular pressure. When this happens, the blood from the aorta and pulmonary artery begin to flow back towards the ventricles so WHAT HAPPENS?
Semi lunar valves shut! (heart sound 2)
Isovolumetric contraction is followed by..
Ventricular ejection
Isovolumetric relaxation is followed by..
Ventricular filling
What follows ventricular filling?
Atrial contraction
Atrial filling occurs during..
Both systole and diastole
bc there are no valves between the junctions of central veins and the atria
Right atrial pressure is decreased during…
Inspiration
Preload
Afterload
Cardiac contractility
Heart rate
all affect the hearts ability to…
increase its output
The amount of blood that the heart must pump with each beat and represents the volume of blood stretching the ventricular muscle fibers at the end of diastole
Pre load
It is determined by the amount of blood that remains in the ventricle at the end of systole (end systolic volume) plus the amount of venous blood returning to the heart during diastole
Pre load
The increased force of contraction that accompanies an increase in ventricular end-diastolic volume is referred to as the..
Frank Starling mechanism
The pressure or tension work of the heart
After load
An _____ influence is one that modifies the contractile state of the myocardium independent of the Frank Starling mechanism
inotropic
(i.e. sympathetic nervous system produces a positive inotropic effect by increasing calcium averrable for interaction between actin and myosin)
Sympathetic nervous system exerts a positive inotropic effect, hypoxia exerts a..
Negative inotropic effect
by interfering with ATP generation
What is constant across changing heart rates?
Time spent in Systole
Ejection period
What changes with changing heart rates?
Time spent in diastole
shorter time in diastole with a quicker HR
One of the dangers of ventricular tachycardia is the reduction in..
Cardiac output
heart doesn’t have adequate time to fill
