Heart and Blood - Exam 1 Flashcards
What does the heart anchor to in order to generate force?
Itself
What creates heart sounds?
Valves closing
What is the average heart rate for a normal person?
72 bpm
What is the average heart rate for an athlete?
55-60 bpm
What does the difference in average heart rates for normal and athletic people say about the heart?
Shows that the heart can adapt to physical stress
What happens when the heart is challenged?
Contracts harder
Do we have conscious control of the heart?
No. It is controlled by the Autonomic Nervous System
How many beats occur per lifetime?
2.5-3 Billion contractions
Where is the heart located?
Somewhat midline but tilted toward the left lung to fit in cardiac notch
What is the heart encapsulated by?
Connective tissue and fluid
What is the purpose of the fluid around the heart?
Provides lubrication for movement
What are the layers around the heart, from the inside-out?
Endocardium
Myocardium
Epicardium
What is the difference between the parietal and visceral layers?
Parietal is touching the organ
Visceral is not touching the organ
What is inside the sack around the heart?
Pericardial fluid
What happens to the pericardial fluid with inflammation? And why could this cause a problem?
It increases with increased inflammation, and with too much fluid around the heart, function decreases
What is pericarditis?
Inflammation
Arteries provide what?
Outflow
Veins provide what?
Inflow
What happens to cardiac muscle that is similar to that of skeletal muscle?
It responds and grows thicker with increased challenge
Which side of the heart has thicker walls?
Why?
Left side
Because it experiences more stress
What happens to the thickness of each side of the heart in the case of lung failure?
Right side will become thicker rather than the left
What are the two purposes of the heart valves?
Prevent backflow
Open and close in response to pressure
What is the name of the left atrioventricular valve?
Mitral/bicuspid valve
What is the name of the right atrioventricular valve?
Tricuspid valve
What is the name of the left semilunar valve?
Aortic valve
What is the name of the right semilunar valve?
Pulmonary valve
Which valve is used for blood pressure?
Aortic
The layer where valves are located is what type of tissue?
Connective tissue
What is located in the connective tissue of the heart?
Nodes
What is special about the connective tissue that holds the nodes of the heart?
It is electrically insulated, allowing for electrical impulses/signals to travel through it
Where are aortic valve sounds heard?
Second intercostal space at right sternal margin
Where are pulmonary valve sounds heard?
Second intercostal space at left sternal margin
Where are tricuspid valve sounds heard?
5th intercostal space at right sternal margin
Where are mitral valve sounds heard?
5th intercostal space (over apex) in line with middle clavicle
Explain the process of a cardiac contraction as blood returns to the heart (in terms of valves opening and closing)
1) . AV Valves Open- blood flows into and pressurizes the atria, forcing AV valves open to allow blood to flow into the ventricles, and then atria contracts to allow further ventricular blood flow
2) . AV Valves Close- ventricles contract which forces AV valves closed, and papillary muscles contract to keep chordae tendinea tight, which prevents AV valves from everting into ventricles
3) . Semilunar Valves Open- Intraventricular pressure rises with ventricular contractions, pushing against semilunars and forcing them open
4) . Semilunar Valves Close- intraventricular pressure falls and ventricles relax, causing backflow from arteries, which closes the semilunar valves
What are the characteristics of cardiac muscle?
striations intercalated disc uninucleated occurs in walls of the heart involuntary
What are the characteristics of skeletal muscle?
striations multinucleated more organized usually attached to the skeleton voluntary
What ion must come in to stimulate cardiac muscle contraction?
Calcium
What allows the heart to refill during a cardiac cycle?
Lag time
How is every cell in the heart connected?
via gap junctions for communication
Which cells stimulate action potentials on their own?
autorhythmic cells
What is the resting membrane potential for a cardiac muscle cell?
-90mV
What is the resting membrane potential for a modified muscle cell?
-60mV
Where are autorhythmic cells found?
nodes of the heart
What are the nodes of the heart?
SA
AV
Purkinje Fibers
Which node paces the heart and why?
SA node because it is the fastest
What happens if one of the nodes in the heart stop working?
the average bpm would adjust to whatever the next node accomodates
What is the average bpm for the SA node?
60-100
What is the average bpm for the AV node?
40-60
What is the average bpm for the Purkinje Fibers?
20-40
Does the brain or heart have stronger electromagnetic signal and why?
heart
every beat creates a magnetic field that can be measured at any point on the body
What is the process of an impulse traveling through the nodes of the heart?
- SA node generalizes impulse
- Impulse pauses at AV node
- AV bundle connects atria to the ventricle
- Bundle branches conduct impulse through interventricular septum
- Purkinje Fibers depolarize contractile cells of both ventricles
Why does ventricular muscle have a longer plateau?
more calcium coming in for a longer period of time
What are the steps of the PQRST waves in terms of depolarization and repolarization?
- P wave- atrial depolarization- SA node initiation
- Between P & Q- atrial depolarization complete- impulse delay at AV node
- QRS complex- ventricular depolarization and atrial repolarization- impulse spreads to apex and down/away
- Between QRS complex & T- ventricular depolarization completion
- T wave- ventricular repolarization- impulse starts at apex and spreads up
What are the characteristics of a junctional rhythm in an ECG?
SA node is nonfunctional
P wave absent
AV node paces heart at 40-60 bpm
What are the characteristics of a second-degree heart block in an ECG?
Some P waves not conducted through AV node
More P than QRS seen
2:1 P waves to QRS
What are the characteristics of ventricular fibrillation in an ECG?
Irregular ECG deflections
What cases V-Fib?
No blood is being pushed out, things are just vibrating
What is an ectopic focus?
cell with positive charge leakage caused by lack of blood flow
What does a heart shock do?
completely depolarizes the heart and resets to normal contractions
What is ventricular filling also known as?
Passive filling
How is cardiac output calculated?
Stroke Volume (SV) + Heart Rate (HR)
How is SV calculated?
EDV-ESV
What is EDV
End diastolic volume
volume of blood in ventricle during diastole
What is ESV
end systolic volume
volume of blood in ventricle after contraction
What is preload?
degree of cardiac muscle stretch before contraction
What does the Frank-Starling law of the heart state?
stroke volume of the heart increases with increased EDV
Increased preload does what to stroke volume?
increases it
What does an increase in preload do to the muscles of the heart?
stretches out the muscle to generate more force
What is contractility?
contractile strength at a given muscle length
Increased contractility does what to stoke volume?
increases it
What is afterload?
pressure that must be overcome to eject blood
back pressure on aortic and pulmonary valves by arterial blood
Increased afterload does what to stoke volume?
decreases it because more energy is needed to overcome the pressure value
What regulates or influences heart rate?
autonomic nervous system
chemicals
age, gender, exercise
How does the sympathetic nervous system influence heart rate?
increases HR
increases contractility
increases calcium
works on nodes and heart muscle
How does the parasympathetic nervous system influence heart rate?
decreases heart rate
only reaches the nodes
What division of the autonomic nervous system is more active in athletes and why?
parasympathetic
HR (bpm) is decreased
What is the effect of athleticism and vagal tone?
athletes have increased vagal tone
What kind of relationship does the parasympathetic and sympathetic nervous system share?
push and pull
What happens when the valves of the heart become dysfunctional?
cardiac muscle gets bigger
affects preload
heart adapts and builds muscle to remain efficient
What affect do electrical events have on the heart?
arrhythmias
lose efficiency in the heart
What happens when arteries are blocked or there is a change in blood supply?
hypoxia or ischemia
What is ischemia?
decreased oxygen
decreased nutrients
muscles will die