Unit 2-Heart Physiology Flashcards
Why doesn’t cardiac muscle require nervous stimulus?
Because the heart uses an intrinsic method of conduction
What kind of cells are autorhytmeic cells? Where can these cells be found
- Noncontractile, leaky cells
- In the heart muscle
What does leaky cells mean?
Cells have an unstable resting membrane potential where there is reduced permeability to potassium ( This means sodium is able to leak in but potassium isn’t moving out)
Describe the movement and type of ion that leads to an action potential.
The influx of calcium will cause an action potential
How are the autorhytmic cells connected?
Intercalated disk
In regards to the heart muscle, what will an action potential lead to?
Muscle contraction
What allows for the inflow of calcium ions during an intrinsic conduction?
Threshold being reached and at that threshold ion channels open up which allow for calcium to flow in
Depolarization in the intrinsic conduction is called _____ potential
Pacemaker potential
Describe the process that gives rise to the pacemaker potential
- Sodium flows into noncontractile leaky cells
- Potassium can’t flow out so positive accumulates
- Once threshold is reached, ion channels open which allow for Calcium to flow in
- The influx of calcium triggers muscle contraction
Where is the sinoatrial node? What action comes from sinoatrial node?
-top right atrium beneath coronary sinus
-Main pacemaker of the heart; generates action potential and depolarization occurs here
(Depolarization starts here)
Where is the AV node? What actions are involved in the AV node?
- top of ventricles
- Directional pathway down the apex: signal shoots down the bundle of his
Where is the bundle his? What actions are associated with the bundle his?
- Middle of the heart and down the interventricular septum
- Branches into the left and right bundles branches
Where is the bundle branches? What action is associated with the bundle branches?
- where the bundle of his has split into right and left
- Sends signal up walls of purkinje fibers
Where are the purkinje fibers? What are the actions associated with Purkinje fibers?
- Ventricle walls at apex
- Deliver impulse to papillary muscle
Describe the type of innervation and effect on heart in the cardioacceleratory center
- Sympathetic innervation
- Increases heart rate
Describe the type of innervation and effect on the heart at the cardioinhibitory center.
- Parasympathetic innervation
- Decreases heart rate: asleep/ at rest
What kind of recording does the ECG reflect?
ECG is a graphical recording of electrical events of the heart.
List the types of deflection waves that can occur in a ECG.
- P wave
- T wave
- QRS complex
In an ECG, what does the P wave show?
-depolarization of the atria
In an ECG, what does the QRS complex show?
Depolarization of ventricles
Repolarization of atria
In an ECG, what does the T wave show?
Repolarization of the ventricles
What information can be drawn from an ECG?
- Diagnosis of disruptions/pathologies in conduction of system heart
- Heart rate determined by picking any particular portion of ECG and then determining time from that point to the next point.
What causes normal heart sounds?(Give broad answer)
Closing of valves
What cause the LUB sound heard in a normal heart sound?
LUB sound comes from the AV (atrioventricular) valve closing
What causes the DUP sound heard in a normal heart sound?
-DUP sound comes from SL (semilunar ) valves closing
What is a murmur
A third abnormal sound that results in an extra sound which is caused by the backflow of blood thru the valves.
What are components of the cardiac cycle
- Systole and diastole of atria
- Systole and diastole of ventricles
In the cardiac cycle, how does blood move?
The contraction of the heart chambers (atria and ventricles) creates pressure which moves the blood
Describe the contraction and relaxing seen in cardiac cycles.
As the atria contracts, the ventricle is relaxing
As the ventricles contract, the atria is relaxing
What is the average BP on the LEFT side of the heart:
120/80
What is the average BP on RIGHT side of the heart?
24/8
What is cardiac output?
The quantity of blood leaving the heart per minute
The difference between amount of blood at maxmium and the rest amount possible
Formula for Cardiac Output
stroke volume * heart rate
What is the cardiac reserve?
The quantity of excess blood that can be pushed thru the heart in times of need
What is the average cardiac reserve for our age group?
20-26L
What is stroke volume?
Quantity of blood that can be pushed out of the heart during each contraction
The difference between the quantity of blood in ventricles before and after they systolate (contract)
What is end diastolic volume?
The end systolic volume.
What is seen in a tachycardia pathology?
-Abnormally high resting heart (bpm >100)
What is seen in a bradycardia pathology?
Abnormally slow resting heart (BPM <60)
disincludes people who are athletic
What is something that will be seen in every type of congestive heart failure?
-Low cardiac output
What occurs in myocardial infarctions?
-Heart attack; lower level of blood supply results in less ability to contract
What occurs in high blood pressure?
The excess pressure from blood in aorta reduces ejection fraction from heart
Diastolic value
Describe the process of heart development.
- embryonic orgin at the mesoderm layer
- Two separate tubes of endothlieum
- Tubes fuse together
- Formation of chamber
- D-looping( heart flipping and dosing there is a rightward bending)
- Chamber continues to develop and separate from each other
- Short cut hole closes at birth and now becomes fossa ovalis
What is the ductus arteriosus?
- In an unborn baby this is the connection that will allow blood to bypass the lungs
- is between the aorta and pulmonary trunk
What is the ligamentum arteriosum?
-remnants of the ductus arteriosus
What is valve sclerosis?
- happens due to age
- build up of plaque of raphe which makes them more thick
- reduced cardiac output
- valves become less functional-> blood leakage
- natural process
What happens in decreased cardiac reserve?
Indirect relationship where as you age there is a loss in the ability to have a large cardiac reserve
What happens in fibrosis of myocardium?
- Failing to use the myocardium can result in atropy where it becomes noncontractile tissue
- Loss in ability to contract strongly
What happens in atherosclerosis
- Buildup of plaque and deposits along the inside of blood vessels
- This reduces the diameter of the blood vessel
How can you offset valve sclerosis?
Healthy diet that is low in sodium and lipids/fats
