Chapter 18 - The Heart Flashcards
What is the function of the heart valves?
Prevent back-flow of blood. Keep moving blood forward.
What are the two sets of valves in the heart? How are they different?
Atrioventicular (AV) Valves (atrium to ventricle), Semilunar Valves (ventricle and vessels leaving)
What are the two atrioventricular valves? What are their job?
Tricuspid Valve (right AV) and Mitral Valve (biscuspid, left av); Prevent back flow into atria
What are the two semilunar valves?
Aortic and Pulmonary Valves, prevent back flow into the ventricles
What makes heart valves open and close?
Open - atrial pressure greater than ventricle pressure (increase in pressure) Close- Atrial pressure less than ventricle pressure (decrease in pressure)
What are the major set of vessels entering the heart in the right atrium? What type of blood do they carry?
superior vena cava, inferior vena cava, coronary sinus (deoxygenated blood)
What are the major set of vessels entering the heart in the left atrium? What type of blood do they carry?
Right + Left pulmonary veins (from lungs) - oxygenated blood
Where do the vessels enter the heart in the left atrium?
Lungs
What are the major vessels leaving the heart?
Pulmonary Trunk and Aorta
Where does the pulmonary trunk leave from? What type of blood is it carrying?
leaves from right ventricle heading to lungs with deoxygenated lungs
Where does the aorta leave from? What type of blood is it carrying?
Leaves from left ventricle to body w/ oxygenated blood
What name is given to the blood vessels that supply the heart?
coronary arteries
What is the pathway on the right side of the heart known as?
Pulmonary Circuit
What type of blood does the pulmonary circuit?
Deoxygenated
What type of blood does the pulmonary circuit carry?
Deoxygenated
What type of blood does the systemic circuit carry?
Oxygenated blood to body
What is the pathway of blood through the right side of the heart?
right atrium, tricuspid valve, right ventricle, pulmonary semilunar valve, pulmonary trunk to lungs
What is the pathway of blood through the left side of the heart?
lungs, pulmonary veins, left atrium, bicuspid valve, left ventricle, aortic semilunar, aorta
What is the pathway of blood through the left side of the heart?
left atrium, bicuspid valve, left ventricle, aortic semilunar, aorta
What is the visceral pleura?
Lining of the heart wall
What is the pericardium?
double lined sac containing the heart
What is depolarization?
An electrical event that initiates contractions; rhythmic and spontaneous
About 1% of cells are…
self-excitable/have automaticity
What do gap junctions ensure?
Ensure heart contracts as unit, keeps heart contracting
What are the features of cardiac muscle?
Striated, branching, involuntary, intercalated discs, uninucleate
What is an intrinsic conduction system?
Conduction coming from within the heart
What are the 5 pathways of an intrinsic conduction system?
Sinoatrial Node (SA Node), Atrioventricular Node (AV Node),
What are the 5 pathways of an intrinsic conduction system?
Sinoatrial Node (SA Node), Atrioventricular Node (AV Node), Atrioventricular Bundle, R + L Bundle Branches, Purkinje Fibers
Atrioventricular Node: How does it compare to the SA Node? How are impulses affected? What is the depolarization rate?
1) Smaller diameter fibers, fewer gap junctions 2) delays impulses by .1 seconds 3) depolarization is 50 times/minute in absence of SA node input
Atrioventricular Node: How does it compare to the SA Node? How are impulses affected? What is the depolarization rate?
1) Smaller diameter fibers, fewer gap junctions 2) delays impulses by .1 seconds 3) depolarization is 50 times/minute in absence of SA node input
What is a atrioventricular bundle?
Bundle of His, the only electrical connection between atria and ventricles
What is the role of the right and left bundle branches?
Carry impulses toward the apex of the heart
Where do purkinje fibers carry impulses?
Carry impulses into the apex and ventricular walls for direct innervation to ventricular muscle walls
What is the rate of depolarization of both AV bundle and Purkinje fibers if AV node is inactive?
30 times/minute
Who regulates the extrinsic innervation of the heart?
Autonomic nervous system - sympathetic and parasympathetic
In extrinsic innervation, the rate of the heartbeat is modified by the…
autonomic nervous system
Where in the brain is the cardiac control center located?
medulla oblongata
The sympathetic nervous system is activated by what? What is the neurotransmitter? And what effect does it have on heart rate?
emotional or physical stressors; norepinephrine; increase heart rate
What is the neurotransmitter of the parasympathetic nervous system? What effect does it have on heart rate? How do impulses arrive at the heart?
acetylcholine; decrease heart rate, vagus nerve (cranial nerve X)
What is the difference between an ECG and EKG?
There is not a difference; an ECG is the European nomenclature
What does an ECG/EKG measure?
The action potential generated by nodal and contractile cells at a given time
What are the 3 waves on an ECG/EKG?
P wave, QRS complex, T wave
What is a P wave?
Shows depolarization of the atrium
What is a QRS complex?
Ventricular depolarization
What is a T wave?
Ventricular re-polarization
What type of wave is found at A?
P wave (atrial depolarization)
What type of wave is found at B?
QRS Complex (ventricular depolarization)
What type of wave is found at C?
T wave (ventricular repolarization)
What are the segments featured at D, E, and F?
Q,R,S
What is the first heart sound caused by?
AV valve closing
What is the second heart sound caused by?
SL valves closing
What is systole?
The period when either the atrial or ventrical are contracting
What is diastole?
Period during the cardiac cycle when the ventricles or the atria are relaxing
Define cardiac output
Volume of blood pumped by each ventricle in one minute
What is the formula to calculate cardiac output?
CO = heart rate (HR) x stroke volume (SV)
What is stroke volume?
Volume of blood pumped out by a ventricle with each beat
What is the approximate cardiac output at rest?
5.25L/min
In non-athletic people, maximum CO is about how much greater than resting CO?
4.5 times resting
In athletic people, CO can get up to even…
35 L/min
What is the cardiac reserve?
Difference between resting and maximum cardiac output
How do you calculate stroke volume?
SV = End diastolic - end systolic
What are the 3 main factors affecting stroke volume?
Preload, contractivity, afterload
What is preload?
Degree of stretch of cardiac muscle cells before they contract (affects EDV)
What is contractivity?
Contractile strength at a given muscle length (impacts ESV)
What is afteload?
Pressure htat must be overcome in orde for ventricles to eject (impacts ESV)
Hypertension increases afterload, how does this affect ESC and SV?
Increase ESV, decrease SV; this is why heart failure occurs in individuals w/ undiagnosed high blood pressure
What are two homeostatic imbalances that cause a blockage in circulation?
Angina pectoris and myocardial infraction (heart attack)
What is angina pectoris?
Temporary chest pain in thoracic cavity caused by fleeting deficiency in blood delivery to myocardium; cells are weakened bu not dead
What is a myocardial infraction?
- Heart Attack
- Prologned coronary blockage
- Dead cells repaired with non-contractive scar tissue
What are 6 abnormal intrinsic heart conditions?
- Arrhythmia
- Lack of coordination between atria and ventricles
- Fibrillation
- Defective SA node
- Defective S
- AV Node
What is an arrythmia?
Irregular heart rhythm
What is fibrillation? Why is it bad?
- Rapid irregular contractions
- Useless for pumping blood
What is a defective SA node? What happens if the AV node takes over?
- Ecotopic focus, abnormal pacemaker
- If AV node takes over, there will be slower junctional rhthym of 40 to 60 bpm
What is a defective AV Node?
- Partial or total heart block
- Lack of impulses reaching the ventricles from the SA node
What are types of abnormal heart rates?
- Tachycardia
- Bradycardia
What is tachycardia?
Too fast. HR >100 bpm which can lead to fibrillation
What is bradycardia?
- Too slow, heart rate <60 bpm
- Can result in inadequate circulation of blood
- common in endurance athletes
Congenital Heart Defects
- Some lead to mixng of deoxygenated and oxygenated blood
- Some include narrowed valves or vessels which increases pressure on heart
2 Types of Mitral Valve Malfunction
- Heart Murmur
- Stenosis
What is the cause of a heart murmur?
Caused by turbulent flow due to a leaky/damaged valve
What does stenosis cause?
Reduces flow due to stiff valve
What is the function of the superior and inferior vena cava?
- Superior - returns blood from body regions superior to the diaphragm
- Inferior - returns blood from body regions inferior to the diaphgragm
What is the role of the right and left pulonary arteries?
Deliver blood to the lungs to be oxygenated
Function of right and left pulmonary veins
deliver freshly oxygenated blood
What is another name for the right AV valve?
riscuspid valve,
Atria
two superior receivng chambers of the heart; right and left
Ventricle Functions
2 inferior located chambers for pumping blood, right and left
What is the function of the interventricular septum?
Separates the left and right ventricles
What is the role of the aorta?
Major systemic artery, arises from left ventricle
Function of pulmonary trunk
Main pulmonary artery,
The left AV valve is also called the…
bicuspid valve
Function of chordae tendinae
pull walls of inward during contraction
Role of papillary muscle
prevent valves from opening when ventricles contract
