Chapter 20 - Heart Flashcards
What does the pulmonary circuit do?
Carries blood between the heart and the lungs
What does the systemic circuit do?
Carries blood between the heart and body tissues
Name the four chambers of the heart.
- Right Atrium
- Right Ventricle
- Left Atrium
- Left Ventricle
What is the function of the right atrium?
Receives blood from the systemic circuit
What is the function of the right ventricle?
Pumps blood into the pulmonary circuit
What is the function of the left atrium?
Receives blood from the pulmonary circuit
What is the function of the left ventricle?
Pumps blood into the systemic circuit
Where is the heart located?
In the thoracic cavity
What are the two layers of the pericardium?
- Outer parietal layer
- Inner visceral layer (epicardium)
What is the pericardial cavity?
The space between the parietal and visceral layers
What is the purpose of pericardial fluid?
Lubricates and reduces friction
What is an auricle in relation to the heart?
An expandable outer extension of each atrium
What do the sulci on the heart’s surface contain?
Fat and blood vessels
What does the coronary sulcus mark?
The border between atria and ventricles
What separates the atria?
Interatrial septum
What separates the ventricles?
Interventricular septum
What are the atrioventricular (AV) valves?
Valves between atria and ventricles
What happens to the AV valves during atrial contraction?
They open
What happens to the AV valves during ventricular contraction?
They close
What are the semilunar valves?
Valves between ventricles and great vessels
What is the tricuspid valve?
The valve between the right atrium and right ventricle with 3 cusps
What is the mitral valve also known as?
Bicuspid valve
What is the function of the pulmonary valve?
Between the right ventricle and pulmonary trunk
What is the function of the aortic valve?
Between the left ventricle and aorta
What does the foramen ovale do?
Allows blood flow through the interatrial septum before birth
What are trabeculae carneae?
Muscular ridges on the internal surface of both ventricles
What returns blood from the head, neck, upper limbs, and chest to the right atrium?
Superior vena cava
What returns blood from the trunk, viscera, and lower limbs to the right atrium?
Inferior vena cava
What is the pathway of blood flow from the right atrium to the lungs?
Right atrium → tricuspid valve → right ventricle → pulmonary valve → pulmonary trunk → pulmonary arteries
What is the pathway of blood flow from the lungs to the left atrium?
Pulmonary veins → left atrium → mitral valve → left ventricle
What is the pathway of blood flow from the left ventricle to the body?
Left ventricle → aortic valve → ascending aorta → systemic circulation
How do the left and right ventricles differ?
- Left ventricle is larger with a thicker wall
- Left ventricle generates 4-6 times more pressure
- Left ventricle is round in cross-section; right ventricle is crescent-shaped
What is coronary circulation?
Supplies blood to the muscle tissue of the heart
What does the right coronary artery supply?
Right atrium and portions of both ventricles
What does the left coronary artery supply?
Left atrium, left ventricle, and interventricular septum
What is the great cardiac vein?
Drains blood from regions supplied by the anterior interventricular artery
What is coronary artery disease?
Partial or complete blockage of the coronary arteries
What causes a myocardial infarction?
Blocked coronary circulation leading to cardiac cell death
What is a heartbeat?
A single cardiac contraction
What are the two types of cardiac muscle cells?
- Autorhythmic cells (pacemaker and conducting cells)
- Contractile cells
What does autorhythmicity refer to?
Ability of cardiac muscle tissue to contract without neural or hormonal stimulation
Where are pacemaker cells primarily found?
Sinoatrial (SA) Node
What is the function of the atrioventricular (AV) node?
Coordinates electrical impulses between atria and ventricles
What is the pacemaker potential?
Gradual depolarization of pacemaker cells due to slow inflow of Na+
What is the rate of spontaneous depolarization of the SA node?
60-100 action potentials per minute
What is the rate of spontaneous depolarization of the AV node?
40-60 action potentials per minute
What does the SA node establish?
The sinus rhythm
What happens at the AV node during impulse conduction?
Impulse is delayed to allow atrial contraction before ventricular contraction
What are arrhythmias?
Abnormal heart rhythms
What is bradycardia?
Abnormally slow heart rate
What is tachycardia?
Abnormally fast resting heart rate
What is an ectopic pacemaker?
Abnormal cells generating action potentials faster than the SA node
What is an electrocardiogram (ECG or EKG)?
Recording of electrical events in the heart
What does the P Wave represent in an ECG?
Depolarization of atria
What does the QRS Complex represent in an ECG?
Depolarization of ventricles
What does the T Wave represent in an ECG?
Repolarization of ventricles
What is a P-R interval?
Time from start of atrial depolarization to start of ventricular depolarization
What is the significance of a prolonged Q-T interval?
Indicates electrolyte disturbances, conduction problems, or myocardial damage
What is ischemic heart disease?
Characterized by inadequate oxygen due to reduced blood flow
What is the absolute refractory period?
Time during which cardiac contractile cells cannot generate another action potential
What is the relative refractory period?
Time during which cardiac contractile cells respond only to strong stimuli
What is the cardiac cycle?
Period between the start of one heartbeat and the next
What happens during systole?
Contraction of the heart chambers
What happens during diastole?
Relaxation of the heart chambers
What is the Frank-Starling Principle?
As the end-diastolic volume increases, the stroke volume also increases
What is cardiac output (CO)?
Amount of blood pumped by the left ventricle in 1 minute
What factors affect stroke volume?
- End diastolic volume (EDV)
- Filling time
- Venous return
- Preload
What is contractility?
Amount of force produced during contraction at a given preload
What is cardiac reserve?
Difference between resting cardiac output and maximal cardiac output
What does preload correspond with?
Increase in contractile force
Define contractility.
The amount of force produced during contraction at a given preload
What effect does sympathetic stimulation have on the ventricles?
Causes the ventricles to contract with more force and increases the ejection fraction
What effect does parasympathetic stimulation have on cardiac contractions?
Reduces the force of cardiac contractions and decreases the ejection fraction
What is cardiac reserve?
The difference between the resting cardiac output and the maximal cardiac output
By how much can trained athletes increase their cardiac output?
700%
True or False: Cardiac output can increase indefinitely.
False
What happens to cardiac output when increased heart rate shortens filling time?
Stroke volume decreases and cardiac output plateaus and declines
