Module 07: Cardiovascular System (The Heart) Flashcards
This is a muscular organ that is essential for life because it pumps blood through the body.
Heart
How does the heart pump blood?
The heart contracts or pumps to generate a force to increase the pressure of the liquid at the pump above the pressure in the pipe. Thus allowing the liquid to flow from an area of higher pressure to lower pressure (If the pressure of the pump increases, the flow of the liquid through the pipe also increases)
These make up the cardiovascular system.
(1) Heart
(2) Blood Vessels
(3) Blood
How many blood is pumped of a healthy heart of an adult at rest?
5 Liters of Blood per minute
What happens to the pumping of the blood when we are exercising?
The amount of blood pumped per minute increases several fold. However if the heart loses its pumping ability for even a few minutes, blood flow from the blood vessels is detrimentally impeded.
This happens when the right side of the heart pumps blood to the lungs back to the left side of the heart through the vessels.
Pulmonary Circulation
This happens when the left side of the heart pumps blood to all other tissues of the body back to the right side of the heart through the vessels
Systemic Circulation
What is the function of the cardiovascular system?
(1) Generating blood pressure. Contractions of the heart generate blood pressure, which forces blood through the blood vessels.
(2) Routing blood. The heart separates the pulmonary and systemic circulations, which ensures that the blood flowing to tissues has adequate levels of O,.
(3) Ensuring one-way blood flow. The valves of the heart ensure a one-way flow of blood through the heart and blood vessels.
(4) Regulating blood supply. Changes in the rate and force. of heart contraction match blood flow to the changing metabolic needs of the tissues during rest, exercise, and changes in body position.
Explain the shape of the heart.
The adult heart is shaped like a blunt cone and is approximately the size of a closed fist, weighs less than 1 lb (It is larger when you are physically active, but decreases in size after approximately the age of 65)
This is the blunt, rounded point of the heart.
Apex
This is the flat part at the opposite end of the heart
Base
Where is the heart located?
The heart is located in the thoracic cavity between the two pleural cavities that surround the lungs.
This structure pertains to the heart, trachea, esophagus, and associated structures form a midline partition.
mediastinum
The heart is surrounded by its own cavity, which is known as the “_______________”
pericardial cavity
Why is it important for heath professionals to know the location and the shape of the heart in the thoracic cavity?
This knowledge enables them to accurately place a stethoscope to hear the heart sounds, to place chest leads for an electrocardiogram or to administer cardiopulmonary resuscitation
This is an emergency procedure that maintains blood flow in the body if a person’s heart stops.
cardiopulmonary resuscitation (CPR)
Describe the orientation of the heart.
The heart lies obliquely (at an angle) in the mediastinum, with its base directed posteriorly and slightly superiorly and its apex directed anteriorly and slightly inferiorly.
Describe the orientation of the apex.
The apex is also directed to the left of the midline of the sternum. The apex is just behind the 5th and 6th ribs at the 5th intercostal space and just to the left of the sternum.
Describe the orientation of the base
The base of the heart is located just behind the sternum and extends to the space just below the second rib, called the second intercostal space.
This is where the heart lies (space around the heart).
Pericardial Cavity
This is a double-layered sac that anchors and protects heart. This also forms the Pericardial Cavity. It also surrounds the heart and anchors it within the mediastinum.
Pericardium or pericardial sac
This pericardium is the outer layer of the pericardium and is composed of tough, fibrous connective tissue.
fibrous pericardium
This pericardium is the inner layer and consists of epithelial cells with a thin layer of connective tissue.
serous pericardium
This is the two parts of the serous pericardium
(1) Parietal pericardium
(2) Visceral pericardium or Epicardium
This serous pericardium lines the fibrous pericardium
Parietal pericardium (The parietal and visceral pericardia are continuous with each other where the great vessels enter or leave the heart. )
This serous pericardium covers the heart.
Visceral pericardium or Epicardium (The parietal and visceral pericardia are continuous with each other where the great vessels enter or leave the heart. )
This is located between the visceral and parietal pericardia, is filled with a thin layer of pericardial fluid produced by the serous pericardium
Pericardial fluid
This is the fluid produced by the serous pericardium. This also helps reduce friction as the heart moves within the pericardium.
pericardial fluid
Where are left and right atria located?
The right and left atria (entrance chamber) are located at the base of the heart,
Where are the left and right ventricles located?
They extend from the base of the heart toward the apex
This is known as the that extends around the heart, separating the atria from the ventricles.
Coronary sulcus (Two additional grooves, or sulci extend inferiorly from the coronary sulcus and indicate the division between the right and left ventricles. )
This lies on the anterior surface of the heart. This extend inferiorly and helps in indicating the division between the right and left ventricles
anterior interventricular sulcus
This lies on the posterior surface of the heart. This extends inferiorly and helps in indicating the division between the right and left ventricles
posterior interventricular sulcus
These carry blood from the body to the right atrium
superior and inferior vena cava
These carry blood from the lungs to the left atrium
four pulmonary veins
(1) left superior pulmonary vein
(2) left inferior pulmonary vein
(3) right superior pulmonary vein
(4) right inferior pulmonary vein
Blood flows from the ventricles through large arteries, often called the “_________________”
great vessels or great arteries.
This, arising from the right ventricle, splits into the right and left pulmonary arteries, which carry blood to the lungs.
pulmonary trunk
This, arising from the left ventricle, carries blood to the rest of the body.
aorta
How is blood conveyed from the heart to the rest of the body?
(1) Blood first enters the heart at the atria. Veins carry blood to the atria.
(2) The superior vena cava and inferior vena cava carry blood from the body to the right atrium, and four pulmonary veins carry blood from the lungs to the left atrium.
(3) Blood exits the heart at the ventricles.
(4) Blood flows from the ventricles through large arteries, often called the great vessels or great arteries.
(5) The pulmonary trunk, arising from the right ventricle, splits into the right and left pulmonary arteries, which carry blood to the lungs.
(6) The aorta arising from the left ventricle, carries blood to the rest of the body.
What are the four (4) chambers of the heart?
(1) left atrium (LA)
(2) right atrium (RA)
(3) left ventricle (LV)
(4) right ventricle (RV)
Blood enters the atria of the heart through blood vessels called “___________.”
veins
These function primarily as reservoirs, where blood returning from veins collects before it enters the ventricles. These are often characterized as small thin walled superior and holding chambers.
Atria (Contraction of the atria forces blood into the ventricles to complete ventricular filling.
The right atrium receives blood from three major openings:
(1) the superior vena cava
(2) the inferior vena cava, and
(3) the coronary sinus.
They drain blood from most of the body
(1) the superior vena cava
(2) the inferior vena cava
This drains blood from most of the heart muscle.
the coronary sinus.
These supplies the blood in the left atrium and usually drain blood from the lungs.
four pulmonary veins
(1) left superior pulmonary vein
(2) left inferior pulmonary vein
(3) right superior pulmonary vein
(4) right inferior pulmonary vein
The two atria are separated from each other by a partition called the ___________________.
interatrial (between the atria) septum.
These are the heart’s major pumping chambers. They eject blood into the arteries and force it to flow through the circulatory system.
Ventricles
What is the relationship between the ventricles and the atria.
The atria open into the ventricles, and each ventricle has one large outflow route located superiorly near the midline of the heart.
This pumps blood into the pulmonary trunk,
Right Ventricle
This pumps blood into the aorta
Left Ventricle
The two ventricles are separated from each other by the “_______________”
muscular interventricular (between the ventricles) septum
What is the difference between the right and the left ventricle in terms of structure.
The wall of the left ventricle is thicker than the wall of the right ventricle. As such, the wall of the left ventricle contracts more forcefully and generates a greater blood pressure than the wall of the right ventricle.
When the left ventricle contracts, the pressure increases to approximately _____________.
120 mm Hg.
When the right ventricle contracts, the pressure increases to approximately____________.
24 mm Hg or one-fifth of the pressure in the left ventricle.
The higher pressure generated by the left ventricle moves blood through _____________.
the larger systemic circulation
The lower pressure generated by the right ventricle moves blood through the ___________.
the smaller pulmonary circulation
What are the different valves of the heart?
(1) Tricuspid Valve
(2) Bicuspid Valve
(3) Pulmonary Valve
(4) Aortic Valve
What are the two types of valves?
(1) atrioventricular valves and
(2) semilunar valves.
The one-way flow of blood through the heart chambers is maintained by the ____________.
Heart Valves
This is located between each atrium and ventricle.
atrioventricular valves
This is the AV valve between the right atrium and the right ventricle . It is composed of three cusps or flaps of tissue.
Tricuspid Valve
This is the AV valve between the left atrium and the left ventricle. It is composed of two cusps
Bicuspid Valve
The bicuspid valve is also known as the “__________.”
mitral (resembling a bishop’s miter, a two-pointed hat)
What is the role of the Tricuspid and Bicuspid Valve?
These valves allow blood to flow from the atria into the ventricles but prevent it from flowing back into the atria.
What happens to the atrioventricular valves when the ventricles relax.
When the ventricles relax, the higher pressure in the atria forces the AV valves to open, and blood flows from the atria into the ventricles.
What happens to the atrioventricular valves when the ventricles contract.
In contrast, when the ventricles contract, blood flows toward the atria and causes the AV valves to close
This is the cone-shaped, muscular pillars found in each ventricle attached to the chordae tendinea.
Papillary muscles
The papillary muscles muscles are attached by thin, strong, connective tissue strings called ____________________to the free margins of the cusps of the atrioventricular valves.
chordae tendineae
What happens to the papillary muscles when the ventricles contract?
When the ventricles contract, the papillary muscles contract and prevent the valves from opening into the atria by pulling on the chordae tendineae attached to the valve cusps
These have three half-moon shaped cusps, and are valves between the pulmonary trunk and aorta. These are located between each ventricle and is associated with the great artery.
Semilunar heart valve
This is located between the right ventricle and the pulmonary trunk. They contain three pocketlike semilunar (half-moon-shaped) cusps
Pulmonary valve:
This is located between the left ventricle and aorta. They contain three pocketlike semilunar (half-moon-shaped) cusps
aortic semilunar valve
What happens to the semilunar valves when the ventricles relax?
When the ventricles relax, the pressures in the aorta and pulmonary trunk are higher than in the ventricles. Blood flows back from the aorta or pulmonary trunk toward the ventricles and enters the pockets of the cusps, causing them to bulge toward and meet in the center of the aorta or pulmonary trunk, thus closing the vessels and blocking blood flow back into the ventricles
What happens to the semilunar valves when the ventricles contract?
When the ventricles contract, the increasing pressure within the ventricles forces the semilunar valves to open
This is the plate of connective tissue that consists mainly of fibrous rings that surround the atrioventricular and semilunar valves and give them solid support. They also separate the atria from the ventricles and provides a rigid attachment site for cardiac muscle.
cardiac skeleton, or fibrous skeleton,
What is route of blood flow through the heart?
(1) Deoxygenated blood enters the right atrium from the systemic circulation through the superior and inferior vena cavae, and from heart muscle through the coronary sinus.
(2) Most of the blood flowing into the right atrium flows through the tricuspid valve and into the relaxed right ventricle. Before the end of ventricular relaxation, the right atrium contracts, and enough blood is pushed from the right atrium into the right ventricle to complete right ventricular ring
(3) Following right atrial contraction, the right ventricle begins to con- tract. This contraction pushes blood against the tricuspid valve, forcing it closed. After pressure within the right ventricle increases, the pulmonary semilunar valve is forced open, and blood flows into the pulmonary trunk. As the right ventricle relaxes, its pressure falls rapidly, and pressure in the pulmonary trunk becomes greater than in the right ventricle. The backflow of blood forces the pulmonary semilunar valve to close.
(4) The pulmonary trunk branches to form the right and left pulmonary arteries, which carry blood to the lungs, where CO, is released and O, is picked up.
(5) Oxygenated blood returning from the lungs enters the left atrium through the four pulmonary veins.
(6) Most of the blood flowing into the left atrium passes through the bicuspid valve and into the released left ventricle. Before the end of ventricular relaxation, the left atrium contracts, and enough blood is pushed from the left atrium into the left ventricle to complete left
(7) Following left atrial contraction, the left ventricle begins to contract. This contraction pushes blood against the bicuspid valve, forcing it closed. after pressure within the left ventricle increases, the aortic semilunar valve is forced open, and blood flows into the aorta.
(8) Blood flowing through the aorta is distributed to all parts of the body. except to those parts of the lungs supplied by the pulmonary blood vessels. As the left ventricle relaxes, its pressure tails rapidly, and pressure in the aorta becomes greater than in the left ventricle. The backflow of blood forces the aortic semilunar valve to close.
This is s thick and metabolically very active and therefore requires an ample blood supply
Cardiac muscle
They provide the pathway for blood through the heart wall.
Coronary arteries and cardiac veins
They supply blood to the wall of the heart. They also originate from the base of the aorta, just above the acetic semilunar valves.
Coronary arteries
Where does the left coronary artery open?
The left coronary artery originates on the left side of the aceta.
What are the three major branches of the left coronary artery?
(1) the anterior interventricular artery,
(2) the circumflex artery, and
(3) the left marginal artery.
This lies in the anterior interventricular sulcus
anterior interventricular artery
This extends around the coronary sulcus on the left to the posterior surface of the heart
circumflex artery
This extends inferiorly along the lateral wall of the left ventricle from the circumflex artery. This also supply much of the anterior wall of the heart and most of the left ventricle.
left marginal artery.
This originates on the right side of the aorta. It extends around the coronary sulcus on the right to the posterior surface of the heart and gives rise to the posterior interventricular artery, which lies in the posterior interventricular sulcus. This supplies blood to the right ventricle.
Right coronary artery:
This supplies blood to anterior heart wall and left ventricle
Left coronary artery:
This extends inferiorly along the lateral wall of the right ventricle.
Right marginal artery
In a resting person, blood flowing through the coronary arteries gives up approximately how much O2?
70% of its O2
Blood flowing through arteries to skeletal muscle gives up only about how much O2?
25% of its O2
Simplify the blood route in and from the heart.
(1) Superior and inferior vena cava
(2) Right atrium
(3) Tricuspid Valve
(4) Right Ventricle
(5) Pulmonary Semilunar Valve
(6) Pulmonary Trunk
(7) Pulmonary arteries (Lungs for pulmonary circulation)
(8)Pulmonary Veins
(9) Left Atrium
(10) Bicuspid Valve
(11) Left Ventricle
(12) Aortic Semilunar Valve
(13) Aorta (Body tissues - systematic circulation)
What happens to the percentage of O2 during exercise?
The percentage of O, the blood releases to skeletal muscle increases to 70% or more during exercise, but the percentage of O, the blood releases to cardiac muscle cannot increase substantially during exercise. Therefore, the rate of blood flow through the coronary arteries must increase above its resting level to provide cardiac muscle with adequate O, during exercise.
When is blood flow through the coronary arteries the greatest?
When the heart contracts, the blood vessels of the coronary circulation are compressed, reducing blood flow through them. As a consequence, blood flow into the coronary circulation is greatest while the ventricles of the heart are relaxed.
This drain blood from the cardiac muscle.
cardiac veins
This is a large vein located within the coronary sulcus on the posterior aspect of the heart.
coronary sinus
The heart wall is composed of three layers of tissues.
(1) the epicardium,
(2) the myocardium, and
(3) the endocardium
This is a thin, serous membrane forming the smooth outer surface of the heart. It consists of simple squamous epithelium overlying a layer of loose connective tissue and adipose tissue.
epicardium also called the visceral pericardium,
This is the thick, middle layer of the heart, composed of cardiac muscle cells. The myocardium is responsible for contraction of the heart chambers.
myocardium
This is the smooth inner surface of the heart, which consists of simple squamous epithelium over a layer of connective tissue. This also allows blood to move easily through the heart.
endocardium
The surfaces of the interior walls of the ventricles are modified by ridges and columns of cardiac muscle called “________________.” These are also present in the portions of the atria
trabeculaete carneae
These are elongated, branching cells that contain one, or occasionally two, centrally located nuclei and is rich in mitochondria. These contain actin and myosin myofilaments organized to form sarcomeres, which makes it striated.
Cardiac Muscle
These are formed by actin and myosin myofilaments and is used to create myofibrils
sarcomeres
These are responsible for muscle contraction, and their organization gives cardiac muscle a striated (banded) appearance much like that of skeletal muscle.
actin and myosin myofilaments
Where does the cardia muscle rely on for contraction:
Ca2+ and ATP (Calcium ions enter cardiac muscle cells in response to action potentials and activate the process of con- traction much as they do in skeletal muscle.
Why are cardiac muscles rich in mitochondria?
Cardiac muscle cells have many mitochondria, which produce ATP at a rate rapid enough to sustain the normal energy requirements of cardiac muscle. An extensive capillary network provides adequate O, to the cardiac muscle cells.
What happens when there is a large oxygen deficit in the cardiac muscle?
Development of a large oxygen deficit could result in muscular fatigue and cessation of cardiac muscle contraction.
What happens to the spiral bundles when the cardiac muscles contract
the spiral bundles twist to compress the contents of the heart chambers
The cardiac muscle cells are bound end-to-end and laterally to adjacent cells by specialized cell-to-cell contacts called “_____________” The membranes of these are highly folded, and the adjacent cells fit together, greatly increasing contact between them and preventing cells from pulling apart
intercalated disks
These specialized cell membrane structures in the intercalated disks allow cytoplasm to flow freely between cells. This enables action potentials to pass quickly and easily from one cell to the next. Thus allowing the the cardiac muscle cells of the atria or ventricles to contract at nearly the same time.
Gap Junctions
Describe the coordination of the stimulation and contraction of the areas of the heart.
(1) The heart is at rest and all chambers are relaxed.
(2) Cardiac muscle cells in the atrial wall are stimulated as action poten- tials spread across the atrial wall and towards the ventricles.
(3) Cardiac muscle cells in the atrial wall contract, pushing blood into the
ventricles.
(4) Cardiac muscle cells in the ventricular wall are stimulated as action potentials spread across the ventricular wall from the apex of the heart towards its base.
(5) Cardiac muscle cells in the ventricular wall contract, pushing blood into the great arteries.
How long does action potentials in the cardiac muscle take?
In contrast to action potentials in skeletal muscle, which take less than 2 milliseconds (ms) to complete, action potentials in cardiac muscle take approximately 200 to 500 ms to complete.
What initiates action potentials in the cardiac muscle?
action potentials in cardiac muscle can spread from one cell to adjacent cells through gap junctions at intercalated disks.
This is the initial phase where Na+ is critical for the next steps in producing contractions of cardiac muscle. This results from the opening of voltage-gated Na+ channels, which increases the permeability of the cell membrane to Nat. Sodium ions then diffuse into the cell, causing this.
Depolarization
What is the peak of depolarization?
At the peak of depolarization, the Na+ channels close, and a small number of K+ channels open. However, the Ca2+ channels remain open.
What happens in depolarization?
In this, sodium entry triggers opening of voltage-gated Ca2+ channels, and Ca2+ begins diffusing into the cell, contributing to the overall process.
This is where rapid repolarization takes place. This is primarily the result of the opening of voltage- regulated Ca2+ channels. The slow diffusion of Ca2+ into the cell is the reason the cardiac muscle fiber action potential lasts longer than the action potentials in skeletal muscle fibers. The
plateau phase
What is the peak of the plateau phase?
Na+ channels close, Some K+ channels open, Ca2+ channels remain open
What is the beginning of the repolarization phase?
The Ca2+ channels close and many K+ channels open, allowing K+ to move out of the cell.
This is when the membrane potential achieves its maximum degree of repolarization (figure 12.156) and returns to the resting membrane potential.
final repolarization phase
These are exhibited by the action potentials in the cardiac muscles and lasts about as long as the plateau phase of the action potential in cardiac muscle. These also allow cardiac muscle to contract and relax almost completely before another action potential can be produced.
refractory period
Why is the refractory period important?
The long refractory period in cardiac muscle prevents tetanic, sustained contractions from occurring, thus ensuring a rhythm of contraction and relaxation for cardiac muscle.
Which phase makes the action potential and its refractory period last longer.
Plateau phase
All the cells of the conduction system can produce spontaneous action potentials. The conduction system of the heart includes
(1) the sinoatrial node,
(2) atrioventricular node,
(3) atrioventricular bundle,
(4) the bundle branches, and
(5) Purkinje fibers.
This functions as the heart’s pacemaker, is located in the superior wall of the right atrium and initiates the contraction of the heart. It produces action potentials at a faster rate than other areas of the heart and has a larger number of Ca2+ channels than other cells in the heart.
sinoatrial node
Contraction of the atria and ventricles is coordinated by specialized cardiac muscle cells in the heart wall that form the ___________________ of the heart.
conduction system
These are drugs that slow the heart by decreasing the rate of action potential production in the SA node. These also decrease the rate at which Ca2+ moves through Ca2+ channels. As a result, it takes longer for depolarization to reach threshold, and the interval between action potentials increases.
Calcium channel blockers
This is located in the lower portion of the right atrium. The action potentials from SA node sent to this node, which allows action potentials spread slowly through it. The slow rate of action potential conduction allows the atria to complete their contraction before action potentials are delivered to the ventricles
atrioventricular node
This is a group of specialized cardiac muscle cells in the interventricular septum. The action potentials from AV node travel to this where it divides into a left and right bundle branches
atrioventricular bundle
This is formed from the branching of left and right bundles. This pass to the apex of the heart and then extend to the cardiac muscle of the ventricle walls
Purkinje fibers.
Explain the conduction system of the heart.
1 Action potentials originate in the SA node and spread through the myocardium of the right and left atrium, causing atrial contraction.
2 Action potentials reach the atrioventricular node/ When action potentials reach the AV node, they spread slowly through it and then into the atrioventricular (AV) bundle. The slow rate of action potential conduction in the AV node allows the atria to complete their contraction before action potentials are delivered to the ventricles.
3 The AV bundle then divides into two branches of conducting tissue, called the left and right bundle branches. Action potentials pass down the bundle branches toward the apex of the heart.
4 At the tips of the left and right bundle branches, the conducting tissue forms many small bundles of Purkinje fibers. The Purkinje fibers pass to the apex of the heart and then extend to the cardiac muscle of the ventricle walls.
The organization of the conduction system of the heart, particularly this, ensures that ventricular contractions begin at the apex
Purkinje fibers.
The SA node is the pacemaker of the heart, but other cells of the conduction system are also capable of producing action potentials spontaneously. For example, if the SA node is unable to function, another area, such as the AV node, becomes the pace- maker. The resulting heart rate is much slower than normal. When action potentials originate in an area of the heart other than the SA node, the result is called an “_____________________-.”
Ectopic beat
Ectopic beats may cause very small portions of the heart to contract rapidly and independently of all other areas. This condition reduces the output of the heart to only a few milliliters of blood per minute when it occurs in the ventricles.
Fibrillation
What happens when ventricular fibrillation stops?
Unless ventricular fibrillation is stopped, the person dies in just a few minutes.
During fibrillation, what should physicians do?
Defibrillation, where they apply a strong shock in the chest region which causes depolarization therefore allowing the SA node to recover and produce action potentials
These entail electrodes placed on the body surface and attached to this recording device that can detect the small electrical changes resulting from the action potentials in all of the cardiac muscle cells.
electrocardiogram
The normal ECG consists what?
(1) P wave,
(2) a QRS complex, and
(3) a T wave.
This results from depolarization of the atrial myocardium, and the beginning of this wave precedes the onset of atrial contraction.
P wave
This complex results from depolarization of the ventricles, and the beginning of this precedes ventricular contraction.
QRS complex
This represents repolarization of the ventricles, and the beginning of this precedes ventricular relaxation.
T-wave ( A wave representing repolarization of the atria cannot be seen because it occurs during the QRS complex)
The time between the beginning of the P wave and the beginning of the QRS complex is the ______________, commonly called the PR interval because the Q wave is very small. During this, the atria contract and begin to relax.
PQ Interval
This extends from the beginning of the QRS complex to the end of the T wave and represents the length of time required ventricular depolarization and repolarization.
QT Interval
The major waves and intervals of an electrocardiogram are labeled. Each thin horizontal line on the ECG recording represents __________________
I millivolt (mV)
The major waves and intervals of an electrocardiogram are labeled. Each thin vertical line on the ECG recording represents __________________
0.04 second. (length of time required for ventricular depolarization and repolarization.)
What is the role of the ECG?
ECG is a record of electrical events of the heart and is not a direct measurement of mechanical events. Each deflection in the ECG record indicates an electrical event within the heart and correlates with a subsequent mechanical event
Why is the atria known as the primer pump
The atria act as primer pumps because they complete the filling of the ventricles with blood,
Why is the ventricles known as the power pump
The ventricles act as power pumps because they produce the major force that causes blood to flow through the pulmonary and systemic circulations
This is the repetitive pumping process that begins with the onset of cardiac muscle contraction and ends with the beginning of the next contraction
cardiac cycle
What happens to the pressure when there is cardiac muscle contraction?
Pressure changes produced within the heart chambers as a result of cardiac muscle contraction move blood from areas of higher pressure to areas of lower pressure.
This refers to contraction of the two atria
Atria Systole
This refers to contraction of the two ventricles
Ventricular systole
This refers to the relaxation of the two atria
Atrial diastole
This refers to the relaxation of the two ventricles
Ventricular diastole
When the terms systole and diastole are used alone, they refer to ventricular _________________.
contraction or relaxation.
At the beginning of the cardiac cycle, what is the state of the atria and the ventricles?
At the beginning of the cardiac cycle, the atria and ventricles are relaxed, the AV valves are open, and the semilunar valves are closed
What are the major events of the cardiac cycle?
(1) Blood returning to the heart first enters the atria. Since the AV valves are open, blood flows into the ventricles, filling them to approximately 70% of their volume.
(2) Atrial systole-The atria contract, forcing additional blood to flow into the ventricles to complete their filling. The semilunar valves remain closed.
(3) Ventricular systole-At the beginning of ventricular systole, contraction of the ventricles pushes blood toward the atria, causing the AV valves to close as the pressure in the ventricles begins to increase.
(4) As ventricular systole continues, the increasing pressure in the ventricles
exceeds the pressure in the pulmonary trunk and aorta, the semilunar valves are forced open, and blood is ejected into the pulmonary trunk and aorta.
(5) Ventricular diastole-At the beginning of ventricular diastole, the pressure in the ventricles decreases below the pressure in the aorta and pulmonary trunk.
(6) The semilunar valves close and prevent blood from flowing back into the ventricles. As diastole continues, the pressure continues to decline in the ventricles until atrial pressures are greater than ventricular pressures. Then the AV valves open, and blood flows directly from the atria into the relaxed ventricles.
This presents the changes in the left ventricular volume as blood flows into and out of the left ventricle as a result of the pressure changes.
Volume Graph
This records the closing of valves caused by blood flow/
Blood Flow
This was originally developed to listen to the sounds of the lungs and heart and is now used to listen to other sounds of the body as well.
Stethoscope
This sound can be represented by the syllable lubb. This has a lower pitch than the second. It occurs at the beginning of ventricular systole and results from closure of the AV valves
First Heart Sound
This heart sound can be represented by dupp. This occurs at the beginning of ventricular diastole and results from closure of the semilunar valves
Second Heart Sound
When does the ventricular diastole occur in terms of heart sounds?
Ventricular diastole occurs between the sec- ond heart sound and the first heart sound of the next beat.
When does the ventricular systole occur in terms of heart sounds?
ventricular systole occurs between the first and second heart sounds.
This heart valve does not close completely, they also leak when they are supposed to be closed and allow blood to flow in the reverse direction.
Incompetent valve
These are known as abnormal heart sounds and are usually a result of faulty valves.
murmurs
This happens when the opening of the valve is narrowed; hence enabling a swishing sound to precede it.
stenosed
This is the volume of blood pumped by either ventricle of the heart each minute
Cardiac Volume
This is the volume of blood pumped per ventricle each time the heart contracts,
Stroke volume (SV)
This is the number of times the heart contracts each minute.
heart rate (HR)
How is the Cardiac Volume computed?
Cardiac output can be calculated by multiplying the stroke volume times the heart rate: (mL/min) SV X HR (ml/beat) (beats/min)
What is the normal value of the cardiac output, the stroke volume, and the heart rate
(1) the heart rate is approximately 72 beats/min,
(2) the stroke volume is approximately 70 mL/beat
(3) cardiac output is slightly more than 5 L/min
This results from the heart’s normal functional characteristics and does not depend on either neural or hormonal regulation. It is functional whether the heart is in place in the body or is removed and maintained outside the body under proper conditions.
Intrinsic regulation
This involves neural and hormonal control.
Extrinsic regulation
This extrinsic regulation of the heart results from sympathetic and parasympathetic reflexes
Neural regulation
This extrinsic regulation of the heart results from the epinephrine and norepinephrine secreted by the adrenal medulla
hormonal regulation
This refers to mechanisms contained within the heart itself.
Intrinsic regulation
This is the degree to which the ventricular walls are stretched at the end of diastole, and venous return is the amount of blood that returns to the heart.
Preload
What happens when the venous return increases?
If venous return increases, the heart fills to a greater volume and stretches the cardiac muscle fibers, producing a greater preload and stroke volume and cardiac output.
What happens when the venous return decreases?
If venous return decreases, resulting in a lower preload, the cardiac output decreases.
The relationship between preload and windows stroke volume is called ____________ of the heart.
Starling’s law (Starling’s law of the heart has a major influence on cardiac output. For example, muscular activity during exercise causes increased venous return, resulting in increased preload, stroke volume, and cardiac output.)
This refers to the pressure against which the ventricles must pump blood
Afterload
Describe the case of patients with hypertension
The heart must do more work to pump blood from the left ventricle into the aorta, which increases the workload on the heart and can eventually lead to heart failure.
This is the amount of blood that returns to heart
Venous return
This refers to mechanisms external to the heart, such as either nervous or chemical regulation.
Extrinsic regulation
