heart chapter 18
peripheral congestion
Right side fails -> blood pools in body organs -> edema (swelling of limbs)
Pumps deoxygenated blood into the pulmonary trunk via the pulmonary valve.
Right ventricle
The normal pacemaker of the heart is the __________.
SA node right answer feedback: The SA node generates impulses faster than the other node and sets the pace for the heart.
Describe this vessel of the heart: Inferior vena cava
Vein that brings deoxygenated blood from the lower half of the body, which is received by the right atrium.
Describe this vessel of the heart: Aorta
Largest artery in the body; receives blood from the left ventricle via the aortic valve; branches into the left common carotid, left subclavian, and brachiocephalic trunk.
Describe the structure of the myocardium?
Layer of the heart that is the muscle of the heart
When the cardiac cycle begins all four chambers are _____ and ventricles are ______with blood.
Relaxed, filled
step 2 of how the blood flows
The blood flows through the tricuspid valve into the right ventricle.
step 5 of how the blood flows
The blood releases carbon dioxide as waste and picks up a fresh supply of oxygen.
Describe this vessel of the heart: Superior vena cava
Vein that drains deoxygenated blood from the upper half of the body, which is received by the right atrium.
The right atrium Into which chamber of the heart do the superior vena cava, inferior vena cava, and coronary sinus return deoxygenated blood?
right atrium
The inferior vena cava brings blood from the lower regions of the body and empties into the __________.
right atrium right answer feedback: The right atrium receives blood both from the superior and inferior venae cavae.
The tricuspid valve is located between the __________.
right atrium and right ventricle right answer feedback: The tricuspid valve is located between the right atrium and the right ventricle.
The lining of the heart chambers is called the __________.
endocardium
Murmurs
Abnormal heart sounds caused by valvular disesase
The superior chambers of the heart are called the __________.
Atria
Describe coronary circulation
Blood flow through coronary arteries delivers oxygenated blood & nutrients to the myocardium Coronary veins remove carbon dioxide & wastes from mycardium
Describe the function of the myocardium?
Describe the function of the myocardium?provides a scaffolding for the heart chambers and assists in contraction/relaxation
What is pericarditis?
Inflammation of pericardium - Roughens membrane surfaces • Pericardial friction rub (creaking sound) heard with stethoscope
Step 8 of how the blood flows
Left ventricular contraction forces blood through the aortic valve into the aorta for distribution to the systemic circulation
Age-Related Changes Affecting the Heart
Sclerosis and thickening of valve flaps • Decline in cardiac reserve • Fibrosis of cardiac muscle • Atherosclerosis
Tachycardia
abnormally fast heart rate (>100 beats/min) - If persistent, may lead to fibrillation
The second "lub-dub"
he sound of the aortic and pulmonary valves closing soon after
initial phase of ventricular contraction in which tension and pressure in the ventricle increase, (av valves close) but no blood is pumped or ejected from the heart (semilunar can't open yet)
isovolumetric contraction
The first "lub-dub"
the sound of the mitral and tricuspid valves closing
Defective SA node may cause....
- Ectopic focus - abnormal pacemaker - AV node may take over • Sets junctional rhythm (40-60 beats/min)
What is Extrasystole? (premature contraction)
- Ectopic focus sets high rate - Can be from excessive caffeine or nicotine • To reach ventricles, impulse must pass through AV node
Defective AV node may cause..
- Heart block• Few (partial) or no (total) impulses reach ventricles • Ventricles beat at intrinsic rate - too slow for life - Artificial pacemaker to treat • ↑Rwaves enlarged ventricles • ↑ or↓ S-T segment cardiac ischemia • ↑ Q-T interval repolarization abnormality - ↑ risk of ventricular arrhythmias • Junctional blocks, blocks, flutters, & fibrillations
Potassium and the heart
- Hyperkalemia:• Alters membrane potentialsheart block & cardiac arrest - Hypokalemia:• Results in feeble heartbeat & arrhythmias
What Two conditions that severely weaken heart?
- Incompetent valve• Blood backflows so heart repumps same blood over and over - Valvular stenosis• Stiff flaps that constrict opening• Heart needs to exert more force to pump blood
What is Arrhythmias ?
- Irregular heart rhythms - Uncoordinated atrial and ventricular contractions
Pulmonary congestion (Lungs)
- Left side fails leads to blood backs up in lungs
Congestive heart failure (CHF)
- Progressive condition - CO is so low that blood circulation inadequate to meet tissue needs - Reflects weakened myocardium • Coronary atherosclerosis • Persistent high blood pressure • Multiple myocardial infarcts
What is Fibrillation?
- Rapid, irregular contractions - Useless for pumping blood to circulation ceases to brain death - Defibrillation to treat
Treatment for incompetent valve and or Valvular stenosis
- Replacing defective valve• Mechanical, animal, or cadaver valve
Describe the structure and function of the intrinsic conduction system.
-Network of noncontractile (autorhythmic) cells .-Initiate and distribute impulses to coordinate depolarization and contraction of the heart.
Junctional Rhythm
40-60 Regular! -the SA node is non functional as an result... - P wave often absent - slow rate - narrow QRS (not wide like ventricular)
What is an pulmonary valve?
A type of semilunar valve through which unoxygenated blood leaves the right ventricular.
Describe this vessel of the heart: Pulmonary trunk
Artery that supports pulmonary circulation by carrying deoxygenated blood from the right ventricle to the lungs for gas exchange; the pulmonary trunk and its branching arteries are the only arteries in the body that carry deoxygenated blood.
What is angina pectoris?
Chest Pain - What is is: thoracic pain caused by fleeting deficiency in blood delivery to myocardium - What it results in: weakened cells
relaxation phase of the heartbeat
Diastole
Papillary muscles
Each ventricle contains cone-shaped, muscular pillars called
ventricular fibrillation
Electrical activity is disorganized. Action potentials occur randomly throughout the ventricles. - results in chaotic, grossly abnormal ECG deflections - seen in acute heart attacks and after electrical shock
What do the atrioventricular valves do?
Ensure blood flows from the atria into the ventricles, preventing blood from flowing back into the atria These 2 valves are located between the atria and the ventricles. These valves are considered entrance valves because they allow blood to enter the ventricles. These look like basketball nets.
What are the coverings of the heart? Order from Superior to Inferior
Fibrous pericardium Parietal Layer of serous pericardium Pericardial Cavity Epicardium Myocardium Endocardium Heart Chamber
Step 7 of how the blood flows
From the left atrium, the blood flows through the bicuspid, or mitral valve into the left ventricle.
step 3 of how the blood flows
From the right ventricle, the blood flows through the pulmonic valve into the pulmonary artery.
calcium and the heart
Hypocalcemia: ↓ heart rate- Hypercalcemia: ↑ heart rate and contractility
Which of the following is NOT a role of the fibrous pericardium?
It facilitates heart contraction.
Choose the correct sequence of electrical current flow through the heart wall.
SA node, AV node, AV bundle, right and left bundle branches, subendocardial conducting network right answer feedback: Impulses generated by the SA node spread to the AV node, then to the AV bundle, then to the bundle branches, and finally to the subendocardial conducting network (Purkinje fibers).
period of time when the heart muscle is contracting
Systole
second degree heart block
The AV node fails to conduct some SA node impulses As a result.. there are more P waves than QRS waves In this tracing there are usually 2 P waves for each QRS waves
What is the Bicuspid valve?
The atrioventricular valve between the left atrium and the left ventricle
What is the tricuspid valve?
The atrioventricular valve between the right atrium and the right ventricle
skeletal muscle
The contractile molecules are very organized giving skeletal muscle a striated pattern, hence the name, "striated muscle". It is under voluntary control.
Why do cardiac muscle cells have intercalated discs?
The intercalated discs are low-resistance cell membranes that separate individual cardiac muscle cells. At each intercalated disc the cell membranes fuse with one another to form communicating junctions (gap junctions) that allow for nearly free diffusion of ions. The intercalated discs enable the muscle cells to synchronize during contraction.
step 6 of how the blood flows
The oxygenated blood flows through fpur pulmonary veins from the lungs into the left atrium.
step 4 of how the blood flows
The right and left pulmonary arteries carry unoxygenated blood to the right and left lungs for gas exchange.
What are the Semilunar Valves?
These 2 valves earned their name because the cusps of the valves resemble a half-moon. These valves control the outflow of blood from the right and left ventricles and are there-fore exit valves.
Chordae tendineae
These muscles are attached to the cusps of the atrioventricular valves by thin, strong connective tissue strings called
What is an aortic valve?
This is a type of semilunar valve. It is an exit valve that sees only oxygenated blood.
step 1 of how the blood flows
Unoxygenated blood blood enters the right atrium from the superior and inferior vanae cavae.
What is pulmonary circulation?
What is pulmonary circulation? flow of blood between the heart and lungs
What is systemic circulation?
What is systemic circulation? carries oxygenated blood away from the heart to the body, and returns deoxygenated blood back to the heart
What is a Myocardial infarction (heart attack)?
What it is: prolonged coronary blockage - What it results in: areas of cell death repaired with noncontractile scar tissue (i.e. fibrosis) • one heart attack makes another more likely • Caused by defects inintrinsic conduction system
Describe the location of the heart
Within the mediastinum of the thorax
Heart murmurs
abnormal heart sounds heard when blood hits obstructions• Usually indicate valve problems - Incompetent (or insufficient) valve: fails to close completely, allowing backflow of blood • Swishing sound - Stenotic valve: fails to open completely, restricting blood flow through valve • High-pitched sound or clicking
The coronary arteries arise from the __________.
aorta The two coronary arteries that supply the heart arise from the base of the aorta.
the period between atrial contractions when the atria are repolarizing
atrial diastole
During _____ systole, the atria contract, completely filling the relaxed ventricles with blood
atrial systole
Which of the following statements is NOT true about the shape, position, and location of the heart? a. The heart is located between the two lungs within the mediastinum. b. The heart is enclosed in a double-layered sac called the pleural membrane. c. Approximately two-thirds of the heart is found to the left of the midline. d.The heart is shaped like a cone with the base facing the right shoulder.
b. The heart is enclosed in a double-layered sac called the pleural membrane. right answer feedback: The heart is enclosed in a double-layered membrane called the pericardium.
The structure just deep to the fibrous pericardium is the __________.
parietal layer of the serous pericardium right answer feedback: The pericardial sac is lined by a serous membrane called the parietal pericardium.
cardiac muscle
branched striated fibers with one or two centrally located nuclei; -has intercalated discs and under involuntary control. - located in the heart wall. - pumps blood all over the body.
The __________ are attached to the AV valve flaps.
chordae tendineae The chordae tendineae, also known as the heartstrings, are attached to the flaps of the AV valves and prevent the valves from blowing into the atria when the ventricles contract.
The vessels that carry oxygen to the myocardium are called __________.
coronary arteries right answer feedback: The arterial supply of the coronary circulation is provided by the right and left coronary arteries.
Which of the following structures is superficial to the heart wall and serves to protect the heart, anchor the heart, and prevent the heart from overfilling?
epicardium right answer feedback: The epicardium lies on the outside surface of the heart and is an integral part of the cardiac wall.
Which is the correct sequence of layers in the heart wall, starting with the outer layer?
epicardium, myocardium, endocardium right answer feedback: The superficial epicardium, the middle myocardium, and the inner endocardium form the heart wall.
The contractile cardiac muscle fibers of the myocardium behave as a single, coordinated unit called a __________.
functional syncytium right answer feedback: Because cardiac cells are electrically coupled by gap junctions, they behave as a single unit called a functional syncytium.
Bradycardia
heart rate slower than 60 beats/min - May result in grossly inadequate blood circulation in nonathletes - May be desirable result of endurance training
normal sinus rhythm
heart rhythm originating in the sinoatrial node with a rate in patients at rest of 60 to 100 beats per minute
Blood flows from areas of _____ pressure to low pressure
high to low
heart valve purpose
keep blood flowing forward
The interventricular septum forms a dividing wall between the __________.
left and right ventricles right answer feedback: The interventricular septum separates the two ventricles.
Freshly oxygenated blood is delivered to the __________, and then it passes into the __________ to be pumped to the body tissues (systemic circuit).
left atrium; left ventricle
Which chamber of the heart sends oxygenated blood to the systemic circuit via the aorta?
left ventricle
During systemic circulation, blood leaves the __________.
left ventricle and flows directly to the aorta right answer feedback: The movement of oxygenated blood from the left ventricle to the aorta constitutes part of the systemic circuit.
When the mitral valve closes, it prevents the backflow of blood from the __________.
left ventricle into the left atrium right answer feedback: The mitral valve closes to prevent the backflow of blood from the left ventricle into the left atrium.
Guided by powerful signaling molecules, the human heart develops from __________.
mesoderm right answer feedback: The human heart, derived from mesoderm, forms a single chamber, or heart tube, that is pumping blood by the 23rd day of gestation.
The noncontractile cardiac muscle cells that initiate their own depolarization and cause depolarization of the rest of the heart are called __________.
pacemaker cells right answer feedback: Pacemakers are noncontractile cardiac muscle cells with an unstable resting membrane potential.
From the perspective of blood returning from the systemic circuit, identify the correct sequence of blood flow through the chambers of the heart.
right atrium, right ventricle, lungs, left atrium, left ventricle right answer feedback: As oxygen-poor blood returns to the heart from the system circuit, it will pass through the right atrium, right ventricle, lungs, left atrium, and left ventricle.
During pulmonary circulation, blood leaves the __________.
right ventricle and flows directly to the lungs right answer feedback: The movement of oxygen-poor blood from the right ventricle to the lungs is part of the pulmonary circuit.
The endocardium is composed of __________.
simple squamous epithelium
Cardiac output is __________.
the amount of blood pumped out of each ventricle in one minute remember ! cardiac output = heart rate × stroke volume
The period between the start of one heartbeat and the beginning of the next. Alternating period of contraction and relaxation.
the cardiac cycle
Receives oxygenated blood from pulmonary veins and empties it into the left ventricle?
the left atrium
What part of the heart is considered the systemic circuit pump?
the left ventricle right answer feedback: The left ventricle pumps blood to most body tissues and is considered the systemic circuit pump.
Which of the following valves is most often faulty in the heart?
the mitral, or bicuspid, valve ommon problems include when a valve can't open wide enough to let blood through (stenosis) or can't close tightly enough to prevent blood from flowing back into the heart (regurgitation).
The absolute refractory period refers to the time during which __________.
the muscle cell will not respond to a stimulus of any strength right answer feedback: During the absolute refractory period, a muscle cell will not respond to a stimulus of any strength.
The cardiac cycle includes all of the following events EXCEPT __________.
the number of times the heart beats in one minute right answer feedback: The cardiac cycle refers to the mechanical events occurring during ONE heartbeat.
The trabeculae carneae are located in the __________.
ventricles right answer feedback: The trabeculae carneae are located in the ventricles.