Chapter 20: The Cardiovascular System-The Heart
Briefly describe why cardiac tissue cannot repair itself after damage?
**Cardiac tissue lacks stem cells in cardiac muscle and mature cardiac muscle fibers cannot go through MITOSIS. [When tissue becomes damaged the cells are replaced by non-contractile fibrous scar tissue.]
All of the following are true of sympathetic nerves extending from the cardiac accelerator never of the medulla oblongata
- Innervation of the heart speeds up the RATE of DEPOLARIZATION of the SA node - It is composed of two neurons a short one, and a long one - It innervates the SA node, AV node and myocardium [WRONG the neurons release epinephrine, binding beta 1 receptors]
Which of the following are true of the parasympathetic division of the ANS and the heart
- It decreases normal SA rhythm - It releases acetylcholine at the SA node - It is cranial nerve X [Vagus nerve] innervates SA node
During the cardiac cycle the
- P-Q segment lasts 0.4 segments [WRONG 0.1 sec] - Ventricular pressure is highest during QRS complex [CORRECT] - 2nd heart sound corresponds to T wave on an ECG - 1st heart sound corresponds to P wave on an ECG
Cardiovascular benefits when exercising
- Physiological cardiomegaly - Reduced blood pressure - Increased delivery of oxygen to tissues
Which of the following techniques is not used on an end-stage heart patient that undergoes a cardiac transplant? - The patient is placed on a heart lung bypass machine - The patient will remain on immunosuppressants - The chest cavity is exposed through a midsternal incision - The vagus nerve is reattached
- The vagus nerve is reattached
A patient under care for a cardiac condition is given a calcium channel blocker. This drug will?
- decrease the strength of contraction - decrease BP, dilate coronary arteries - produce negative inotropic effect
significant predictors of coronary artery disease are
- elevated levels of lipoproteins, fibrogen, homocysteins, C-reactive proteins - HIGH BP, diabetes, obesity, sedentary lifestyle and smoking - family history
the length of time in a normal ECG from R to R is
0.8 seconds
In comparison to skeletal muscle fibers, the contractile fibers of the heart are depolarized for ____ period of time.
A Longer
Hemorrhage with a large loss of blood causes ________.
A lowering of blood pressure due to change in cardiac output
a pain in the chest related to reduced coronary circulation due to coronary artery disease (CAD) or spasms of vascular smooth muscle in coronary arteries.
ANGINA PECTORIS
After the T wave on an ECG what corresponding event occurs in the cardiac cycle?
ATRIAL and VENTRICULAR diastole
Damage to the ________ is referred to as heart block.
AV Node
Which events occur when the semilunar valves are open?
AV valves are closed, ventricles are in systole, and blood enters pulmonary arteries and aorta.
Where in the conduction system do action potentials propagate most slowly?
Action potentials propagate most slowly through the AV node.
What is the function of foramen ovale during fetal life?
Allowing blood to flow directly from the right atrium into the left atrium.
What is the significance of an enlarged Q wave?
An enlarged Q wave may indicate a myocardial infarction (heart attack).
This groove found on the surface of the heart marks the boundary between the right and left ventricles.
Anterior Interventricular Sulcus
Blood leaving the left ventricle passes through which structure?
Aortic Semilunar Valve
What is the disorder in which the aortic semilunar valve is narrowed?
Aortic Stenosis
damage to the truncus arteriosus would hinder the development of the?
Ascending Aorta and Pulmonary trunk
This pouch-like structure increases the total filling capacity of the atrium.
Auricle
The process of listening to heart sounds using a stethoscope is referred to as
Auscultation
The right ventricle will not form if there is damage to the
BULBUS CORDIS [arises from primitive heart tube]
Which factors influence heart rate?
Body temperature, gender, and age.
Elevated levels of _______________ increases HR and strengthens the contractions.
CALCIUM
The area in the mesodermal tissue that the heart arises from is the
CARDIOGENIC AREA [which forms the endocardial tubes and fuses into the primitive heart tube]
This is a network of specialized cardiac muscle fibers that provide a path for each cycle of cardiac excitation to progress through the heart.
Cardiac Conduction System
The difference between a person's maximum cardiac output and resting cardiac output is called the
Cardiac Reserve
A corrective cardiac procedure in which a large piece of a patient's own latissimus dorsi muscle is wrapped around the heart and stimulated by an implanted pacemaker to assist the pumping action of a damaged heart.
Cardiomyoplasty
Normal heart sounds are caused by which events?
Closure of the Heart Valves
Foramen ovale ________.
Connects the two atria in the fetal heart.
Which diagnostic procedure for CAD is used to visualize coronary blood vessels?
Coronary angiography is used to visualize blood vessels.
After the semilunar valves close, elastic recoil of the aorta causes a slight increase in aortic pressure producing
DICROTIC NOTCH
If cardiac muscle is deprived of its normal blood supply, damage would primarily result from ________.
Decreased Delivery of Oxygen
What type of tissue comprises the valves of the heart?
Dense Connective Tissue
In a fetus, this structure allows blood to flow directly from the pulmonary trunk into the aorta.
Ductus Arteriosus
During the cardiac cycle the amount of blood remaining in the ventricles when the semilunar valves close (AFTER EJECTION) is called the?
END SYSTOLIC VOLUME
Physiological cardiomegaly is a result of
EXCESSIVE EXERCISE
(T/F) When heart rate exceeds 160 bpm venous return increases
FALSE
True or False: An ECG provides direct information about valve function.
False
What are some age-related changes of the heart?
Fibrosis of cardiac muscles, atherosclerosis, and decline in cardiac reserve.
The outermost layer of the pericardium, which consists of inelastic dense irregular connective tissue, is called the
Fibrous Pericardium
What is the role of HDL?
HDL removes excess cholesterol from body cells and transports it to the liver for elimination.
In comparison to a sedentary individual, a well-trained athlete will usually have which characteristics?
Higher cardiac reserve, higher stroke volume, hypertrophy of the heart, and resting bradycardia.
Which condition would lead to an increase in the afterload for the ventricles thus lowering stroke volume and cardiac output?
Hypertension
All of the following are indicators of increased afterload EXCEPT: increase in ESV, decrease in ESV, hypertension, decrease in stroke volume.
INCREASE in ESV since increased afterload makes it harder for the ventricle to push blood through the vessels
The cardia assisted device aids in delivery of blood to the myocardium and to the peripheral tissue by providing counterpulsations.
INTRA-aortic balloon pump
Which patients are candidates for cardiac transplantation?
Individuals with end-stage heart failure or severe coronary artery disease are candidates for cardiac transplantation.
Contraction of the ventricles of the heart leads to blood moving directly
Into Arteries
The second heart sound is heard during which phase of the cardiac cycle?
Isovolumetric Relaxation
Rising ventricular pressure corresponds to the
LUBB sound
Which chamber of the heart is surrounded by the thickest layer of myocardium?
Left Ventricle
Cardiac output is the volume of blood ejected from the ______ ventricle into the _____ each minute.
Left or right, aorta or pulmonary trunk
What is the pathway of systemic circulation?
Left ventricle --> aortic valve --> aorta and systemic arteries --> in systemic capillaries, blood loses oxygen and gains carbon dioxide --> superior vena cava/inferior vena cava/coronary sinus --> right atrium (deoxygenated blood).
The anatomical region found between the lungs that extends from the sternum to the vertebral column and from the first rib to the diaphragm.
Mediastinum
This part of the brain contains the cardiovascular center that regulates heart rate.
Medulla Oblongata
Which layer of the heart wall consists of cardiac muscle tissue?
Myocardium
Which electrocardiogram (EKG) wave represents atrial depolarization?
P Wave
the sinus venosus of the heart arises from the
PRIMITIVE HEART TUBE
Second degree heart block can be identified by
PROLONGED P-Q segment
Small muscle masses attached to the chordae tendineae are the ________.
Papillary Muscles
When is the partitioning of the heart complete?
Partitioning of the heart is complete by the end of the fifth week.
These muscular ridges are found on the anterior wall of the right atrium and extend into the auricles.
Pectinate Muscles
This is used to reduce friction between the layers of membranes surrounding the heart.
Pericardial Fluid
The membrane that surrounds and protects the heart is called the
Pericardium
Which valve prevents blood from flowing back into the right ventricle?
Pulmonary Semilunar Valve
The fact that the left ventricle of the heart is thicker than the right ventricle reveals that it ________.
Pumps blood against a greater resistance
What is the pathway of pulmonary circulation?
Right ventricle --> pulmonary valve --> pulmonary trunk and pulmonary arteries --> in pulmonary capillaries, blood loses carbon dioxide and gains oxygen --> pulmonary veins (oxygenated blood) --> left atrium.
List the sequence of structures that a cardiac action potential follows in order to excite normal contraction of the heart.
SA node, AV node, Bundle of His, Purkinje fibers
What are the parts of the conduction system of the heart?
SA node, AV node, bundle of his, right and left bundle branches, and purkinje fibers.
In what procedure is a section of skeletal muscle used to create a pouch inserted between the heart and the aorta to function as a booster pump?
SKELETAL MUSCLE ASSIST DEVICE
To auscultate the aortic semilunar valve, you would place your stethoscope in the ________.
Second intercostal space to the right of the sternum.
The second heart sound (dupp) closely follows which event?
Semilunar Valves Closing
This structure in the heart initiates action potentials that stimulate contraction of the heart at constant rate of about 100 beats per minute.
Sinoatrial Node
During contraction of heart muscle cells ________.
Some calcium enters the cell from the extracellular space and triggers the release of larger amounts of calcium from intracellular stores
This term refers to the period of time during a cardiac cycle when contraction of a chamber occurs and pressure within the chamber rises.
Systole
Which wave in an electrocardiogram represents repolarization of the ventricles?
T Wave
No SA node signal reaching the ventricles is a condition known as
THIRD DEGREE HEART BLOCK [any damage done to SA node = heart block]
(T/F) The death of cardiac muscle as a result of an interrupted blood supply is called INFARCTION
TRUE
(T/F) The innate heart rate is 100 BPM however the parasympathetic pathway of the autonomic nervous system slows the SA node down to 75 bpm.
TRUE
If the length of the absolute refractory period in cardiac muscle cells was the same as it is for skeletal muscle cells ________.
Tetanic contractions might occur, which would stop the heart's pumping action
Which four developmental defects occur in tetralogy of Fallout?
Tetralogy of Fallout involves an interventricular septal defect, an aorta that emerges from both ventricles, a stenosed pulmonary valve, and an enlarged right ventricle.
How much blood remains in each ventricle at the end of ventricular diastole in a resting person? What is this volume called?
The amount of blood in each ventricle at the end of ventricular diastole - called the end-diastolic volume - is about 130 mL in a resting person.
Which coronary blood vessel delivers oxygenated blood to the walls of the left atrium and left ventricle?
The circumflex artery delivers oxygenated blood to the left atrium and left ventricle.
The coronary sulcus forms an external boundary between which chambers of the heart?
The coronary sulcus forms a boundary between the atria and ventricles.
How does the duration of an action potential in a ventricular contractile fiber compare with that in a skeletal muscle fiber.
The duration of an action potential is much longer in a ventricular contractile fiber (.3 sec = 300 msec) than in a skeletal muscle fiber (1-2 msec).
In what two ways does the fibrous skeleton contribute to the functioning of heart valves?
The fibrous skeleton attaches to the heart valves and prevents overstretching of the valves as blood passes through them.
Which heart sound is related to blood turbulence associated with closure of the atrioventricular valves?
The first heart sound (S1), or lubb, is associated with closure of the atrioventricular valves.
How does thickness of the myocardium relate to the workload of a cardiac chamber?
The greater the workload of a heart chamber, the thicker its myocardium.
When during embryonic development does the primitive heart begin to contract?
The heart begins to contract by the twenty-second day of gestation.
What are the functions of intercalated discs in cardiac muscle fibers.
The intercalated discs hold the cardiac muscle fibers together and enable action potentials to propagate from one muscle fiber to another.
What is the mediastinum?
The mediastinum is the anatomical region that extends from the sternum to the vertebral column, from the first rib to the diaphragm, and between the lungs.
Which component of the conduction system provides the only electrical connection between the atria and the ventricles.
The only electrical connection between the atria and the ventricles in the atrioventricular bundle.
How do papillary muscles prevent atrioventricular valve cusps from everting (swinging upward) into the atria?
The papillary muscles contract, which pulls on the chordae tendinae and prevents cusps of the atrioventricular valves from everting and letting blood flow back into the atria.
When you are exercising, contraction of skeletal muscles helps return blood to the heart more rapidly. Would this tend to increase or decrease stroke volume?
The skeletal muscle "pump" increases stroke volume by increasing preload (end-diastolic volume).
Define arrhythmia and discuss different categories of arrhythmias.
The term arrhythmia or dysrhythmia refers to an abnormal rhythm as a result of a defect in the conduction system of the heart. Arrhythmias are categorized by their speed, rhythm, and origination of the problem. Bradycardia refers to a slow heart rate (below 50 bpm); tachycardia refers to rapid heart rate (over 100 bpm); and fibrillation refers to rapid uncoordinated heartbeats. Arrhythmias originating in the atria are call supraventricular or atrial arrhythmias; those that originate in the ventricles are called ventricular arrhythmias.
What region of the heart is innervated by the sympathetic division but not by the parasympathetic division?
The ventricular myocardium receives innervation from the sympathetic division only.
Which layer is both a part of the pericardium and a part of the heart wall?
The visceral layer of the serous pericardium (epicardium) is both a part of the pericardium and a part of the heart wall.
Coronary Artery Bypass Grafting (CABG)
This treatment for coronary artery disease (CAD) uses blood vessels from other locations in the patient to repair blocked coronary arteries.
If we were able to artificially alter the membrane permeability of pacemaker cells so that sodium influx is more rapid, ________.
Threshold is reached more quickly and heart rate would increase
Contraction of the atria of the heart leads to blood moving directly
Through Atrioventricular Valves
The apex of the heart is normally pointed
To the Left of the Midline
Through which structure does blood pass from the right atrium to the right ventricle?
Tricuspid Valve
True or False: The myocardium is the layer of the heart that actually contracts.
True
True or False: Tissues damaged by myocardial infarction are replaced by connective tissue.
True
During heart transplants, the ________ nerves are severed resulting in a faster resting heart rate (approximately 100 beats per minute) after the transplant.
Vagus
Stimulation of this nerve reduces heart rate.
Vagus Nerve
Heart murmurs are often heard in individuals with abnormalities in the ______of the heart.
Valves
During which period does the largest volume of blood enter the arteries?
Ventricular Systole
Why is ventricular fibrillation such a serious arrhythmia?
Ventricular fibrillation is a serious arrhythmia because ventricular pumping stops, blood ejection ceases, and circulatory failure and death can occur without immediate medical intervention.
Isovolumetric contraction is the phase of the cardiac cardiac cycle in which
Ventricular pressure increases and ventricular volume remains the same.
The tricuspid valve is closed ________.
When the Ventricle is in Systole
during the prolonged depolarization called the plateau
calcium influx is balanced by the efflux of POTASSIUM ions
heart murmurs affecting the left AV valve would?
decrease Cardiac Output
One sign of hyperthyroidism is tachycardia. What can occur due to tachycardia?
decreased EDV
List conditions that would lead to increased stroke volume?
increased preload, decreased afterload, increased contractility
The primitive ventricle of the heart arises from the
primitive heart tube
QRS complex is the second wave seen on an ECG which represents
ventricular depolarization 0.08 seconds
