Chapter 15: CARDIOVASCULAR SYSTEM
Describe the tissue composing the each of the following 3 layers in the wall of a blood vessel: Tunica intima (endothelium)- Tunica media- Tunica externa-
-The wall of an artery consists of three distinct layers, or tunics. The innermost tunic, tunica interna (intima), is composed of a layer of simple squamous epithelium, called endothelium, that rests on a connective tissue membrane rich in elastic and collagen fibers. -The middle layer, tunica media, makes up the bulk of the arterial wall. It includes smooth muscle cells, which encircle the tube, and a thick layer of elastic connective tissue. The connective tissue gives the vessel a tough elasticity that enables it to withstand the force of blood pressure and, at the same time, to stretch and accommodate the sudden increase in blood volume that accompanies ventricular contraction. -The outer layer, tunica externa (adventitia), is relatively thin and chiefly consists of connective tissue with irregular elastic and collagen fibers. This layer attaches the artery to the surrounding tissues. It also contains tiny vessels (vasa vasorum) that give rise to capillaries and provide blood to the more external cells of the artery wall.
Describe the cardiac conduction system, including the roles of the SA node, the AV node, the AV bundle (bundle of His), and the Purkinje fibers.
A key portion of the conduction system is the SA node (sinoatrial node or sinuatrial node), which is a small, elongated mass of specialized cardiac muscle tissue just beneath the epicardium.The junctional fibers lead to a mass of specialized cardiac muscle tissue called the AV node (atrioventricular node). Once the cardiac impulse reaches the distal side of the AV node, it passes into a group of large conduction fibers that make up the AV bundle (atrioventricular bundle or bundle of His), and the impulse moves rapidly through them. The AV bundle enters the upper part of the interventricular septum and divides into right and left bundle branches that lie just beneath the endocardium. About halfway down the septum, the branches give rise to enlarged Purkinje fibers. These larger fibers conduct the impulse to distant regions of the ventricular myocardium much faster than cell-to-cell conduction could. As a result, the massive ventricular myocardium contracts as a functioning unit.
ischemia
A thrombus or embolus that partially blocks or narrows a coronary artery branch causes a decrease in blood flow
tachycardia
An abnormally fast heartbeat, usually more than 100 beats per minute at rest
The 5 types of blood vessels are: capillaries, arteries, veins, arterioles, and venules. Which blood vessels carry blood away from the heart?
Arteries
The 5 types of blood vessels are: capillaries, arteries, veins, arterioles, and venules. Which blood vessels carry blood back to the heart?
Arterioles
located between an atrium and a ventricle
Atrioventricular (AV) Valves-
How does blood pressure differ in arteries, arterioles, capillaries, venules, and veins?
Blood is carried through the body via blood vessels. An artery is a blood vessel that carries blood away from the heart, where it branches into ever-smaller vessels. Eventually, the smallest arteries, vessels called arterioles, further branch into tiny capillaries, where nutrients and wastes are exchanged, and then combine with other vessels that exit capillaries to form venules, small blood vessels that carry blood to a vein, a larger blood vessel that returns blood to the heart.
The 5 types of blood vessels are: capillaries, arteries, veins, arterioles, and venules. Which blood vessels are the sites of exchange of substances between the blood and body cells?
Capillaries
systole
Contraction of the heart chambers
What happens to the heart rate as a result of high blood pressure in the aorta and carotid arteries?
Decrease the heart rate. This action helps lower blood pressure toward normal.
tricuspid valve
Guards the atrioventricular orifice between the right atrium and the right ventricle. It is composed of three leaflets, or cusps, as its name implies. This valve permits the blood to move from the right atrium into the right ventricle and prevents it from moving in the opposite direction. The cusps fold passively out of the way against the ventricular wall when the blood pressure is greater on the atrial side, and they close passively when the pressure is greater on the ventricular side.
One cardiac cycle results in several deflections, or waves, which can be seen on an ECG. Which wave appears during atrial depolarization?
P wave
Which wave appears during ventricular depolarization?
QRS complex
What valves are located between the upper and lower chambers on each side?
Right -tricuspid Left -bicuspid/mitral
Now, trace the pathway of the coronary circuit, including these structures:
Right coronary artery, left coronary artery, circumflex artery, anterior interventricular artery, marginal artery, posterior interventricular artery, cardiac veins, coronary sinus, right atrium
Which part of the cardiac conduction system usually acts as the heart's pacemaker?
SA node (sinoatrial node or sinuatrial node)
Which wave/complex appears during ventricular repolarization?
T wave
The "heartbeat" heard through a stethoscope that sounds like "lubb-dupp" is due to the closing of the valves. Which valves close during the 1st sound (lubb)? Which close during the 2nd sound (dupp)?
The first part of a heart sound (lubb) occurs during ventricular systole, when the AV valves close. The second part (dupp) occurs during ventricular diastole, when the pulmonary and aortic valves close.
bicuspid (mitral) valve
The left atrium receives the blood from the lungs through four pulmonary veins—two from the right lung and two from the left lung. The blood passes from the left atrium into the left ventricle through the atrioventricular orifice, which a valve guards. This valve consists of two leaflets (shaped like a mitre, a type of headpiece). It prevents the blood from flowing back into the left atrium from the left ventricle when the ventricle contracts.
Distinguish between "systolic pressure" and "diastolic pressure".
The maximum pressure achieved during ventricular contraction
Distinguish between the pulmonary and systemic circuits of the cardiovascular system.
The pulmonary circuit sends oxygen-poor blood to the lungs to pick up oxygen and unload carbon dioxide. The systemic circuit sends oxygen-rich blood and nutrients to all body cells and removes wastes. Without circulation, tissues would lack a supply of oxygen and nutrients, and wastes would accumulate.
Describe the systole and diastole of the atria and ventricles during one cardiac cycle.
Their actions are regulated so that atria contract, called atrial systole, while ventricles relax, called ventricular diastole; then ventricles contract (ventricular systole) while atria relax (atrial diastole). Then the atria and ventricles both relax for a brief interval. This series of events constitutes a complete heartbeat, or cardiac cycle.
Where are the functional syncytia of the heart located?
Two such structures are in the heart—in the atrial walls and in the ventricular walls
What is the "blood-brain barrier"?
a filtering mechanism of the capillaries that carry blood to the brain and spinal cord tissue, blocking the passage of certain substances.
What is a functional syncytium?
a mass of merging cells that act as a unit
Tachycardia
a rapid heartbeat.
What is an electrocardiogram (ECG)?
a recording of the electrical changes in the myocardium during a cardiac cycle
bradycardia
a slow heart rate fewer than 60 beats per minute
What is a "murmur"?
abnormal sound caused by faulty valve
Atrial flutter
an abnormally rapid rate of atrial depolarization.
Which valves are closed during ventricular diastole?
aortic and pulmonary valves
Which valve is at the base of the aorta? Describe its structure and action:
aortic valve (aortic semilunar valve) which consists of three cusps. It opens and allows blood to leave the left ventricle as it contracts. When the ventricular muscles relax, this valve closes and prevents blood from backing up into the left ventricle.
he 5 types of blood vessels are: capillaries, arteries, veins, arterioles, and venules. Put these 5 in the correct order that blood will pass through from the time it leaves a heart ventricle until it gets to a heart atrium.
arteries, arterioles, capillaries, venules, and veins
Which of the 5 blood vessels in #32 above blood vessels have the thickest tunica media and the most elastic fibers?
artery
What are the 2 upper chambers of the heart called?
atria
Which valves are open during ventricular systole?
atrioventricular or AV valves
. What are precapillary sphincters? Why are they so important?
band of smooth muscle;close a capillary by contracting or open it by relaxing
angina pectoris
chest pain that results when the heart does not get enough oxygen
The coronary circuit is the pathway blood takes from the aorta to the surface of the heart (supplying the heart tissues with oxygen and nutrients) and then into the right atrium. Name and locate the 1st two branches of the aorta that carry blood into this circuit.
circumflex branch and anterior interventricular artery (or left anterior descending artery)
Describe how skeletal muscles and venous valves aid in the movement of blood through veins.
contracting skeletal muscles press on veins, moving blood from one valve section to another. This contraction of skeletal muscles helps push the blood through the venous system toward the heart
coronary thrombosis
damage to the heart muscle caused by a thrombus blocking a coronary artery
What is the name of the instrument used to record ECGs?
electrocardiogram
Name the heart wall layers described below:Inner layer (lines chambers and valves)-
endocardium
Name the heart wall layers described below:Outer layer (also called visceral pericardium) -
epicardium
What serous membrane lines this sac?
fibrous pericardium
What is blood pressure?
force of blood against arterial walls
myocardial infarction
heart attack
vasoconstriction
helps to reduce blood loss
Name two important ions which influence heart action.
high K+--->slows rate high Ca++--->increases rate
Identify the location of each of the following blood vessels connected to the heart: Pulmonary veins-
left atrium
Which side contains oxygenated blood?
left atrium
Which side of the heart receives deoxygenated blood from the body and pumps it to the lungs?
left atrium
Identify the location of each of the following blood vessels connected to the heart: Aorta-
left ventricle
Where is the "cardiac control center" located?
medulla oblongata (brain stem)
Name the heart wall layers described below:Middle layer (made of cardiac muscle tissue)-
myocardium
Why can you not see a wave during atrial repolarization?
no detectable electrical changes
What is the name of the loose-fitting fibrous sac around the heart?
parietal pericardium
What is the name of the space between the two serous membranes?
parietal pericardium
What is the purpose of the valves?
prevent backflow
Which valve is at the base of the pulmonary trunk?Describe its structure and action:
pulmonary valve (pulmonary semilunar valve), which consists of three cusps. This valve opens as the right ventricle contracts.
Ventricular fibrillation
rapid, uncoordinated depolarization of the ventricles.
diastole
relaxation of the heart chambers
Identify the location of each of the following blood vessels connected to the heart: Inferior vena cava-
right atrium
Identify the location of each of the following blood vessels connected to the heart: Superior vena cava-
right atrium
Which side of the heart contains deoxygenated blood?
right atrium
Which side of the heart receives oxygenated blood from the lungs and pumps it to the rest of the body?
right atrium
Identify the location of each of the following blood vessels connected to the heart: Pulmonary trunk (which branches into left and right pulmonary arteries)-
right ventricle
Bradycardia
slow heart rate
Trace the pathway that a drop of blood would travel from the venae cavae to the aorta. Know when it is oxygenated and when it is deoxygenated. As you describe this pathway, you will need to make sure you mention the following structures: the 4 chambers, the 4 valves, blood vessels (those mentioned in #7 above). A picture of the heart, such as Figure 15.9 in your textbook, will be very useful in tracing this pathway.
superior/inferior vena cava-->right atrium -->tricuspid valve-->right ventricle --> pulmonary SL valve --> pulmonary trunk --> pulmonary artery --> lungs (now blood becomes oxygenated) --> pulmonary veins --> left atrium --> bicuspid valve --> left ventricle --> aortic SL valve --> aorta --> body
How do sympathetic impulses affect the heart? How do parasympathetic impulses affect the heart?
the SA node normally controls heart rate, changes in this rate often involve factors that affect the pacemaker, such as the motor impulses carried on the parasympathetic and sympathetic nerve fibers
What happens to the heart rate as a result of high venous blood pressure in the venae cavae?
the receptors signal the cardioaccelerator reflex center, and sympathetic impulses reach the heart. As a result, heart rate and force of contraction increase, and the venous pressure is reduced.
Why do these vessels need to be thick-walled and elastic?
they carry much higher blood pressure
vasodilation
vasomotor impulses are inhibited, the smooth muscle cells relax, and the diameter of the vessel increases.
Which blood vessels have valves?
veins
What are the 2 lower chambers called?
ventricles
What serous membrane covers the heart?
visceral pericardium (epicardium)
