Chapter 5 Flashcards
What are the two parts of the cardiovascular system? Briefly, what are their functions?
a) heart, which pumps blood, and
b) blood vessels through which blood flows.
What is the purpose of circulation? What is the function of blood? Where is blood purified or
cleared of its wastes? At what sites does blood gain nutrients? What system collects and returns excess tissue fluid to the general circulation?
The purpose of circulation is to service the cells.
Blood brings oxygen and nutrients that cells need and removes their waste products.
Blood is purified of its wastes at the kidneys, liver, and lungs.
Blood gains nutrients at the lungs and intestines.
The lymphatic system collects excess tissue fluid and returns it to the cardiovascular system.
Name and describe the three types of blood vessels. What are their functions? How are they structurally different?
The three types of blood vessels are arteries, capillaries, and veins.
The Arteries: From the Heart
Arteries and arterioles always take blood away from the heart.
The arterial wall has three layers:
a) Endothelium = thin inner layer
b) Smooth muscle and elastic tissue = thick middle layer to give support under pressure and expand and spring back to absorb pressure
c) Connective tissue = outer layer for support
The constriction or dilation of arterioles controls blood pressure.
The Capillaries: Exchange
Arterioles branch into capillaries. The capillaries have walls that are only one cell thick and allow exchange of substances with tissue fluid.
Not all capillary beds are open at the same time. For example, after eating, the capillaries supplying the digestive tract are open while most capillaries serving the muscles are closed.
Contraction of a precapillary sphincter muscle closes off the bed, and then blood flows through an arteriovenous shunt, bypassing the capillary bed, going directly into a venule.
The Veins: To the Heart
Venules drain into veins that return blood to the heart.
Veins have much less smooth muscle and connective tissue than arteries.
Veins often have valves that prevent the backward flow of blood due to gravity when closed.
The heart is a double pump. What does this mean?
The heart is made up of myocardium, or cardiac muscle tissue, lying inside a fibrous pericardium.
In the heart, the right and left atria empty into the right and left ventricles, respectively.
Describe the structure of the heart regarding its chambers and valves. What kind of muscle is found in the heart? What is the pericardium? What are chordae tendineae? What is the function of the intercalated disks?
Atrioventricular valves occur between the atria and ventricles, and semilunar valves occur between the ventricles and the attached arteries.
Chordae tendineae strengthen atrioventricular valves.
Intercalated disks contain gap junctions and desmosomes, which join neighboring fibers together and make sure that cardiac fibers contract simultaneously
What is the function of the coronary arteries? What happens if they get clogged with cholesterol?
The myocardium receives oxygen and nutrients from the coronary arteries. If these arteries get clogged with cholesterol, it can lead to myocardial infarction (heart attack).
Trace the pathway of blood through the heart beginning with the superior and inferior vena cavae and ending with the aorta
1) superior and inferior vena cava,
2) right atrium,
3) right atrioventricular valve (tricuspid valve),
4) right ventricle,
5) pulmonary semilunar valve,
6) pulmonary arteries,
7) lungs,
8) pulmonary veins,
9) left atrium,
10) left atrioventricular valve (bicuspid valve),
11) left ventricle,
12) aortic semilunar valve,
13) aorta.
Oxygen-poor blood never mixes with oxygen-rich blood.
Define cardiac cycle. What is systole? What is diastole? What accounts for the “lub-dub” sounds when the heart beats?
Each heartbeat is called a cardiac cycle.
Systole = contraction phase of heartbeat
Diastole = relaxation phase of heartbeat
The heart sounds, “lub-dub,” are due to the closing of the atrioventricular valves, followed by the closing of the semilunar valves.
What are the functions of the following structures related to the electrical activity of the heart? sinoatrial (SA) node, atrioventricular (AV) node, atrioventricular bundle, Purkinje fibers
The sinoatrial (SA) node (pacemaker) initiates the beat and causes the atria to contract. The SA node is located in the upper dorsal wall of the right atrium.
The atrioventricular (AV) node conveys the stimulus and initiates contraction of the ventricles. It is located at the base of the right atrium near the septum.
The signal for the ventricles to contract travels from the AV node through the atrioventricular bundle to the smaller Purkinje fibers.
What role does the medulla oblongata play in control of the heartbeat? What hormones are released from the adrenal medulla to stimulate the heart?
A cardiac control center in the medulla oblongata regulates the heartbeat by way of the parasympathetic (slows heart rate) and the sympathetic (increases heart rate) systems.
Hormones (epinephrine and norepinephrine) of the adrenal medulla also stimulate the heart.
What is an electrocardiogram? What part of the cardiac cycle do the P wave, the QRS complex, and the T wave represent?
An electrocardiogram (ECG) is a recording of the electrical changes that occur in the myocardium during a cardiac cycle.
The P wave signals the atria are about to contract;
the QRS complex signals the ventricles are about to contract, and recovery of the ventricles produces the T wave.
The ECG can also detect various types of abnormalities, including ventricular fibrillation.
In what blood vessel is blood pressure the highest? In what blood vessels is blood pressure the lowest?
When the left ventricle contracts, a surge of blood flows through the arteries. Blood pressure is highest in the aorta and lowest in the superior and inferior vena cavae.
Define pulse. What causes a pulse?
The surge of blood entering the arteries following a heartbeat causes their elastic walls to stretch and then recoil. This is felt as a pulse. The pulse rate of the radial or carotid artery indicates the heart rate.
Define blood pressure. What is a sphygmomanometer? Define systolic pressure and diastolic pressure. Define hypertension and hypotension.
Blood pressure is the pressure of blood against the wall of a blood vessel. It is usually measured in the brachial artery of the arm with a sphygmomanometer. The higher number is the systolic pressure, and the lower number is the diastolic pressure. Normal blood pressure is 120/80. High blood pressure is called hypertension, and low blood pressure hypotension.
What is the advantage of blood moving through capillaries slowly?
Blood moves slowly in capillaries because there are more capillaries than arterioles. This slow pace allows time for exchanges between capillary blood and tissue cells.
