690
UNIT 4
Maintenance of the Body
the brain. Te diagnosis was cardiac tamponade. What is cardiac
tamponade and how does it cause the observed symptoms?
2.
You have been called upon to demonstrate the technique for
listening to valve sounds. (a) Explain where you would position
your stethoscope to auscultate (1) the aortic valve of a patient
with severe aortic valve insufficiency and (2) a stenotic mitral
valve. (b) During which period(s) would you hear these abnormal
valve sounds most clearly? (During atrial diastole, ventricular
systole, ventricular diastole, or atrial systole?) (c) What cues
would you use to differentiate between an insufficient and a
stenotic valve?
3.
Florita Santos, a middle-aged woman, is admitted to the coronary
care unit with a diagnosis of le± ventricular failure resulting
from a myocardial infarction. Her history indicated that she
was aroused in the middle of the night by severe chest pain. Her
skin is pale and cold, and moist sounds are heard over the lower
regions of both lungs. Explain how failure of the le± ventricle can
cause these signs and symptoms.
4.
Heather, a newborn baby, needs surgery because she was born
with an aorta that arises from the right ventricle and a pulmonary
trunk that issues from the le± ventricle, a condition called
transposition of the great vessels. What are the physiological
consequences of this defect?
5.
Gabriel, a heroin addict, feels tired, is weak and feverish, and has
vague aches and pains. ²errified that he has AIDS, he goes to a
doctor and is informed that he is suffering not from AIDS, but
from a heart murmur accompanied by endocarditis. What is the
most likely way that Gabriel contracted endocarditis? (Hint: See
Related Clinical ²erms.)
6.
As Cara worked at her dissection, she became frustrated that
several of the structures she had to learn about had more than
one common name. Provide another name for each of these
structures: (a) atrioventricular groove, (b) tricuspid valve,
(c) bicuspid valve (give two synonyms), and (d) atrioventricular
bundle.
stimulation of the heart decreases time available for ventricular
filling,
(c)
sympathetic stimulation of the heart increases its force
of contraction,
(d)
all of the above.
9.
Freshly oxygenated blood is first received by the
(a)
right atrium,
(b)
le± atrium,
(c)
right ventricle,
(d)
le± ventricle.
Short Answer Essay Questions
10.
Describe the location and position of the heart in the body.
11.
Describe the pericardium and distinguish between the fibrous and
the serous pericardia relative to histological structure and location.
12.
²race one drop of blood from the time it enters the right atrium
until it enters the le± atrium. What is this circuit called?
13.
(a) Describe how heart contraction and relaxation influence
coronary blood flow. (b) Name the major branches of the
coronary arteries, and note the heart regions served by each.
14.
Te refractory period of cardiac muscle is much longer than that
of skeletal muscle. Why is this a desirable functional property?
15.
(a) Name the elements of the intrinsic conduction system of the
heart in order, beginning with the pacemaker. (b) What is the
important function of this conduction system?
16.
Draw a normal ECG pattern. Label and explain the significance
of its deflection waves.
17.
Define cardiac cycle, and follow the events of one cycle.
18.
What is cardiac output, and how is it calculated?
19.
Discuss how the Frank-Starling law of the heart helps to explain
the influence of venous return on stroke volume.
20.
(a) Describe the common function of the foramen ovale and the
ductus arteriosus in a fetus. (b) What problems result if these
shunts remain patent (open) a±er birth?
Critical Thinking and
Clinical Application
Questions
1.
A gang member was stabbed in the chest during a street fight.
He was cyanotic and unconscious from lack of blood delivery to
Related Clinical Terms
Asystole
(a-sis
9
to-le) Situation in which the heart fails to contract.
Cardiac catheterization
Diagnostic procedure that involves passing
a fine catheter (tubing) through a blood vessel into the heart.
Oxygen content of blood, blood flow, and pressures within the
heart can be measured. Findings help to detect valve problems,
heart deformities, and other heart malfunctions.
Commotio cordis
(“concussion of the heart”) Situation in which a
relatively mild blow to the chest causes heart failure and sudden
death because it occurs during a vulnerable interval (2 ms) when
the heart is repolarizing. Explains those rare instances when
youngsters drop dead on the playing field a±er being hit in the
chest by a ball.
Cor pulmonale
(kor pul-mun-nă
9
le;
cor
5
heart,
pulmo
5
lung) A condition of right-sided heart failure resulting from
elevated blood pressure in the pulmonary circuit (pulmonary
hypertension). Acute cases may develop suddenly due to a
pulmonary embolism; chronic cases are usually associated with
chronic lung disorders such as emphysema.
Endocarditis
(en
0
do-kar-di
9
tis) Inflammation of the endocardium,
usually confined to the endocardium of the heart valves.
Endocarditis o±en results from infection by bacteria that have
entered the bloodstream but may result from fungal infection
or an autoimmune response. Drug addicts may develop
endocarditis by injecting themselves with contaminated needles.
Heart palpitation
A heartbeat that is unusually strong, fast, or
irregular so that the person becomes aware of it; may be caused
by certain drugs, emotional pressures (“nervous heart”), or heart
disorders.
Hypertrophic cardiomyopathy (HCM)
Te leading cause of
sudden death in young athletes, this condition, which is usually
inherited, causes the cardiac muscle cells to enlarge, thickening
the heart wall. Te heart pumps strongly but doesn’t relax well
during diastole when the heart is filling.
Mitral valve prolapse
Valve disorder affecting up to 1% of the
population; most o±en seen in young women. It appears to have
a genetic basis resulting in abnormal chordae tendineae
AT T H E C L I N I C
18
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