13Scanlon(p3)-ch13
8/17/06
10:54 AM
Page 304
Copyright © 2007 by F. A. Davis.
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The Vascular System
BOX 13–3
PULSE SITES
A pulse is the heartbeat that is felt at an arterial site.
What is felt is not actually the force exerted by the
blood, but the force of ventricular contraction
transmitted through the walls of the arteries. This is
why pulses are not felt in veins; they are too far
from the heart for the force to be detectable.
The most commonly used pulse sites are:
Radial—the radial artery on the thumb side of the
wrist.
Carotid—the carotid artery lateral to the larynx in
the neck.
Temporal—the temporal artery just in front of the
ear.
Femoral—the femoral artery at the top of the
thigh.
and nutrients from the mother’s blood enter fetal
circulation.
The umbilical vein carries this oxygenated blood
from the placenta to the fetus. Within the body of the
fetus, the umbilical vein branches: One branch takes
some blood to the fetal liver, but most of the blood
Popliteal—the popliteal artery at the back of the
knee.
Dorsalis pedis—the dorsalis pedis artery on the
top of the foot (commonly called the pedal pulse).
Pulse rate is, of course, the heart rate. However,
if the heart is beating weakly, a radial pulse may be
lower than an apical pulse (listening to the heart
itself with a stethoscope). This is called a pulse
deficit and indicates heart disease of some kind.
When taking a pulse, the careful observer also
notes the rhythm and force of the pulse. Abnormal
rhythms may reflect cardiac arrhythmias, and the
force of the pulse (strong or weak) is helpful in
assessing the general condition of the heart and
arteries.
passes through the ductus venosus to the inferior
vena cava, to the right atrium. After birth, when the
umbilical cord is cut, the remnants of these fetal vessels constrict and become nonfunctional.
The other modifications of fetal circulation concern the fetal heart and large arteries (also shown in
Inferior vena cava
Hepatic vein
Left gastric V.
Right gastric V.
Splenic V.
Spleen
Stomach
Liver
Portal vein
Superior
mesenteric V
Pancreas
Left gastroepiploic V.
Inferior mesenteric V.
Left colic V.
Descending colon
Right colic V.
Ascending colon
Figure 13–7. Hepatic portal circulation. Portions of
some of the digestive organs
have been removed to show
the veins that unite to form
the portal vein. See text for
description.
QUESTION: The blood in the
portal vein is going to what
organ? Where is the blood
coming from?