PULSE AND BLOOD PRESSURE
a. Pulse. This is a characteristic associated with the heartbeat and the
subsequent wave of expansion and recoil set up in the wall of an artery. Pulse is
defined as the alternate expansion and recoil of an artery. With each heartbeat, blood
is forced into the arteries causing them to dilate (expand). Then the arteries contract
(recoil) as the blood moves further along in the circulatory system. The pulse can be
felt at certain points in the body where an artery lies close to the surface. The most
common location for feeling the pulse is at the wrist, proximal to the thumb on the palm
side of the hand (radial artery). Alternate locations are in front of the ear (temporal
artery), at the side of the neck (carotid artery), and on the top (dorsum) of the foot
b. Blood Pressure. The force that blood exerts on the walls of vessels through
which it flows is called blood pressure. All parts of the blood vascular system are under
pressure, but the term blood pressure usually refers to arterial pressure. Pressure in
the arteries is highest when the ventricles contract during systole. Pressure is lowest
when the ventricles relax during diastole. The brachial artery, in the upper arm, is the
artery usually used for blood pressure measurement.
The lymphatic system consists of lymph, lymph vessels, and lymph nodes. The
spleen belongs, in part, to the lymphatic system. Unlike the cardiovascular system, the
lymphatic system has no pump to move the fluid that collects, but muscle contractions
and breathing movements aid in the movement of lymph through its channels and its
return to the blood stream.
a. Lymph and Tissue Fluid. Lymph, fluid found in the lymph vessels, is clear
and watery and is similar to tissue fluid, which is the colorless fluid that fills the spaces
between tissues, between the cells of organs, and between cells and connective
tissues. Tissue fluid serves as the "middleman" for the exchange between blood and
body cells. Formed from plasma, it seeps out of capillary walls. The lymphatic system
collects tissue fluid, and as lymph, the collected fluid is started on its way for return to
the circulating blood.
b. Lymph Vessels. Starting as small blind ducts within the tissues, the
lymphatic vessels enlarge to form lymphatic capillaries. These capillaries unite to form
larger lymphatic vessels, which resemble veins in structure and arrangement. Valves in
lymph vessels prevent backflow. Superficial lymph vessels collect lymph from the skin
and subcutaneous tissue; deep vessels collect lymph from all other parts of the body.
The two largest collecting vessels are the thoracic duct and the right lymphatic duct.
The thoracic duct receives lymph from all parts of the body except the upper right side.
The lymph from the thoracic duct drains into the left subclavian vein, at the root of the
neck on the left side. The right lymphatic duct drains into a corresponding vein on the