Blood Vessels: The Vascular SystemNotes

Function/Purpose

• Transport blood to the tissues and back– Carry blood ____________ from the heart

• _______________________• _______________________

– Exchanges between tissues and blood• _______________________

– Return blood _________________ the heart• _______________________• _______________________

Structural Differences

• Arteries have a ______________________________________________ than veins• Capillaries are only _______________________ (tunica intima) to allow for

exchanges between blood and tissue• Veins have a ______________________________________________ than arteries

– Veins also have ____________ to prevent backflow of blood– __________________ of veins are larger than arteries

Venous Aids for Return of Blood to the Heart

• Veins:– Have a thinner tunica media– Operate under _______________________– Have a larger lumen than arteries

• To assist in the movement of blood back to the heart:– Larger veins have valves to prevent backflow– ______________________________________________ blood in veins toward the

heart

Movement of Blood Through Vessels

• Most ______________________________________________• Veins use the milking action of muscles to help move blood

Capillary Beds

• Capillary beds consist of two types of vessels– _______________________—vessel directly connecting an arteriole to a

venule– _______________________—exchange vessels

• Oxygen and nutrients cross to cells• Carbon dioxide and metabolic waste products cross into blood

Pulse• Pulse

– ______________________________________________• Monitored at “_______________________” in arteries where pulse is easily palpated• Pulse averages _________________ beats per minute at rest

Blood Pressure

• Measurements by health professionals are made on the pressure in large arteries– __________________—pressure at the peak of ventricular contraction – __________________—pressure when ventricles relax– Write systolic pressure first and diastolic last (120/80 mm Hg)

• Pressure in blood vessels decreases as distance from the heart increases

Blood Pressure: Effects of Factors

• __________ is blood pressure– BP is affected by

______________________________________________________________ ___________________________________________________________________________

• CO (_______________________) is the amount of blood pumped out of the left ventricle per minute

• PR (_______________________) is the amount of friction blood encounters as it flows through vessels– ___________________________________________________________________________

________________________________________ increases PR• Temperature

– Heat has a __________________ effect– Cold has a ____________________________________ effect

• Chemicals– Various substances can cause increases or decreases

• Diet

Variations in Blood Pressure

• Normal human range is variable– Normal

• _________________ mm Hg systolic• _________________ mm Hg diastolic

– Hypotension

• Low systolic (below 110 mm Hg)• Often associated with illness

– Hypertension• High systolic (above 140 mm Hg)• Can be dangerous if it is chronic

How to Take Blood Pressure1. Deflate the air bladder of the cuff and place it around the upper arm so it fits snugly, but not too tight. If you’re right handed, you should hold the bulb/pump in your left hand to inflate the cuff. Hold it in the palm so your fingers can easily reach the valve at the top to open and close the outlet to the air bladder.2. Put the head of the stethoscope just under the edge of the cuff, a little above the crease of the person’s elbow. Hold it there firmly with the thumb or with the fingers of the right hand. Listen.3. Inflate the cuff with brisk squeezes of the bulb. Watch the pressure gauge as you do it, you should go to around 150 mmHg or until the pulse is no longer heard. At this point blood flow in the underlying blood vessel is cut off by pressure in the cuff. 4. At around 150, slightly open the valve on the air pump (held in your left hand). This part takes practice, it’s important that you don’t let the air out too suddenly or too slowly.5. Now, pay attention to what you hear through the stethoscope as the needle on the pressure gauge falls. You will be listening for a slight “blrrp” or something that sounds like a “prrpshh”. The first time you hear this sound; note the reading on the gauge and immediately following you should hear the sound of a pulse. This value is the systolic blood pressure. 6. The sounds should continue and become louder in intensity. Note the reading when you hear the sound for the last time. This is the diastolic blood pressure. 7. Afterwards, open the air valve completely to release any remaining pressure. You and your partner should perform this operation twice.

Blood pressure is measured in millimeters of mercury (mm Hg). A typical blood pressure is 120/80 mm Hg, or "120 over 80." The first number represents the pressure when the heart contracts and is called the systolic blood pressure. The second number