Download Cardiovascular physiology The circulatory system is responsible for

Cardiovascular physiology
The circulatory system is responsible for the delivery of oxygen and nutrients to all cells, as
well as the removal of carbon dioxide and waste products, maintenance of optimum pH, and
the mobility of the elements, proteins and cells of the immune system.
Arteries carry oxygenated blood (with the exception of the pulmonary artery and umbilical
artery).
that carry blood from the heart to other parts of the body are known as systemic arteries while
those that carry deoxygenated blood to the lungs are known as pulmonary arteries.
The inner layers of the arteries are generally made of thick muscles which is why the blood
moves through it slowly. Pressure is built up and arteries are required to maintain their
thickness to withstand the strain they endure.
Veins carry deoxygenated blood (with the exception of pulmonary veins and umbilical vein).
The coronary circulation.
The heart is made up of four main
chambers, two ventricles and two atria.
Oxygen-depleted blood from the body
enters the heart (the right atrium) through
the superior (upper) vena cava and
inferior (lower) vena cava. The blood is
then pumped through the tricuspid valve
(or right atrioventricular valve), into the
right ventricle. Blood is then pumped
through the pulmonary valve and into the
pulmonary artery.
The
pulmonary
arteries
carry
deoxygenated blood to the lungs, where it
releases carbon dioxide and pick up
oxygen during respiration.
The oxygenated blood then leaves the lungs through pulmonary veins, which
return it to the left heart, completing the pulmonary cycle. This blood then
enters the left atrium, which pumps it through the bicuspid valve, also called
the mitral or left atrioventricular valve, into the left ventricle. The blood is then
distributed to the body through the systemic circulation before returning again
to the pulmonary circulation.
The atria contract simultaneously, and as they start to relax, the ventricles
contract simultaneously in a healthy heart.
The cardiac cycle is equal to one complete heartbeat – where both atria and
ventricles contract and relax.
The average heart beats approximately 75 beats per minute, so the cardiac
cycle length is approximately 0.8 seconds.
Heart Sounds
Two distinct sounds are heard during each cardiac cycle – “lub” and “dup”.
The sequence is designated lub-dup, pause, lub-dup, pause, etc.
The first sound (lub) is called the S1 and is associated with closure of the AV
valves at the beginning of ventricular systole.
The second sound (dup) is called S2 and occurs as the semilunar valves close
and corresponds with the end of systole.
There are four important areas used for listening to heart sound: Aortic area,
pulmonic area, tricuspid area and mitral area.
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I. Pulse Determinations
Pulse refers to the alternating surges of pressure (expansion and recoil) in an
artery that occur with each contraction and relaxation of the left ventricle.
The superficial pulse points are:
1. Temporal artery
2. Carotid artery
3. Common carotid artery
4. Brachial artery
5. Radial artery
6. Ulner artery
7. Femoral artery
8. Popliteal artery
9. Posterior tibial artery
10. Dorsalis pedis artery
Apical is not superficial, heart rate (apical
pulse) counted using Stethoscope.
1- Palpate the Pulse
The radial artery is an easy artery to use when
checking pulse.
1- Place the tips of your index and middle fingers
over the pulse site and press gently. Too much
pressure on the artery could interfere with blood
circulation and stop the pulse.
Do not place your thumb on the pulse site. The thumb
has its own pulse. If you use your thumb, you may be
taking your own pulse rather than the casualty's pulse.
2- Count the Pulse Beats for One Minute
Using a clock with a second hand, count the pulse for
one full minute.
3- Write down pulse rate.
Result:
Pulse rate is ----- beats / minute
A normal pulse rate for an adult when resting is from 60 to 80 beats per
minute.
The average is 75 beats per minute.
Normal pulse rate and strength may vary from individual to individual.
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2- Auscultation of heart rate –apical pulse
Apical pulse is the actual counting of heartbeats and it may be slightly faster
than the radial because of a slight lag in time as the blood rushes from the heart
into the large arteries where it can be palpated.
Equipment:
1. Stethoscope
2. Alcohol swab
Procedure:
1- disinfect the stethoscope ear pieces and
diaphragm with alcohol swab
2- Stethoscope placed over apex of heart (Apex located on the left side of the
chest between the fifth & sixth ribs just below left nipple in men, under left
breast in women )
2- Listen for two sounds – LUB / DUB
3- The louder sound LUB is counted for one full minute
4- Write down pulse rate.
Result:
Heart rate is ----- beats / minute
The pulse deficit is the difference between the
heart rate and the palpable pulse
obtained by having one person count the apical
pulse as heard through a stethoscope over the
heart and a second person count the radial pulse
at the same time.
II. Blood Pressure Determinations
The term blood pressure (BP) refers to the pressure the blood exerts against
any unit area of the blood vessel walls, it is usually measured in the arteries.
Blood pressure is taken in two readings: the systolic and the diastolic.
The systolic pressure (ventricular contraction) is the pressure in the arteries at
the peak of ventricular ejection.
The diastolic pressure (ventricular relaxation) is the pressure during
ventricular relaxation.
Pulse pressure is the difference between systolic and diastolic pressure.
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Measuring Blood Pressure:
Equipment:
1. Stethoscope
2. Mercury sphygmomanometer
3. Alcohol swab
4. Gloves if required
Procedure:
1- Explain the procedure to the client.
2- Ask the client to sit or lie down and rest for 5 minutes before taking the
measurement.
3- Wash hands, wear gloves if required.
4- Remove clothing as necessary to expose extremity.
5- Position arm at heart level, extend elbow with palm turned upward.
6- Make sure bladder cuff is fully deflated and pump valve moves freely.
7- Locate the artery by palpation. Allows for proper placement of stethoscope
to hear BP. Locate brachial artery in the antecubital space.
8- Apply cuff snugly and smoothly over upper arm, 2.5 cm (1 inch) above
antecubital space with center of cuff over brachial artery.
9- Connect bladder tubing to manometer tubing. Position sphygmomanometer
vertically at eye level.
10- Palpate brachial artery, turn valve clockwise to close and compress bulb to
10- Inflate cuff to 30 mm Hg above point where palpated pulse disappears, then
slowly release valve (deflating cuff ), noting reading when pulse is felt again.
11- Insert earpieces of stethoscope into ears with a forward tilt, ensuring
diaphragm hangs freely.
12- Relocate brachial pulse with your nondominant hand and place bell or
diaphragm chestpiece directly over pulse. Chestpiece should be in direct
contact with skin and not touch cuff. Place stethoscope gently over artery.
Too firm a pressure will occlude blood vessel.
13- With dominant hand, turn valve clockwise to close. Compress pump to
inflate cuff until manometer registers 30 mm Hg above diminished pulse
point identified.
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14- Slowly turn valve counterclockwise so that mercury falls slowly. Listen for
a clear tapping sound appears and increases in intensity. Then Sound
disappears.
15- Obtain a blood pressure reading. Systolic pressure: The pressure at which
you first hear sounds. . Diastolic pressure: The pressure at which the sound
disappears .
16- Deflate cuff rapidly and completely.
17- Remove cuff or wait 2 minutes before taking a second reading.
18- Inform client of reading.
19- Record reading.
20- Wash hands.
Notes:
- Do not take a blood pressure (BP) on an injured or painful extremity or one
where there is an intravenous line (IV). Cuff inflation can temporarily interrupt
blood flow and compromise circulation in an extremity already impaired or a
vein receiving IV fluids.
- BP is reported in millimeters of mercury (mm Hg).
Result:
Blood pressure (BP) is ----- mm Hg
The mean arterial pressure (MAP) is computed as:
MAP = diastolic pressure + (pulse pressure / 3)
Normal BP range in adult
120 ± 20
80 ± 15
mm Hg
The average is 120 /80 mm Hg
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