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BLOOD PRESSURE. 12/3/2012 SHMD 139. Blood Pressure. Pg 34. Blood pressure is the pressure the blood exerts on the artery walls Blood pressure (BP) is the result of the heart contracting and forcing blood into the blood vessels
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BLOOD PRESSURE 12/3/2012 SHMD 139
Blood Pressure Pg 34 • Blood pressure is the pressure the blood exerts on the artery walls • Blood pressure (BP) is the result of the heart contracting and forcing blood into the blood vessels • BP is necessary in order for blood to flow around the body
Blood Pressure Pg 34 • Typical BP for the average person: 120Systolic: When the heart is contracting 80 Diastolic: When the heart is relaxing • BP unit of measurement: milligrams of mercury (mmHg)
Calculating Blood Pressure Pg 33 • Cardiac Output: the amount of blood pumped from the heart every minute • Stroke Volume: The amount of blood pumped by the left ventricle of the heart in one contraction. • Heart Rate: the number of times the heart beats in 1 minute, measured in beats per minute (bpm)
Calculating Blood Pressure Pg 34 • Cardiac Output (litres per minute) = heart rate (bpm) x Stroke volume (litres) • Thus, Q = HR x SV • The average stroke volume is 70 – 90 millilitres (ml) • The fitter you are, the larger your SV is • At rest, your cardiac output (Q) is ± 5 litres per minute (L/m), while during exercise it can increase to as much as 30 L/m
Calculating Blood Pressure Pg 34 • Blood Pressure (mmHg) = Cardiac Output (litres per minute) x Resistance to flow (R) • Thus, BP = Q x R • Resistance to blood flow is caused by: • Size of the blood vessels. i.e. The smaller the blood vessel, the greater the resistance • Thickness of the blood. i.e. The thicker the blood, the greater the resistance.
Calculating Blood Pressure • If heart rate = 72 bpm • & stroke volume = 85ml • Cardiac output? • 85ml ÷ 1000 = 0.085L • Thus, • Q = HR x SV = 72 x 0.085 = 6.12 L/m Round off = 6 L/m
Calculating Blood Pressure • If heart rate = 68 bpm Diastolic R = 14 • & stroke volume = 80ml Systolic R = 22 • Cardiac output? Blood Pressure? • 80ml ÷ 1000 = 0.080L • Thus, • Q = HR x SV = 68 x 0.08 = 5.44 L/m • Systolic BP = Q x R Diastolic BP = Q x R = 5 x 22 = 5 x 14 = 110 mmHg = 70 mmHg • Thus BP = 110 mmHg 70
BLOOD PRESSURE & exercise Pg 34 • Exercise increases heart rate, which will result in an increased cardiac output, which will increase blood pressure • Q = HR x SV • BP = Q x R • If Q is increased, and R does not change, then BP will automatically increase • Exercise raises systolic BP, but there is usually only a slight change in diastolic BP
Hypertension Pg 132 • Is a repeatedly elevated blood pressure exceeding 140 over 90 mmHg, and means high pressure (tension) in the arteries. • If a person with high blood pressure does not reduce their BP, they are more at risk of suffering a stroke or heart attack .
The VALSALVA MANOEUVRE Pg 35 • Used by heavy weightlifters • Process of breathing against a closed glottis or against a closed mouth & nose • The valsalva maneouvre helps stabilise the shoulder girdle and torso while lifting heavy weights. This helps the lifter to move the weight more efficiently.
The VALSALVA MANOEUVRE Pg 36 • The valsalva maneouvre causes BP to increase, and reduces blood flow to the thoracic cavity • Thoracic cavity: part of the body that is enclosed by the ribcage and the diaphragm, containing the heart and lungs • Therefore anyone suffering from hypertension or heart problems should avoid this move, as it could cause a stroke or heart attack.
measuring BLOOD PRESSURE Pg 167 • It is vital to measure BP before a client exercises, as it will tell you if they are at risk of having a heart attack. • BP is measured with a blood pressure meter and stethoscope.
measuring BLOOD PRESSURE Pg 167 • The client should be seated and relaxed for 5 minutes • Ask the client to rest their left arm on the arm of the chair. Their elbow should be at 45 degrees, with the palm of the hand facing up. • Find the brachial pulse – it should be on the inner side of the arm, just under the biceps muscle. • Place the cuff just clear of the elbow (about 2-3cm above the elbow). The bladder of the cuff (The part which inflates) should be directly over the pulse. • Place the earpieces of the stethoscope in your ears and place the microphone over the brachial pulse.
measuring BLOOD PRESSURE Pg 167 • Inflate the cuff up to 200mmHg. • Slowly open the valve by turning it anti-clockwise and release the pressure. • Listen out for the first time you hear the thud of the heart beat and make a mental note of it. This is the systolic blood pressure reading. • Keep deflating the cuff, and when the heart beat becomes muffled or disappears, this is your diastolic reading. • Keep deflating the cuff and, if necessary, repeat after around 30 seconds.
QUESTIONS • Define: • Blood pressure. 2 • Cardiac output. 2 • Stroke volume. 2 • Hypertension. 2 • What do the following abbreviations stand for: • BP. 2 • Q. 2 • SV. 2 • Differentiate between ‘systolic’ and ‘diastolic’ blood pressure. 2 • Provide the unit of measurement for: • Blood pressure. 1 • Cardiac output. 1 • Stroke volume. 1
QUESTIONS • Provide the average stroke volume of a person at rest? 2 • Does stroke volume ever change? If so, when? 2 • Provide the average value of cardiac output at rest, as well as during exercise. 2 • List and briefly explain the 2 factors that cause resistance to blood flow. 4 • How does exercise affect blood pressure? 5 • What are the implications of a high BP? 2 • Explain: • The valsalva manoeuvre. 3 • Who uses it, 2 • And why. 2
QUESTIONS • Should someone with a high BP perform the valsalva maneuver? Why/why not? 3 • Which two instruments are used to measure BP? 2 • Why is it important to measure BP before an individual performs exercise testing? 3 • Explain the procedure for measuring blood pressure. 10 • In tabular form, write down the norms for blood pressure. 16
QUESTIONS Calculate: • Calculate cardiac output (Q) of a person at rest; if their heart rate is 72 bpm, and their stroke volume is 75 ml (0.075L). 3 • Calculate the cardiac output of a person who is training at a high intensity; if their heart rate is 180 bpm, and their stroke volume is 140ml (0.14L). 3 • Calculate blood pressure, if Q = 5L/m, systolic R = 23, and diastolic R = 15. Also, classify which category this blood pressure reading falls into. 6 • Calculate blood pressure if: • Heart rate = 75 bpm • Stroke volume = 80ml (remember to convert to liters) • Systolic R = 24 • Diastolic R = 16 • Also, classify which category this blood pressure reading falls into. 8