Measurement of Blood Pressure
Mean B.P. = (mmHg)
(cardiac output)(total peripheral resistance) (ml/min)(TPR units)
Cardiac output (C.O.) = (ml/min)
(heart rate)(stroke volume) (beats/min)(ml/beat)
What are the 4 major heart sounds?
*1st heart sound:* produced at the beginning of systole when the AV valves close and the SV valves open. This is the lower pitched LUB (can be heard without a stethoscope) *2nd heart sound:* occurs at the end of systole when the SV valves close and the AV valves open. The high pitched DUB (can be heard without a stethoscope) *3rd heart sound:* occurs during the rapid filling of the ventricles after the AV valves open *4th heart sound:* occurs at the time of atrial contraction
Direct Method of measuring blood pressure
A cannula is inserted into the artery and the direct, head-on pressure of the blood is measured with a transducer or mercury manometer
Phonocardiogram
A visual display of the vibrations of the heart through the use of a heart sound microphone and physiological recorder
What are the 4 major Auscultatory Areas?
Aortic area (aortic SL valve): Pulmonary area (pulmonary SL valve): Tricuspid area (right AV valve): Mitral area (left AV valve):
Disadvantage of the palpatory method
Cannot be used to measure diastolic pressure ~the systolic pressure is usually around 5 mmHg lower than the systolic pressure obtained using the auscultatory method~
Mean Blood Pressure
Diastolic Pressure + 1/3(Pulse Pressure) Normal value = 96 - 100 mmHg Function of two factors - cardiac output and total peripheral resistance
Sphygmomanometer
It's involved in both indirect methods. It consists of an inflatable rubber bag (cuff), a rubber bulb for introducing air into the cuff, and a mercury or aneroid manometer for measuring the pressure in the cuff.
Total Peripheral Resistance
Mean arterial pressure/cardiac output
Auscultation
Means "to listen to" and to study the various sounds arising from the heart during its pumping activity.
Palpatory Method
Older and less accurate method where one just feels the pulse as pressure is applied to the artery.
Indirect Method of measuring blood pressure (Auscultatory method)
Pressure is applied externally to the artery and the pressure is determined by listening to arterial sounds using a stethoscope below the point where the pressure is applied.
Bradycardia
Slowing of the heart
Pulse Pressure
Systolic Pressure - Diastolic Pressure Normal = 40 mmHg
Mammalian Dive Reflex
The body's response to submersion in cold water and includes selectively shutting down parts of the body in order to conserve energy/oxygen for survival. The diving reflex makes capillaries in the skin and limbs constrict, redirecting blood away from the body's surface and toward the vital organs. This shift saves more oxygen for the brain and heart. The trigeminal nerve (V) transmits information to the brain to innervate vagus nerve (X) which causes bradycardia and peripheral vasoconstriction
Systolic Blood Pressure:
The highest pressure in the artery Produced during contraction Normal P for a 20 year old man is 120mmHg
Diastolic Blood Pressure
The lowest pressure in the artery Produced during relaxation Normal P for a 20 year old man is 80mmHg
Auscultatory Method
The sphygmomanometer is used and placed over the brachial artery. There are four phases of sound changes called the *Korotkow sounds* ~this method has been fairly close to the the direct method~
Why do children survive longer than adults when submerged in cold water?
When infants are submerged in cold water, their windpipes simultaneously close to prevent water from entering the lungs. This reflex usually disappears once the infant is about 6 months old.
