blood vessel physiology. special circulations arterial supply of brain – brain must have oxygen no...
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Blood Vessel Physiology
Special Circulations
• Arterial supply of brain – Brain must have oxygen• No oxygen brain cells die and cannot be regenerated
– 2 pairs of arteries supply brain• Internal carotid– Divides into cerebral arteries that supply cerebrum
• Vertebral arteries– From subclavian arteries at base of neck– Forms basilar artery under skill» Supplies cerebellum and brain stem
Fetal Circulation
• Umbilical cord – Contains one large umbilical vein (carries oxygen)
and 2 umbilical arteries– Fetal lungs are collapsed and non-functional• Closed off from circulation of fetus
• Hepatic Portal– Detour of systemic arteries (mesenteric, splenic,
gastric)– Allows liver to process or store nutrients
Arterial Pulse & Blood Pressure
• Good indication of circulatory system health• Vital signs– BP – Pulse– Temperature– Respiratory rate
• Arterial Pulse– Arteries expand/shrink with heartbeat– Creates a wave through system– Pulse rate = heart rate
• Taking pulse rates– Use pressure points• Most common area in wrist• Use first two fingers to feel pulse
Blood Pressure
• Closed system with pump = pressue• Closer to pump, higher the pressure
• Pressure is exerted against walls of vessels– Keeps blood flowing
• Follows a pressure gradient– High pressure to low pressure• Zero pressure by the time it reaches the venae cavae
Measuring Blood Pressure
• Rise and fall with each beat• 2 measurements are taken– Systolic• Peak of ventricular contraction
– Diastolic• Ventricular relaxation
• Written as a fraction– Systole on top
• Most common site – brachial artery
Steps in Blood Pressure Measurement
• Place the blood pressure cuff above the elbow
• Place the bell of the stethoscope in the center of the inner elbow
• Inflate the cuff by squeezing the bulb
• Inflate until you cannot hear a beat with the stethoscope
Steps in Blood Pressure Measurement
• SLOWLY begin to deflate the blood pressure cuff until you hear the FAINTEST beat.– This is the systole!
• Keep deflating slowly until beats are no longer heard– This is the diastole!
• Record results!
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