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 Hepatic Portal 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 Taking pulse rates 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!