Blood Pressure Keeps blood moving through the body (even during diastole) Blood flows from areas of high pressure (arteries) to low pressure (veins) – Venous return can’t be accomplished solely via BP  why valves in veins and contraction of muscles are important Crucial that arteries have enlarged tunica media to allow stretch and recoil

Made of 2 numbers – Top: systolic pressure in arteries after ventricular contraction – Bottom: diastolic pressure in arteries when ventricles are relaxed /60-90 normal – If too high (140/90) or greater  hypertension – If too low 100/# or less  hypotention

Factors that Change BP BP depends on Cardiac output and peripheral resistance – PR = amount of friction blood overcomes as it flowsthrough blood vessels Factors that change CO or PR affect BP!!!

Factors that Change PR Change in blood vessel diameter – Done in response to Temperature – If blood vessels constrict vasoconstriction – If blood vessels dilate vasodilation Chemicals – alcohol causes vasodilation (dec. PR) – nicotine & epinephrine cause vasoconstriction (inc. PR)

Factors that Change Heart Rate Crisis stressors – Electrical system of the heart is more strongly stimulated to beat  inc heart rate Epinephrine (AKA adrenaline) – is released in “fight or flight” situations  inc heart rate Electrolyte levels (ions) – Low calcium dec. HR – High calcium causes sustained contraction (dec HR)  can cause cardiac arrest

Physical Factors that Affect Heart Rate Age – HR decreases with age (healthy) Gender – Females > males Exercise – increases HR Body temp – higher temp increases HR