Blood pressure

Pulse pressure

1."Taking the pulse" is a measure of heart rate. 2.Caused by increased blood pressure in the artery at systole. a. The difference between blood pressure at systole and at diastole is the pulse pressure. b. If your blood pressure is 120/80, your pulse pressure is 40 mmHg. 3.Degree of pulse pressure is related to stroke volume

Atrial Stretch Reflexes

1.Activated by increased venous return leading to: a. Increased heart rate a.Stimulated secretion of atrial natriuretic peptide (ANP); results in excretion of more salts and water in urine b.Excretion of more urine

How the Baroreceptor Reflex Works

1.Fall in blood pressure causes increased sympathetic and decreased parasympathetic activity, resulting in increased heart rate and total peripheral resistance 2.Rise in BP has the opposite effects. 3.Good for quick beat-by-beat regulation like going from lying down to standing; the kidneys provide a more long-term regulation through controlling blood volume

Mean arterial pressure

1.The average pressure in the arteries in one cardiac cycle is the mean arterial pressure. 2.This is significant because it is the difference between mean arterial pressure and venous pressure that drives the blood into the capillaries. 3.Calculating Mean Arterial Pressure: diastolic pressure + 1/3 pulse pressure

Effect of Cross-Sectional Area on Blood Pressure

1.The blood pressure of blood vessels is related to the total cross-sectional area a. Capillary blood pressure is low because of large total cross-sectional area. b. Artery blood pressure is high because of small total cross-sectional area

Blood Pressure Measurement

1.Units of measurement: mmHg 2.Measuring instrument: sphygmomanometer. 3.A blood pressure cuff produces turbulent flow of blood in the brachial artery, which can be heard using a stethoscope; called sounds of Korotkoff.

person's blood pressure was measured and found to be 138/72 a. What is the systolic pressure? b. What is the diastolic pressure? c. What is the pulse pressure? d. What is the mean arterial pressure?

138,72 138-72=66 mmHg 72 +66/3 = 94 mm Hg

Baroreceptor (Pressure Receptor) Reflex

Activated by changes in blood pressure detected by baroreceptors (stretch receptors) in the aortic arch and carotid sinuses a. Increased blood pressure stretches these receptors, increasing action potentials to the vasomotor and cardiac control centers in the medulla. b. Most sensitive to drops in blood pressure c. The vasomotor center controls vasodilation and constriction to regulate peripheral resistance d. The cardiac center in the medulla oblongata controls heart rate.

Factors affecting pulse pressure

Degree of pulse pressure is related to stroke volume •People with hypertension or who are dehydrated will have a lower pulse pressure •Exercise will increase the pulse pressure

Why is Blood Pressure Important?

Extremely low BP can lead to organ hypoperfusion - insufficient nutrient and oxygen delivery can lead to organ system shutdown •Extremely high blood pressure can damage delicate capillaries in organs leading to organ damage •BP is one of the physiological variables that has a set point and the body maintains within a given range (homeostasis) •Arterial and atrial baroreceptors provide sensory information to the brain stem so that the autonomic system can maintain BP within its proper range

Blood Pressure Regulation

Kidneys can control blood volume and thus stroke volume. •The sympathoadrenal system stimulates vasoconstriction of arterioles (raising total peripheral resistance) and increased cardiac output.

Cuff process

The cuff is first inflated to above systolic blood pressure to pinch off the brachial artery. As pressure is released, the first sound is heard at systole and a reading can be taken. •The last Korotkoff sound is heard when the pressure in the cuff reaches diastolic pressure and a second reading can be taken - laminar flow returns which has no sound. •The average blood pressure is 120/80.

Structures of the Baroreceptor Reflex

a. Located in aortic arch and carotid sinus b. Vasomotor and cardiac control centers in the medulla oblongata c. Parasympathetic and sympathetic axons to the heart and blood vessels

Blood pressure affected by

blood volume/stroke volume, total peripheral resistance, and cardiac rate a. Increase in any of these will increase blood pressure. b. Vasoconstriction of arterioles raises blood pressure upstream in the arteries. c. Arterial blood ∝ cardiac X total peripheral