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Human Anatomy & Physiology
Ninth Edition PowerPoint ® Lecture Slides prepared by Barbara Heard, Atlantic Cape Community College C H A P T E R © Annie Leibovitz/Contact Press © 2013 Pearson Education, Inc. Images
The
Cardiovascular
System: Blood
Vessels: Part B
Monitoring Circulatory Efficiency
- (^) Vital signs : pulse and blood pressure, along with respiratory rate and body temperature
- (^) Pulse : pressure wave caused by expansion and recoil of arteries
- (^) Radial pulse (taken at the wrist) routinely used
- (^) Pressure points where arteries close to body surface - (^) Can be compressed to stop blood flow
Measuring Blood Pressure
- (^) Systemic arterial BP
- (^) Measured indirectly by auscultatory method using a sphygmomanometer
- (^) Pressure increased in cuff until it exceeds systolic pressure in brachial artery
- (^) Pressure released slowly and examiner listens for sounds of Korotkoff with a stethoscope
Measuring Blood Pressure
- (^) Systolic pressure , normally less than 120 mm Hg, is pressure when sounds first occur as blood starts to spurt through artery
- (^) Diastolic pressure , normally less than 80 mm Hg, is pressure when sounds disappear because artery no longer constricted; blood flowing freely
Alterations in Blood Pressure
- (^) Hypertension : high blood pressure
- (^) Sustained elevated arterial pressure of 140/ or higher
- (^) Prehypertension if values elevated but not yet in hypertension range - (^) May be transient adaptations during fever, physical exertion, and emotional upset - (^) Often persistent in obese people
Homeostatic Imbalance: Hypertension
- (^) Prolonged hypertension major cause of heart failure, vascular disease, renal failure, and stroke - (^) Heart must work harder → myocardium enlarges, weakens, becomes flabby - (^) Also accelerates atherosclerosis
Homeostatic Imbalance: Hypertension
- (^) Secondary hypertension less common
- (^) Due to identifiable disorders including obstructed renal arteries, kidney disease, and endocrine disorders such as hyperthyroidism and Cushing's syndrome
- (^) Treatment focuses on correcting underlying cause
Alterations in Blood Pressure
- (^) Hypotension : low blood pressure
- (^) Blood pressure below 90/60 mm Hg
- (^) Usually not a concern
- (^) Only if leads to inadequate blood flow to tissues
- (^) Often associated with long life and lack of cardiovascular illness
Blood Flow Through Body Tissues
- (^) Tissue perfusion involved in
- Delivery of O 2 and nutrients to, and removal of wastes from, tissue cells
- (^) Gas exchange (lungs)
- (^) Absorption of nutrients (digestive tract)
- (^) Urine formation (kidneys)
- (^) Rate of flow is precisely right amount to provide proper function
Velocity of Blood Flow
- (^) Changes as travels through systemic circulation
- (^) Inversely related to total cross-sectional area
- (^) Fastest in aorta; slowest in capillaries; increases in veins
- (^) Slow capillary flow allows adequate time for exchange between blood and tissues
Autoregulation
- (^) Automatic adjustment of blood flow to each tissue relative to its varying requirements
- (^) Controlled intrinsically by modifying diameter of local arterioles feeding capillaries - (^) Independent of MAP, which is controlled as needed to maintain constant pressure
- (^) Organs regulate own blood flow by varying resistance of own arterioles
Blood Flow Through Capillaries
- (^) Vasomotion
- (^) Slow, intermittent flow
- (^) Reflects on/off opening and closing of precapillary sphincters
Fluid Movements: Bulk Flow
- (^) Fluid leaves capillaries at arterial end; most returns to blood at venous end - (^) Extremely important in determining relative fluid volumes in blood and interstitial space
- (^) Direction and amount of fluid flow depend on two opposing forces: ________ and _________________
Hydrostatic Pressures
- Capillary hydrostatic pressure^ (HP c
(capillary blood pressure)
- (^) Tends to force fluids through capillary walls
- (^) Greater at arterial end (35 mm Hg) of bed than at venule end (17 mm Hg)
- (^) Interstitial fluid hydrostatic pressure (HP if
- (^) Pressure that would push fluid into vessel
- (^) Usually assumed to be zero because of lymphatic vessels
