The Cardiovascular System Blood Vessels Physiology Chapter 19

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The Cardiovascular System: Blood Vessels Physiology Chapter 19, Cardiovascular System - Blood Vessel 19

The Cardiovascular System: Blood Vessels Physiology Chapter 19, Cardiovascular System - Blood Vessel 19 1

Capillary Exchange Chapter 19, Cardiovascular System - Blood Vessel 2

Capillary Exchange Chapter 19, Cardiovascular System - Blood Vessel 2

Capillary Beds § A microcirculation of interwoven networks of capillaries, consisting of: § Vascular

Capillary Beds § A microcirculation of interwoven networks of capillaries, consisting of: § Vascular shunts – metarteriole–thoroughfare channel connecting an arteriole directly with a postcapillary venule § True capillaries – 10 to 100 per capillary bed, capillaries branch off the metarteriole and return to the thoroughfare channel at the distal end of the bed Chapter 19, Cardiovascular System - Blood Vessel 3

Blood Flow Through Capillary Beds § Precapillary sphincter § Cuff of smooth muscle that

Blood Flow Through Capillary Beds § Precapillary sphincter § Cuff of smooth muscle that surrounds each true capillary § Regulates blood flow into the capillary § Blood flow is regulated by vasomotor nerves and local chemical conditions, so it can either bypass or flood the capillary bed Chapter 19, Cardiovascular System - Blood Vessel 4

Capillary Beds Chapter 19, Cardiovascular System - Blood Vessel Figure 19. 4 b 5

Capillary Beds Chapter 19, Cardiovascular System - Blood Vessel Figure 19. 4 b 5

Capillary Beds Chapter 19, Cardiovascular System - Blood Vessel Figure 19. 4 a 6

Capillary Beds Chapter 19, Cardiovascular System - Blood Vessel Figure 19. 4 a 6

Methods of Capillary Exchange § Diffusion § Most important mechanism for solute exchange §

Methods of Capillary Exchange § Diffusion § Most important mechanism for solute exchange § Passive § Concentration gradient Chapter 19, Cardiovascular System - Blood Vessel 7

Methods of Capillary Exchange § Transcytosis § Movement of substances (larger molecules in vesicles)

Methods of Capillary Exchange § Transcytosis § Movement of substances (larger molecules in vesicles) § Active transport § From blood plasma through capillary walls: moves across blood vessel § Via endo or exocytosis Chapter 19, Cardiovascular System - Blood Vessel 8

Chapter 19, Cardiovascular System - Blood Vessel 9

Chapter 19, Cardiovascular System - Blood Vessel 9

Methods of Capillary Exchange § Bulk flow § Passive transport due to opposing pressures

Methods of Capillary Exchange § Bulk flow § Passive transport due to opposing pressures § Faster than diffusion § Function: regulate fluid volume of IVF & ISF § Move large amounts in one direction (at a time) § Hydrostatic pressure § Pressure exerted by IVF & ISF on capillary walls § Colloidal osmotic pressure § Pressure exerted by the non-diffusible solutes on the capillary walls Chapter 19, Cardiovascular System - Blood Vessel 10

Methods of Capillary Exchange § Filtration § Requires positive difference between hydrostatic pressure &

Methods of Capillary Exchange § Filtration § Requires positive difference between hydrostatic pressure & colloidal osmotic pressure § Moves fluid from IVF into ISF § Reabsorption § Requires negative difference between hydrostatic pressure & colloidal osmotic pressure § Moves fluid from ISF into IVF Chapter 19, Cardiovascular System - Blood Vessel 11

Chapter 19, Cardiovascular System - Blood Vessel 12

Chapter 19, Cardiovascular System - Blood Vessel 12

Capillary Exchange of Respiratory Gases and Nutrients § Oxygen, carbon dioxide, nutrients, and metabolic

Capillary Exchange of Respiratory Gases and Nutrients § Oxygen, carbon dioxide, nutrients, and metabolic wastes diffuse between the blood and interstitial fluid along concentration gradients § Oxygen and nutrients pass from the blood to tissues § Carbon dioxide and metabolic wastes pass from tissues to the blood § Water-soluble solutes pass through clefts and fenestrations § Lipid-soluble molecules diffuse directly through endothelial membranes Chapter 19, Cardiovascular System - Blood Vessel 13

Capillary Exchange of Respiratory Gases and Nutrients Chapter 19, Cardiovascular System - Blood Vessel

Capillary Exchange of Respiratory Gases and Nutrients Chapter 19, Cardiovascular System - Blood Vessel Figure 19. 14. 1 14

Capillary Exchange of Respiratory Gases and Nutrients Chapter 19, Cardiovascular System - Blood Vessel

Capillary Exchange of Respiratory Gases and Nutrients Chapter 19, Cardiovascular System - Blood Vessel Figure 19. 14. 2 15

Capillary Exchange: Fluid Movements § Direction and amount of fluid flow depends upon the

Capillary Exchange: Fluid Movements § Direction and amount of fluid flow depends upon the difference between: § Capillary hydrostatic pressure (HPc) § Capillary colloid osmotic pressure (OPc) § HPc – pressure of blood against the capillary walls: § Tends to force fluids through the capillary walls § Is greater at the arterial end of a bed than at the venule end § OPc– created by nondiffusible plasma proteins, which draw water toward themselves Chapter 19, Cardiovascular System - Blood Vessel 16

Net Filtration Pressure (NFP) § NFP – considers all the forces acting on a

Net Filtration Pressure (NFP) § NFP – considers all the forces acting on a capillary bed § NFP = (HPc – HPif) – (OPc – OPif) § At the arterial end of a bed, hydrostatic forces dominate (fluids flow out) Chapter 19, Cardiovascular System - Blood Vessel 17

Net Filtration Pressure (NFP) § At the venous end of a bed, osmotic forces

Net Filtration Pressure (NFP) § At the venous end of a bed, osmotic forces dominate (fluids flow in) § More fluids enter the tissue beds than return blood, and the excess fluid is returned to the blood via the lymphatic system PLAY Inter. Active Physiology®: Cardiovascular System: Autoregulation and Capillary Dynamics Chapter 19, Cardiovascular System - Blood Vessel 18

Net Filtration Pressure (NFP) Chapter 19, Cardiovascular System - Blood Vessel Figure 19. 15

Net Filtration Pressure (NFP) Chapter 19, Cardiovascular System - Blood Vessel Figure 19. 15 19

Circulatory Routes Page 8 of notes Chapter 19, Cardiovascular System - Blood Vessel 20

Circulatory Routes Page 8 of notes Chapter 19, Cardiovascular System - Blood Vessel 20

Circulatory Pathways § The vascular system has two distinct circulations: § Know the pathway

Circulatory Pathways § The vascular system has two distinct circulations: § Know the pathway of circulation!! § Pulmonary circulation § Right side of heart - short loop that runs from the heart to the lungs and back to the heart § Systemic circulation § Left side of heart - routes blood through a long loop to all parts of the body and returns to the heart Chapter 19, Cardiovascular System - Blood Vessel 21

Coronary circulation Chapter 19, Cardiovascular System - Blood Vessel 22

Coronary circulation Chapter 19, Cardiovascular System - Blood Vessel 22

Hepatic portal circulation: sketch the larger diagram Function: blood transported to liver – hepatocytes

Hepatic portal circulation: sketch the larger diagram Function: blood transported to liver – hepatocytes store & modify absorbed substances & release to systemic circulation to be used. Inferior mesenteric vein Gall bladder Cystic vein R/L gastric veins 23

Hemodynamics Pages 6 -7 of notes Chapter 19, Cardiovascular System - Blood Vessel 24

Hemodynamics Pages 6 -7 of notes Chapter 19, Cardiovascular System - Blood Vessel 24

Blood flow Page 6 top Chapter 19, Cardiovascular System - Blood Vessel 25

Blood flow Page 6 top Chapter 19, Cardiovascular System - Blood Vessel 25

Blood Flow: top of page 6 § Actual volume of blood flowing through a

Blood Flow: top of page 6 § Actual volume of blood flowing through a vessel, an organ, or the entire circulation in a given period: § Is measured in ml per min. § Is equivalent to cardiac output (CO), considering the entire vascular system § Varies widely through individual organs, according to immediate needs Chapter 19, Cardiovascular System - Blood Vessel 26

The Heart: Cardiac Output · Cardiac output (CO) · Amount of blood pumped by

The Heart: Cardiac Output · Cardiac output (CO) · Amount of blood pumped by each ventricle in one minute · CO = (heart rate [HR]) x (stroke volume [SV]) · Resting values · HR = 75 beats per minute · SV = 70 ml per beat · CO = 5250 ml per minute Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Chapter 19, Cardiovascular System - Blood Vessel 28

Chapter 19, Cardiovascular System - Blood Vessel 28

Chapter 19, Cardiovascular System - Blood Vessel 29

Chapter 19, Cardiovascular System - Blood Vessel 29

Vascular resistance page 7 bottom, page 8 top Chapter 19, Cardiovascular System - Blood

Vascular resistance page 7 bottom, page 8 top Chapter 19, Cardiovascular System - Blood Vessel 30

Resistance: bottom of page 7 & top of page 8 § Resistance – opposition

Resistance: bottom of page 7 & top of page 8 § Resistance – opposition to flow § Measure of the amount of friction between blood and the walls of the blood vessels § Most significant in the systemic circuit § Referred to as peripheral resistance (PR) (or vascular resistance) § The three important sources of resistance are blood viscosity, total blood vessel length, and blood vessel lumen diameter Chapter 19, Cardiovascular System - Blood Vessel 31

Resistance Factors: Viscosity and Vessel Length § Resistance factors that remain relatively constant are:

Resistance Factors: Viscosity and Vessel Length § Resistance factors that remain relatively constant are: § Blood viscosity § Direct relationship § Blood vessel length § Direct relationship Chapter 19, Cardiovascular System - Blood Vessel 32

Resistance Factors: Blood Vessel Diameter § Changes in vessel diameter (esp. arterioles) are frequent

Resistance Factors: Blood Vessel Diameter § Changes in vessel diameter (esp. arterioles) are frequent and significantly alter peripheral resistance § Resistance varies inversely with the fourth power of vessel radius (onehalf the diameter) § Resistance increases, blood flow decreases: and vice versa. § For example, if the radius is doubled, the resistance is 1/16 as much Chapter 19, Cardiovascular System - Blood Vessel 33

Blood Pressure Back to page 6 Chapter 19, Cardiovascular System - Blood Vessel 34

Blood Pressure Back to page 6 Chapter 19, Cardiovascular System - Blood Vessel 34

Blood Pressure (BP) § Measured as: Hydrostatic pressure exerted by blood on larger (close

Blood Pressure (BP) § Measured as: Hydrostatic pressure exerted by blood on larger (close to heart) systemic arterial walls during ventricular systole/diastole. § Expressed in millimeters of mercury (mm Hg) § The differences in BP within the vascular system provide the driving force that keeps blood moving from higher to lower pressure areas Chapter 19, Cardiovascular System - Blood Vessel 35

Systemic Blood Pressure Chapter 19, Cardiovascular System - Blood Vessel Figure 19. 5 36

Systemic Blood Pressure Chapter 19, Cardiovascular System - Blood Vessel Figure 19. 5 36

Systemic Blood Pressure § The pumping action of the heart generates blood flow through

Systemic Blood Pressure § The pumping action of the heart generates blood flow through the vessels along a pressure gradient, always moving from higher- to lower-pressure areas § Pressure results when flow is opposed by resistance § Systemic pressure: § Is highest in the aorta § Declines throughout the length of the pathway § Is 0 mm Hg in the right atrium § The steepest change in blood pressure occurs in the arterioles Chapter 19, Cardiovascular System - Blood Vessel 37

Arterial Blood Pressure § Arterial BP reflects two factors of the arteries close to

Arterial Blood Pressure § Arterial BP reflects two factors of the arteries close to the heart § Their elasticity (compliance or distensibility) § The amount of blood forced into them at any given time § Blood pressure in elastic arteries near the heart is pulsatile (BP rises and falls) Chapter 19, Cardiovascular System - Blood Vessel 38

Arterial Blood Pressure § Systolic pressure – pressure exerted on arterial walls during ventricular

Arterial Blood Pressure § Systolic pressure – pressure exerted on arterial walls during ventricular contraction: average = 120 mm. Hg § Diastolic pressure – pressure exerted on arterial walls during ventricular relaxation: average = 80 mm. Hg § Pulse pressure – the difference between systolic and diastolic pressure § SBP-DBP = PP § Mean arterial pressure (MAP) – pressure that propels the blood to the tissues § MAP = DBP + (PP/3) Chapter 19, Cardiovascular System - Blood Vessel 39

Chapter 19, Cardiovascular System - Blood Vessel 40

Chapter 19, Cardiovascular System - Blood Vessel 40

Capillary Blood Pressure § Capillary BP ranges from 20 to 40 mm Hg §

Capillary Blood Pressure § Capillary BP ranges from 20 to 40 mm Hg § Low capillary pressure is desirable because high BP would rupture fragile, thin-walled capillaries § Low BP is sufficient to force filtrate out into interstitial space and distribute nutrients, gases, and hormones between blood and tissues Chapter 19, Cardiovascular System - Blood Vessel 41

Chapter 19, Cardiovascular System - Blood Vessel 42

Chapter 19, Cardiovascular System - Blood Vessel 42

Venous Blood Pressure § Venous BP is steady and changes little during the cardiac

Venous Blood Pressure § Venous BP is steady and changes little during the cardiac cycle § The pressure gradient in the venous system is only about 20 mm Hg § A cut vein has even blood flow; a lacerated artery flows in spurts Chapter 19, Cardiovascular System - Blood Vessel 43

Factors Aiding Venous Return § Venous BP alone is too low to promote adequate

Factors Aiding Venous Return § Venous BP alone is too low to promote adequate blood return and is aided by the: § Respiratory “pump” – pressure changes created during breathing suck blood toward the heart by squeezing local veins § Muscular “pump” – contraction of skeletal muscles “milk” blood toward the heart § Valves prevent backflow during venous return § SNS control – contraction of smooth muscle in tunica media causing vasocontriction PLAY Inter. Active Physiology®: Cardiovascular System: Anatomy Review: Blood Vessel Structure and Function Chapter 19, Cardiovascular System - Blood Vessel 44

Factors Aiding Venous Return Chapter 19, Cardiovascular System - Blood Vessel Figure 19. 6

Factors Aiding Venous Return Chapter 19, Cardiovascular System - Blood Vessel Figure 19. 6 45

Chapter 19, Cardiovascular System - Blood Vessel 46

Chapter 19, Cardiovascular System - Blood Vessel 46

SUMMARY: Blood Flow, Blood Pressure, and Resistance § Blood flow (F) is directly proportional

SUMMARY: Blood Flow, Blood Pressure, and Resistance § Blood flow (F) is directly proportional to the difference in blood pressure ( P) between two points in the circulation § If P increases, blood flow speeds up; if P decreases, blood flow declines § Blood flow is inversely proportional to resistance (R) § If R increases, blood flow decreases § R is more important than P in influencing local blood pressure Chapter 19, Cardiovascular System - Blood Vessel 47

Examples of factors that affect Cardiovascular system Do not need to memorize Chapter 19,

Examples of factors that affect Cardiovascular system Do not need to memorize Chapter 19, Cardiovascular System - Blood Vessel 48

Heart Regulation § Ions § Calcium § Hypocalcemia – depresses heart – stops beating

Heart Regulation § Ions § Calcium § Hypocalcemia – depresses heart – stops beating § Hypercalcemia – excites heart – prolonged contraction with force heart rigor (cramp) § Sodium § Hypernatremia – blocks calcium causing hypocalcemia

Heart Regulation § Potassium § Hyperkalemia – prevents depolarization – heart becomes less active

Heart Regulation § Potassium § Hyperkalemia – prevents depolarization – heart becomes less active then stops (heart block/cardiac arrest) § Hypokalemia – feeble heart rate and arrhythmias – affects SA node directly

Physical Factors § Age § Fetal rate vs adult § 150 vs. 75 §

Physical Factors § Age § Fetal rate vs adult § 150 vs. 75 § Due to difference in metabolic rate § Gender § Men have slightly lower due to hormones § Exercise § Fit have lower than nonfit due to efficiency of heart muscle contractions § Body Temperature § Hotter has faster rate due to increase in metabolic rate