Chapter 15a

Chapter 15a

Blood Flow and the Control of Blood

Pressure

About this Chapter

• The blood vessels• Blood pressure• Resistance in the arterioles• Distribution of blood to the tissues• Exchange at the capillaries• The lymphatic system• Regulation of blood pressure• Cardiovascular disease

Figure 15-1

Functional Model of the Cardiovascular SystemElastic arteries

Aorta

Aortic valve

Left heart

Right heart

Lungs

Left ventricle

Right ventricle

Left atrium

Right atrium

Pulmonary veins

Pulmonary arteryPulmonary valve

Tricuspid valve

Capillaries

Mitral valve

Venae cavae

Venules

Arteriole withvariable radius

Exchange ofmaterial withcells

Expandable veins

Blood Vessel Structure

Figure 15-2

Blood Vessel Structure & Function

PLAY Interactive Physiology® Animation: Cardiovascular System: Anatomy Review: Blood Vessel Structure & Function

Metarterioles Regulate Flow into Capillary Beds

• Capillaries lack smooth muscle and elastic tissue reinforcement, which facilitates exchange

Figure 15-3

Collateralarteries

Arteriole wall is smooth muscle.

Metarterioles can act asbypass channels.

Vein

Venule

Capillaries

Arteriovenousbypass

Precapillarysphincters

Smallvenule

Angiogenesis

• New blood vessel development• Necessary for normal development• Wound healing and uterine lining growth• Controlled by cytokines• Stimulate (mitogens): VEGF and FGF• Inhibit: angiostatin and endostatin

• Coronary heart disease • Collateral circulation

Elastic Recoil in Arteries

Figure 15-4a

1

2

3

1

Ventricle contracts.

Aorta and arteries expand andstore pressure in elastic walls.

Semilunar valve opens.

(a) Ventricular contraction

Arterioles

2

3

Elastic Recoil in Arteries

Figure 15-4a, step 1

1

1

Ventricle contracts.

(a) Ventricular contraction

Arterioles

Elastic Recoil in Arteries

Figure 15-4a, steps 1–2

1

21

Ventricle contracts.

Semilunar valve opens.

(a) Ventricular contraction

Arterioles

2

Elastic Recoil in Arteries

Figure 15-4a, steps 1–3

1

2

3

1

Ventricle contracts.

Aorta and arteries expand andstore pressure in elastic walls.

Semilunar valve opens.

(a) Ventricular contraction

Arterioles

2

3

Elastic Recoil in Arteries

Figure 15-4b

1

2

3

1

Isovolumic ventricularrelaxation

Elastic recoil of arteries sendsblood forward into rest ofcirculatory system.

Semilunar valve shuts, preventingflow back into ventricle.

(b) Ventricular relaxation occurs.

2

3

Elastic Recoil in Arteries

Figure 15-4b, step 1

1

1

Isovolumic ventricularrelaxation

(b) Ventricular relaxation occurs.

Elastic Recoil in Arteries

Figure 15-4a, steps 1–2

1

21

Isovolumic ventricularrelaxation

Semilunar valve shuts, preventingflow back into ventricle.

(b) Ventricular relaxation occurs.

2

Elastic Recoil in Arteries

Figure 15-4a, steps 1–3

1

2

3

1

Isovolumic ventricularrelaxation

Elastic recoil of arteries sendsblood forward into rest ofcirculatory system.

Semilunar valve shuts, preventingflow back into ventricle.

(b) Ventricular relaxation occurs.

2

3

Review of Blood Flow

Table 15-1

Pressure Throughout the Systemic Circulation

• Blood pressure is highest in the arteries and decreases continuously as it flows through the circulatory system

Figure 15-5

Blood Pressure

• Pulse Pressure = systolic P – diastolic P• Valves ensure one-way flow in veins• MAP = diastolic P + 1/3(systolic P – diastolic P)

PLAY Interactive Physiology® Animation: Cardiovascular System: Measuring Blood Pressure

Cuff pressure> 120 mm Hg

Stethoscope

Cuff pressurebetween 80 and

120 mm Hg

Cuff pressure< 80 mm Hg

Inflatablecuff

Pressuregauge

(a)

(b)

(c)

Measurement of Arterial Blood Pressure

Figure 15-7

Blood Pressure

• Mean arterial pressure is a function of cardiac output and resistance in the arterioles

Figure 15-8

Elastic arteriesArteriolesLeft ventricle

Mean arterial pressureCardiac output Variable resistance

Mean arterial pressure cardiac output resistance

Blood Pressure

• Blood pressure control includes rapid responses from the cardiovascular system and slower responses by the kidneys

Bloodvolume

Bloodpressure

leads to

triggers

Compensationby

cardiovascularsystem

Vasodilation Cardiac output Excretion of fluid in urineblood volume

Bloodpressureto normal

Compensationby kidneys

Stimulus

Integrating center

Tissue response

Systemic response

Slow responseFast response

KEY

Blood Pressure

Figure 15-9

Factors that Influence Mean Arterial Pressure

Figure 15-10

Factors that Influence Mean Arterial Pressure

PLAY Interactive Physiology® Animation: Cardiovascular System: Factors That Affect Blood Pressure