The Heart: Regulation of Heart RateThe Heart: Regulation of Heart Rate

Slide 11.21Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Increased heart rate1. Sympathetic nervous system

Crisis Low blood pressure

2. Hormones Epinephrine Thyroxine

3. Exercise

4. Decreased blood volume

The Heart: Regulation of Heart RateThe Heart: Regulation of Heart Rate

Slide 11.22Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Decreased heart rate

1. Parasympathetic nervous system

2. High blood pressure or blood volume

3. Decreased venous return

Major Arteries of Systemic CirculationMajor Arteries of Systemic Circulation

Slide 11.30Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 11.11

Major Veins of Systemic CirculationMajor Veins of Systemic Circulation

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Figure 11.12

Arterial Supply of the BrainArterial Supply of the Brain

Slide 11.32Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 11.13

Hepatic Portal CirculationHepatic Portal Circulation

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Figure 11.14

Circulation to the FetusCirculation to the Fetus

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Figure 11.15

Blood PressureBlood Pressure

Slide 11.36Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Measurements by health professionals are made on the pressure in large arteries

Systolic – pressure at the peak of ventricular contraction

Diastolic – pressure when ventricles relax

Pressure in blood vessels decreases as the distance away from the heart increases

Measuring Arterial Blood PressureMeasuring Arterial Blood Pressure

Slide 11.37Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 11.18

Comparison of Blood Pressures in Different Comparison of Blood Pressures in Different VesselsVessels

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Figure 11.17

Blood Pressure: Effects of FactorsBlood Pressure: Effects of Factors

Slide 11.39aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

1. Neural factors Autonomic nervous system adjustments

(sympathetic division)

2. Renal factors

Regulation by altering blood volume

Renin – hormonal control

Blood Pressure: Effects of FactorsBlood Pressure: Effects of Factors

Slide 11.39bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

3. Temperature

Heat has a vasodilation effect

Cold has a vasoconstricting effect

4. Chemicals

Various substances can cause increases or decreases

5. Diet

Variations in Blood PressureVariations in Blood Pressure

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Human normal range is variable Normal

120 mm Hg systolic 80 mm Hg diastolic

Hypotension Low systolic (below 110 mm HG) Often associated with illness

Hypertension High systolic (above 140 mm HG) Can be dangerous if it is chronic

Developmental Aspects of the Developmental Aspects of the Cardiovascular SystemCardiovascular System

Slide 11.44Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

A simple “tube heart” develops in the embryo and pumps by the fourth week

The heart becomes a four-chambered organ by the end of seven weeks

Few structural changes occur after the seventh week