CHAPTER 23 Circulation

BIOLOGYCONCEPTS & CONNECTIONS

Fourth Edition

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

Neil A. Campbell • Jane B. Reece • Lawrence G. Mitchell • Martha R. Taylor

From PowerPoint® Lectures for Biology: Concepts & Connections

CHAPTER 23Circulation

Modules 23.1 – 23.3


• As with all land animals, the giraffe and the corn snake are constantly subject to the force of gravity

How Does Gravity Affect Blood Circulation?


• The circulatory system keeps blood pumping despite gravity’s pull

– Muscle contractions help blood travel uphill in the veins of a giraffe’s long legs

– The wriggling of the corn snake squeezes its veins and increases circulation


• Most animals have a circulatory system – It transports O2 and nutrients to cells

– It takes away CO2 and other wastes


• Capillaries are microscopic blood vessels – They form an intricate network among

the tissue cells

23.1 The circulatory system associates intimately with all body tissues

Figure 23.1A

Redbloodcell

Capillary


– No substance has to diffuse far to enter or leave a cell

Figure 23.1B

Capillary

INTERSTITIALFLUID

Tissuecell

Diffusion ofmolecules


• In cnidarians and flatworms, the gastrovascular cavity functions in both – digestion – internal transport

23.2 Several types of internal transport have evolved in animals

MECHANISMS OF INTERNAL TRANSPORT

Figure 23.2A

Mouth

Circularcanal


• Most animals have a separate circulatory system, either open or closed

• Open systems– A heart pumps blood through open-ended

vessels into spaces between cells

Figure 23.2B

PoresTubular heart


• Closed systems– A heart pumps blood through arteries and

capillary beds– The blood returns to the heart via veins

Figure 23.2C

Artery(O2-rich blood)

ArterioleCapillary beds

Venule

Vein

Atrium

VentricleHeartArtery

(O2-poor blood)Gillcapillaries


• A fish has a single circuit of blood flow

23.3 Vertebrate cardiovascular systems reflect evolution

Figure 23.3A

Gill capillaries

Heart:

Ventricle (V)

Atrium (A)

Systemic capillaries


• The cardiovascular system of land vertebrates has two circuits

• The pulmonary circuit– conveys blood

between the heart and gas-exchange tissues

• The systemic circuit– carries blood

between the heart and the rest of the body

Figure 23.3B

PULMONARYCIRCUIT

A

Systemic capillaries

Lung capillaries

VRight

SYSTEMICCIRCUIT

A

VLeft


• The mammalian heart has two thin-walled atria that pump blood into the ventricles– The thick-walled ventricles pump blood to

all other body organs

23.4 The human heart and cardiovascular system typify those of mammals

THE MAMMALIAN CARDIOVACULAR SYSTEM


Figure 23.4A

Pulmonaryartery

Superiorvena cava

RIGHTATRIUM

Pulmonaryveins

Semilunarvalve

Atrioventricularvalve

Inferiorvena cava

Aorta

Pulmonaryartery

LEFTATRIUM

Pulmonaryveins

Semilunarvalve

Atrioventricularvalve

RIGHTVENTRICLE

LEFTVENTRICLE


Figure 23.4B

RIGHT VENTRICLE

1

23

Capillariesof right lung

3

Capillariesof left lung

4

LEFT ATRIUM5

LEFT VENTRICLE

6

Aorta

7Capillaries ofHead and arms

8

Capillaries ofabdominal organsand legs

9

Superiorvena cava

10

Inferiorvena cava

11

RIGHT ATRIUM

Pulmonaryvein

Aorta

Pulmonaryvein

Pulmonaryartery

Pulmonaryartery


• A single layer of epithelial cells forms capillary walls

• Arteries and veins have smooth muscle and connective tissue– Valves in veins prevent the backflow of

blood

23.5 The structure of blood vessels fits their functions


Figure 23.5

Epithelium

Smoothmuscle

Connectivetissue

ARTERY

ARTERIOLE

CAPILLARY

Epithelium Basementmembrane

Epithelium

Smoothmuscle

Connectivetissue

Valve

VEIN

VENULE


• Diastole– Blood flows from

the veins into the heart chambers

23.6 The heart contracts and relaxes rhythmically

Figure 23.6

Heart isrelaxed.AV valvesare open.

1 2

3

Atriacontract.

Ventriclescontract.Semilunarvalvesare open.

SYSTOLE

DIASTOLE

0.4 sec

0.1 sec

0.3 sec

• Systole– The atria briefly

contract and fill the ventricles with blood

– Then the ventricles contract and propel blood out


• Heart valves prevent backflow

• Cardiac output – The amount of blood pumped into the

aorta by the left ventricle per minute


• The SA node (pacemaker) generates electrical signals that trigger the contraction of the atria

• The AV node then relays these signals to the ventricles

23.7 The pacemaker sets the tempo of the heartbeat

Figure 23.7

Pacemaker(SA node)

1 2 3 4

Rightatrium

Rightventricle

AV nodeSpecializedmuscle fibers

ECG


• An electrocardiogram (ECG) is a recording of electrical changes in the skin resulting from the electrical signals in the heart– Control centers in the brain adjust heart

rate to body needs


• A heart attack is damage that occurs when a coronary feeding the heart is blocked

23.8 Connection: What is a heart attack?

Figure 23.8A

Rightcoronaryartery

Aorta

Leftcoronaryartery

Blockage

Dead muscle tissue


• Blood vessel blockage is usually due to blood clots

Figure 23.8B

Connectivetissue

Smoothmuscle Epithelium Plaque


• Blood pressure depends on– cardiac output– resistance of vessels

23.9 Blood exerts pressure on vessel walls


• Pressure is highest in the arteries– It drops to

zero by the time the blood reaches the veins

Figure 23.9A

Diastolicpressure

Systolicpressure

Relative sizes andnumbersof blood vessels


• Three factors keep blood moving back to the heart– muscle contractions– breathing– one-way valves

Figure 23.9B

Direction ofblood flowin vein

Valve (closed)Skeletal muscle

Valve (open)


• Blood pressure is measured as systolic and diastolic pressures

23.10 Connection: Measuring blood pressure can reveal cardiovascular problems

Figure 23.10

Blood pressure120 systolic80 diastolic(to be measured)

1 2 3 4

Rubber cuffinflated with air

Pressurein cuffbelow120

Pressurein cuffbelow 80

Artery

Pressurein cuffabove120

Soundsaudible instethoscope

Soundsstop

Arteryclosed


• Hypertension is persistent systolic pressure higher than 140 mm Hg and/or diastolic pressure higher than 90 mm Hg– It is a serious cardiovascular problem


• Muscular constriction of arterioles and precapillary sphincters controls the flow through capillaries

23.11 Smooth muscle controls the distribution of blood

Figure 23.111 Sphincters relaxed 2 Sphincters contracted

Precapillary sphincters Thoroughfarechannel

CapillariesArteriole Venule Arteriole Venule

Thoroughfarechannel


23.12 Capillaries allow the transfer of substances through their walls

Figure 23.12A


• The transfer of materials between the blood and interstitial fluid can occur by– leakage through clefts in the capillary

walls– diffusion through the wall– blood pressure– osmotic pressure


Figure 23.12B

Arterialend of

capillary

Tissue cells

Osmoticpressure

INTERSTITIALFLUID NET PRESSURE

OUT

Bloodpressure

Bloodpressure

Osmoticpressure Venous

end ofcapillary

NET PRESSUREIN


• Plasma is an aqueous solution of various substances

23.13 Blood consists of cells suspended in plasmaSTRUCTURE AND FUNCTION OF BLOOD


Figure 23.13

Withdrawblood

Place in tubePLASMA 55%

CONSTITUENT MAJOR FUNCTIONS

WaterSolvent forcarrying othersubstances

SaltsOsmotic balance,pH buffering, andregulation ofmembranepermeability

SodiumPotassiumCalciumMagnesiumChlorideBicarbonate

Plasma proteinsOsmotic balance,pH bufferingClottingImmunity

Albumin

FibrinogenImmunoglobins(antibodies)

Substances transported by bloodNutrients (e.g., glucose, fatty acids, vitamins)Waste products of metabolismRespiratory gases (O2 and CO2)Hormones

Centrifuge

CELLULAR ELEMENTS 45%

CELL TYPE NUMBER(per mm3 of blood)

FUNCTIONS

Erythrocytes(red blood cells) 5–6 million Transport of

oxygen (and carbon dioxide)

Leukocytes(white blood cells) 5,000–10,000

Defense andimmunity

BasophilEosinophil

Neutrophil

Lymphocyte

Monocyte

Platelets 250,000–400,000 Blood clotting


23.14 Red blood cells transport oxygen

Figure 23.14

• Red blood cells contain hemoglobin – Hemoglobin enables

the transport of O2


23.15 White blood cells help defend the body

Figure 23.15

• White blood cells function both inside and outside the circulatory system – They fight infections and cancer

Basophil

Neutrophil

Monocyte

Eosinophil

Lymphocyte


23.16 Blood clots plug leaks when blood vessels are injured

Figure 23.16B

• When a blood vessel is damaged, platelets respond– They help trigger

the formation of an insoluble fibrin clot that plugs the leak


Figure 23.16A

Platelet releases chemicalsthat make nearby platelets sticky

Injury to lining of bloodvessel exposes connectivetissue; platelets adhere

1 2 3Platelet plug forms Fibrin clot trapsblood cells

Connectivetissue

Plateletplug

Clotting factors from:

Platelets

Damaged cells

Calcium andother factorsin blood plasma

Prothrombin Thrombin

Fibrinogen Fibrin


23.17 Connection: Stem cells offer a potential cure for leukemia and other blood cell diseases

Figure 23.17

• All blood cells develop from stem cells in bone marrow– Such cells may prove

valuable for treating certain blood disorders

CHAPTER 23 Circulation

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