Copyright © 2009 Pearson Education, Inc. MECHANISMS OF INTERNAL TRANSPORT.

Copyright © 2009 Pearson Education, Inc.

MECHANISMS OF INTERNAL TRANSPORT


23.1 Circulatory systems facilitate exchange with all body tissues

All cells need

– Nutrients

– Gas exchange

– Removal of wastes

Diffusion alone is inadequate for large and complex bodies



An internal transport system assists diffusion by moving materials between

– Surfaces of the body

– Internal tissues



A gastrovascular cavity in cnidarians and flatworms serves

– Digestion

– Distribution of substances

Most animals use a circulatory system

– Blood

– Heart

– Blood vessels



Open circulatory systems

– Arthropods and many molluscs

– Heart pumps blood through open-ended vessels

– Cells directly bathed in blood

PoresTubular heart



Closed circulatory systems

– Vertebrates, earthworms, squids, octopuses

– Blood stays confined to vessels

– A heart pumps blood through arteries to capillaries

– Veins return blood to heart

Capillary beds

Artery(O2-rich blood)

Arteriole

Artery(O2-poor blood)

HeartVentricle

Atrium

Vein

Venule

Gillcapillaries


23.2 EVOLUTION CONNECTION: Vertebrate Cardiovascular systems reflect evolution

Two-chambered heart

– Fish

– Pumps blood in a single circuit

– From gill capillaries

– To systemic capillaries

– Back to heart

Gill capillaries

Heart:

Ventricle (V)

Atrium (A)

Systemic capillaries



Land vertebrates have double circulation

– Separate pulmonary and systemic circuits

Three-chambered hearts

– Amphibians, turtles, snakes, lizards

– Two atria

– One undivided ventricle

– Permits blood diversion away from lungs when diving

– But some blood from body and lungs mixes in the ventricle when not diving

Lung and skin capillaries

Pulmocutaneouscircuit

VRight


A A

LeftSystemic

circuit



Four-chambered hearts

– Crocodilians, birds, mammals

– Two atria and two ventricles

– Two circuits that do not mix

– Right side pumps blood from body to lungs

– Left side pumps blood from lungs to body

– Higher blood pressure

– Supports more efficient movement of blood

– Needed in endothermic animals

Lung capillaries

Pulmonarycircuit

VRight


A A

LeftSystemic

circuit

V


THE HUMAN CARDIOVASCULAR

SYSTEM


23.3 The human cardiovascular system illustrates the double circulation of mammals

Blood flow through the double circulatory system of humans

Animation: Path of Blood Flow in Mammals

Superiorvena cava

Pulmonaryartery

Capillariesof right lung

8

9

2

3

Aorta

4 510

16

Pulmonaryvein

9Right atrium

Inferiorvena cava

Right ventricle

4

8

3

Pulmonaryartery

Capillariesof left lung

Aorta

Pulmonaryvein

Left atrium

Left ventricle

27

Capillaries ofhead, chest, andarms

Capillaries ofabdominal regionand legs


23.3 The human cardiovascular system illustrates the double circulation of mammals

The mammalian heart

– Two thin-walled atria that

– Pump blood

– To ventricles

– Thick-walled ventricles that

– Pump blood

– To lungs and all other body regions

Right atrium To lung

From lung

Semilunarvalve

Atrioventricular(AV) valve

Left atrium

To lung

From lung

Semilunarvalve

Atrioventricular(AV) valve

Rightventricle

Leftventricle


23.4 The heart contracts and relaxes rhythmically

During diastole, blood flows

– From veins

– Into heart chambers

During systole, blood flows

– From atria

– Into ventricles

Semilunarvalvesclosed1 Heart is

relaxed.

AV valvesare open.

Diastole

0.4 sec


relaxed.

AV valvesare open.

Diastole

0.4 sec

2 Atriacontract.

Systole0.1 sec


relaxed.

AV valvesare open.

Diastole

0.4 sec

2 Atriacontract.

Systole0.1 sec

Semilunarvalvesare open.

3 Ventriclescontract.

AV valvesclosed

0.3 sec


23.4 The heart contracts and relaxes rhythmically

Cardiac output

– Amount of blood/minute pumped into systemic circuit

Heart rate

– Number of beats/minute

Heart valves

– Prevent the backflow of blood

Heart murmur

– A defect in one or more heart valves


23.5 The pacemaker sets the tempo of the heartbeat

The pacemaker (SA node)

– Sets the rate of heart contractions

– Generates electrical signals in atria

The AV node

– Relays these signals to the ventricles

Pacemaker(SA node) AV node

Rightatrium

1 Pacemakergeneratessignalsto contract

2 Signals spreadthrough atriaand are delayedat AV node

ECG

3 Signals relayedto apex of heart

4 Signals spreadthroughventricle

Apex

Specializedmuscle fibers


23.5 The pacemaker sets the tempo of the heartbeat

An electrocardiogram (ECG)

– Records electrical changes in heart

Heart rate normally adjusts to body needs

Abnormal rhythms may occur in a heart attack

– External defibrillator can restore rhythm

– Implanted artificial pacemakers can trigger normal rhythms


23.6 CONNECTION: What is a heart attack?

A heart attack is damage to cardiac muscle

– Typically from a blocked coronary artery

Stroke

– Death of brain tissue from blocked arteries in the head

Blockage

Deadmuscletissue

Rightcoronaryartery

Superiorvena cava

Pulmonaryartery

Aorta

Leftcoronaryartery


23.6 CONNECTION: What is a heart attack?

Atherosclerosis

– Plaques develop inside inner walls of blood vessels

– Plaques narrow blood vessels

– Blood flow is reduced

PlaqueEpitheliumConnectivetissue

Smoothmuscle


23.7 The structure of blood vessels fits their functions

Arteries and veins

– Lined by single layer of epithelial cells

– Smooth muscle in walls can reduce blood flow

– Elastic fibers permit recoil after stretching

– Veins have one-way valves that restrict backward flow

Connectivetissue

Capillary

Venule

Smoothmuscle

Arteriole

Artery Vein

Valve

Epithelium

Basal lamina

Epithelium

Smoothmuscle

Epithelium

Connectivetissue


23.7 The structure of blood vessels fits their functions

Capillaries

– Thin walls—a single layer of epithelial cells

– Narrow—blood cells flow in a single file

– Increase surface area for gas and fluid exchange

Nuclei ofsmoothmusclecells

Redbloodcell

Capillary

Diffusion ofmolecules

Capillary

Interstitialfluid

Tissuecell


23.8 Blood pressure and velocity reflect the structure and arrangement of blood vessels

Blood pressure

– The force blood exerts on vessel walls

– Depends on

– Cardiac output

– Resistance of vessels

– Decreases as blood moves away from heart

Systolicpressure

Diastolicpressure

120100

806040200

Relative sizes andnumbersof bloodvessels

Pre

ssu

re (

mm

Hg

)V

elo

city

(cm

/sec

)

5040302010

0

Ao

rta

Ven

ae c

avae

Art

erie

s

Cap

illar

ies

Ven

ule

s

Vei

ns

Art

erio

les



Blood pressure is

– Highest in arteries

– Lowest in veins

Blood pressure is measured as

– Systolic pressure—caused by ventricular contraction

– Diastolic pressure—low pressure between contractions



How does blood travel against gravity, up legs?

– Pressure from muscle contractions

– Between two muscles

– Between muscles and bone or skin

– Squeezes veins

– One-way valves limit blood flow to one direction, towards heart

Direction ofblood flowin vein

Valve(open)

Skeletalmuscle

Valve(closed)


23.9 CONNECTION: Measuring blood pressure can reveal cardiovascular problems

Hypertension is a serious cardiovascular problem

– Consistent pressures above either

– 140 systolic

– 90 diastolic

Typical bloodpressure120 systolic70 diastolic

Pressurein cuffabove 120120Rubber cuff

inflatedwith air

Arteryclosed

Artery

1 2

Pressurein cuffat 120120

Soundsaudible instethoscope

3

70

Soundsstop

4

Pressurein cuffat 70


23.9 CONNECTION: Measuring blood pressure can reveal cardiovascular problems

Hypertension causes

– Heart to work harder, weakening heart over time

– Increased plaque formation from tiny ruptures

– Increased risk of blood clot formation

Hypertension can cause

– Heart attacks

– Strokes

– Kidney failure


23.10 Smooth muscle controls the distribution of blood

Blood flow through capillaries– Is restricted by smooth muscle sphincters

– Only about 5–10% of capillaries are open at one time

Capillaries

Thoroughfarechannel

Precapillary sphincters

Venule

Sphincters relaxed

Thoroughfarechannel

VenuleArteriole

2

1

Sphincters contracted

Arteriole


23.11 Capillaries allow the transfer of substances through their walls

Capillaries have very thin walls

Substances can cross through these thin walls

– Between blood and interstitial fluids

Nucleus ofepithelial

cell

Capillarylumen

Interstitialfluid

Capillarywall

Musclecell

Clefts betweenthe epithelialcells of thecapillary wall


23.11 Capillaries allow the transfer of substances through their walls

Blood and interstitial fluid exchange substances

– By diffusion

– By pressure flow through clefts between epithelial cells

Blood pressure forces fluid out of capillaries at the arterial end

Osmotic pressure draws in fluid at the venous end

Tissue cells

Osmoticpressure

Interstitialfluid

Net fluidmovement in

Bloodpressure

Osmoticpressure Venous

end ofcapillary

Arterialend of

capillary

Bloodpressure

Net fluidmovement out


STRUCTURE AND FUNCTION

OF BLOOD


23.12 Blood consists of red and white blood cells suspended in plasma

Plasma is about 90% water

Plasma contains

– Various inorganic ions

– Proteins, nutrients

– Wastes, gases

– Hormones


23.12 Blood consists of red and white blood cells suspended in plasma

Red blood cells (erythrocytes)

– Transport O2 bound to hemoglobin

White blood cells (leukocytes)

– Function inside and outside the circulatory system

– Fight infections and cancer

Plasma (55%)

Constituent

Osmotic balance,pH buffering, andmaintaining ionconcentration ofinterstitial fluid

Solvent forcarrying othersubstances

Water

Ions (blood electrolytes)

Major functions

SodiumPotassiumCalciumMagnesiumChlorideBicarbonate

Plasma proteins

ClottingFibrinogen

Osmotic balanceand pH buffering

Defense Immunoglobulins(antibodies)

Substances transported by blood

Nutrients (e.g., glucose, fatty acids, vitamins)Waste products of metabolismRespiratory gases (O2 and CO2)Hormones

Cellular elements (45%)

Centrifugedblood

sample

Numberper µL (mm3) of blood

Cell type Functions

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

oxygen (andcarbon dioxide)

Leukocytes(white blood cells)

BasophilLymphocyte

Defense andimmunity

Eosinophil

5,000–10,000

250,000–400,000

Neutrophil Monocyte

Blood clottingPlatelets


23.14 Blood clots plug leaks when blood vessels are injured

The blood-clotting process

– Platelets adhere to exposed connective tissue

– Platelets form a plug

– Platelets help trigger the conversion of fibrinogen to fibrin

– A fibrin clot traps blood cells

Platelets adhereto exposedconnective tissue

1

Epithelium

Connective tissue

Platelet


1

Epithelium

Connective tissue

Platelet

Platelet plugforms

2

Platelet plug


1

Epithelium

Connective tissue

Platelet

Platelet plugforms

2

Platelet plug

Fibrin clottrapsblood cells

3


23.13 CONNECTION: Too few or too many red blood cells can be unhealthy

Anemia

– Abnormally low amounts of hemoglobin or red blood cells

– Causes fatigue due to lack of oxygen in tissues


23.13 CONNECTION: Too few or too many red blood cells can be unhealthy

Hormone erythropoietin (EPO)

– Regulates red blood cell production

Some athletes artificially increase red blood cell production by injecting erythropoietin

– Can lead to

– Clotting

– Stroke

– Heart failure

– Death


23.15 CONNECTION: Stem cells offer a potential cure for blood cell diseases

Stem cells divide in bone marrow

– To produce all the types of blood cells throughout life

– Are used to treat some blood disorders

Multipotentstem cell

Lymphoidstem cell

Myeloidstem cells

Erythrocytes

PlateletsEosinophils

Basophils

NeutrophilsMonocytesLymphocytes


23.15 CONNECTION: Stem cells offer a potential cure for blood cell diseases

Leukemia is cancer of white blood cells

– Leukemia results in extra leukocytes that do not function properly

– Leukemia is usually fatal unless treated

– Some treatments

– Destroy all bone marrow in the patient

– Transplant new bone marrow from a donor with similar bone marrow

Capillary

EpitheliumValve

Basementmembrane

Connectivetissue

Smoothmuscle

VeinArtery

a.

c.

d.

e.

f.

g.

h.

i.

b.

p.

o.

n.

m.

l.

k.

j.

a.

b.


You should now be able to

1. Explain how the circulatory systems of a giraffe and snake resist gravity

2. Describe the general need for and functions of a circulatory system

3. Compare the structures and functions of gastrovascular cavities, open circulatory systems, and closed circulatory systems

4. Compare the circulatory systems of a fish, frog, and mammal



5. Explain how heartbeats are controlled

6. Describe the causes and consequences of a heart attack and cardiovascular disease

7. Relate the structure of blood vessels to their functions

8. Describe the components of blood and their functions



9. Describe the process of blood clotting

10. Describe the causes and treatments for leukemia

Copyright © 2009 Pearson Education, Inc. MECHANISMS OF INTERNAL TRANSPORT.

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Transcript of Copyright © 2009 Pearson Education, Inc. MECHANISMS OF INTERNAL TRANSPORT.