LE 42-14

Capillary Red bloodcell

15 µm

Tissue cell

CapillaryNet fluidmovement out

INTERSTITIAL FLUID

Net fluidmovement in

Blood pressureOsmotic pressure

Inward flow

Direction ofblood flow

Pre

ssu

re

Outward flow

Venous endArterial end of capillary

Fluid Return by the Lymphatic System

• The lymphatic system returns fluid to the body from the capillary beds

• This system aids in body defense

Blood Composition and Function

• Blood consists of several kinds of cells suspended in a liquid matrix called plasma

• The cellular elements occupy about 45% of the volume of blood

Plasma

• Blood plasma is about 90% water• Among its solutes are inorganic salts called

electrolytes• Plasma proteins influence blood pH, osmotic

pressure, and viscosity• Various plasma proteins function in lipid

transport, immunity, and blood clotting

LE 42-15

SodiumPotassiumCalciumMagnesiumChlorideBicarbonate

Osmotic balance,pH buffering, andregulation ofmembranepermeability

Plasma 55%

Constituent Major functions

Water Solvent forcarrying othersubstances

Ions (blood electrolytes)

Albumin Osmotic balance,pH buffering

Plasma proteins

Fibrinogen

Immunoglobulins(antibodies)

Clotting

Defense

Nutrients (such as glucose, fatty acids, vitamins)Waste products of metabolismRespiratory gases (O2 and CO2)Hormones

Substances transported by blood

Cellular elements 45%

Cell type Number Functionsper µL (mm3) of blood

5–6 million Transport oxygenand help transportcarbon dioxide

Leukocytes(white blood cells)

5,000–10,000Defense andimmunity

Monocyte

Basophil

Eosinophil

Lymphocyte

Neutrophil

PlateletsBlood clotting250,000–

400,000

Erythrocytes(red blood cells)

Separatedbloodelements

Erythrocytes

• Red blood cells, or erythrocytes, are by far the most numerous blood cells

• They transport oxygen throughout the body

Leukocytes

• There are five major types of white blood cells, or leukocytes: monocytes, neutrophils, basophils, eosinophils, and lymphocytes

• They function in defense by phagocytizing bacteria and debris or by producing antibodies

Platelets

• Platelets function in blood clotting

LE 42-16Pluripotent stem cells(in bone marrow)

Myeloidstem cells

Lymphoidstem cells

B cells T cells

Lymphocytes

Erythrocytes

Eosinophils

Basophils

Neutrophils

MonocytesPlatelets

Blood Clotting• A cascade of complex reactions converts

fibrinogen to fibrin, forming a clotEndothelium ofvessel is damaged,exposing connectivetissue; platelets adhere

Platelets form a plug Seal is reinforced by a clot of fibrin

Collagen fibersPlatelet plug

Platelet releases chemicalsthat make nearby platelets sticky

Clotting factors from:

PlateletsDamaged cellsPlasma (factors include calcium, vitamin K)

Prothrombin Thrombin

Fibrinogen Fibrin

Fibrin clot Red blood cell

5 µm

• One type of cardiovascular disease, atherosclerosis, is caused by the buildup of cholesterol within arteries

Connectivetissue

Smoothmuscle Endothelium

50 µmNormal artery Partly clogged artery 250 µm

Plaque

• Hypertension, or high blood pressure, promotes atherosclerosis and increases the risk of heart attack and stroke

• A heart attack is the death of cardiac muscle tissue resulting from blockage of one or more coronary arteries

• A stroke is the death of nervous tissue in the brain, usually resulting from rupture or blockage of arteries in the head

Concept 42.5: Gas exchange occurs across specialized respiratory surfaces

• Gas exchange supplies oxygen for cellular respiration and disposes of carbon dioxide

• Animals require large, moist respiratory surfaces for adequate diffusion of gases between their cells and the respiratory medium, either air or water

LE 42-19

Respiratorymedium(air or water)

Organismallevel

Cellular level

Energy-richfuel molecules

from food

Respiratorysurface

Circulatory system

Cellular respiration

CO2O2

ATP

LE 42-20a

Gills

Coelom

Tube foot

Sea star

LE 42-20b

Gill

Parapodia

Marine worm

LE 42-20c

Gills

Scallop

LE 42-20d

Gills

Crayfish

LE 42-21

Gillarch

Waterflow Operculum

Gillarch

Bloodvessel

Oxygen-richblood

Water flowover lamellaeshowing % O2

Gillfilaments

O2

Oxygen-poorblood

Lamella

15%40%

70%

100%

90%

60%

30% 5%

Blood flowthrough capillariesin lamellaeshowing % O2

Countercurrent exchange

Tracheal Systems in Insects

• The tracheal system of insects consists of tiny branching tubes that penetrate the body

Air sacs Tracheae

Spiracle

LE 42-22bBodycell

TracheoleAirsac

Trachea

Air Body wall

MyofibrilsTracheoles Mitochondria

2.5 µm

Lungs

• Spiders, land snails, and most terrestrial vertebrates have internal lungs

LE 42-23

Branchfrompulmonaryvein(oxygen-richblood)

Terminalbronchiole

Branchfrompulmonaryartery(oxygen-poorblood)

Alveoli

50 µ

m

Colorized SEMSEM

Nasalcavity

50 µ

m

Leftlung

Heart

Larynx

Pharynx

EsophagusTrachea

Rightlung

Bronchus

Bronchiole

Diaphragm

How an Amphibian Breathes

• An amphibian such as a frog ventilates its lungs by positive pressure breathing, which forces air down the trachea

How a Mammal Breathes

• Mammals ventilate their lungs by negative pressure breathing, which pulls air into the lungs

• Lung volume increases as the rib muscles and diaphragm contract

LE 42-24

Rib cageexpands asrib musclescontract

Airinhaled

Lung

Diaphragm

INHALATIONDiaphragm contracts

(moves down)

Rib cage getssmaller asrib musclesrelax

Airexhaled

EXHALATIONDiaphragm relaxes

(moves up)

How a Bird Breathes

• Birds have eight or nine air sacs that function as bellows that keep air flowing through the lungs

• Air passes through the lungs in one direction only

Anteriorair sacs

LungsPosteriorair sacs

Trachea

Air

Lungs

Air

Air tubes(parabronchi)in lung 1 mm

EXHALATIONAir sacs empty; lungs fill

INHALATIONAir sacs fill

Control of Breathing in Humans

• Breathing• control• centers

• Cerebrospinal• fluid

• Medulla• oblongata

• Pons

• Carotid• arteries

• Aorta

• Diaphragm

• Rib muscles

Concept 42.7: Respiratory pigments bind and transport gases

• The metabolic demands of many organisms require that the blood transport large quantities of O2 and CO2

Respiratory Pigments

• Respiratory pigments, proteins that transport oxygen, greatly increase the amount of oxygen that blood can carry

• The respiratory pigment of almost all vertebrates is the protein hemoglobin, contained in erythrocytes

LE 42-28

Polypeptide chain

O2 unloadedin tissues

O2 loadedin lungs

Iron atomHeme group

LE 42-29a

O2 unloaded fromhemoglobinduring normalmetabolism

O2 reserve that canbe unloaded fromhemoglobin totissues with highmetabolism

P and hemoglobin dissociation at 37°C and pH 7.4O2

P (mm Hg)O2

Tissues duringexercise

Tissues at rest

Lungs

1008060402000

20

40

60

80

100

O2

satu

rati

on

of

hem

og

lob

in (

%)

LE 42-29b

Bohr shift:additional O2 released fromhemoglobin atlower pH(higher CO2

concentration)

pH and hemoglobin dissociation

P (mm Hg)O2

1008060402000

20

40

60

80

100

O2

satu

rati

on

of

hem

og

lob

in (

%)

pH 7.2

pH 7.4