Respiration

Part 1

STUDY

This Information

Impacts, IssuesUp in Smoke

Smoking immobilizes ciliated cells and kills white blood cells that defend the respiratory system; highly addictive nicotine discourages quitting

The Nature of Respiration

All animals must supply their cells with oxygen and rid their body of carbon dioxide

Respiration• The physiological process by which an animal

exchanges oxygen and carbon dioxide with its environment

Interactions with Other Organ Systems

Fig. 39-2b, p. 682

food, water intake oxygen intake

Digestive System

Respiratory System

elimination of carbon dioxide

nutrients, water, salts

oxygen carbon dioxide

Circulatory System

Urinary System

water, solutes

elimination of food residues

rapid transport to and from all living cells

elimination of excess water, salts, wastes

The Basis of Gas Exchange

Respiration depends on diffusion of gaseous oxygen (O2) and carbon dioxide (CO2) down their concentration gradients

Gases enter and leave the internal environment across a thin, moist layer (respiratory surface) that dissolves the gases

Fig. 39-3, p. 682

760 mm Hg

Partial Pressure

Partial pressure• Of the total

atmospheric pressure measured by a mercury barometer (760 mm Hg), O2 contributes 21% (160 mm Hg)

Factors Affecting Diffusion Rates

Factors that increase diffusion of gases across a respiratory surface:• High partial pressure gradient of a gas across the

respiratory surface• High surface-to-volume ratio• High ventilation rate (movement of air or water

across the respiratory surface)

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Respiratory Proteins

Respiratory proteins contain one or more metal ions that reversibly bind to oxygen atoms• Hemoglobin: An iron-containing respiratory

protein found in vertebrate red blood cells• Myoglobin: A respiratory protein found in

muscles of vertebrates and some invertebrates

STUDY

Rising water temperatures, slowing streams, and organic pollutants reduce the dissolved oxygen (DO) available for aquatic species

Gasping for Oxygen

Principles of Gas Exchange

Respiration is the sum of processes that move ________ from air or water in the environment to all metabolically active ________ and move __________ from those tissues to the outside

Oxygen levels are more stable in air than in water

Principles of Gas Exchange

Respiration is the sum of processes that move oxygen from air or water in the environment to all metabolically active tissues and move carbon dioxide from those tissues to the outside

Oxygen levels are more stable in air than in water

Invertebrate Respiration

Integumentary exchange• Some invertebrates that live in aquatic or damp

environments have no respiratory organs; • Gases diffuse across the skin

Gills• Filamentous respiratory organs that increase

surface area for gas exchange in water Lungs• Saclike respiratory organs with branching tubes

that deliver air to a respiratory surface Snails and slugs that spend some time on land

have a lung instead of, or in addition to, gills

STUDY

Snails with Lungs

Invertebrate Respiration

Tracheal system• Insects and spiders with a hard integument have

branching tracheal tubes that open to the surface through spiracles (no respiratory protein required)

Book lungs• Some spiders also have thin sheets of respiratory

tissue that exchange oxygen with a respiratory pigment (hemocyanin) in blood

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Fig. 39-7, p. 685

trachea (tube inside body)

spiracle (opening to body surface)

Insect Tracheal System

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Fig. 39-8, p. 685

book lung

air-filled spaceblood-filled space

A Spider’s Book Lung

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Key Concepts Gas Exchange in Invertebrates

Gas exchange occurs across the body surface or gills of aquatic invertebrates

In large invertebrates on land, it occurs across a moist, internal respiratory surface or at fluid-filled tips of branching tubes that extend from the surface to internal tissues

Vertebrate Respiration

Fishes use gills to extract oxygen from water• Countercurrent flow aids exchange (blood flows

through gills in opposite direction of water flow)

Amphibians exchange gases across their skin, and at respiratory surfaces of paired lungs• Larvae have external gills

Fig. 39-9a, p. 686

gill cover

Fish Gills

(a) Location of the gill cover of a bony fish.

Fig. 39-9b, p. 686

mouth open

gill cover closed(b) Water is sucked into the mouth and

over the gills when a fish closes its gill covers, opens its mouth, and expands its oral cavity.

STUDY

Fig. 39-9c, p. 686

mouth closed

gill cover open(c) The water moves out when

the fish closes its mouth, opens its gill covers, and squeezes the water past its gills.

STUDY

Fig. 39-10a, p. 686

gill filaments

water is sucked into mouth

Water exits through gill slits

A A bony fish with its gill cover removed. Water flows in through the mouth, flows over the gills, then exits through gill slits. Each gill has bony gill arches to which the gill filaments attach.

one gill arch

Countercurrent FlowSTUDY

Fig. 39-10 (b-c), p. 686

gill arch respiratory surface

gill filament

fold with a capillary bed inside

water flow

direction of blood flow

oxygen-poor blood from deep in bodyoxygenated blood

back toward body

B Two gill arches with filaments

C Countercurrent flow of water and blood

STUDY

Fig. 39-11, p. 687

ALowering the floor of the mouth draws air inward through nostrils.

BClosing nostrils and raising the floor of the mouth pushes air into lungs.

CRhythmically raising and lowering the floor of the mouth assists gas exchange.

DContracting chest muscles and raising the floor of the mouth forces air out of lungs, and the frog exhales.

Frog RespirationSTUDY

Vertebrate Respiration

Reptiles, birds and mammals exchange gases through paired lungs, ventilated by chest muscles

Birds have the most efficient vertebrate lungs• Air sacs allow oxygen-rich air to pass respiratory

surfaces on both inhalation and exhalation

Fig. 39-12, p. 687

A Inhalation 1 Muscles expand chest cavity, drawing air in through nostrils. Some of the air flowing in through the trachea goes to lungs and some goes to posterior air sacs.

trachea

anterior air sacs

Anterior air sacs empty. Air from posterior air sacs moves into lungs.

B Exhalation 1 lung

posterior air sacs

C Inhalation 2 Air in lungs moves to anterior air sacs and is replaced by newly inhaled air.

D Exhalation 2 Air in anterior air sacs moves out of the body and air from posterior sacs flows into the lungs.

Bird Respiratory System

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Fig. 39-12 (inset), p. 687

Human Respiratory System

The human respiratory system functions in gas exchange, sense of smell, voice production, body defenses, acid-base balance, and temperature regulation

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Airways

Air enters through nose or mouth, flows through the pharynx (throat) and the larynx (voice box)• Vocal cords change the size of the glottis

The epiglottis protects the trachea, which branches into two bronchi, one to each lung• Cilia and mucus-secreting cells clean airways

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Fig. 39-14, p. 689

vocal cords

glottis (closed)epiglottis

tongue’s base

glottis closed

glottis open

Larynx: Vocal Cords and Glottis

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From Airways to Alveoli

Inside each lung, bronchi branch into bronchioles that deliver air to alveoli

Alveoli are small sacs, one cell thick, where gases are exchanged with pulmonary capillaries

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Muscles and Respiration

Muscle movements change the volume of the thoracic cavity during breathing

Diaphragm• A broad sheet of smooth muscle below the lungs• Separates the thoracic and abdominal cavities

Intercostal muscles• Skeletal muscles between the ribs

STUDY

Fig. 39-13a, p. 688

Nasal CavityChamber in which air is moistened, warmed, and filtered, and in which sounds resonateOral Cavity (Mouth)

Supplemental airway when breathing is labored

Pharynx (Throat)Airway connecting nasal cavity and mouth with larynx; enhances sounds; also connects with esophagusEpiglottisCloses off larynx during swallowingLarynx (Voice Box)Airway where sound is produced; closed off during swallowing

Pleural MembraneDouble-layer membrane with a fluid-filled space between layers; keeps lungs airtight and helps them stick to chest wall during breathing

Trachea (Windpipe)Airway connecting larynx with two bronchi that lead into the lungs

Lung (One of a Pair)Lobed, elastic organ of breathing; enhances gas exchange between internal environment and outside air

Intercostal Muscles At rib cage, skeletal muscles with roles in breathing. There are two sets of intercostal muscles (external and internal)

Bronchial TreeIncreasingly branched airways starting with two bronchi and ending at air sacs (alveoli) of lung tissue

Diaphragm Muscle sheet between the chest cavity and abdominal cavity with roles in breathing

Functions of the Respiratory System

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Fig. 39-13b, p. 688

bronchiole alveolar sac (sectioned)

alveolar duct

alveoliSTUDY

Fig. 39-13c, p. 688

alveolar sac

pulmonary capillary

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Cyclic Reversals in Air Pressure Gradients

Respiratory cycle• One inhalation and one exhalation

Inhalation is always active• Contraction of diaphragm and external intercostal

muscles increases volume of thoracic cavity• Air pressure in alveoli drops below atmospheric

pressure; air moves inward

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Cyclic Reversals in Air Pressure Gradients

Exhalation is usually passive• As muscles relax, the thoracic cavity shrinks• Air pressure in the alveoli rises above

atmospheric pressure, air moves out

Exhalation may be active• Contraction of abdominal muscles forces air out

STUDY

The Thoracic Cavity and the Respiratory Cycle

Fig. 39-15a, p. 690

Inward flow of air

A Inhalation. Diaphragm contracts, moves down. External intercostal muscles contract, lift rib cage upward and outward. Lung volume expands.

Fig. 39-15b, p. 690

Outward flow of air

B Exhalation. Diaphragm, external intercostal muscles return to resting positions. Rib cage moves down. Lungs recoil passively.

Supplemental: First Aid for Choking

Heimlich maneuver• Upward-directed force on the diaphragm forces

air out of lungs to dislodge an obstruction

Respiratory Volumes

Air in lungs is partially replaced with each breath• Lungs are never emptied of air (residual volume)

Vital capacity• Maximum volume of air the lungs can exchange

Tidal volume• Volume of air that moves in and out during a

normal respiratory cycle

Respiratory Volumes

Control of Breathing

Neurons in the medulla oblongata of the brain stem are the control center for respiration• Rhythmic signals from the brain cause muscle

contractions that cause air to flow into the lungs

Chemoreceptors in the medulla, carotid arteries, and aorta wall detect chemical changes in blood, and adjust breathing patterns

Fig. 39-18, p. 691

CO2 concentration and acidity rise in the blood and cerebrospinal fluid.

STIMULUS

Chemoreceptors in wall of carotid arteries and aorta

Respiratory center in brain stem

Diaphragm, Intercostal muscles

Stepped Art

RESPONSE

CO2 concentration and acidity decline in the blood and cerebrospinal fluid.

Tidal volume and rate of breathing change.

Respiratory Responses

Gas Exchange and Transport

Gases diffuse between a pulmonary capillary and an alveolus at the respiratory membrane• Alveolar epithelium• Capillary endothelium• Fused basement membranes

O2 and CO2 each follow their partial pressure gradient across the membrane

Fig. 39-19, p. 692

pore for air flow between adjoining alveoli

red blood cell inside pulmonary capillary

alveolar epithelium

capillary endotheliumfused basement membranes of both epithelial tissues

a Surface view of capillaries associated with alveoli

air space inside alveolus

b Cutaway view of one of the alveoli and adjacent pulmonary capillaries

c Three components of the respiratory membrane

The Respiratory Membrane

Oxygen Transport

In alveoli, partial pressure of O2 is high; oxygen binds with hemoglobin in red blood cells to form oxyhemoglobin (HbO2)

In metabolically active tissues, partial pressure of O2 is low; HbO2 releases oxygen

Myoglobin, found in some muscle tissues, is similar to hemoglobin but holds O2 more tightly

Fig. 39-20a, p. 693

alpha globin alpha globin

beta globin beta globinHemoglobin

Structure of hemoglobin, the oxygen-transporting protein of red blood cells. It consists of four globin chains, each associated with an iron-containing heme group, color-coded red.

Fig. 39-20b, p. 693

heme

Myoglobin, an oxygen-storing protein in muscle cells. Its single chain associates with a heme group. Compared to hemoglobin, myoglobin has a higher affinity for oxygen, so it helps speed the transfer of oxygen from blood to muscle cells.

Myoglobin

Carbon Dioxide Transport

Carbon dioxide is transported from metabolically active tissues to the lungs in three forms• 10% dissolved in plasma

• 30% carbaminohemoglobin (HbCO2)

• 60% bicarbonate (HCO3-)

Carbonic anhydrase in red blood cells catalyzes the formation of bicarbonate

CO2 + H2O → H2CO3 → HCO3- + H+

Fig. 39-21, p. 693

DRY INHALED AIR160 0.03

MOIST EXHALED AIR120 27

104 40alveolar sacs

pulmonary arteries

40 45

pulmonary veins

100 40

start of systemic

veins

40 45

start of systemic capillaries

100 40

cells of body tissuesless than 40 more than 45 Stepped Art

Partial Pressures for Oxygen and Carbon Dioxide

Partial pressures (in mm Hg) for oxygen (pink boxes) and carbon dioxide (blue boxes) in the atmosphere, blood, and tissues.

Figure It Out: What is the partial pressure of oxygen in arteries that carry blood to systemic capillary beds?

Answer: 100 mm Hg

The Carbon Monoxide Threat

Carbon monoxide (CO)• A colorless, odorless gas that can fill up O2

binding sites on hemoglobin, block O2 transport, and cause carbon monoxide poisoning

Carbon monoxide poisoning often results when fuel-burning appliance are poorly ventilated• Symptoms include nausea, headache, confusion,

dizziness, and weakness

Key Concepts Gas Exchange in Vertebrates

Gills or paired lungs are gas exchange organs in most vertebrates

The efficiency of gas exchange is improved by mechanisms that cause blood and water to flow in opposite directions at gills, and by muscle contractions that move air into and out of lungs

Respiratory Diseases and Disorders

Interrupted breathing• Brain-stem damage, sleep apnea, SIDS

Potentially deadly infections• Tuberculosis, pneumonia

Chronic bronchitis and emphysema• Damage to ciliated lining of bronchioles and walls

of alveoli; tobacco smoke is the main risk factor

Fig. 39-22a, p. 694

Cigarette Smoke and Ciliated Epithelium

Fig. 39-22b, p. 694

free surface of a mucus- secreting cell

free surface of a cluster of ciliated cells

Risks Associated With Smoking and Emphysema

(a) From the American Cancer Society, a list of major risks incurred by smoking and the benefits of quitting. (b) Appearance of normal lung tissue in humans. (c) Appearance of lung tissues from someone who was affected by emphysema.

Key Concepts Respiratory Problems

Respiration can be disrupted by damage to respiratory centers in the brain, physical obstructions, infectious disease, and inhalation of pollutants, including cigarette smoke

High Climbers and Deep Divers

Altitude sickness• Hypoxia can result when people who live at low

altitudes move suddenly to high altitudes• People who grow up at high altitudes have more

alveoli and blood vessels in their lungs

Acclimatization to altitude includes adjustments in cardiac output, rate and volume of breathing • Hypoxia stimulates erythropoietin secretion

Adaptation to High Altitude

Llamas that live at high altitudes have special hemoglobin that binds oxygen more efficiently

Deep-Sea Divers

Water pressure increases with depth; human divers using compressed air risk nitrogen narcosis (disrupts neuron signaling)

Returning too quickly to the surface from a deep dive can release dangerous nitrogen bubbles into the blood stream (‘the bends”)

Without tanks, trained humans can dive to 210 meters; sperm whales can dive 2,200 meters

Adaptations for Deep Diving

Leatherback turtles dive up to one hour• Move air to cartilage-reinforced airways• Flexible shell for compression

Four ways diving animals conserve oxygen• Deep breathing before diving• High red-cell count, large amounts of myoglobin• Slowed heart rate and metabolism• Conservation of energy

Deep Divers

Key Concepts Gas Exchange in Extreme Environments

At high altitudes, the human body makes short-term and long-term adjustments to thinner air

Built-in respiratory mechanisms and specialized behaviors allow sea turtles and diving marine mammals to stay under water, at great depths, for long periods

Video Supplements

Animation: Bird respiration

Animation: Human respiratory system

Animation: Examples of respiratory surfaces

Animation: Vertebrate lungs

Animation: Bony fish respiration

Animation: Frog respiration

Animation: Respiratory cycle

Animation: Heimlich maneuver

Animation: Changes in lung volume and pressure

Animation: Partial pressure gradients

Animation: Bicarbonate buffer system

Animation: Globin and hemoglobin structure

Animation: Pressure-gradient changes during respiration

Animation: Structure of an alveolus

Animation: Vocal cords

ABC video: Blood test for lung cancer

Video: Up in smoke