RESPIRATION

RESPIRATION

Respiratory system

Functions

O2 uptake

CO2 expulsion

2

Atmospheric Gasses

Nitrogen (N2)

78%

PN2 593 mmHg

Oxygen (O2)

21%

PO2 160 mmHg

Carbon dioxide (CO2)

0.05%

PCO2 0.4 mmHg

760 mm Hg

3

Elements of Gas Exchange

Movement directed by concentration &

pressure gradients

Diffusion

Concentration: [high] [low]

Pressure: H L

Factors affecting rates of diffusion

Temperature

Moisture

4

Mechanisms of Gas Exchange

Cutaneous respiration (integumentary

exchange)

E.g., Annelida, Platyhelminthes, Amphibia

5

Mechanisms of Gas Exchange

Tracheal respiration

E.g., Insecta

6

Mechanisms of Gas Exchange

Gills

E.g., mollusks, aquatic arthropods, fish,

amphibians

7

Gills

FISH GILL

water flows

over gills,

then out

mouth

open

operculum

closed mouth

closed

operculum

open

8

Gills

gill arch

filament

of gill

Countercurrent flow

Efficient O2 uptake

direction

of water

flow

surface for gas

exchange

direction

of blood

flow

9

Mechanisms of Gas Exchange

Lungs

Compromise efficiency for water retention

Gas exchange requires pressure differential

inside / outside body

E.g., mammals, birds, reptiles, amphibians (most)

10

Lungs

Slide 10

Fig. 41.8, p. 713

AMPHIBIAN

(salamander;

still rather like

fishes, early

amphibians)

REPTILE

(lizard;

adapted

to dry

habitats)

AMPHIBIAN

(frog; only

adults are

adapted

to dry

habitats)

MAMMAL

(human;

adapted to

dry habitats)

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Quick Quiz: The primary function of

the respiratory system of any animal

is…

A) Gas Exchange

B) Removal of wastes from the body

C) Breathing

D) Circulation

12

Mechanics of Breathing

Boyle’s Law

The pressure of a gas varies

inversely with its volume

volume, pressure

= inhalation

volume, pressure

= exhalation

13

Amphibian Respiratory System

frog_respiration 14

Avian Respiratory System

air

sacs

trachea

air

sacs

Structures

Lungs

Air sacs

Oxygenated air

continually passes

over lungs

Need for increased

efficiency?

bird_respiration 15

Human Respiratory System

Primary structures

Oral / Nasal cavities

Pharynx

Larynx

Epiglottis

Vocal folds

Trachea

Bronchi

Bronchioles

Alveoli

human_respiration 16

Human Respiratory System

Other structures

Hyaline cartilage

Ciliated epithelia

Mucus cells

Diaphragm

17

Mechanics of Breathing

Inhalation

Diaphragm contracts

Moves downward

External intercostals

contract

Elevates rib cage

Effect

Volume pressure

Air forced into lungs

INWARD BULK

FLOW OF AIR

18

Mechanics of Breathing

Exhalation

Diaphragm relaxes

Moves upward

Internal intercostals contract

Depresses rib cage

Recoil properties of lungs

Effect

Volume pressure

Air forced out of lungs

OUTWARD BULK

FLOW OF AIR

breathing 19

Quick Quiz: Breathing depends on …

A) Changing pressure inside the chest cavity

B) Changing volume of the chest cavity

C) The contraction and relaxation of the

diaphragm

D) All of the above

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Lung Capacities

Total lung capacity

6 L (adult male)

Tidal volume

Normal breath

0.5 L

Vital Capacity

Max. inhale & exhale

5 L

Residual volume

Air not forcibly exhaled

1 L

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Gas Exchange & Transport

The surface of the lung

Alveoli

Capillaries

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Gas Exchange & Transport

O2 transport

Red blood cells

Binds to hemoglobin (98%)

4 O2 / Hb

CO2 transport

Red blood cells

Some binds to hemoglobin ( 30%)

Most converted to bicarbonate ion

Plasma

Free CO2 ( 10%)

Bicarbonate ( 60%)

Buffer 23

Gas Exchange &

Transport

Movement based on

partial pressure

gradients for O2 &

CO2

alveolar sacs

cells of body tissue

MOIST

EXHAILED AIR

120 27

pulmonary

arteries

40 45

start of

systematic

veins

40 45

DRY

INHAILED AIR

160 0.03

pulmonary

veins

100 40

start of

systematic

capillaries

100 40

more than 45 less than 40 24

Quick Quiz: Oxygen moves to the

tissues because…

A) Oxygen concentration is higher in the blood

than in the tissues

B) Oxygen concentration is lower in the blood

than in the tissues

C) Oxygen partial pressure is higher in the

blood than in the tissues

D) Oxygen partial pressure is lower in the

blood than in the tissues 25

Respiratory Control

Voluntary

Diaphragm (skeletal muscle)

Involuntary

Respiratory centers in medulla oblongata & pons

Control rate & depth of breathing

Influenced most by [CO2]

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Respiratory Disease

27

Environmental Effects on Respiration

Altitude

pressure ( PO2)

Less O2 available

pressure differential

Decreased force of diffusion

28

Altitude

Effects (short term)

Breathing difficulty

Muscular / neurological dysfunction

Altitude sickness (>8,000 ft; ~2,400 m)

29

Altitude

Acclimatization

Change in breathing patterns

2-3 L/min

Increase cardiac output

Increased rbc production

Increased lung & heart mass

30

Environmental Effects on Respiration

Depth

external pressure

1 atm / 10 m (33 ft)

Human divers

SCUBA

Maintain alveolar pressures relative to water

pressure

Nitrogen narcosis & “the bends”

Descent of 100 ft or more

N2 forced into blood tissues

CNS “intoxication”

Rapid ascent

N2 rapidly released from tissues & bubbles 31

Depth

Diving mammals Sperm whales

Submerge > hour

Depths > 1,000 m

Mechanisms Increased O2 storage

Increased rbc / hemoglobin content

O2 bound to myoglobin (muscle)

Decreased O2 usage

Decreased metabolic rate

Shunting (selective use)

Anaerobic metabolism

32

Quick Quiz: Changes in altitude are

detrimental because…

A) Your ears pop and that makes the oxygen

come out of your lungs

B) The blood can’t get oxygen out of the air

C) Air is too dense

D) Oxygen partial pressure in the lungs are

different than they are at sea level

33