Lecture AP Biology Chapter 42B Circulation and gas exchange

LECTURE PRESENTATIONS
For CAMPBELL BIOLOGY, NINTH EDITION
Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson

Chapter 42

Circulation and Gas Exchange

Lectures by
Erin Barley
Kathleen Fitzpatrick
© 2011 Pearson Education, Inc.


Chapter 42 Warm-Up
1. How does the heart beat?
2. What are the 3 types of blood cells and their
function?
3. What is the function of the lymphatic
system?
4. List the pathway of one molecule of O2 from
the air into your pinky toe.


What you need to know:
• General characteristics of a respiratory
surface
• How O2 and CO2 are transported in blood
• Pathway of O2 from airRBCtissues

Respiration
• Gas exchange supplies O2 for cellular respiration
and disposes of CO2
• Partial pressure = pressure exerted by a
particular gas in a mixture of gases
• Gases always diffuse from higher partial pressure
 lower partial pressure

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• Respiratory media: O2 in air or water
• Respiratory surface: body wall, skin, gills,
tracheae, lungs
• Characteristics:
– Moist
– Large surface area-to-volume ratio
– Larger animals: associated with vascular system

© 2011 Pearson Education, Inc.


Gills in aquatic animals

Coelom
Gills
Parapodium
(functions as gill)
(a) Marine worm

Gills
Tube foot

(b) Crayfish

(c) Sea star


Fish gills: absorb O2 through countercurrent
exchange (blood flows opposite of water)


Tracheal systems in insects


Respiratory system in birds (lungs + air sacs)


Mammalian respiratory system


Pathway of O2
•
•
•
•
•
•
•

Nose/mouth: filtered, warmed, humidified
Pharynx
Larynx: contains vocal cords
Trachea: windpipe; lined with cartilage
Bronchi: branches to lungs
Bronchioles
Alveoli: air sacs for gas exchange

• Mucus: traps particles
• Cilia: sweeps particles up to pharynx


Alveoli


Figure 42.30a

1 Inhaled air

8 Exhaled air
Alveolar
epithelial
cells

2 Alveolar
spaces
CO2

O2

Alveolar
capillaries

7 Pulmonary
arteries

3 Pulmonary
veins

6 Systemic
veins

4 Systemic
arteries

Heart

CO2

O2

Systemic
capillaries
5 Body tissue

(a) The path of respiratory gases in the circulatory
system


Diaphragm: dome-shaped muscle

separating thoracic/abdominal cavities


Control of Breathing in Humans
• Control center =
medulla oblongata
• Responds to pH
changes in blood
• High CO2  carbonic
acid forms  lowers pH
• Sensors in the aorta
and carotid arteries

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Adaptations for gas exchange
• Hemoglobin: respiratory pigment in vertebrates
– 4 subunits, each with heme group with iron (Fe)
– Can carry 4 molecules of O2
– Bohr shift: O2 dissociates from hemoglobin when blood pH is low
• Arthropods, mollusks:
– blue hemocyanin pigment
– contains copper (Cu)

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How CO2 is transported
1. Bicarbonate ions (70%)

2. Hemoglobin (23%)
3. Dissolved in plasma (7%)

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Respiratory Adaptations of Diving Mammals
• Diving mammals have evolutionary adaptations that
allow them to perform extraordinary feats
– For example, Weddell seals in Antarctica can
remain underwater for 20 minutes to an hour
– For example, elephant seals can dive to 1,500 m
and remain underwater for 2 hours

• High blood to body volume ratio
• Stockpile O2 and deplete it slowly
• Store oxygen in their muscles in myoglobin
proteins
© 2011 Pearson Education, Inc.


Respiratory Disorders
• Asthma: airways constricted
• Bronchitis: bronchi swollen and clogged
• Pneumonia: inflammation of lung caused by
infection
• Tuberculosis (TB): infectious disease caused by
M. tuberculosis
• Emphysema: lose elasticity of lung tissue
• Lung Cancer: abnormal cell growth in lungs