Lecture AP Biology Chapter 42B Circulation and gas exchange

After studying this chapter you will be able to: Compare and contrast open and closed circulatory systems; compare and contrast the circulatory systems of fish, amphibians, reptiles, and mammals or birds; distinguish between pulmonary and systemic circuits and explain the function of each; trace the path of a red blood cell through the human heart, pulmonary circuit, and systemic circuit.

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

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Lectures by Erin Barley Kathleen Fitzpatrick

Circulation and Gas Exchange

Chapter 42

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

• 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

tracheae, lungs

• Characteristics:

– Moist

– Large surface area-to-volume ratio

– Larger animals: associated with vascular system

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(functions as gill)

(a) Marine worm (b) Crayfish

Gills Gills

Tube foot (c) Sea star

Coelom

Gills in aquatic animals

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

Exhaled air Inhaled air

Pulmonary arteries

Systemic veins Systemic arteries

Pulmonary veins

Alveolar capillaries

Alveolar spaces

Alveolar epithelial cells

Heart

Systemic capillaries

CO 2 O 2

Body tissue

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

CO 2 O 2

2

3 7

5

Diaphragm: dome-shaped muscle

separating thoracic/abdominal cavities

Control of Breathing in Humans

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

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Respiratory Disorders

by infection

caused by M tuberculosis