1. Circulation and Gas Exchange
Chapter 42
Circulation and Gas Exchange

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

3. 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

4. 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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5. 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
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6. Gills in aquatic animals
Coelom
Gills
Gills
Figure Diversity in the structure of gills, external body surfaces that function in gas exchange.
Tube foot
Parapodium
(functions as gill)
(a) Marine worm
(b) Crayfish
(c) Sea star

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

8. Tracheal systems in insects

9. Respiratory system in birds (lungs + air sacs)

10. Mammalian respiratory system

11. 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

12. Alveoli

13. (a) The path of respiratory gases in the circulatory system
Figure 42.30a 8
Exhaled air 1
Inhaled air 2
Alveolar
spaces
Alveolar
epithelial
cells
CO2 O2
Alveolar
capillaries 7
Pulmonary
arteries 3
Pulmonary
veins 6
Systemic
veins 4
Systemic
arteries
Heart
Figure Loading and unloading of respiratory gases.
Systemic
capillaries
CO2 O2 5
Body tissue
(a) The path of respiratory gases in the circulatory
system

14. Diaphragm: dome-shaped muscle separating thoracic/abdominal cavities

15. 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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16. 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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17. How CO2 is transported Bicarbonate ions (70%) Hemoglobin (23%)
Dissolved in plasma (7%)
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18. 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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19. 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