Chapter 49: Gas Exchange in Animals
What Physical Factors Govern Respiratory Gas
Exchange?
What Adaptations Maximize Respiratory Gas Exchange?
How does the Fish Gill, Mammalian Lung & Bird Lung
Work?
How Does Blood Transport Respiratory Gases?
How Is Breathing Regulated?
Each respiratory system depends on:
A. Respiratory Medium –
B. Respiratory Surface –
Fick Equation: Describes Diffusion Across Respiratory
Surfaces
Rate of Diffusion =
1
Where…
D is
A is
P1 & P2 are
L is
(P1 – P2)/L is
Design Parameters: Fick’s Law of Diffusion
Increase diffusion rate (Q) by:
1)
2)
3)
2
Changes in Oxygen with Altitude:
Affects Partial Pressure Gradient
Proportion of oxygen in air is 0.21
Sea Level
760 mm Hg X 0.21 = 160 mm Hg
On top of Mt. Everest
250 mm Hg X 0.21 = 53 mm Hg
CO2 Exchange
3
Organs of Gas Exchange
(Respiratory Surface)
1) Direct diffusion across body surface
2) Organs for gas exchange:
•Insect trachea
•Fish gills
•Mammal lungs
•Bird lungs
Direct Diffusion Across Skin
Small aquatic animals or earthworms (moist environments)
1)
2)
4
Insect Tracheae
Tracheae:
Spiracles.
Make this Table in your Notebook
Mammals
Birds
Fish
Respiratory Organ
Gas Exchange
Surface
Airflow
Model
Pump
5
Problems with Gas Exchange in Water
1)
2)
3)
How Do Gases Behave in Water?
Amount of gas dissolved in liquid depends on:
1)
2)
3)
4)
5)
6
Figure 49.2 The Double Bind of Water Breathers
Fish Respiration Fig. 49.5 & 49.6
4 gill arches
gill filaments
Gill lamellae:
H2O flow across gills is:
H20 & blood flow are:
-
7
Ram Ventilation
Problems with Gas Exchange in Water
Solved
1)
2)
3)
8
The Fish Respiratory System
Respiratory Type:
Gas Exchange Surface:
Waterflow:
Model:
Pump:
Problems with Gas Exchange in Air
9
Mammalian Respiratory Definitions (Fig. 49.9)
Tidal volume:
Inspiratory & expiratory reserve volumes:
Vital capacity
Residual volume:
Total lung capacity
Dead Space:
Ventilation in lungs is Tidal:
air flows in & out via same pathway
-
10
Figure 49.10 The Human Respiratory System
Air Pathway:
1.
2.
3.
4.
5.
6.
*series of branching tubes get smaller & smaller
What Happens With a Long Neck?
How do respiratory ailments impact breathing?
11
Mammalian Lungs Produce 2 Secretions
1. Mucus:
2.. Surfactant:
-
Role in reducing surface tension
-
Respiratory Distress Syndrome
MECHANICS OF BREATHING (Fig. 49.11)
INHALATION
EXHALATION
Most Important Muscle Is:_______________________
1. External intercostal muscles:
2. Internal intercostal muscles:
(you can breathe if intercostal muscles paralyzed!)
12
The Mammalian Respiratory System
Respiratory type:
Gas Exchange Surface:
Airflow:
Model:
Pump:
Figure 49.7 The Respiratory System of a Bird
•Air flow is ________________ & ______________
-maintains high _______________
•Inhalation:
•Exhalation:
Air enters:
-divides into:
-divides into:
-divides into:
Map air flow in bird lung (fig. 49.8):
13
Avian Respiration is Efficient
1.
2.
3.
4.
The Avian Respiratory System
Respiratory Type:
Gas Exchange Surface:
Airflow:
Model:
Pump:
14
Who Has The Most Efficient Respiratory System?
(i.e. Who Extracts More Oxygen?)
How Is Breathing Regulated
(Fig. 49.15 & 49.16)?
-Mammals:
-PCO2 monitored by
-PO2 monitored by
-Chemoreceptors send nerve impulses to
-Breathing rate controlled in
- Medullary respiratory center (MRC)
15
BLOOD: Site of Respiratory Gas Transport
Blood:
Packed-cell volume:
Erythrocytes:
Hemoglobin (Hb) – Transporter of Oxygen
Fig. 49.12
Cooperative binding
Sigmoidal Curve
16
CO2 Transport & Buffering of Blood pH
Fig. 49.14
Homeostatic Control of
Oxygen-Carrying Capacity
17