1. Chapter 35 BIOL1000 Dr. Mohamad H. Termos
Respiratory Systems
Chapter 35 BIOL1000 Dr. Mohamad H. Termos

2. Biology, 9th ed, Sylvia Mader
Chapter 37
Gas Exchange Surfaces
Respiration: Events associated with gas exchange between the body’s cells and the environment
Why is respiration needed?
Can occur in organisms at: skin/body surface, gills, tracheae, lungs
Gas exchange takes place by diffusion
For external respiration to be effective, gas-exchange regions must be: moist, thin, large in relation to body size
Respiratory Systems

3. Body Surface Gas Exchange
Biology, 9th ed, Sylvia Mader
Chapter 37
Body Surface Gas Exchange
Body surface gas exchange
Small animals with large surface area
Most cells exchange gases directly with the environment
Body shape plays a role in whether this is possible (Many openings to outside).
Examples: planaria, earthworm, sponges, frog
Respiratory Systems

4. Biology, 9th ed, Sylvia Mader
Chapter 37
Gas Exchange Surfaces
Larger aquatic animals often have gills
Finely divided vascularized outgrowths of the body surface or pharynx
Respiratory Systems

5. Biology, 9th ed, Sylvia Mader
Chapter 37
Gas Exchange Surfaces
Tracheae
Insects and other terrestrial arthropods
Oxygen enters at spiracles
Tracheae branch into small tubules
End in tracheoles that are in direct contact with body cells
Respiratory Systems

6. Biology, 9th ed, Sylvia Mader
Chapter 37
Human Respiration
In terrestrial vertebrates, respiration includes: Ventilation, External respiration, and Internal respiration
Terrestrial vertebrates have lungs
Functions of human respiration:
Oxygen and carbon dioxide exchange
Speech and other vocalizations
Smell
Controls pH of body fluids (by eliminating carbon dioxide)
Pressure gradients between thoracic and abdominal cavities
Respiratory Systems

7. Breathing and Transport of Gases
Inspiration: contraction of diaphragm produces inspiration. As it contracts, it makes thoracic cavity larger - Expansion of thorax results in decreased intrapleural pressure, leading to a decreased alveolar pressure - Air moves into lungs when alveolar pressure drops below atmospheric pressure - Compliance: ability of pulmonary tissues to stretch, making inspiration possible

8. Mechanism of pulmonary ventilation
Expiration: a passive process that begins when inspiratory muscles are relaxed, decreasing size of thorax
- Decreasing thoracic volume increases intrapleural pressure and thus increases alveolar pressure above atmospheric pressure
Air moves out of lungs when alveolar pressure exceeds atmospheric pressure
- Elastic recoil: tendency of pulmonary tissues to return to a smaller size after having been stretched passively during expiration

9. Breathing and Transport of Gases
Biology, 9th ed, Sylvia Mader
Breathing and Transport of Gases
Chapter 37
Breathing rate: ventilations/ minute
Controlled by a respiratory center in the medulla oblongata of the brain
Sends out impulses to the diaphragm and intercostal muscles
Respiratory Systems

10. Biology, 9th ed, Sylvia Mader
Chapter 37
Path of Air in Humans
Nasal cavities/mouth: intake of air. Lined with mucous membranes. Filter, warm and moisten air.
Pharynx: crossing of nasal and digestive pathways. It connects to larynx and esophagus
As air moves through upper respiratory system: It is filtered to free it of debris (Warmed and Humidified). When air reaches lungs It is at body temperature saturated with water
Respiratory Systems

11. Biology, 9th ed, Sylvia Mader
Chapter 37
Gas Exchange Surfaces
Pharynx  Larynx  trachea (“windpipe”)
The trachea is Permanently held open by cartilage rings. It facilitates movement of air
When food is swallowed
The larynx rises and is closed by the epiglottis
Respiratory Systems

12. Biology, 9th ed, Sylvia Mader
Chapter 37
Gas Exchange Surfaces
Trachea divides  two primary bronchi
Bronchi enter the right and left lungs
Bronchi branch  bronchioles
Each bronchiole terminates in an elongated space enclosed by alveoli
Respiratory Systems

13. Gas Exchange and Transport
Biology, 9th ed, Sylvia Mader
Chapter 37
Gas Exchange and Transport
Gases diffuse from areas of higher to lower partial pressure
Ventilation causes the alveoli to have a higher partial pressure of oxygen and a lower partial pressure of carbon dioxide than the blood in the pulmonary capillaries
This accounts for the exchange of gases in the lungs
The opposite occurs in the tissues of the body
Respiratory Systems

14. How Blood Transports Gases
Oxygen and carbon dioxide are transported as solutes and as parts of molecules of certain chemical compounds
Transport of oxygen
Hemoglobin: carbon dioxide can bind to amino acids in the hemoglobin and oxygen can bind to iron in the heme groups
Hemoglobin increases the oxygen-carrying capacity of blood
Oxygen travels in two forms: as dissolved O2 in plasma and associated with hemoglobin (oxyhemoglobin).
Oxyhemoglobin carries the majority of the total oxygen transported by blood

15. How Blood Transports Gases: CO2
- A small amount of CO2 dissolves in plasma and is transported as a solute (10%)
Less than one fourth of blood CO2 combines with NH2 (amine) groups of hemoglobin and other proteins to form carbaminohemoglobin (20%).
More than two thirds of the carbon dioxide is carried in plasma as bicarbonate ions (70%)

16. Disorders of the Upper Respiratory Tract
Biology, 9th ed, Sylvia Mader
Chapter 37
Disorders of the Upper Respiratory Tract
Cold (Rhinovirus)
Mild viral infections
Characterized by sneezing, runny nose, mild fever
Antibiotics ?
Strep Throat
Acute pharyngitis caused by a bacterium
Severe sore throat, high fever, swollen tonsils
Curable with antibiotics
Respiratory Systems

17. Disorders of the Lower Respiratory Tract
Biology, 9th ed, Sylvia Mader
Chapter 37
Disorders of the Lower Respiratory Tract
Acute bronchitis: Infection of primary and secondary bronchi
Chronic bronchitis: Airways become inflamed and filled with mucus
Asthma: Airways are unusually sensitive to specific irritants. When exposed to these irritants, smooth muscles in the bronchioles undergo spasms
Respiratory Systems

18. Disorders Affecting the Lungs
Biology, 9th ed, Sylvia Mader
Disorders Affecting the Lungs
Chapter 37
Pneumonia: Viral, bacterial, or fungal infection of the lungs in which bronchi and alveoli fill with fluid.
Pulmonary tuberculosis: Caused by bacteria. Results in lung damage and reduced function.
Pulmonary fibrosis: Fibrous connective tissue builds up in the lungs
Respiratory Systems

19. Disorders Affecting the Lungs
Biology, 9th ed, Sylvia Mader
Chapter 37
Disorders Affecting the Lungs
Emphysema: Alveoli are distended and walls are damaged, reducing the surface area available for gas exchange.
Lung Cancer: Begins with thickening and callusing of the cells lining the airways. Atypical cells appear in the thickened lining. Cells from the tumor break loose and metastasize
Respiratory Systems

20. Disorders Affecting the Lungs
Biology, 9th ed, Sylvia Mader
Chapter 37
Disorders Affecting the Lungs
Cystic fibrosis (CF)
Defective gene results in accumulation of mucus secretions in the lungs
Secretions become sticky and form plugs that interfere with breathing
Treatment involves clearing mucus from airways administering mucus- thinning drugs and vigorously slapping the patient on the back!!
Respiratory Systems