1. Biology, 9th ed, Sylvia Mader
Chapter 37
Chapter 37
Respiratory Systems
Respiratory Systems

2. Biology, 9th ed, Sylvia Mader
Gas Exchange Surfaces
Chapter 37
Respiratory Systems
Respiration:
The events associated with gas exchange between the cells and the external environment
Consists of these steps:
Ventilation = inspiration (air in) & expiration (air out)
External Respiration = gas exchange between external environment & the blood within respiration surfaces. Blood then transports oxygen to the tissues.
Internal Respiration = gas exchange between blood & tissue fluid. Cells exchange gases with tissue fluid. Blood transports carbon dioxide back to respiratory surfaces.

3. Biology, 9th ed, Sylvia Mader
Gas Exchange Surfaces
Chapter 37
Respiratory Systems
For diffusion to be effective, gas-exchange tissues must be:
Moist because gases must be in solution
Thin to allow for rapid diffusion
Relatively large in relation to size of body to ensure that cells get oxygen in a timely fashion
Relatively small, and flat, animals don’t need a specialized respiration system:
Planaria - flat, 2-dimensional body allows surface of animal to be gas-exchange surface
Larger, more 3-dimensional animals need specialized gas-exchange surfaces such as gills or lungs.

4. Biology, 9th ed, Sylvia Mader
Gas Exchange Surfaces
Chapter 37
Respiratory Systems
Effectiveness of diffusion is enhanced by vascularization:
• Gas-exchange surfaces are usually associated with capillary beds so that oxygen and carbon dioxide can be exchanged efficiently.
Delivery of oxygen to cells is promoted by respiratory pigments such as hemoglobin that can pick up the oxygen and carry it.

5. Gas Exchange in Water Environments
Biology, 9th ed, Sylvia Mader
Gas Exchange in Water Environments
Chapter 37
Respiratory Systems
I. Difficulties obtaining oxygen in water compared to air:
A. Water contains only a fraction of the oxygen that would be present in the same volume of air
1. Oxygen has low solubility in water
0.004% in seawater; 21% in air.
B. Diffusion of oxygen in water is thousands of times slower than in air
C. Water is more dense than air
1. Use more energy to respire than do land animals.
•Fish use up to 25% of energy output to respire while terrestrial animals only use 1-2% of their energy output.

6. Gas Exchange in Water Environments
Biology, 9th ed, Sylvia Mader
Gas Exchange in Water Environments
Chapter 37
Respiratory Systems
II. Small, simple multicellular animals:
A. Planaria, hydra
1. Gastrovascular cavity helps put cells in contact with oxygenated water
B. Aquatic worms
1. Use skin that is supplied with blood vessels

7. Animal Shapes and Gas Exchange
Biology, 9th ed, Sylvia Mader
Animal Shapes and Gas Exchange
Chapter 37
Respiratory Systems

8. Gas Exchange in Aquatic Environments
Biology, 9th ed, Sylvia Mader
Gas Exchange in Aquatic Environments
Chapter 37
Respiratory Systems
III. Larger aquatic animals like bony fishes
•Often have gills:
Outward extensions of pharynx; said to be evaginated
Have finely subdivided surfaces with a huge total surface area
Contain a rich supply of blood vessels (vascularized)
Ventilation is brought about by combined action of the mouth drawing water in and gill covers (operculum) forcing water out of head area

9. Anatomy of Gills in Bony Fishes
Biology, 9th ed, Sylvia Mader
Anatomy of Gills in Bony Fishes
Chapter 37
Respiratory Systems

10. Countercurrent Exchange System
Biology, 9th ed, Sylvia Mader
Countercurrent Exchange System
Chapter 37
Respiratory Systems
Countercurrent Exchange System in Fish Gills:
•In lamella of gills:
Blood flows in the direction opposite to the movement of water across the gills.
This maximizes the amount of oxygen picked up by the blood:
- As the blood gains oxygen, it always encounters water having an even higher oxygen content.
- No equilibrium is ever reached % of dissolved oxygen is extracted.
If flow of blood was concurrent to water (same direction) an equilibrium point would occur and less oxygen would be transferred into blood.

11. Anatomy of Gills in Bony Fishes
Biology, 9th ed, Sylvia Mader
Anatomy of Gills in Bony Fishes
Chapter 37
Respiratory Systems

12. Respiration in Terrestrial Environments:
Biology, 9th ed, Sylvia Mader
Respiration in Terrestrial Environments:
Chapter 37
Respiratory Systems
Air has much more available oxygen than water but it is a drying environment. Thus, terrestrial animals tend to have invaginated respiratory systems to protect them from too much water loss.
- Exception is earthworms which breathe through their skin but must keep body surface moist by secreting mucus, etc.
- Earthworms also do their best to remain in damp soil during the daytime.

13. Land Environments: Tracheae
Biology, 9th ed, Sylvia Mader
Land Environments: Tracheae
Chapter 37
Respiratory Systems
Insects and other terrestrial arthropods
Respiratory system consists of branched air tubes called tracheae
Oxygen enters tracheae at spiracles, valvelike openings on each side of the body.
Tracheae branch & branch until they end in tiny channels, the tracheoles, that are in direct contact with body cells.
Very efficient system for delivering oxygen to cells that does NOT involve any respiratory pigments or circulatory system.

14. Biology, 9th ed, Sylvia Mader
Tracheae of Insects
Chapter 37
Respiratory Systems

15. Land Environments: Lungs of Vertebrates
Biology, 9th ed, Sylvia Mader
Land Environments: Lungs of Vertebrates
Chapter 37
Respiratory Systems
Terrestrial vertebrates have evolved lungs
Vascular outgrowths from lower pharyngeal region
Lungs of amphibians
Possess a short tracheae which divides into two bronchi that open into lungs
Many also breathe to some extent through skin
Reptiles
Inner lining of lungs is more finely divided in reptiles than in amphibians
Lungs of birds and mammals are elaborately subdivided
All terrestrial vertebrates, except birds, use a tidal ventilation system
Air moves in and out by the same route. Thus, fresh incoming air is mixed with some left-over stale air.

16. Biology, 9th ed, Sylvia Mader
Ventilation in Frogs
Chapter 37
Respiratory Systems
Amphibians use both negative & positive pressure to ventilate their lungs:
1. Negative pressure: With mouth closed but nostrils open, the floor of the mouth is lowered. The lower air pressure will cause air to rush into their mouth cavity.
2. Positive pressure: With mouth & nostrils shut, floor of mouth rises & pushes air into the lungs.

17. Ventilation in Terrestrial Vertebrates
Biology, 9th ed, Sylvia Mader
Ventilation in Terrestrial Vertebrates
Chapter 37
Respiratory Systems
Inspiration in mammals (Inhalation)
Create negative pressure in lungs
The rib cage is elevated by intercostal muscles.
The diaphragm contracts and pushes down towards belly
Thoracic pressure decreases to less than atmospheric pressure
Atmospheric pressure forces air into the lungs
Expiration in mammals (Exhalation)
Create positive pressure in lungs
The rib cage is lowered as intercostal muscles relax
The diaphragm relaxes and rises back up towards chest
Thoracic pressure increases to more than atmospheric pressure
Forces air out the lungs

18. Inspiration Versus Expiration
Biology, 9th ed, Sylvia Mader
Inspiration Versus Expiration
Chapter 37
Respiratory Systems

19. Biology, 9th ed, Sylvia Mader
Ventilation in Birds
Chapter 37
Respiratory Systems
Birds use a one-way ventilation mechanism in lungs
How does this work?
- Incoming air does not directly enter the lungs, instead it is carried by trachea to a set of posterior air sacs.
- Air is then pushed through tiny tubes called parabronchi which are surrounded by capillaries
- Air ends up in anterior air sacs which expel it from body.
Thus, fresh & used air never mix in the lungs of birds.
Results in a higher partial pressure of oxygen in the lungs
Oxygen uptake with each breath is greater than in other vertebrates

20. Respiratory System in Birds
Biology, 9th ed, Sylvia Mader
Respiratory System in Birds
Chapter 37
Respiratory Systems

21. Human Respiratory System
Biology, 9th ed, Sylvia Mader
Human Respiratory System
Chapter 37
Respiratory Systems
As air moves through upper respiratory system (nostrils, nasal cavities, pharynx, larynx, trachea):
It is filtered to free it of debris (cilia help this
Warmed, and
Humidified
When air reaches lungs
It is at body temperature, and
Its humidity is 100%

22. The Human Respiratory Tract
Biology, 9th ed, Sylvia Mader
The Human Respiratory Tract
Chapter 37
Respiratory Systems

23. Human Respiratory System
Biology, 9th ed, Sylvia Mader
Human Respiratory System
Chapter 37
Respiratory Systems
Air passes from pharynx through glottis, an opening in larynx
Larynx (voice box) contains vocal cords which allow us to produce sounds
Trachea
Permanently held open by cartilage rings
Facilitates movement of air
When food is swallowed:
The larynx rises, and
The glottis is closed by a flap of tissue called the epiglottis
Backward movement of soft palate covers the entrance of nasal passages into the pharynx

24. The Human Respiratory Tract
Biology, 9th ed, Sylvia Mader
The Human Respiratory Tract
Chapter 37
Respiratory Systems

25. Human Respiratory System
Biology, 9th ed, Sylvia Mader
Human Respiratory System
Chapter 37
Respiratory Systems
Trachea divides and forms two primary bronchi
Bronchi enter the right and left lungs
Bronchi branch until there are a great number of tiny bronchioles. The walls of bronchioles get thinner & rings of cartilage are no longer present.
Each bronchiole terminates in an elongated space enclosed by a great number of air pockets, or sacs, called alveoli. Gas exchange occurs between air in sacs and blood in surrounding capillaries.

26. The Human Respiratory Tract
Biology, 9th ed, Sylvia Mader
The Human Respiratory Tract
Chapter 37
Respiratory Systems

27. Control of Breathing Rate in Humans
Biology, 9th ed, Sylvia Mader
Control of Breathing Rate in Humans
Chapter 37
Respiratory Systems
Average person takes a breath about 14 times per minute when at rest
Respiratory control center, located in pons & medulla oblongata of the brain, can change the normal rate according to circumstances.
- When a drop in pH is noted (due to increase in CO2) the control center increases rate & depth of breathing.
- Normally, O2 concentration in blood has little effect on breathing rate. However, if O2 level is very low detectors in aorta & carotid arteries send an alarm to resp. control centers in brain.

28. Gas Exchange and Transport
Biology, 9th ed, Sylvia Mader
Gas Exchange and Transport
Chapter 37
Respiratory Systems
External Respiration
1. Blood flowing into pulmonary capillaries has higher CO2 concentration than air in the alveolar air sacs.
CO2 diffuses out of pulmonary capillaries & into air sacs.
2. Blood coming into pulmonary capillaries has lower concentration of O2 than alveolar air.
O2 diffuses from alveoli into capillaries.

29. External and Internal respiration
Biology, 9th ed, Sylvia Mader
External and Internal respiration
Chapter 37
Respiratory Systems

30. Biology, 9th ed, Sylvia Mader
Transport of Oxygen
Chapter 37
Most oxygen that enters the pulmonary capillaries combines with hemoglobin in red blood cells to form oxyhemoglobin.
- Each of the 4 polypeptide chains of hemoglobin is folded around a heme (iron) group.
 Iron forms a loose bond with oxygen.
•At normal partial pressure of O2 in lungs, hemoglobin is almost saturated with oxygen.
•At partial pressure of O2 in tissues, oxyhemoglobin gives up much of its oxygen during internal respiration.
- Acidity & warm temperatures promote this response in the tissues.
Respiratory Systems

31. Biology, 9th ed, Sylvia Mader
Chapter 37
Hemoglobin
Respiratory Systems

32. Hemoglobin Saturation in Relation to Temperature and Acidity
Biology, 9th ed, Sylvia Mader
Hemoglobin Saturation in Relation to Temperature and Acidity
Chapter 37
Respiratory Systems

33. Transport of Carbon Dioxide
Biology, 9th ed, Sylvia Mader
Transport of Carbon Dioxide
Chapter 37
Respiratory Systems
Internal Respiration
Carbon dioxide enters blood from the tissues
1. Some carbon dioxide combines with hemoglobin to form carbaminohemoglobin
2. Most carbon dioxide is transported in the form of bicarbonate ions (HCO3-)
- CO2 combines with water, forming carbonic acid (H2CO3) & then dissociates into H+ & HCO3-.
- Carbonic anhydrase, an enzyme, speeds up this reaction.
- H+ combines with globin part of hemoglobin (HHb) & HCO3- diffuses into plasma. This plays vital role in maintaining proper pH of blood.

34. External and Internal respiration
Biology, 9th ed, Sylvia Mader
External and Internal respiration
Chapter 37
Respiratory Systems

35. Transport of Carbon Dioxide
Biology, 9th ed, Sylvia Mader
Transport of Carbon Dioxide
Chapter 37
Respiratory Systems
External Respiration
1. As blood enters the pulmonary capillaries, most of the CO2 is present in plasma as HCO3-
2. HHb gives up the H+ it has been carrying & carbonic anhydrase speeds up this reaction:
H+ + HCO3-  H2CO3  H2O + CO2
3. Now free CO2 diffuses out of blood into the alveoli of lungs.

36. External and Internal respiration
Biology, 9th ed, Sylvia Mader
External and Internal respiration
Chapter 37
Respiratory Systems

37. Respiration and Health
Biology, 9th ed, Sylvia Mader
Respiration and Health
Chapter 37
Respiratory Systems
Upper Respiratory Tract Infections
Consists of nose, pharynx & larynx. Infections can spread from nasal cavities to sinuses, to middle ears & to larynx
Strep Throat
Usually starts as viral infection that becomes a secondary bacterial infection.
Caused by Streptococcus pyogenes. Can become generalized upper respiratory infection.
Symptoms: severe sore throat, high fever, white patches on dark red throat

38. Respiration and Health
Biology, 9th ed, Sylvia Mader
Respiration and Health
Chapter 37
Respiratory Systems
Sinusitis
Infection of sinuses, facial cavities that drain into nasal cavities
Develops when nasal congestion blocks openings into the sinuses
Tonsillitis
Infection of tonsils, masses of lymphatic tissue.
Tonsils help to remove pathogens from pharynx
Laryngitis
Infection of larynx accompanied by hoarseness & possibly an inability to talk.

39. Respiration and Health
Biology, 9th ed, Sylvia Mader
Respiration and Health
Chapter 37
Respiratory Systems
Lower Respiratory Tract Infections
Infections of trachea, bronchi, bronchioles & lungs
Acute bronchitis
Infection of primary and secondary bronchi
Usually preceded by a viral upper respiratory infection that led to secondary bacterial infection

40. Respiration and Health
Biology, 9th ed, Sylvia Mader
Respiration and Health
Chapter 37
Respiratory Systems
Pneumonia
Viral, bacterial or fungal infection of the lungs in which bronchi and alveoli fill with pus & fluid
Most often preceded by influenza, the “flu”.
Can be localized in specific lobules of lungs; more lobules the more serious the infection
AIDS patients often get a rare pneumonia caused by a fungus called Pneumocystis carinii.

41. Respiration and Health
Biology, 9th ed, Sylvia Mader
Respiration and Health
Chapter 37
Respiratory Systems
Pulmonary tuberculosis (TB)
Caused by tubercle bacillus, a type of bacterium.
Can test people with a simple skin test to see if they have been exposed to tuberculosis
Reaction to bacterium:
1. When the bacteria invade the lung, the cells build a protective capsule around the bacteria. This capsule is called a tubercle.
2. With a good immune system the body might kill the encapsulated bacteria
3. With a weakened immune system, like in AIDS, the bacteria can be released & hurt the body

42. Common Bronchial and Pulmonary Diseases
Biology, 9th ed, Sylvia Mader
Common Bronchial and Pulmonary Diseases
Chapter 37
Respiratory Systems

43. Biology, 9th ed, Sylvia Mader
Disorders
Chapter 37
Respiratory Systems
Pulmonary fibrosis
Fibrous connective tissue builds up in the lungs
Due to inhalation of particles such as silica, coal dust, asbestos & fiberglass.
Lungs can’t inflate properly
Asbestos also associated with cancer
Chronic bronchitis
Airways inflamed and filled with mucus
Coughing causes bronchi to undergo changes, including loss of cilia & normal cleansing action
Most frequent cause is smoking.

44. Common Bronchial and Pulmonary Diseases
Biology, 9th ed, Sylvia Mader
Common Bronchial and Pulmonary Diseases
Chapter 37
Respiratory Systems

45. Biology, 9th ed, Sylvia Mader
Disorders
Chapter 37
Respiratory Systems
Emphysema
Alveoli are distended (stretched) and walls are damaged reducing surface area available for gas exchange
Often preceded by chronic bronchitis
Elastic recoil of lungs is reduced; thus expiration is very difficult
Heart works harder to force more blood to lungs
Symptoms: breathlessness & cough, depression & irritability

46. Common Bronchial and Pulmonary Diseases
Biology, 9th ed, Sylvia Mader
Common Bronchial and Pulmonary Diseases
Chapter 37
Respiratory Systems

47. Biology, 9th ed, Sylvia Mader
Disorders
Chapter 37
Respiratory Systems
Asthma
Airways are unusually sensitive to specific irritants
When exposed to the irritants, the smooth muscles in the bronchioles undergo spasms
Irritants can be pollen, animal dander, dust, cigarette smoke, fumes & even cold air
Not curable but is treatable with inhalers that can control inflammation of bronchioles & prevent attack or stop muscle spasms during an attack

48. Common Bronchial and Pulmonary Diseases
Biology, 9th ed, Sylvia Mader
Common Bronchial and Pulmonary Diseases
Chapter 37
Respiratory Systems

49. Biology, 9th ed, Sylvia Mader
Disorders
Chapter 37
Respiratory Systems
Lung Cancer
Begins with thickening and callusing of the cells lining the airways
Loss of cilia follows; thus it is impossible to prevent dust & dirt from settling into lungs
Atypical nuclei appear in callused lining
Creates a tumor of such cells
Final step is when some cells break loose & penetrate other tissues (metastasis)