Chapter 34 Part B: Respiratory System

Question 1

Vertebrate Respiratory Systems

• Cellular metabolism requires that…

Answer 1

– O2 be delivered to the tissues

– CO2 be removed

Question 2

Vertebrate Respiratory Systems

• Major duties here fall to two systems

Answer 2

– Circulatory system
• Connects cells deep in the body with cells exposed to the environment
• Essentially reduces effective distance over which diffusion must occur
– Respiratory system
• Involves gas exchange between the surface of an organism (e.g., gills or lungs) and its environment

Question 3

The circulatory system essentially reduce _____ distance over which diffusion must occur

Answer 3

Effective

Question 4

Vertebrate Respiratory Systems

• At their simplest, these two systems aid in the process of passive diffusion

Answer 4

– O2 is at higher partial pressure in the environment and so tends to diffuse into the animal
– CO2 collects in the tissues and so tends to diffuse out

Question 5

Vertebrate Respiratory Systems

Answer 5

• At their simplest, these two systems aid in the process of passive diffusion
– O2 is at higher partial pressure in the environment and so tends to diffuse into the animal
– CO2 collects in the tissues and so tends to diffuse out
• Diffusion BY ITSELF is INadequate in large, multicellular organisms
– Simple spherical aquatic organism could be no larger than 0.5 mm RADIUS
• If larger, core tissues would not receive adequate O2 even if surrounding water was saturated with oxygen
– Would require several years for O2 to DIFFUSE from lungs to tip of fingers through tissue
• Thus circulatory and respiratory systems aid passive diffusion, and speed O2 delivery and CO2 removal.

Question 6

O2 tends to diffuse __1__ the animal, while CO2 tends to diffuse __2__

Answer 6

1. Into

2. Out

Question 7

True or False: Diffusion by itself is adequate in large, multicellular organisms

Answer 7

False, Diffusion by itself is inadequate in large, multicellular organisms

Question 8

Thus circulatory and respiratory systems aid ______ diffusion, and speed O2 delivery and CO2 removal.

Answer 8

Passive

Question 9

Vertebrate Respiratory Systems

• Evolutionary modifications have addressed 4 factors which limit rate of diffusion (Fick’s Law of Diffusion):

Answer 9

– R: Rate of Diffusion (best for organism to maximize this)
– D: Diffusion Constant (increase)
• Affected by solvent & molecule diffusing
• Can’t change this: O2 & CO2, water
– A: Surface area (increase)
– ∆p: Concentration gradient (increase; i.e., keep steep)
• countercurrent & cross current, sequester O2 in RBC’s, and CO2 as bicarbonate ion
– d: Distance (reduce)

Question 10

Fick’s Law of Diffusion Equation:

Answer 10

R = D × A (Δp/d)

Question 11

Fick’s Law of Diffusion Factors:

- R = ________

Answer 11

Rate of Diffusion (best for organism to maximize this)

Question 12

Fick’s Law of Diffusion Factors:

- D =_________

Answer 12

Diffusion Constant (increase)

Question 13

Fick’s Law of Diffusion Factors:

- A =_________

Answer 13

Surface area (increase)

Question 14

Fick’s Law of Diffusion Factors:

- Δp =________

Answer 14

Concentration gradient (increase; i.e., keep steep)
   • countercurrent & cross current, sequester O2 in RBC’s, and CO2 as bicarbonate ion

Question 15

Fick’s Law of Diffusion Factors:

- d = _________

Answer 15

Distance (reduce)

Question 16

Vertebrate Respiratory Systems

• Respiratory systems also have had to deal with differences in physical properties of water and air.

Answer 16

• e.g., water is more dense and viscous than air
– 800X more dense & 50X more viscous
– So, more expensive to pump water over gills than to pump air (cost is 20% of available energy vs. 1-2%)
– Water therefore is more buoyant than air and helps support gills
• Gills are not self-supporting out of water, where they tend to collapse together and fail as gas exchangers
• Lungs are reinforced structurally, and of course work better in air

Question 17

Water is 1 times more dense & 2 times more viscous

Answer 17

1. 800X more dense

2. 50X more viscous

Question 18

Vertebrate Respiratory Systems

• e.g., O2 typically is MUCH LESS available in water than in air

Answer 18

– at 5 degrees C, ~1/20: [saturated water ~9 ml/L O2, air 209 ml/L.]
– at 25 degrees C, ~1/35 [saturated water ~6 ml/L O2, air 209 ml/L.]
– O2 diffusion in air 10,000X faster than in water
– But #1: O2 availability DECREASES as water WARMS!
– But #2: decaying organic matter in water REMOVES O2
• Hypoxia: low O2; Anoxia: no O2
• Summer fish kills in Lake Erie and Cuyahoga River, worsened by “blooms” brought on by nutrient loads
– So, supplemental respiratory organs tend to occur in aquatic critters, rather than in purely terrestrial ones
• Supplemental lungs in fish, urinary bladder in turtles, loose skin in some frogs, among others

Question 19

O2 availability _____ (increases/decreases) as water warms

Answer 19

Decreases

Question 20

Decaying organic matter in water _______ O2

Answer 20

Removes

Question 21

Vertebrate Ventilation Mechanisms

• Water ventilation – the “Dual Pump”

Answer 21

– Buccal & opercular pumps, UNIDIRECTIONAL flow of water

– Can achieve NEARLY CONTINUOUS water flow over gills

Question 22

Vertebrate Ventilation Mechanisms

• Air ventilation – the “Pulse Pump”

Answer 22

– Air-breathing fish and amphibians

– Air is forced into the lungs by compression of buccal cavity

Question 23

Vertebrate Ventilation Mechanisms

• Air ventilation – the “Aspiration Pump”

Answer 23

– Air is “sucked into” the lungs by a low pressure created around the lungs
– In-out flow is described as “tidal”
– Buccal cavity no longer part of pump
– Found in amniotes (reptiles, birds, mammals)

Question 24

Dual pump (buccal & opercular): flow of water is ___1___ and nearly ___2___

Answer 24

1. Unidirectional

2. Continuous

Question 25

__1__ and __2__ cavities form the 2 pumps of the “dual pump” system

Answer 25

1. Buccal | 2. Opercular

Question 26

Countercurrent flow helps to maintain a steep ______ gradient

Answer 26

Concentration

Question 27

View diagram on the "pulse pump"

Answer 27

Good to look through all diagrams on slides

Question 28

Pulse pump in an amphibian (as in air- breathing fish ancestors) – how to use mouth to ___ and breathe at same time?

Answer 28

Eat

Question 29

Structure and function of aspiration pump in mammals:

Answer 29

• “Box” housing lungs consists of rib cage & diaphragm • Diaphragm – Forms posterior wall of box – Dome-shaped sheet of muscle, with dome bulging up into thoracic cavity • Cavity housing lungs in mammals is pleural cavity, a compartment of coelom • Rib cage muscles – External & internal obliques, run between ribs. • Part of what you eat when you have “ribs” – Various other muscles insert on rib cage but originate elsewhere (see diagram – don’t learn names)

Question 30

The ______ is a dome-shaped sheet of muscle that forms the posterior wall of "box" housing lungs. Also separates the pleural cavity from the abdominal cavity and bulges into the thoracic cavity

Answer 30

Diaphragm

Question 31

The _____ cavity houses the lungs in mammals

Answer 31

Pleural

Question 32

Rib cage muscles that run between the ribs are the ___1___ & ___2___

Answer 32

1. External | 2. Internal

Question 33

Ventilation (in mammals) | • Inhalation – rib cage expands

Answer 33

– External obliques contract, rib cage lifts and expands • Other muscles may contribute during higher activity (see diagram) – Diaphragm contracts, flattening and pulling down – Enlarging rib cage expands the pleural cavity, decreasing pressure therein, and drawing air down the airways and into lungs

Question 34

Ventilation (in mammals) | • Active exhalation

Answer 34

– Internal intercostals contract, pulling rib cage down • Other muscles may contribute (see diagram) – Diaphragm relaxes, rebounds to “domed” position – Decreasing rib cage contracts pleural cavity, forcing air out of lungs and airways

Question 35

Ventilation (in mammals) | • Passive exhalation

Answer 35

– Gravity and elastic recoil suffice to contract rib cage – Occurs at rest – So – normally we have active inhalation and passive exhalation

Question 36

Ventilation (mammals) | • Quadrupedal animals

Answer 36

– Locomotion brings additional forces to ventilation • Affect shape of rib cage • Movement of viscera (e.g., viscera serve as piston, changing volume of pleural cavity) • Rhythmic movements during locomotion related to limb movement • So – breathing patterns may be in synch with gait

Question 37

Aspiration pump:

Answer 37

* pump is rib cage & diaphragm * bidirectional or “tidal” * air is “sucked in”, not forced by buccal pressure * found in amniotes (i.e., fully terrestrial taxa) * the “swing” of intrapleural pressure is ~4 mm Hg (i.e., -2 to - 6); normal atmospheric pressure is ~760 mm Hg

Question 38

During _______ the external obliques contracts as does the diaphragm which flattens and pulls down

Answer 38

Inhalation, the rib cage then lifts and expands

Question 39

During ______ _______ the internal intercostals contract and the diaphragm relaxes

Answer 39

Active exhalation

Question 40

During ______ _______ gravity and elastic recoil suffice to contract rib cage which occurs at rest

Answer 40

Passive exhalation

Question 41

True or False: Normally we have both active and passive exhalation

Answer 41

True

Question 42

In quadrupedal animals _______ brings additional forces to ventilation

Answer 42

Locomotion | - Breathing patterns may be in synch with gait (pattern of movement of the limbs of animals)

Question 43

In the "aspiration pump" the pump is the ___1___ & __2__

Answer 43

1. Rib cage | 2. Diaphragm

Question 44

The "aspiration pump" is ___1___

Answer 44

1. Bidirectional or "tidal"

Question 45

In the "aspiration pump" the “swing” of intrapleural pressure is ~__1__ mm Hg (i.e., -__2__ to - __3__); normal atmospheric pressure is ~760 mm Hg

Answer 45

1. ~4 mm Hg 2. -2 3. -6

Question 46

Airway and lung structure | - Part 1

Answer 46

• Air enters via an external naris (pleural nares) into one of the paired (left/right) nasal cavities • Each nasal cavity holds 3 “scrolled” bones called CONCHAE (“kahn – key”, singular is concha) or turbinate bones – Increase surface area: facilitate humidification, warming, and cleaning of inspired air • Nasal cavities lead to PHARYNX where airway and digestive tract “cross” • GLOTTIS is opening into larynx at top of trachea; epiglottis helps block food from entering airway

Question 47

Airway and lung structure | - Part 2

Answer 47

• Below larynx is TRACHEA a tube supported by C- shaped cartilaginous “rings” (does “hyaline” ring a bell?) • Trachea travels down neck, enters rib cage, splits into 2 PRIMARY BRONCHI • Each primary bronchus splits into SECONDARY BRONCHI, etc. – Overall, about 23 such branchings, giving rise to the “respiratory tree” • BRONCHIOLES: passages < 1 mm diameter • ALVEOLAR DUCTS: walls consist almost entirely of alveoli • Alveolar ducts lead to ALVEOLAR SACS • ALVEOLUS: blind-ended sac where gas exchange occurs

Question 48

Airway and lung structure | • Alveolus (plural alveoli): microscopic, blind-ended, sac where gas exchange occurs

Answer 48

– ~ 300 million in each human lung • Alveolar diameter ~250 μm (varies with inhalation/exhalation) • wall thicknesses of ~ 0.2 μm – Total alveolar surface area ~ 80 m2 (~ 43 X body surface area) – Distance between air in alveolus and blood in capillary is ~ 0.5–1.0 μm; compare with • red blood cell at 7-8 μm • capillaries at ~ 8 μm • “typical” eukaryotic cell at 10-100 μm

Question 49

3 nasal conchae ______ (increase/decrease) surface area: facilitate humidification, warming, and cleaning of air

Answer 49

Increase

Question 50

Nasal cavities lead to ______ where airway and digestive tract "cross"

Answer 50

Pharynx

Question 51

___1___ is opening into larynx at top of trachea; ___2___ helps block food from entering airway

Answer 51

1. Glottis | 2. Epiglottis

Question 52

Below larynx is ______, a tube supported by C- shaped cartilaginous “rings” (does “hyaline” ring a bell?)

Answer 52

Trachea

Question 53

Trachea travels down neck, enters rib cage, splits into 2 ______ ______

Answer 53

Primary bronchi

Question 54

Each primary bronchus splits into _______ ______, etc.

Answer 54

Secondary bronchi

Question 55

Overall, about ___ such branchings, giving rise to the “respiratory tree”

Answer 55

23

Question 56

_________: passages < 1 mm diameter

Answer 56

Bronchioles

Question 57

_______ _____: walls consist almost entirely of alveoli

Answer 57

Alveolar ducts

Question 58

Alveolar ducts lead to ______ ______

Answer 58

Alveolar sacs

Question 59

_______: blind-ended sac where gas exchange occurs

Answer 59

Alveolus

Question 60

Airway and lung structure | • Anatomical dead space

Answer 60

– Typical tidal volume is ~ 500 cc – Volume of airways is ~ 150 cc • This air NOT involved in gas exchange because never gets to alveoli, hence “anatomical dead space”

Question 61

There are ~____ million alveolus in a human

Answer 61

~600 million

Question 62

Alveolar diameter is ~__1__ (varies with inhalation/exhalation) and the wall thickness is ~__2__

Answer 62

1. ~250 μm | 2. ~0.2 μm

Question 63

Total alveolar surface area ~ __1__ m2 (~ __2__ times body surface area)

Answer 63

1. ~ 80 m2 | 2. ~ 43 X

Question 64

Distance between air in alveolus and blood in capillary is ~ _____; compare with • red blood cell at 7-8 μm • capillaries at ~ 8 μm • “typical” eukaryotic cell at 10-100 μm

Answer 64

~ 0.5–1.0 μm

Question 65

Typical tidal volume is ~ __1__ and volume of airways is ~ __2__

Answer 65

1. 500 cc (1/2 liter) | 2. 150 cc

Question 66

__1__ of air is involved in gas exchange because it gets to the alveoli and __2__ of air occupies "anatomical dead space"

Answer 66

1. 350 cc (70%) | 2. 150 cc (30%)

Question 67

On average, red blood cell spends about how much time traversing the alveolus?

Answer 67

3/4 sec

Question 68

What keeps lungs inflated? | • Forces tending to collapse lungs

Answer 68

– Surface tension of water on inner alveolar surface | – Natural elasticity of lungs

Question 69

What keeps lungs inflated? | • Forces opposing collapse

Answer 69

– Surfactants weaken surface tension of water on alveolar surface • Secreted by cells lining alveolus – Adhesion of water on inner chest wall and outer surface of lungs • Likened to moisture between two microscope slides – Low pressure in pleural cavity (2-4 mm Hg below atmospheric) • Hole in chest wall or in lungs destroys this, causes collapse – Called pneumothorax • Excess water in pleural cavity weakens this, can cause collapse. – Fluid is “pumped out” continuously into lymphatic vessels – Low blood pressure in pulmonary capillaries swings balance to colloid osmotic pressure so always pulling water out

Question 70

True or False: Surface tension of water on inner alveolar surface is a force that tends to collapse the lungs

Answer 70

True

Question 71

The natural _______ of lungs tends to collapse the lungs

Answer 71

Elasticity

Question 72

________ weaken surface tension of water on alveolar surface to help oppose collapse

Answer 72

Surfactants

Question 73

True or False: Adhesion of water on inner chest wall and outer surface of lungs tends to collapse lungs

Answer 73

False, Adhesion of water on inner chest wall and outer surface of lungs tends to oppose collapsing of lungs

Question 74

The ____ (high/low) pressure in pleural cavity opposes collapsing of lungs

Answer 74

Low (2-4 mm Hg below atmospheric)

Question 75

Gas transport | • Oxygen

Answer 75

• Blood leaving lungs has nearly as much O2 dissolved in plasma as possible, but this isn’t much – O2 not very soluble in water – Only about 3 ml of O2 dissolved per liter blood, but blood carries ~ 200 ml O2 per liter (so ~1.5% vs. 98.5%) – Most of the rest bound to iron atom of heme group of hemoglobin inside red blood cells – Oxyhemoglobin dissociation curves describe release of O2 in the tissues • Decreasing pH causes hemoglobin to release more O2 (Bohr effect) – to what effect ?? • Increasing temperature has similar effect – to what effect ??

Question 76

True or False: O2 is very soluble in water

Answer 76

False, O2 not very soluble in water

Question 77

Only about ____ ml of O2 dissolved per liter blood, but blood carries ~ 200 ml O2 per liter (so ~1.5% vs. 98.5%)

Answer 77

3 ml

Question 78

Most of the rest of oxygen that doesn't dissolve in blood is bound to iron atom of __1__ (aa/heme) group of hemoglobin inside __2__ (red/white) blood cells

Answer 78

1. Heme | 2. Red

Question 79

___________ dissociation curves describe release of O2 in the tissues

Answer 79

Oxyhemoglobin

Question 80

Bohr effect: Decreasing ____ (pH/temperature) causes hemoglobin to release more O2

Answer 80

pH

Question 81

Increasing ______ (pH/temperature) causes hemoglobin to release more O2

Answer 81

Temperature

Question 82

"For mothers to deliver oxygen to a fetus, it is necessary for the fetal hemoglobin to extract oxygen from the maternal oxygenated hemoglobin across the placenta. This requires the fetal hemoglobin to have a ______ (higher/lower) oxygen affinity than that of the maternal carrier.”

Answer 82

Higher

Question 83

Gas transport | • Carbon dioxide

Answer 83

* ~ 8% dissolved in plasma; 20% bound to hemoglobin (but to aa of globin, not to heme groups); 72% as bicarbonate in solution * In tissues, CO2 diffuses into red blood cells * Bicarbonate formed there then diffuses out of red blood cell into plasma * Reverse reaction occurs in lungs * See figure

Question 84

~ ___% of CO2 is dissolved in plasma

Answer 84

8%

Question 85

_1_% of CO2 is bound to the __2__ site of hemoglobin

Answer 85

1. 20% | 2. aa

Question 86

True or False: When CO2 binds to hemoglobin it inhibits the binding of O2.

Answer 86

False, when CO2 binds to hemoglobin it DOES NOT inhibit the binding of O2. - CO2 binds to aa of globin - O2 binds to heme groups

Question 87

Control of breathing

Answer 87

• Breathing normally involuntary but can come under voluntary control • Control centers are in reticular formation of medulla and pons – Generate rhythmical signals to stimulate normal inhalation (normal exhalation is passive) – Precise source of rhythmicity is not clear, but it is medulla – Chemoreceptors in medulla, and major blood vessels of neck in neck & near heart respond to CO2 levels in blood, and pH of blood (and in cerebrospinal fluid) • Send signals to control centers, which increase breathing rate • Hyperventilating can blow off so much CO2 that stimulus to breathe is delayed; result can be that 02 levels drop enough to cause blackout. In swimmers can cause drowning.

Question 88

Breathing is normally ___1____ (voluntary/involuntary), but can come under ___2____ (voluntary/involuntary) control

Answer 88

1. Involuntary | 2. Voluntary

Question 89

Control centers for breathing are in reticular formation of __1__ and __2__

Answer 89

1. Medulla | 2. Pons

Question 90

Fick's Law of Diffusion Factors: | - If the distance is decreased, the rate of diffusion will ________ (increase/decrease)

Answer 90

Increase

Question 91

Fick's Law of Diffusion Factors: | - If the concentration gradient is increased, the rate of diffusion will _________ (increase/decrease)

Answer 91

Increase

Question 92

Fick's Law of Diffusion Factors: | - If the surface area is decreased, the rate of diffusion will ________ (increase/decrease)

Answer 92

Decrease