Chapter 34 Part B: Respiratory System Flashcards
Vertebrate Respiratory Systems
• Cellular metabolism requires that…
– O2 be delivered to the tissues
– CO2 be removed
Vertebrate Respiratory Systems
• Major duties here fall to two systems
– 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
The circulatory system essentially reduce _____ distance over which diffusion must occur
Effective
Vertebrate Respiratory Systems
• 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
Vertebrate Respiratory Systems
• 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.
O2 tends to diffuse __1__ the animal, while CO2 tends to diffuse __2__
- Into
2. Out
True or False: Diffusion by itself is adequate in large, multicellular organisms
False, Diffusion by itself is inadequate in large, multicellular organisms
Thus circulatory and respiratory systems aid ______ diffusion, and speed O2 delivery and CO2 removal.
Passive
Vertebrate Respiratory Systems
• Evolutionary modifications have addressed 4 factors which limit rate of diffusion (Fick’s Law of Diffusion):
– 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)
Fick’s Law of Diffusion Equation:
R = D × A (Δp/d)
Fick’s Law of Diffusion Factors:
- R = ________
Rate of Diffusion (best for organism to maximize this)
Fick’s Law of Diffusion Factors:
- D =_________
Diffusion Constant (increase)
Fick’s Law of Diffusion Factors:
- A =_________
Surface area (increase)
Fick’s Law of Diffusion Factors:
- Δp =________
Concentration gradient (increase; i.e., keep steep) • countercurrent & cross current, sequester O2 in RBC’s, and CO2 as bicarbonate ion
Fick’s Law of Diffusion Factors:
- d = _________
Distance (reduce)
Vertebrate Respiratory Systems
• Respiratory systems also have had to deal with differences in physical properties of water and air.
• 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
Water is 1 times more dense & 2 times more viscous
- 800X more dense
2. 50X more viscous
Vertebrate Respiratory Systems
• e.g., O2 typically is MUCH LESS available in water than in air
– 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
O2 availability _____ (increases/decreases) as water warms
Decreases
Decaying organic matter in water _______ O2
Removes
Vertebrate Ventilation Mechanisms
• Water ventilation – the “Dual Pump”
– Buccal & opercular pumps, UNIDIRECTIONAL flow of water
– Can achieve NEARLY CONTINUOUS water flow over gills
Vertebrate Ventilation Mechanisms
• Air ventilation – the “Pulse Pump”
– Air-breathing fish and amphibians
– Air is forced into the lungs by compression of buccal cavity
Vertebrate Ventilation Mechanisms
• Air ventilation – the “Aspiration Pump”
– 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)
Dual pump (buccal & opercular): flow of water is ___1___ and nearly ___2___
- Unidirectional
2. Continuous
__1__ and __2__ cavities form the 2 pumps of the “dual pump” system
- Buccal
2. Opercular
Countercurrent flow helps to maintain a steep ______ gradient
Concentration
View diagram on the “pulse pump”
Good to look through all diagrams on slides
Pulse pump in an amphibian (as in air- breathing fish ancestors) – how to use mouth to ___ and breathe at same time?
Eat
Structure and function of aspiration pump in mammals:
• “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)
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
Diaphragm
The _____ cavity houses the lungs in mammals
Pleural
Rib cage muscles that run between the ribs are the ___1___ & ___2___
- External
2. Internal
Ventilation (in mammals)
• Inhalation – rib cage expands
– 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
Ventilation (in mammals)
• Active exhalation
– 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
Ventilation (in mammals)
• Passive exhalation
– Gravity and elastic recoil suffice to contract rib cage
– Occurs at rest
– So – normally we have active inhalation and passive exhalation
Ventilation (mammals)
• Quadrupedal animals
– 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
Aspiration pump:
- 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
During _______ the external obliques contracts as does the diaphragm which flattens and pulls down
Inhalation, the rib cage then lifts and expands
During ______ _______ the internal intercostals contract and the diaphragm relaxes
Active exhalation
During ______ _______ gravity and elastic recoil suffice to contract rib cage which occurs at rest
Passive exhalation
True or False: Normally we have both active and passive exhalation
True
In quadrupedal animals _______ brings additional forces to ventilation
Locomotion
- Breathing patterns may be in synch with gait (pattern of movement of the limbs of animals)
In the “aspiration pump” the pump is the ___1___ & __2__
- Rib cage
2. Diaphragm
The “aspiration pump” is ___1___
- Bidirectional or “tidal”
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
- ~4 mm Hg
- -2
- -6
Airway and lung structure
- Part 1
• 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
Airway and lung structure
- Part 2
• 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
Airway and lung structure
• Alveolus (plural alveoli): microscopic, blind-ended, sac where gas exchange occurs
– ~ 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
3 nasal conchae ______ (increase/decrease) surface area: facilitate humidification, warming, and cleaning of air
Increase
Nasal cavities lead to ______ where airway and digestive tract “cross”
Pharynx
___1___ is opening into larynx at top of trachea; ___2___ helps block food from entering airway
- Glottis
2. Epiglottis
Below larynx is ______, a tube supported by C- shaped cartilaginous “rings” (does “hyaline” ring a bell?)
Trachea
Trachea travels down neck, enters rib cage, splits into 2 ______ ______
Primary bronchi
Each primary bronchus splits into _______ ______, etc.
Secondary bronchi
Overall, about ___ such branchings, giving rise to the “respiratory tree”
23
_________: passages < 1 mm diameter
Bronchioles
_______ _____: walls consist almost entirely of alveoli
Alveolar ducts
Alveolar ducts lead to ______ ______
Alveolar sacs
_______: blind-ended sac where gas exchange occurs
Alveolus
Airway and lung structure
• Anatomical dead space
– 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”
There are ~____ million alveolus in a human
~600 million
Alveolar diameter is ~__1__ (varies with inhalation/exhalation) and the wall thickness is ~__2__
- ~250 μm
2. ~0.2 μm
Total alveolar surface area ~ __1__ m2 (~ __2__ times body surface area)
- ~ 80 m2
2. ~ 43 X
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
~ 0.5–1.0 μm
Typical tidal volume is ~ __1__ and volume of airways is ~ __2__
- 500 cc (1/2 liter)
2. 150 cc
__1__ of air is involved in gas exchange because it gets to the alveoli and __2__ of air occupies “anatomical dead space”
- 350 cc (70%)
2. 150 cc (30%)
On average, red blood cell spends about how much time traversing the alveolus?
3/4 sec
What keeps lungs inflated?
• Forces tending to collapse lungs
– Surface tension of water on inner alveolar surface
– Natural elasticity of lungs
What keeps lungs inflated?
• Forces opposing collapse
– 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
True or False: Surface tension of water on inner alveolar surface is a force that tends to collapse the lungs
True
The natural _______ of lungs tends to collapse the lungs
Elasticity
________ weaken surface tension of water on alveolar surface to help oppose collapse
Surfactants
True or False: Adhesion of water on inner chest wall and outer surface of lungs tends to collapse lungs
False, Adhesion of water on inner chest wall and outer surface of lungs tends to oppose collapsing of lungs
The ____ (high/low) pressure in pleural cavity opposes collapsing of lungs
Low (2-4 mm Hg below atmospheric)
Gas transport
• Oxygen
• 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 ??
True or False: O2 is very soluble in water
False, O2 not very soluble in water
Only about ____ ml of O2 dissolved per liter blood, but blood carries ~ 200 ml O2 per liter (so ~1.5% vs. 98.5%)
3 ml
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
- Heme
2. Red
___________ dissociation curves describe release of O2 in the tissues
Oxyhemoglobin
Bohr effect: Decreasing ____ (pH/temperature) causes hemoglobin to release more O2
pH
Increasing ______ (pH/temperature) causes hemoglobin to release more O2
Temperature
“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.”
Higher
Gas transport
• Carbon dioxide
- ~ 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
~ ___% of CO2 is dissolved in plasma
8%
1% of CO2 is bound to the __2__ site of hemoglobin
- 20%
2. aa
True or False: When CO2 binds to hemoglobin it inhibits the binding of O2.
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
Control of breathing
• 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.
Breathing is normally ___1____ (voluntary/involuntary), but can come under ___2____ (voluntary/involuntary) control
- Involuntary
2. Voluntary
Control centers for breathing are in reticular formation of __1__ and __2__
- Medulla
2. Pons
Fick’s Law of Diffusion Factors:
- If the distance is decreased, the rate of diffusion will ________ (increase/decrease)
Increase
Fick’s Law of Diffusion Factors:
- If the concentration gradient is increased, the rate of diffusion will _________ (increase/decrease)
Increase
Fick’s Law of Diffusion Factors:
- If the surface area is decreased, the rate of diffusion will ________ (increase/decrease)
Decrease
