Respiration Flashcards
What is respiration?
the process in which oxygen is exchanged for CO2 across external environment and cells
What is mitochondrial respiration?
the oxygenic process that involves the production of ATP by oxidizing carbohydrates, amino acids, or fatty acids in which oxygen is consumed and CO2 is produced
How is diffusion across respiratory surfaces maximized?
increased surface area
thin surfaces
How does Fick’s law of diffusion apply to respiration?
the rate of diffusion is increased when the surface area of membrane is maximized and the distance for diffusion is minimized
= larger SA and thinner surface
What are major challenges to respiration for aquatic organisms?
O2 is 30x less soluble in water than air = significantly less O2 available to aquatic organisms
O2 is 10000x less mobile in water than air = requires more energy to move the water
Why is O2 consumption and metabolic rate higher in smaller, unicellular organisms?
because they rely solely on diffusion for gas exchange = it’s fast and efficient
What do larger organisms require for respiration?
bulk flow and gas exchange = a close relationship between respiration and circulation
What is ventilation?
when medium (air/water) is moved over a respiratory surface
How does gas exchange occur in larger organisms?
ventilation of air/water across respiratory surfaces
How are gases moved throughout a larger organism’s body?
the circulatory system
What are 3 non-directional ventilation strategies
non-directional ventilation across thin surface
non-directional ventilation across thick surface
tidal ventilation (kinda bidirectional)
What organisms use nondirectional ventilation across thin surfaces?
cutaneous respiration in frogs
Describe non-directional ventilation across thin surfaces
medium flows over respiratory surface at random to the flow of blood
concentration of O2 in medium is steady and blood picks up O2 from medium quickly = efficient
Describe non-directional ventilation across thick surfaces
medium flows over respiratory surface at random to the flow of blood
concentration of O2 in medium is steady and blood slowly picks up O2 from medium = not very efficient
Describe tidal ventilation
medium with high O2 is inhaled, medium flows across respiratory surface, medium with low O2 is exhaled
efficient because bringing high O2 medium over respiratory surface and pushing low O2 medium out
What are the 3 types of unidirectional ventilation?
concurrent flow - medium flows with blood flow
countercurrent flow - medium flows against blood flow
crosscurrent flow - medium crosses over blood flow
Which type of unidirectional ventilation is really uncommon in nature?
concurrent flow - not very efficient
Which type of unidirectional ventilation is really most common in aquatic organisms?
countercurrent
Which type of unidirectional ventilation do birds use?
crosscurrent
describe concurrent ventilation
medium flows in same direction as blood flow in respiratory surface
as blood picks up O2 from medium, medium decreases in O2 = eventually they plateau together at mid level of O2
describe countercurrent ventilation - why is it so efficient?
medium flows in opposite direction of blood flow in respiratory surface
as blood uptakes O2, medium continues moving along and allows fresh O2 to come in contact with blood
this method ensures that respiratory surface is always being ventilated by medium with fresh O2
describe crosscurrent ventilation - why is it so efficient?
medium flows across blood flow in respiratory surface
as medium flows across capillaries, blood uptakes O2
what is the most efficient strategy for ventilation?
crosscurrent
What is the purpose of ventilation?
to reduce formation of static boundary layers and ensure gas exchange
Describe unidirectional ventilation
medium enters chamber at a different point than it exits
How do aquatic organisms overcome the challenges of respiration (water is more dense, viscous, water contains significantly less dissolved O2)?
by utilizing countercurrent ventilation to maximize contact between water with O2 and blood
what structures do water breathing fish have to facilitate respiration?
fish gills are made up of several gill arches
each gill arch has primary and secondary lamella
primary lamella stack vertically, secondary lamella are parallel ridges along each primary lamella
secondary lamella are covered in capillaries for gas exchange
How do air breathing fish conduct respiration?
fish open their mouth to expand their buccal cavity and draw air into the buccal cavity
fish close their mouth and the buccal cavity compresses pushing the air into the anterior chamber of breathing organ
anterior chamber closes and poster chamber contracts to push air out through operculum
anterior chamber opens and contracts for air to flow into the posterior chamber for gas exchange
What type of respiratory system do insects use? why is this unique?
gas exchange occurs via the tracheal system and does not involve the circulatory system to deliver gases
What type of respiratory structures can air breathing fish have?
reinforced gills (ex. mud-skippers)
vascularized mouth or pharyngeal cavity (ex. electric eels)
vascularized stomach (ex. catfish)
special gut pockets (ex. bichirs)
lungs (ex. lungfish)
What type of ventilation in air breathing fish?
tidal using buccal force
Describe the steps of insect respiration via the tracheal system
air filled tubes (tracheae) have spiracles (openings) to external environment
tracheae branch to form tracheoles
abdominal or thorax muscles contract for tidal or unidirectional air flow over spiracles
What type of ventilation do insects use?
either tidal or unidirectional
What type of respiratory organs do amphibians have?
cutaneous respiration (skin)
bilobed lungs
What type of ventilation occurs in frogs?
tidal using buccal pump
What amphibians are exceptions to general amphibian respiration (ex. lungs and/or cutaneous respiration)?
Axolotl have external gills only (no lungs)
salamanders can have:
- gill slits
- gills and lungs
- only cutaneous
Explain the steps in frog lung respiration
air is drawn into buccal cavity through nares
glottis opens behind buccal cavity
lungs recoil and compress to reduce lung volume
air is pushed out of lungs and out of the nares
nares close and the buccal cavity floor rises to push air into the lungs
glottis closes and gas exchange occurs in lungs
What type of respiratory organs do reptiles have?
most have 2 lungs, snakes have 1 or a reduced second
lungs can be really simple sacs or highly divided chambers for more active species
Why might a more active species of reptile have more divided lung chambers?
more division = more surface area = more gas exchange
What type of ventilation is used in reptiles? why is it unique?
unidirectional!! not tidal as would be expected for lung respiration
What type of pumps are used in generating force for respiration in reptiles?
usually aspiration pumps for suction
sometimes also buccal pump
What are the 2 phases of reptile respiration?
inspiration and expiration
T or F: reptiles have different muscles for feeding than for respiration
true
T or F; Some reptiles are intermittent breathers
true - ex. crocodiles
How do non-bird reptiles change the volume of their chest/thoracic cavity to create pressure gradients for respiration?
lizards: muscles lining rib (intercostal) contraction/relaxation
turtles/tortoises: abdominal muscle contraction/relaxation
crocodiles: diaphragmaticus muscle contraction/relaxation
How do lungs in birds differ from other reptiles?
lungs in birds are stiff and do not change in volume
they are arranged between a series of air sacs that act as bellows (expand/contract)
How and where does gas exchange occur in birds?
in parabronchi in lungs
What type of ventilation do birds use?
unidirectional crosscurrent
What is the respiratory organ of birds?
parabronchi in lungs
How many respiratory circuits are there in birds?
2
inhalation circuit
exhalation circuit
- inhale
- exhale
- inhale
- exhale
Describe the steps of respiration in birds
chest expands for the first inhalation = fresh air flows through bronchi in posterior air sac
chest compresses for first exhalation = fresh air pushed from air sacs into lungs
chest expands for second inhalation = stale air from lungs flows into anterior air sacs
chest compresses for second exhalation = stale air pushed out trachea from anterior air sacs
inhalations are simultaneous
exhalations are simultaneous
How does crosscurrent ventilation in birds occur?
parabronchi carrying fresh air extend down and across capillaries carrying blood in opposite direction
What are alveoli?
gas exchange surfaces in mammals
What are the 2 main parts of the mammalian respiratory system?
upper respiratory tract (mouth, nasal cavity, pharynx, trachea)
lower respiratory tract (bronchi, alveoli both gas exchange surfaces)
What are the 2 cell types of alveoli in mammals?
type 1 alveolar cells are thin walled and specialize in gas exchange
type II surfactant cells secrete fluid and reduce surface tension, provide structural support for alveoli and reduce breathing effort
Where are capillaries on the gas exchange surfaces for mammals?
capillaries coat the outer surface of alveoli
What are the gas exchange surfaces in mammals?
bronchi and alveoli
What are pleural sacs?
two layers of cells with space between (pleural cavity) that surround each of the two mammalian lungs
How do mammal lungs stay expanded?
the pleural cavity between the 2 ways of the pleural sac contains some pleural fluid to maintain subatmospheric intrapleural pressure = prevents lungs from collapsing
Describe the structure of mammalian lungs
chest wall surrounds the pleural sac which surrounds the lungs
bronchi branch extensively throughout the lung with alveoli on ends
describe bronchi
the respiratory organ that branches throughout mammalian lungs and contain alveoli on the tips
What type of ventilation do mammals use?
tidal
Describe steps of mammal inhalation (inspiration)
motor neuron stimulates inspiratory muscles
intercostals and diaphragm contract to move ribs outward and expand thorax
expanded thorax = decreased pressure inside
this increases transpulmonary pressure gradient and causes the lungs to expand and draw in air
Describe steps of mammal exhalation (expiration)
motor neurons stop stimulating inspiratory muscles
intercostal and diaphragm muscles relax
volume of thorax decreases causing intrathoracic pressure to increase
lungs passively recoil and push out air
Do mammalian lungs contract and relax?
no, they are not muscles, they just expand and recoil in response to other muscles contracting and moving
What causes rapid, heavy breathing?
contraction of internal intercostal muscles
how does the intra-alveolar pressure change between mammalian inhalation and exhalation?
during inhalation, alveolar pressure is low
during exhalation, alveolar pressure increases
(looks like a sinusoidal wave)
how does the intrapleural pressure change between mammalian inhalation and exhalation?
decreases until end of inhalation then increases during exhalation
how does the volume of air moved change between mammalian inhalation and exhalation?
the same amount of air is moved in during inhalation as is moved out during exhalation
What is surface tension?
the force that pulls a liquid’s surface molecules together at an air-liquid interphase
What are surfactants? What do they do?
they are cells in the alveoli that function to reduce surface tension on the alveoli in order to reduce the amount of work needed to expand alveolar volume
overall to increase compliance
What is lung compliance? How is it regulated?
the ability of the lungs to stretch during inhalation
controlled by the surface tension in alveolar fluid
How do surfactants increase lung compliance?
by reducing the surface tension of alveoli by disrupting and decreasing density of water molecules on alveoli surface = reduces alveolar walls and airways sticking together
When does surfactant synthesis develop in humans?
late gestation
What is lung elasticity?
the ability of the lung to return to resting volume after it has been stretched for inhalation
What happens if lungs have low elasticity?
lungs less easily recoil to resting state when respiratory muscles have relaxed and expiration must be active (not passive)
What are 4 examples of lung diseases?
respiratory distress syndrome
fibrotic lung disease
emphysema
asthma
Describe respiratory distress syndrome
reduced lung compliance that occurs in premature babies that have not produced enough surfactants
Describe fibrotic lung disease
reduced lung compliance in which inhalation is difficult caused by lung tissue scarring
causes shallow breathing
Describe emphysema
Lungs are less elastic due to damaged elastin fibers and alveoli = lungs are more compliant but more likely to collapse and have inflammation
caused for example by smoking
Describe asthma
a chronic inflammatory disease characterized by bronchiospasm and airway constriction
common symptoms: wheezing, cough, shortness of breath
How common is asthma in Canada? how is it treated?
~15% occurrence
corticosteroids
beta-adrenergic agonists
antileukotriene
What factors influence air flow?
airway diameter influences resistance which influences air flow
small diameter = more resistance = less air flow
How is higher resistance of an airway to air flow overcome?
with a large transpulmonary pressure gradient
How is the nervous system involved in air flow and resistance?
parasympathetic neurons cause bronchoconstriction (more resistance)
sympathetic neurons can bronchodilation (less resistance)
How is lung volume and capacity measured?
spirometer
What is tidal volume?
the volume of air moved in one ventilation cycle
What is dead space?
the amount of air (of the tidal volume) that isn’t involved in gas exchange
What are the 2 components of dead space?
anatomical dead space - volume of trachea and bronchi
alveolar dead space - volume of alveoli not permeated
What is inspiratory reserve volume?
the volume of air inhaled above the resting tidal volume
What is inspiratory capacity?
tidal volume + inspiratory reserve volume
What is expiratory reserve volume?
the maximum air that can be forcibly exhaled above resting tidal volume
What is vital capacity?
the maximum volume of air that can be moved in and out of lungs with a single breath
tidal volume + inspiratory reserve volume + expiratory reserve volume
What is total lung capacity ?
the sum of the vital capacity + residual volume (volume of air left in the lungs after maximal exhalation)
What is alveolar ventilation volume?
the volume of fresh air that enters the alveoli with each respiratory cycle
= tidal volume - dead space
What is alveolar minute ventilation?
the volume of fresh air that enters alveoli every minute
breathing rate (breath pm) * (tidal volume - dead space)
How do animals with large volumes of dead space (ex. cranes with long trachea) overcome this?
by having larger tidal volumes
bringing in more air
How much more soluble is oxygen in air than water?
30x more soluble in air than water
How soluble is CO2 in water? in air?
almost completely soluble in both
How do large animals transport gases throughout their bodies?
blood via circulatory system
T or F: the solubility of oxygen in aqueous solutions is low
true
What are metalloproteins?
respiratory pigments
proteins that contain metal ions
What is the function of metalloproteins in respiration?
they reversibly bind oxygen and increase the oxygen carrying capacity of aqueous solution in the circulatory system by 50x
How much do metalloproteins increase the oxygen carrying capacity of blood?
50x increase
What are the 3 major types of respiratory pigments in animals?
hemoglobins
hemocyanins
hemerythrins
What animals have hemoglobins?
vertebrates
some nematodes
some annelids
some arthropods
What 3 components are in hemoglobins?
- a globin protein bound to
- a heme molecule that contains
- iron
What metal ion is bound in hemoglobins?
iron
Where do hemoglobins exist?
within blood cells
Describe the structure of hemoglobin
globin: 4 protein subunits - tetrameric - 2 alpha subunits and 2 beta subunits
bound to a
a heme group containing iron
What colour are hemoglobin when oxygenated?
red
What is myoglobin?
a similar protein (but a monomer) to hemoglobin that’s ffound in skeletal and cardiac muscles
What animals have hemocyanins?
arthropods (crustaceans, arachnids, centipedes)
molluscs
Describe the structure of hemocyanin
a very large multi-subunit protein composed of up to 48 subunits
contains 2 coppers bound to the protein directly
What metal ion is bound in hemocyanin?
2 copper ions
Up to how many subunits can hemocyanins have?
up to 48 subunits
T or F: hemocyanin is a massive respiratory pigment
true
How many oxygen molecules can each hemocyanin protein bind to?
one
Where are hemocyanins located?
they’re dissolved in hemolymph or blood
NOT within blood cells
T or F: hemocyanins are within blood cells
false!
Which respiratory pigments are found within blood cells?
hemoglobin
hemerythrins but specifically in coelom blood cells
What colour are hemocyanins when oxygenated? deoxygenated?
blue when oxygenated
colourless when deoxygenated
What animals are hemerythrins found in?
invertebrates
ex. sipunculids, priapulids, brachiopods
some annelids
What metal ion is contained in hemerythrins?
iron
Describe the structure of hemerythrins
either trimeric or octomeric, each subunit binds 2 iron molecules
How many subunits can hemerythrins have?
either 3 or 8
How many iron molecules can each subunit of hemerythrin bind?
2 irons per subunit
Where are hemerythrins usually found?
in the coelomic cells (blood cells of the coelom)
What colour are hemerythrins when oxygenated? deoxygenated?
violet-pink when oxygenated
colourless when deoxygenated
How is the PO2 related to amount of O2 bound to pigment molecules?
as PO2 increases in plasma, more pigment molecules bind to oxygen until saturation
What is PO2?
What is P50?
the PO2 at which the respiratory pigment in blood is 50% saturated
What does it mean if P50 has a higher value?
the pigment has a lower affinity for binding O2
How is the % of oxygenated respiratory pigment in blood related to PO2 in plasma?
As PO2 in plasma increases, the % oxygenated respiratory pigment in blood increases until saturation
T or F: the amount of respiratory pigments in blood is the same in all animals
false, it has diversified over evolution
How does the amount of respiratory pigments in diving mammals differ from terrestrial mammals?
diving mammals have higher levels of blood hemoglobin than terrestrial
What is unique about respiratory pigments in Antarctic icefish?
they lost the gene for hemoglobin in blood = no hemoglobin
How do Antarctic icefish transport O2 if they don’t have hemoglobin?
they have low metabolic rates and low demand for O2
and because of cold water temperatures
there’s increased O2 solubility in the water and their plasma
How is PO2 related to % saturation of hemoglobin in humans? How does this compare to myoglobin in humans?
As PO2 increases, % saturation of hemoglobin increases until 100% saturation
there is a steep increase of % saturation of hemoglobin in myoglobin with a little increase in PO2 (curve is super steep) = 100% saturation occurs much faster
What shapes of oxygen equilibrium curves have?
hyperbolic or sigmoidal
What type of oxygen equilibrium curve does myoglobin have? why?
a hyperbolic curve because oxygen binds independently
What type of oxygen equilibrium curve does hemoglobin have? why?
sigmoidal because cooperativity = higher affinity to O2 because more of its heme groups bind O2
What is the Bohr effect?
when there’s a decrease in pH or increase in CO2, the O2 equilibrium curve shifts to the RIGHT = O2 affinity is decreased
What happens to O2 affinity of pigments when pH is decreased or CO2 is increased?
O2 affinity is decreased
Bohr Effect
What is the Root Effect?
When pH is decreased or CO2 is increased, the O2 carrying capacity is reduced
What organs does the root effect occur in?
swim bladders and gas glands in fish
how does the Bohr effect affect P50?
P50 is increased
What factors affect oxygen affinity of pigments?
pH
PCO2
temperature
organic modulators
How does the Bohr effect function in respiration?
to facilitate O2 transport to active tissues and O2 binding at respiratory surfaces
How does temperature affect oxygen affinity?
temperature increases = oxygen affinity decreases (right shift)
P50 is increased
How does an increase in temperature affect O2 circulation?
increased temperature causes increased O2 delivery to warm muscles during exercise
What is an example of an organic modulator that affects O2 affinity?
2,3-DPG
2,3-biphosphoglycerate
How do organic modulators affect O2 affinity?
increased organic modulator decreases O2 affinity = right shift
How does increased organic modulators affect O2 transport?
organic modulators help unload O2 at tissues
What stimulates 2,3-DPG synthesis?
anemia and high altitudes
What 3 ways is CO2 transported in blood?
in the plasma
bound to proteins
as bicarbonate
Why is it more effective to transport CO2 than O2 in the plasma?
CO2 is more soluble in plasma than O2
What is an example of a protein that binds CO2?
carbaminohemoglobin
What is the reaction forming bicarbonate (HCO3-)?
CO2 + H2O <> H2CO3 <> HCO3- + H+
What enzyme catalyzes bicarbonate formation?
carbonic anhydrase
Where is carbonic anhydrase active in vertebrates?
red blood cells
What is bicarbonate exchanged for in vertebrate plasma?
Cl-
What is the Haldane effect?
deoxygenated blood can carry more CO2 than oxygenated blood
What is the relationship between PCO2 and total CO2 content of oxygenated and deoxygenated blood?
as PCO2 increases
CO2 in oxygenated blood increases but at a slower rate than in deoxygenated blood
What does the shape of CO2 equilibrium curve depend on?
the kinetics of bicarbonate formation
How does CO2 diffuse out of blood at the respiratory surface? how does this effect the formation of bicarbonate?
carbominohemoglobin in the blood releases CO2, causing the bicarbonate reaction to shift left
What 2 factors affect the [bicarbonate] and pH of body fluids?
PCO2
What happens when PCO2 increases?
[bicarbonate] increases
pH decreases ([H+] increases)
and reaction shifts right
What happens when PCO2 decreases?
[bicarbonate] decreases
pH increases ([H+] decreases)
and reaction shifts left
What factor affects body fluid pH?
ventilation
How does hyperventilation affect PCO2?
decreased PCO2
How does hypoventilation affect PCO2?
increased PCO2
How is ventilation regulated?
rhythmic activation of the central pattern generators in the medulla activate nerves to trigger ventilation
What detects changes in CO2, H+ and O2?
chemoreceptors
What is the primary regulator of ventilation in water-breathers?
O2
What is the primary regulator of ventilation in air-breathers?
CO2
What regulates the output of central pattern generators?
chemosensory input received by chemoreceptors
What type of feedback regulates ventilation?
negative feedback
