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176 Cards in this Set

  • Front
  • Back
respiration
-sequence of events that result in exchange of oxygen and carbon dioxide between the external environment and the mitochondria
external respiration
gas exchange at the respiratory surface
internal respiration
gas exchange at the tissues
mitochondrial respiration
production of ATP via oxidation of carbohydrates, animo acids, or fatty acids. Oxygen is consumed and carbon dioxide is produced
gas molecules move______ concentration gradients
down
mitochondria consume oxygen to produce_______. In the process of doing this they produce________. Organisms must have mechanisms to obtain________ from__________ and to get rid of __________. They do this by____________.
ATP, carbon dioxide, Oxygen, environment, carbon dioxide, external respiration.
unicellular organisms are small and can rely on _________ for gas exchange
diffusion
larger organisms for gas exchange must rely on
a combination of bulk flow and diffusion

they need a respiratory system
diffusion
the movement of molecules from high concentration to low concentration. It is slow over long distances and fast over short distances
fick equation
J=DAdC/dx

J=rate of diffusion
D=diffusion coefficient
A=area of the membrane
dC= concentration gradient
dx= diffusion distance

*for gases use partial pressures instead of concentrations
rate of diffusion is greatest when
the diffusion coefficient(D), area of membrane(A) and energy gradients (dC/dx) are large but the diffusion distance is small.
gas exchange surfaces are typically
thin with a large surface area
total pressure exerted by a gas is related to
the number of moles and the volume of the chamber
ideal gas law
PV=nRT
air is a mixture of gases such as
Nitrogen (78%)
Oxygen (21%)
Argon (0.9%)
Carbon Dioxide (0.03%)
daltons law of partial pressures is
in a gas mixture, each gas exerts its own partial pressure that sum to the total pressure of the mixture

Total P= P oxygen + P carbon dioxide
gas molecules in the air must dissolve in liquid in order to diffuse into a
cell
Henry's Law
[G]=Pgas x Sgas

P=pressure
S=solubility
CO2 is more soluble in water then O2 so at the same partial pressure more
CO2 will dissolve in the solution then O2
Graham's Law
the relative diffusion of a given gas is proportional to its solubility in the liquid and inversely proportional to the square root of its molecular weight
O2 is 32 amu and CO2 is 44 amu
in air they have the same solubilities but O2 diffuses 1.2x faster but in aqueous solutions...
CO2 is 24x more soluble then O2 so will diffuse about 20x faster then O2
combining Fick and Grahams laws we get that
diffusion rate is inversely proportional to dP x A x S / X x sqrt(MW)

At constent temp:

so proportional to
dP=partial pressure gradient
A=cross sectional area
S=solubility of gas in the fluid

and inversely proportional
X=diffusion distance
MW=Molecular weight
Bulk flow
mass movement of water or air as the result of pressure gradients
-fluids flow from high to low pressure
boyles law
P1V1=P2V2
*temp and number of gas molecules stay constant
respiratory systems use changes in volume to produce
changes in pressure
as systems grow larger the ratio of surface area to volume
decreases which limits of area available for diffusion and increases diffusion distance
animals more then 3mm thick use one of these three respiratory strategies
1.circulating the external medium through the body (sponges, cnidarians and insects)

2. diffusion of gases across the body surface accompanied by circulatory transport *cutaneous respiration* (most aquatic inverts, some amphibians, eggs of birds0

3. Diffusion of gasses across a specialized respiratory surface accompanied by circulatory transport *Gills or Lungs* (vertebrates)
tracheal system for circulating external medium through body
-narrow tubes leading from surface to deep within the body. Gases move in the tubes via a combination of diffusion and bulk flow.
cutaneous respiration
-respiration through skin
-found in aquatic invert and a few verts
-disadvantages are relatively low SA and conflict between respiration and protection
External Gills
-gills originate as outpocketings (evaginations)
ADVANTAGES: high SA, exposed to medium
DISADVANTAGES: easily damaged and not suitable in air
Internal Gills
ADVANTAGES: high SA and protected

DISADVANTAGES: not suitable for air
Lungs
-originate as infoldings (invaginations)
ADVANTAGES: high SA, protected and suitable for breathing air

DISADVANTAGES: not suitable in water
Ventilation
-the active movement of the respiratory medium (air or water) across the respiratory surface
Ventilation of respiratory surfaces reduces the formation of
static boundery layers i.e. improves the efficiency of gas exchange
types of ventilation are
-nondirectional
-tidal
-unidirectional
nondirectional ventilation
-medium moves past the respiratory surface in a unpredictable pattern
tidal ventilation
medium moves in then out
unidirectional ventilation
medium enters the chnamber at one point and exists at another

-blood can flow in 3 ways relative to flow of medium
cocurrent flow (same direction)
countercurrent flow (opposite direction)
crosscurrent flow(across medium flow)
in concurrent the blood and medium Po2 will
equilibrate
in counter current flow
Po2 of blood will approach that of the inhalant medium
in crosscurrent
the Po2 of blood is derived from a mixture of all serial air-blood capillary units and exceeds the P of the end parabronchial values
animals respond to changes in their environmental oxygen or metabolic demands by altering the rate or pattern of
ventilation
-[O2] 30x greater in are then water
-water is more dense and viscous then air
-evaporation is only a issue for air breathers

so
-most water breathers use unidirectional
-most air breathers use tidal
-most insects use air filled tubes
strategies of gas exchange in water
-circulate the external medium through an internal cavity
-other strategies depend on if external or internal gills
sponges and cnidarians
-circulate the external medium though an internal cavity
-In sponges flagella move water in through ostia and out through osculum
-in cnidarians muscle contractions move water in and out through the mouth
molluscs
-have two strategies for ventilating their gills and mantle cavity

1.beating of cilia move water acoss
the gills unidirectionally
-blood flow is countercurrent
-snails and clams

2. muscular contractions of the mantle propel water unidirectionally through the mantle cavity past the gills
-blood flow is countercurrent
-squids
crustaceans
-barnacles or small species lack gills and rely on diffusion
-shrimp, crabs, and lobsters have gills derived from modified appendages located within a branchial cavity
-movements of gill bailer propels water out of the brachial chamber; the negative pressure sucks water across the gills
echinoderms
most sea stars and sea urchins
use their tube feet for gas exchange
-water is sucked in and exits through the madreporite
-sea stars also have external gill like structures (respiratory papulae); cilia move water over the surface
echinoderms
brittle stars and sea cucumbers
-have internal invaginations
-brittle stars use cilia to move water into bursae
-sea cucumbers use muscular contractions of the cloaca and the respiratory tree to breathe water tidally through the anus
hag fish
-multiple pairs of gill sacs
-muscular pump propels water through the respiratory cavity
-water enters the medium nostril and leaves through a gill opening
-flow is unidirectional
-blood flow is countercurrent
in crosscurrent
the Po2 of blood is derived from a mixture of all serial air-blood capillary units and exceeds the P of the end parabronchial values
animals respond to changes in their environmental oxygen or metabolic demands by altering the rate or pattern of
ventilation
-[O2] 30x greater in are then water
-water is more dense and viscous then air
-evaporation is only a issue for air breathers

so
-most water breathers use unidirectional
-most air breathers use tidal
-most insects use air filled tubes
strategies of gas exchange in water
-circulate the external medium through an internal cavity
-other strategies depend on if external or internal gills
sponges and cnidarians
-circulate the external medium though an internal cavity
-In sponges flagella move water in through ostia and out through osculum
-in cnidarians muscle contractions move water in and out through the mouth
molluscs
-have two strategies for ventilating their gills and mantle cavity

1.beating of cilia move water acoss
the gills unidirectionally
-blood flow is countercurrent
-snails and clams

2. muscular contractions of the mantle propel water unidirectionally through the mantle cavity past the gills
-blood flow is countercurrent
-squids
crustaceans
-barnacles or small species lack gills and rely on diffusion
-shrimp, crabs, and lobsters have gills derived from modified appendages located within a branchial cavity
-movements of gill bailer propels water out of the brachial chamber; the negative pressure sucks water across the gills
echinoderms
most sea stars and sea urchins
use their tube feet for gas exchange
-water is sucked in and exits through the madreporite
-sea stars also have external gill like structures (respiratory papulae); cilia move water over the surface
echinoderms
brittle stars and sea cucumbers
-have internal invaginations
-brittle stars use cilia to move water into bursae
-sea cucumbers use muscular contractions of the cloaca and the respiratory tree to breathe water tidally through the anus
hag fish
-multiple pairs of gill sacs
-muscular pump propels water through the respiratory cavity
-water enters the medium nostril
and leaves through a gill opening
-flow is unidirectional
-blood flow is countercurrent
lampreys
-ventilation is similar to hag fish when not feeding
-multiple pairs of gill sacs
-when feeding mouth is attached to prey
-ventilation is tidal through gill opening
Elasmobranchs

sharks/skates/rays
steps in ventilation
-expand buccal cavity
-increased volume sucks fluid into buccal cavity via mouth and spiracles
-mouth and spiracles close
-muscles around buccal cavity contract forcing water past the gills and out the external gill slits
-blood flow is countercurrent
Telostat fish
-water in via the mouth and out via the opercular opening
-gills arranged for counter current flow
steps in ventilation for telostat fish
1. mouth open/ opercular valve closed/ buccal cavity expanded/ opercular cavity expands

2. mouth closed/ opercular valve closed/ buccal cavity compressed/ opercular cavity expanded

3. mouth closed/ opercular valve open/ buccal cavity compressed/ opercular cavity compressing

4.mouth open/ opercular valve open/ buccal cavity expands/ opercular cavity compressed
terrestrial molluscs
-the "pulmonate" mulluscs lack gills or have reduced gills
-instead mantle cavity is highly vascularized and acts as a lung
-pumping of the mantle cavity moves air in and out of these lungs
terrestrial crabs
-part of crustaceans in anthropods

- respiratory structures and process of ventilation is similar to marine relatives except:
-gills are stiff so they do not collapse in air
-branchial cavity is highly vascularized and acts as primary site for gas exchange
-movements of gill bailer propels air in and out of the branchial chamber
terrestrial isopods (woodlice and snow bugs)
-part of crustaceans in anthropods
-have a thick layer of chitin on one side of the gill for support and other side is thin walled and used for gas exchange.
-anterior gills contain air filled tubules, oxygen diffuses down the pseudotrachea and dissolves in interstitial fluid.
chelicerates-spiders and scorpions

-part of anthropods
Have four book lungs
-consists of 10-100 lamellae
-open outside to spiracles
-gases diffuse in and out

Some spiders also have a tracheal system (series of air filled tubes)
-oxygen diffuses into trachea and dissolves in the interstitial fluid before dissolving into the tissues
insects
-have an extensive tracheal system (series of air filled tubes)
-opens to outside via spiracles
-gases diffuse in and out
-high diffusion coefficient of oxygen in the air allows oxygen to diffuse through the tracheal system
tracheoles
are the terminating ends of tubes that are filled with hemolymph in insects
-oxygen dissolves in the hemolymph
ventilation in insects
-some species can expand and compress the trachea
-changes in tracheal volume cause changes in pressure, which causes air to flow through the system
3 types of insect ventilation
-contraction of abdominal muscles or movements of the thorax

-ram ventilation

-discontinuous gas exchange
contractions of abdominal or movements of the thorax
-can be tidal or unidirectional (enter anterior spiracles and exit adominal spiracles
ram ventilation
-aka draft ventilation
-in some flying insects
discontinuous gas exchange
Phase 1 (closed phase): no gas exchange; o2 used and co2 converted in hco3, decrease in total pressure

Phase 2(flutter phase): air pulled in

Phase 3: total pressure increases as co2 can nolonger be stored as hco3, spiracles open and co2 is released

see notes
most aquatic insects breathe air
-some have snorkels kept dry by hydrofuge hairs
-water beetles carry scuba tanks (air bubbles)
air breathing evolved in fishes
-aquatic habitats can become hypoxic
-air breathing benefit under these conditions
evolution of air breathing
- some fish use aquatic surface respiration when hypoxic
-swim to surface to ventilate their gills with water from the thin well oxygenated layer near surface
-some fish can gulp air into mouth (buccal cavity)
-buccal cavity is high vascularized for gas exchange
types of respiratory structures evolved for air breathing
-reinforced gills that dont collapse in air
-mouth or pharyngeal cavity for gas exchange(highly vascularized)
-vascularized stomach
specialized pockets in gut
-lungs
Ventilation is tidal using buccal force similar to other fish
ventilation steps in air breathing fish
-mouth opens/buccal cavity expands/air enters buccal cavity

-mouth closes/buccal cavity compresses/air enters anterior chamber of air breathing organ

-mouth closed/anterior chmaber closed/posterior chamber contracts/ spent air exhaled from posterior chamber/ air exits through the operculum

-mouth closed/anterior chamber opens/anterior chamber contracts/air flows into posterior chamber/gas exchange occurs
amphibians
-lungs form as ventral outpocketings of the gut
-simple sac like lungs
types of respiratory structures in amphibians
-cutaneous respiration
-external gills
-simple bilobed lungs

-tidal ventilation is used
external gills in amphibians
advantages and disadvantages
A:high surface area exposed to medium

D:easily damaged and not suitable for breathing air
steps in amphibian breathing
1.air enters pocket of buccal cavity through mouth
-mouth open glottis closes

2.-glottis opens
-elastic recoil of the lungs and compression of chest wall reduces lung volume
-air forced out of lungs and out of the mouth and nares

3. mouth and nares close
-floor of buccal cavity rises
-air pushed into lungs

4.-glottis closes
-gas exchange in lungs
reptiles-respiratory structures
-most have 2 lungs (snakes one is reduced or absent)
-can be simple sacs with honeycomb walls or divided chambers
reptiles-ventilation
-tidal ventilation
-rely on suction pumps
-results in the separation of feeding and respiratory muscles

-has two phases: exhalation and inhalation
-use several mechanisms to change the volume of the chest cavity
snakes and lizards
use intercostal muscles
-contraction of intercostal muscles moves the ribs forward and upward, increasing the volume
turtles and tortoises
-use abdominal muscles that expand and compress the lungs
crocodilians
-hepatic septum is attached to the anterior side of the liver. paired diaphramaticus muscles run from the hepatic septum to the pelvic girdle. Diaphramaticus muscles contract which decreases the volume in the abdominal cavity and increases the volume of the lungs. As a result lung pressure decreases.
when volume increases, pressure decreases so
air flows into the body
birds use unidirectional ventilation
-lung is stiff and changes very little in volume
-rely on a series of flexable air sacs
-gas exchange at parabronchi
-lung volume doesn't chnage, get volume chnage in air sacs
-crosscurrent blood flow = high oxygen extraction efficiency
bird ventilation
-requires two cycles of inhalation and exhalation to move one bolus of air
-air flow is unidirectional
steps in bird ventilation
-first inhalation causes fresh air through the bronchi and into posterior air sacs(inc volume dec pressure)

-first exhalation pushes posterior air from posterior air sacs into lungs(dec volume inc pressure)

-second inhalation causes stale air to flow from lungs into anterior air sacs(inc volume dec pressure)
-second exhalation pushes stale air from the anterior air sacs out via trachea(dec volume inc pressure)
mammals
-upper respiratory tract and lower
-alveoli are site of gas exchange
-both lungs surrounded by pleural sac
type 1 alveoli
-for gas exchange, they lower diffusion distance
type 2 alveoli cells
secret surfactant that increases pulmonary compliance (ability to change volume/stretch in response to changes in pressure) and prevents collapsing of lung on exhalation
order air travels in mammalian lungs
-larynx to trachea to bronchii to bronchioles to alveoli
compliance of lungs
-how easily they can expand
-distensibility
-causes more effective volume changes
-reduced by factors that produce resistance to distension
elasticity of lungs
-tendency to return to initial size after distension

High content of elastic protiens
-they are very elastic and resist distension
-recoil ability

Exhalation is passive
atmospheric pressure
pressure of air outside the body

760 mmHg
transpulmonary pressure
difference in pressure across the wall of the lung
-keeps lungs against chest wall
intrapulmonary/intraalveolar pressure
-pressure inside the alveoli in lungs
-same as atmosphere at rest (inc during exhalation, dec during inhalation)
intrapleural pressure
-pressure within the pleural cavity

-pressure is always negative compared to atmosphere (756 at rest) due to lack of air in intrapleural space

-dec during inhalation and increase during exhalation
airway resistance
-flow = deltaP/R
-airway resistance is inversly proportional to airway radius to the 4th power. (1/r^4)
-r gets bigger R gets smaller
-viscosity also effects resistance
bronchoconstriction
reduction in airway radius
-r gets smaller so flow is harder
bronchodilation
-increase in radius means easier to flow
-stimulation of sympathetic system, high alveolar PCO2
steps in mammal tidal ventilation
Inhalation
-somatic motor neuron innervation (elevates muscles associated with ventilation)
-contraction of the external intercostals and the diaphragm
-ribs move outward and diaphragm moves down
-volume of thorax increases (dec pressure)
-air is pulled in

Exhalation
-innervation stops
-muscles relax
-ribs and diaphragm move to original positions
-volume of thorax decreases
-air is pushed out via elastic recoil of the lungs
during rapid and heavy breathing exhalation is active via
contraction of the internal intercostal muscles
air moves into and out of the lungs along pressure gradients that are a result of
volume changes

-as long as alveolar pressure is less then atmosphere air moves in
surfactants
reduce surface area tension by disrupting the cohesive forces between water molecules

-results in increase in lung compliance and a decrease in the force needed to inflate lungs

-in humans surfactant synthesis doesnt begin until late gestation
Tidal volume
total volume of air moved in one ventilatory cycle
dead space
air that doesnt participate in gas exchange
Two components:
1. anatomical dead space (volume of trachea and bronchi)
2. alveolar dead space (physiological dead space)= volume of any alveolar that is not being perfused with blood
emphysema
-the walls of alveoli break down
-increases lung compliance but decreases lung elasticity
-the work to ventilate increases
ventilation of the respiratory system must be matched to the perfusion of the respiratory system
Va/Q should equal 1

Va= ventilation
Q=perfusion
o2 in ventilation is bulk flow and then diffuses into circ system
circ system is also bulk flow and o2 diffuses into tissues
oxygen transport
-low solubility of oxygen in aqueous fluids
-metalloprotiens contain metal ions that bind reversibly to oxygen and increase oxygen carrying capacity by 50x
-binding by o2 carriers, Po2 in the blood remains low and results in improved o2 extraction
-respiratory pigments
-help increase the amount of o2 in blood
-oxygen binding molecules
-contain metal ions
-gives strong color
-oxygen binds reversibly to metal ion
-bind to pigment in lungs
release from pigment at tissues due to chnage in affinity
hemoglobin
-most common

-verts, nematodes, some annelids, some crustaceans, some insects

-consists of globin protien bound to heme molecule containing iron

-appears red when oxygenated

-usually located within blood cells

-two alpha two beta chains each with a heme group

-each heme group can bind one oxygen so one Hb can bind 4 oxygen molecules
Myoglobin
-special type of hemoglobin in vert muscles
-high affinity to o2=holds onto it stronger
-is a monomer and each Mb can carry only one oxygen molecule
hemocyanin
-anthropods and molluscs

-contain copper instead of iron

copper directly complexed to aminoacids in the protien

-blue when oxygenated
hemerythrins
- worms and some annelids

-do not contain heme

-iron is bound directly to aminoacids

-violet when oxygenated no color when deoxy

-each bind 2 oxygen molecules
carrying capacity
maximum amount of of oxygen that can be carried in blood
total o2 in blood
is equal to the dissolved o2 in blood plus the o2 bound to respiratory pigment

-increase amount of respiratory pigment means increase in carrying capacity for oxygen
Low solubility of oxygen in aqueous solutions means only small amount can dissolve in blood
the Po2 of plasma is equal to that of lungs but o2 content of plasma is much lower because of low solubility in plasma b/c of henrys law [G]=Pgas*Solubilitygas
if oxygen binds to pigment it not longer contributes to Po2
therefore with same Po2 as before can have higher oxygen content
at low Po2 in the environment
the total oxygen content of blood is still higher then if there was no respiratory pigment
Review slides on o2 curves
review
lower P50
higher affinity
Bohr effect
-a decrease in pH or increase in PCO2 reduced oxygen affinity and causes the curve to shift right but plateaus at same point still

-inc in co2 causes increase in h+ so dec in pH

-facilitates transport of oxygen to active tissues and binding at respiratory surfaces
increase in temperature
decrease oxygen affinity=right shift

-promotes oxygen delivery during exercise
organic modulators (DPG,ATP,GTP)
increase in modulators decrease oxygen affinity=right shift

-helps oxygen unloading at tissues
carbon monoxide and Hb
-CO is byproduct of combustion
-binds to Hb with 250x affininty then o2
-CO displaces oxygen
Root effect
-a bohr effect with a reduction in the oxygen carrying capacity (plateau is lower)

-seen in telostat fish hemoglobin
-helps oxygen delivery to the eye an to the swim bladder
swim bladder
-fish
-helps maintain buoyancy
-gas filled sac
-fill with gas inc buoyancy
-remove gas dec buoyancy
-in most species gas is o2
swim bladder 2
-gas glands secrete lactic acid
-acidity causes hemoglobin to lose 02
-o2 diffuses into the bladder through complex structure called rete mirabile
rete mirabile
net around swimbladder
steps in root effect
see sheet
contributing factors to o2 content in blood
see sheet
carbon dioxide transport
-more soluble then o2 in blood
-some binds to protiens (carbaminohemoglobin)
-most co2 is transported via bicarbonate
carbonic anhydrase
catalyzes the formation of HCO3-
carbon dioxide curve
see notes
haldane effect
-removal of o2 from hemoglobin increases its affinity for carbon dioxide at tissues
-allows co2 to bind to hemoglobin (deoxy blood carrys more co2)
vert red blood cells and co2 transport
-contain carbonic anhydrase in RBCs
-reaction to synthesize hco3- occurs mainly in rbcs even though it it carried in plasma
-hco3- exits rbc by chloride shift
carbon dioxide transport at tissues
-co2 is produced by aerobic respiration
-rapidly diffuses out of cells and into rbcs
-carbonic anhydrase catalyzes formation of bicarbonate
-H+ formed in this reaction binds to Hb
-hco3 moved out of rbc by transporter protien band III
-band III exchnages hco3- for cl-
-if bicarbonate is not removed will inhibit the CA reaction
carbon dioxide transport at respiratory surface
-PCO2 is lower in air/water then in blood so co2 diffuses out
-co2 diffuses out of rbc into plasma and equilibrium of co2-bicarbonate is shifted
-bicarbonate ions move into rbcs (reverse chloride shift)
-bicarbonate and H+ form carbonic acid and then co2
-co2 diffuses out of rbc into plasma and across respiratory surface
regulation of respiratory system
-respiratory systems are closely regulated
-respond to chnages in external and internal environments
-must be able to remove co2 to prevent pH disturbance
regulate gas delivery by
-regulating ventilation (breathing freq/ tidal volume)

-altering o2 carrying capacity and affinity (More rbcs and bohr shifts)

-altering perfusion
buffer
modulates changes but doesn't prevent the changes in pH
-protiens, phosphate ions, bicarbonate

-try to dampen the change
lungs buffer via
respiratory compensation
-acts fast
kidneys buffer via
use of ammonia and phosphate buffers

-slow long term
regulation of ventilation
-rhythmic firing of central pattern generators within the medulla initiate ventilatory movements
pre-botzinger complex
is an important respiratory rhythm generator in mammals
ventilation is a automatic process
-continues even when unconscious
central chemoreceptors
medulla and pons
chemosensory input helps modulate the output of the central pattern generators
-chemoreceptors detect o2, h+, co2
-oxygen is primary regulator in water breathers and co2 in air breathers
rhythm generator neurons of prebotzinger complex send output via
motor neurons

-motor neurons innervate intercostal muscles, diaphragm and abdominal muscles
-cause muscle contraction resulting in either inspiration or expiration
ascending sensory input comes from
chemosensory neurons in carotid and aortic bodies, vasculature of lungs, and chemoreceptors in the medulla

-this modulates the rate and depth of breathing

-negative feedback maintains blood Pco2 and Po2 within narrow range
glomus cells
chemosensory cells in the carotid and aortic chemoreceptors
mechanisms of chemosensory in carotid body
-glomus cells contain o2 gated k+ channels
-o2 sensor detects low o2
-closes k+ channels
-cell depolarizes
-vgate calcium channels open
-causes release of dopamine
-stimulates sensory neuron
mechanisms in central chemoreceptors
-blood brain barrier has tight junctions
-sensitive to chnages in PCO2 and pH
-CO2 crosses blood brain barrier
-carbonic anhydrase converts co2 to hco3 and H+
-H+ stimulates receptor which stimulates ventilation
chemoreceptor reflex
-most responses mediated by central chemoreceptors
-increased Pco2 stimulates ventilation
irritant receptor
-trigger coughing
-trigger sneezing
-trigger bronchoconstriction (dec radius)
stretch receptors
-prevent over inflation
-hering breuer inflation reflux
-reduces ventilation when lungs are over inflated
-usually only experienced during/ after intense exercise
regulation of ventilation in h20 breathers
-sense Po2 (o2 chemoreceptor in gills)
-dec in Po2=inc in ventilation
most species sensitive to blood Po2
causes of low alveolar Po2
-alveolar ventilation is inadequate
-dec lung compliance
-increase airway resistance
-overuse of drugs

inspired air has abnormally low o2 content (high altitude)
emphysema
-destruction of alveoli so reduces surface area for gas exchange

-Po2 in alveoli is normal but Po2 in blood is low
pulmonary edema
-fluid in interstitial space so increase in diffusion distance
-pO2 in alveoli is normal but Po2 in blood is low
asthma
-increased airway resistance (decreases airway ventilation)
-Po2 low in blood and alveoli
hypoxia
lower then normal oxygen levels

causes: lower then normal o2 in environment, inadequate ventilation, reduced blood hemoglobin content
hyper-hypocapnia
-high or lower then normal levels of CO2
at high altitude
-pressure of o2 changes not content
-since inhalation depends on partial pressure of o2...you get less o2 per breath
initial symptoms of moderate altitude sickness
headache, nausea, fatigue, loss of appetite, difficulty sleeping, frequent urination
high altitude initial symptoms
-confusion
-reduced mental acuity
-loss of coordination
-cerebral edema
-pulmonary edema
-death
response to altitude
-low inspired oxygen
-normal co2 production

arterial chemoreceptors sense low o2 and increase frequency and depth of breathing

as result develop hyocapnia (respiratory alkalosis) which reduces drive to breath and causes apnea periods at night and difficulty sleeping

-kidneys start to kick in
acclimatization to altitude by
inc rbcs

inc hemocrit which also increases viscosity of blood

-peripheral vasodilation to deal with inc viscosity of blood
dive response
-apnea
-bradycardia
-peripheral vasoconstriction
-redistribution of cardiac out put