gas transport and control of breathing Flashcards
two ways oxygen is transported
haemaglobin
disolved in blood plasma, small perentage
how much can each haemoglobin carry?
4 oxygen molecules
what is cooperative binding?
each time one oxygen binds to haemoglobin it makes it easier for the others to bind also
Hb with oxygen
oxyhaemoglobin
Hb without oxygen
deoxyheamoglobin
whats the structure of haemoglobin
haem group within a globin chain
iron atom in centre
2 alpha chains, 2 beta chains
how can the affinity of haemglobin be increased?
increase pH
decrease CO2 conc
decrease body temp
how can the affinity of haemglobin be decreased
decreased pH
increased CO2
increased body temp
increase in 2,3-DGP synthesis
what is an oxygen dissociation curve?
the relationship between oxygen carried in hB and alveolar oxygen
what does the flat top of the cruve show?
plateau region
oxygen binds in the lungs
how much oxygen is released into tissues?
25%
in highly active tissues where is the curve?
shifted to the RIGHT more oxygen released low pH, acidic high temp more CO2
in resting tissue what happens to the curve?
shifted to the LEFT decreased oxygen release low temp low Co2 alkaline pH, high
what is the shifting of the dissociation curve called?
Bohr effect
what causes the borh effect?
increase of CO2 from active tissues lowers the pH triggers an incerase in oxygen release
curve moves to the right
what happens to the oxygen dissocation curve in anaemia?
lower conc of HB
100% saturated but less of it so cant carry as much
oxygen levels lower
three ways carbon dioxide is transprted
disolved in plasma as gas
attached to globin chains in Hb
bicarbonate
describe the passage of carbon dioxide
enters RBC
carbonic anhydrase increases rate water and CO2 combining to make bicarbonate
carbonic acid dissocates
H proton left
bicarbonate leaves RBC in exchange for cl ion
water moves into RBC, more swollen now
lots f protons, low ph
how are the muscle associated with ventilation controlled?
cant contract on their own and require continuous stimulationfrom the CNS
where do signals for ventilation come from?
respiratory centre which has neurnes located in the pons and medulla
what are the respiratory centres
dorsal and ventral
apneustic and pneumotaxic
what is the dorsal and ventral respiratory centre?
medulla
inspiratory and expiratory centres
what is the apneustic and pneumotaxic centres?
pons
involved in pacemaking the lumg
what role does the dorsal group have
neurones send signals to the diaphram through the phrenic nerve to control inspiration
what role does the ventral group have
involved in both inspiration and expiration
controls the intercostals and abdominal muscles
what role does the apneusic group have
promotes inspiration
what role does the pneumotoxic group have?
turns off apneustic centre allowing the expiration
what keeps respiratory rhythm?
neurones firing and inhibiting others and vice verse keeping a pace
during exercise what had more activity
phrenic and intercostal nerves
during quiet breathing wha happens with nerves
no intercostal nerve
no effort
no tension in muscles
what are the two systms regulating breathing
voluntary and automatic
how does the voluntay system control breathing
signals in premotor and motor cortext instruct the respiratory centre allowing us to regulate it outselves
sign, speak, hold breath etc
how does the automatic system control breathing>
mechanical and chemical receptors
how do chemoreceptors monitor breathing
monitor blood oxyge, carbon dioxide, pH
signl and adjust ventilation
how do mechanoreceptors monitor breathing
ense stretching and irritants in the lungs and relays information to respiratory centres
where are central chemoreceptrs found?
close to the medulla
how do chemoreceptrs work?
sense partial pressures of CO2
monitor hydrogen ions in spinal flui
how do the chemireceptors work to signal to increasing breathing rate?
hydrogen ions cant get through blood brain barrier
carbon dioxide can.
no buffering in this spina fluid
hydrogen ions get in through the CO2 then turned int bicarbonate
hydrogen ions reach the receptors
causes the need to breath
slow but effective
where are peripheral chemireceptors found?
arotic branch
carotid bodies
how do carotid bodies act as chemoreceptors
monitor the oxygen conc mainly and sometimes Co2 also
signal the respiratory centre to increase ventilation when partial pressure of oxygen drops belw 60mmhg
very fast
where are mechanoreceptors found?
lung and chest wall
how do mechanoreceptors monitor stretch
when we breathe in signals are send
more stretching means stronger signals
stops over streching of the lungs
they promote expiration and stop damage
what do mechanoreceptors do for irritants
stimulated by gasses, dust smoke. cold air
constrict the bronchioles and protect the airways and lungs
what is a juxtacapillary?
J-receptors
in alvelar walls
sense the fluid in alveoli
induce rapid shallow brething to clean fluid
when are juxacapillaries used?
pneumonia and diseases
what is dysponea
feeling of breathlessness
what is a abstructive disease
expiration defects
whats a resitrcitve diease
hard to breathe in
what type of disease is asthma?
obstructive
what causesastham
allergens in the environment
causes sudden dyspnea and difficulty breathing
what happens during asthma attack?
FRC and RV increased
FEV and peak flow reduced
chronic fimflmtion of the bronchi
what type of disease is emphysema
obstructive
what causes emphysema
smoking
neurphils invade alveli releasing enymes to destroy the lining
what happens in emphyema
supporting connetive tissue destroyed large aveoli more dead space chronic inflmation cili dont work inefficient gas exchange
what lung function tests are done for emphysema
FEV and peak flow are reduced
what type of disease is pulmonary fibrosis
restrictive
what is pulmonary fibrosis
excessive fibrous tissue in the lungs
large alveoli with scars
oxygen has long distances to travel
what does pulmonary fbrosis cause/ theeffects of it
less oxygen in blood
stiff lungs
hard to inhale
chronic breathlessness
what causes pulmonary fibrosis?
idiopathic
maybe overactive imune system secreting desructive enzymes to destroy lining
what type of diseae is COPD
obstructive
what is COPD
combination of emphysema and chronic bhrnchitis
what des COPD cause?
reduced peak flow and FEV
impaired diffusion reduced airway diameter
lung function generally reduced
what is obstructive sleep apnoea
temporary ceasing of breathing during sleep
what causes sleep apnoea
obstruction is physical caused by muscles obstructing the airways
what happens during sleep apnoea
oxygen decreases and carbn dioxide inceased
muscles can sometimes collapse due to lack to tone
what overcomes the obstruction in sleep apnoea?
stimulation to breathe increases in the intrathroaciic pressure to overcome obstruction
what is central sleep apnoea?
respiratory centres cant initiate breathing
no conscous ability while asleep
what sort of breathing happens during central sleep apnoea
Cheyne-stokes sleep
slow shallow breathing that gradully increased before apnoea
what changes during exercise?
CO rises
increased stroke volume and HR
more blood to muscles
heart empties better
what triigers an increase in CO
increse in sympatetic activiy and decrease in parasympatetic
resting systems dont need much output so vessels shut off
more blood sent to musces
how is muscle perfusion increased in exercise
increase in metabolites and adrenaline increased arteriolar dilation increased muscle perfusion
at rest how much of the cardiac output goes to the muscles
5L
to which organ does blood flow change during exercise?
gut and renal flow
what is steady state?
during exercise ventilation is increased until a steady state is reached
this is when oxygen delivery matches demand
when exercise starts what happens in the body
a partial pressure of oxygen and carbon idoxide in venous blood chnge
changes in chemoreceptor signalling
SV and HR increase due to higher brain signals
increase in ventilation due to neural and humoral factors
beats with more force and faster
what happens to reach a steady state?
central effects in respiration and cardiac are reinforced from exercising limbs
ventilation rises
peripheral chemoreceptors help
movement of limbs detected and gives and response
what happens during a steady state
ventilation and CO meet needs of the body!
nothing changed now
maintained by K conc
limb movement and metabolism maintains everything
regular training will…
lower resting HR increase heart size thicker ventricles natural hypertrophy end diastolic volume and SV increased higher maximal CO bone remodels for higher strength more capillary density for more blood supply
what effects does training have on the respiratory system
modest increase in vital capactiy increased minute ventiltion pulmonary dffuion more efficient new capillaries formed alveoli more efficient now muscles higher strength muscle density higher
what changes can happen in elite swimmers?
chest cavity increases in size and can gain more alveoli/larger ones
only swimmers this happens
what effects does altitude have?
sickness brain starved of oxygen not able to inhale as much oxygen as before respiration goes down breathe less and with less oygen
consequences of attitude
central sleep apnoea
pulmonary odemea: lack of pressure and fluid accumulates on the lungs
what effects are there for chronic altitude
chronic hypoxia
double the content of Hb and RBCs
increase: CO, minute volume, tissue vascularisation
what effects does deep diving have on the respiratory system?
bradychardia: redirection of blood to brain and a lowered heart rate
what is is bad to do before diving?
hyperventilation to store oxygen as it can lead to cerebral hypoxia and drowning
it removes carbon dioxide from the blood but it cant be more saturated
what adaptations do mammals have that dive often?
low heart rates and blood that can be easily diverted to key organs
