week 4: pulmonary response to exercise Flashcards
four key components of external respiration
air moves from atmosphere to lungs
gas exchange between lung and blood
O2 and CO2 transported in blood
gas exchange: systemic tissue and blood
internal resp
O2 utilised in mitochondria to generate ATP to enable muscular contraction
external resp=
internal resp
upper airway function
warms air
moistens and filters air as it passes through the mouth and naval passages
lower airway tract function
air passes through trachea
traves to a lung via a bronchi
passes through many bronchioles to alveoli
where does gas exchange take place
alveoli
can divide respiratory tract into
conducting zone
respiratory zone
conducting zone airways
trachea
bronchi
bronchioles
terminal bronchioles
respiratory zone airways
respiratory bronchioles
alveolar ducts
alveolar sacs
respiratory muscles divided into
inspiratory
expiatory
primary muscle of inspiration
diaphragm- highly oxidative domed shape muscle
what does the diaphragm seperate
thoracic cavity from abdominal cavity
accessory inspiratory muscles
scalenes
pectoralis minor
sternocleidomastoid
other primary inspiratory muscles
intercoastal muscles
at rest muscles of expiration
no muscular contraction
as it is driven by elastic recoil of thoracic wall
as ventilation rate increases,
expiratory muscles are recruited
abdominal wall muscles:
rectus abdominus
internal abdominal oblique
transverse abdominis
external abdominal oblique
pulmonary ventilation
mechanical process that allows the flow of air between the atmosphere and the lungs and occurs due to differences in pressure
at rest
pressure outside the lungs and pressure inside lung equal- no flow of air form atmoshphere to air or vise versa
inhalation pressure changes
diaphragm contracts- pulling downwards, increasing vol of chest
intercoastal muscle contract- expanding ribcage
pressure inside chest lowered
when air pressure in chest is lowered
air moves from atmosphere into chest
Boyle’s law
pressure and volume of a gas have an inverse relationship
exhalation pressure changes
intercostal muscles relax-ribcage drops inwards and downwards
diaphragm relaxes - moves back upwards
decrease vol in chest
decrease in alveoli vol and increase in alveoli pressure
air moves from lung to atmophere
difference between capacities and volumes
capacities are the summation of volumes
tidal volume
amount of air that moves in or out of lungs with each respiratory cycle
normal breathing sat at rest
inspiratory reserve volume - IRV
the extra volume of air that can be inspired with maximal effort after reaching the end of a normal, quiet inspiration
expiratory reserve volume- ERV
the extra volume of air that can be expired with maximum effort beyond the level reached by a normal quiet expiration
why can we not completely empty lungs
to maintain pressure and avoid lobes of lungs collapsing
residual volume
amount left in lungs after complete expiration
inspiratory capacity
normal tidal vol + inspiratory reserve vol
functional residual capacity
expiratory reserve vol + residual col
vital capacity
maximum amount of air we can expire after maximum inspiration
(important for lung function)
total lung capacity
all volumes and capacitys
predicted lung vols and capacities based on
sex
age
stature
can predict
forced via capacity in litres - FVC
forced expiratory volume in the first second in litres per second- FEV1
stature measurment
stature in meters
minute ventilation- VE
refers to the total amount of air that flows into or out of the lungs per minute
tidal vol x breaths per min
average respiratory rate at rest
12 breaths per min
average tidal vol
500ml per breath
average VE
6L per minute
why is it important to differentiate between minute and alveoli ventilation
only a proportion of air that is breathed in participates in gas exchange-
remaining air fills trachea, bronchi and bronchioles (dead space)
respiratory responses to exercise
- ensures arterial PO2 is well maintained for exercising muscles
- eliminates metabolic and non-metabolic C02 ( in order to maintain arterial PCO2)
- assist with maintaining acid-base balance of blood
what does gas diffuse down
its partial pressure grad
from high to low
pp of O2 in atmosphere at sea lelvel
160mmHg
partial pressure of CO2 in atmosphere at sea level
0.3mmHg
partial pressure of gasses in lung
PAO2: 100mmHg
PACO2: 40mmHg
sig decrease P02
sig increase pCO2
why
never completly empty lung (residual vol)
gas from atmosphere mixes with residual volume
interstitial fluid surrounding capillaries
lower because cells are respiring to consume oxygen
cells produce carbon dioxide
depends on metbailic activity in cell
in the pulmonary capillaries
02 diffuses from alveolar air to blood in pulmonary capillaries
binds to haemoglobin
systemic capillaries
dissociation of oxygen from haemoglobin
oxygen diffuses from blood into tissue
haemoglobin- oxygen dissociation curve shifts to the right when
decreased affinity of oxygen and haemoglobin
hgiher PO2 required to acheive any given level of saturation
rightward shift indicates
oxygen unloaded more easily
makes it more available to metabolically active tissue
decrease in pH and increase in body temp facilitates
unloading of oxygen from Hb into working muscle
how is metabolic CO2 produced
oxidative breakdown of macronutrients for ATP production
why does metabolic CO2 need to be removed by the respiratory system during exercise
to maintain PCO2
CO2 action at systemic capillaries
CO2 produced in tissues diffuses in red blood cells
what does an increased PCO2 in red blood cells cause
majority of carbon dioxide molecules converted to bicarbonate
some bind to Hb
some dissolve in blood
bicarbonate action
transported out of rbc into plasma
H+ ions buffered by binding to haemoglobin
CO2 movement at lungs
CO2 diffuses from blood (pulmonary vein) to alveolar air
decreases PCO2 in blood
what happens as PCO2 of red blood cells decreases
-bicarbonate enters rbc
-H+ ions released form haemoglobin
-H+ and bicarbonate converted to CO2
-diffuses into alveoli
expired from lung
what is respiratory system controlled by
autonomic nervous system
respiratory control centre includes
medulla oblongata
pons in brain-breathing control cnetres
what type of feedback loop is ventilation
negative
central chemoreceptors
located in medulla
detect change in PCO2
CHEMORECEPTORS
highly specialised cells responsible for acquiring information about chemical environment
convey info to neurons
(control centre)
peripheral chemoreceptors
located in carotid and aortic bodies
detect change in PO2 PCO2 and H+
when chemoreceptors feed back to brainstem and respiratory centers
feed forward to breathing muscles to increase/ decrease rate and force of contraction according to metabolic demand
increase/ decrease alveolar ventilation rate
changes blood pH, PaCO2, PaO2
then detected by chemoreceptors again (loop)
exercise hypernoea
increase rate and depth of breathing in response to exercise intensity
two ways to increase minute ventilation
increase tidal vol
increase breathing freq
