respiration during exercise- week 7 Flashcards
what is the primary purpose of the respiratory system ?
to maintain arterial blood-gas homeostasis
how is arterial blood gas homeostasis accomplished ? (4-step process)
pulmonary ventilation
alveolar gas exchange
gas transport
systemic gas exchange
what is the epiglottis ?
separates upper and lower respiratory tracts
the lungs are enclosed within membranes called …
pleura
parietal pleura - outside membrane
visceral pleura - directly covers lungs
what is the pleural cavity ?
space and fluid in-between pleura membranes
reduces friction when lungs move
what prevents the alveoli form collapsing ?
intrapleural pressure is less than atmospheric pressure
what pets of the airways is part of the conducting zone ?
trachea, bronchi and the bronchioles
what parts of the airway is part of the respiratory zone ?
bronchioles and the alveoli
what occurs in the respiratory zone ?
gas exchange
where does pulmonary gas exchange take place?
across pulmonary capillary
what are the types of alveolar calls (pneumocytes) ? (2)
type 1 - 95% of internal surface
type 2 - release surfactant that lowers surface tension
what is the volume of gas passing though a sheet dependent on ?? (4)
surface area
thickness
diffusion coefficient
pressure gradient
what is ficks law of diffusion ?
volume of gas proportional to ( surface area/thickness) x diffusion x pressure gradient
mechanics of breathing is caused by changes in ….
pressure - contraction force
flow - contraction velocity
volume - contraction length
wha is the bucket handle motion ?
increased transverse(lateral) diameter of thorax during inspiration
sides go in and out
what is the pump handle motion?
increased anteroposterior diameter of thorax during inspiration
front moves forward and back
at rest diaphragm contraction is responsible for what ?
what does this mean for expiration ?
majority of pulmonary ventilation
expiration is passive
what muscles is the diaphragm assisted by during exercise (pulmonary ventilation)?
external intercostals
scalenes
sternocleidomastoid
what muscles is the diaphragm assisted by during exercise (expiration)?
rectus abdominis
internal intercostals
external obliques
what does long endurance exercise lead to ?
fatigue in respiratory muscles
de line in muscle pressure
what is ohm’s law?
current= voltage(change in pressure)/resistance
airflow dependent on pressure gradient and airway resistance
what is poiseuille’s law?
resistance dependent on length and radius of a tube
radius raised to 4th power
- major determinant of airway resistance
what can be seen when someone with COPD (chronic obstructive pulmonary disease) expires/inspires air compared to normal lungs ? (3)
someone with COPD has increased airway resistance
people w COPD struggle to expire air as quick as normal
breath higher lung volumes with COPD and need to increase lung pressure to breathe
what are the 3 phases of ventilatory response to constant loads steady-state exercise?
phase 1: immediate increase in minute ventilation
phase 2: exponential increase increase in ventilation
- increase in PCO2 too
phase 3: plateau - steady state
what is hyperpnoea ?
PaCO2 regulation due to proportional changes in alveolar ventilation and metabolic rate
ventilation increases linearly with exercise intensity until a point which is known as…
ventilatory threshold (Tvent)
after Tvent, ventilation increases leading to…
hyperventilation
decrease PaCO2
what is exercise-induced arterial hyperaemia (EIAH) and who does it occur in ?
reduction in PaO2 of ≥ 10 mmHg from rest
in highly trained males - high intensity exercise
in all females regardless of fitness and intensity
why was EIAH originally theorised to occur ?
ventilatory demand exceeds capacity
demand vs capacity theory
what are the causes of EIAH believed to be due to ?
diffusion limitation - increased CO2, too high blood flow doesn’t allow effective diffusion in red blood cells
V/Q mismatch - air breathed in has to be matched be blood CO. more perfusion than air in lungs
relative hypoventilation - can’t increase ventilation efficiently if don’t increase breathing enough causing hyperventilation
how do you measure mechanical work of breathing ? (2)
oesophageal pressure
calculates mechanical work of breathing during exercise
what are the 3 groups of neutrons that control breathing ?
ventral respiratory group (inspiratory/expiratory)
Dorsal respiratory (inspiratory)
pontine respiratory group (modulatory)
What is Dalton’s law ?
Total pressure of gas mixture is equal to sum of pressure that each gas would exert independently
What is the equation for partial pressure ?
Pgas= fraction of gas in air (Fgas) x barometric pressure (Pbar)
What is partial pressure for O2 and CO2?
O2 = 159mmHg
CO2 = 0.3 mmHg
What happens when oxygenated air mixes with deoxygenated air ?
Causes some impairment
Arterial PO2 (100) is less than Alveolar PO2 (105)
What are the differences between systemic and pulmonary circulation in terms of pressure and resistance ?
Pulmonary - low pressure low resistance
(Pulmonary artery pressure15mmHg)
Systemic arterial pressure 100 mmHg
High pressure high resistance
Why is pulmonary circuit have low pressure and resistance ?
Thin walled and little smooth muscle
No need for redistribution of blood flow so low resistance
Explain the ventilation perfusion relationship
Gas exchange requires matching ventilation to blood flow
Underperfused - (apex of lung) more air than blood
Overperfused- (base of lung) more blood than air
Blood flow increases disproportionally due to gravity
