week 4: pulmonary response to exercise Flashcards by daisy barnwell

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

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internal resp

O2 utilised in mitochondria to generate ATP to enable muscular contraction

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external resp=

internal resp

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upper airway function

warms air
moistens and filters air as it passes through the mouth and naval passages

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lower airway tract function

air passes through trachea
traves to a lung via a bronchi
passes through many bronchioles to alveoli

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where does gas exchange take place

alveoli

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can divide respiratory tract into

conducting zone
respiratory zone

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conducting zone airways

trachea
bronchi
bronchioles
terminal bronchioles

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respiratory zone airways

respiratory bronchioles
alveolar ducts
alveolar sacs

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respiratory muscles divided into

inspiratory
expiatory

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primary muscle of inspiration

diaphragm- highly oxidative domed shape muscle

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what does the diaphragm seperate

thoracic cavity from abdominal cavity

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accessory inspiratory muscles

scalenes
pectoralis minor
sternocleidomastoid

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other primary inspiratory muscles

intercoastal muscles

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at rest muscles of expiration

no muscular contraction
as it is driven by elastic recoil of thoracic wall

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as ventilation rate increases,

expiratory muscles are recruited

abdominal wall muscles:
rectus abdominus
internal abdominal oblique
transverse abdominis
external abdominal oblique

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pulmonary ventilation

mechanical process that allows the flow of air between the atmosphere and the lungs and occurs due to differences in pressure

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at rest

pressure outside the lungs and pressure inside lung equal- no flow of air form atmoshphere to air or vise versa

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inhalation pressure changes

diaphragm contracts- pulling downwards, increasing vol of chest
intercoastal muscle contract- expanding ribcage
pressure inside chest lowered

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when air pressure in chest is lowered

air moves from atmosphere into chest

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Boyle’s law

pressure and volume of a gas have an inverse relationship

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exhalation pressure changes

intercostal muscles relax-ribcage drops inwards and downwards
diaphragm relaxes - moves back upwards
decrease vol in chest

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decrease in alveoli vol and increase in alveoli pressure

air moves from lung to atmophere

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difference between capacities and volumes

capacities are the summation of volumes

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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

1. ensures arterial PO2 is well maintained for exercising muscles 2. eliminates metabolic and non-metabolic C02 ( in order to maintain arterial PCO2) 3. 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