1.2 Respiratory system Flashcards
describe the pathway of air
- mouth & nose
- pharynx
- Larynx (voice box)
- trachea
- bronchus
- bronchi
- smaller branches bronchioles
- alveoli
how are alveoli adapted for gas exchange
- thin walls = short diffusion distance
- extensive capillary network around it = good blood supply
- millions of alveoli = large SA
what needs to happen to pressure in the lungs for air to be inhaled & exhaled
AIR IN - pressure needs to be lower in the lungs than in the atmosphere
AIR OUT - pressure needs to be higher in the lungs than in the atmosphere
what muscles are used in inspiration at rest
- diaphragm
- external intercostal muscles
what muscles are used in inspiration when exercising
- diaphragm
- external intercostals
- sternocleidomastoid
- scalenes
- pectorals minor
what muscles are used in expiration at rest & exercise
REST:
- diaphragm & external intercostals relax
EXERCISE:
- internal intercostals & abdominals
what happens to the rib cage & lungs (diaphragm) when air is brought in & out
AIR IN
- Ribcage moves up and out
- diaphragm contracts and pulled flat
AIR OUT
- ribcage falls
- diaphragm relaxes and rises back to dome shaped position
define: tidal volume, residual volume and minute ventilation
tidal vol - volume of air breathed in or out per breath
residual vol - volume of air left in the lungs after maximum expiration
minute ventilation - volume of air breathed in or out per minute
define: inspiratory reserve volume and expiratory reserve volume
IRV - vol of air that can be forcibly inspired following a normal breath
ERV - vol of air that can be forcibly expired following a normal breath
what happens to the lung volumes during exercise
Tidal vol - increases
IRV - decreases
ERV - slight decrease
Residual vol - remains the same
Minute ventilation - big increase
how is a spirometer trace created
- breath in and out of a sealed chamber through a mouthpiece
- chamber inflates and deflates
- pen recorder traces the beginning movements onto a chart
Gase Exchange:
describe the process of gas exchange in the alveoli
- partial pressure of o2 in the alveoli is higher than in the capillary blood vessels
- cas o2 removed by the working muscles so the conc in the blood is lower
- the difference in p.p = concentration gradient - larger the gradient the faster diffusion
- o2 diffuses until the pressure is equal in both
describe how oxygen exchange occurs at the muscles
- in the capillary membranes surrounding the muscle, the p.p of o2 is 40mmHg, in the blood 100mmHg
- this lower p.p allows o2 to diffuse from the blood to the muscles
describe how Co2 exchange occurs at the muscles
- p.p of Co2 in the blood is lower than at the tissues
- so diffusion occurs and Co2 moves into the blood
- to be transported to the lungs
what is the role of the receptors during exercise
. receptor systems send impulses to the medulla oblongata in the brain
. stimulates sympathetic nervous system & the breathing rate is increased
receptors role following exercise
. receptors send impulses to the medulla oblongata
. stimulates the parasympathetic nervous system & breathing rate is decreased
what are the 2 main areas of the Respiratory centre
. inspiratory centre (= responsible for inspiration & expiration)
. expiratory centre (= stimulates the expiratory muscles during exercise)
what does the inspiratory centre do during exercise
- sends nerve impulses via the phrenic nerve to the inspiratory muscles (diaphragm & external intercostals) cause them to contract
- acts for approx. 2 seconds then stops
- passive expiration occurs due to electric recoil of the lungs
what does the expiratory centre do during exercise
- respiratory centre sends impulse down the phrenic nerve
- to stimulate more inspiratory muscles: sternocleidomastoid, scalenes & pectoralis minor
- rate & depth of breathing increases
what do the chemoreceptors do during exercise to increase HR
- blood acidity increases (cas of increased Co2 & lactic acid)
- detected by chemoreceptors
- they send impulse to the inspiratory centre to increase ventilation until the blood acidity is normal (depth and rate of breathing)
what are the other factors effecting neural control of breathing
- mechanical factors: proprioceptors
- baroreceptors
- stretch receptors
describe the role of proprioceptors in breathing
- sensory receptors in joints and muscles
- provide feedback to the respiratory centre to increase breathing during exercise
describe the role of baroreceptors in breathing
- decrease in b.p detected by baroreceptors in the aorta & carotid artery
- results in increase in breathing rate
how does the hormonal regulation of pulmonary ventilation occur during exercise
- brain sends impulse to renal glands
- which respond & pump adrenaline in to the blood in anticipation of the increased need for o2 and Co2 exchange
- so breathing rate increases in preparation for Ex. & the demand to take in more o2 and remove more Co2
how does smoking effect the respiratory system (general)
- irritation of the trachea and bronchi
- reduces lung function and increases breathlessness caused by the swelling and narrowing of the lungs airways
how does cigarette smoke effect the respiratory system
- damages the cells lining the trachea, bronchi and bronchioles
- the tiny cells have microscopic hair-like cilia which help push the mucus out the lungs
- when they are damaged, excess mucus builds up in the lung passages
- leads to a smokers cough to get rid of mucus
how does smoking damage the alveoli
- walls break down & join together forming large air spaces
- reduces the efficiency of gas exchange, which also increases the risk of COPD
how does smoking effect the body during exercise
- affects o2 transport cas the C monoxide combines with Hb in RBC more than o2
- reduces the o2 carrying capacity of the b. - increases breathlessness during exercise
