3.1.1.3 Respiratory system Flashcards
respiratory system order
1-nasal cavity/mouth
2-epiglottis
3-larynx (voice box)
4-trachea (rings of cartilage) = stop collapsing
5-bronchi
6-bronchioles (lungs & ribs)
7-alveoli
Gas exchange and alveoli
- gas exchange occurs at alveoli
- essential features of alveoli = efficient gas exchange to occur between lungs and blood
4 features of alveoli
- big surface area (350million alveoli 90 square metres)
- thin of diffusion barrier = single celled alveolar & capillary walls = total thickness = 0.005mm
- extensive blood supply to alveoli = ensures steep concentration gradients
- moist alveoli walls = promote gas exchange
smoking effect on oxygen transportation and the causes:
-smoking = -ve O2 transportation
- tar= stain lung tissue
- carbon monoxide = bind to Hb more readily than O2
- hydrogen cyanide = prevents lungs cleaning system from working = build up go chemicals in lungs
causes:
breathlessness, windpipe irritation, risk of lung infection, permanent lung damage (shrinking/blackening of tissue)
mechanics of respiration at rest:
- contraction & relaxation of external intercostal muscles & diaphragm
- movements of rib cage & diaphragm = pressure diff between lungs & atmosphere = inspiration & expiration achieved
-inspiration and expiration = mechanical processes involving ribs intercostal muscles and diaphragm
mechanics of inspiration at rest:
external intercostal muscles contract &pull ribs up& out
diaphragm contract & flatten
increase vol of thoracic cavity = decrease in pressure
- pressure in thoracic cavity = lower than outside air,
- air moves from high to low in lungs (pressure gradient) -air rushes in via trachea = equalise pressure difference
- lungs inflate elastic alveoli fibres/walls are stretched
mechanics of expiration at rest:
external intercostals (ribs move down & in) diaphragm (return to dome shape) relax (passive process = no energy needed have gravity)
decreasing vol of thoracic cavity = increase in pressure
- air moves from high to low pressure out of the lungs
- pressure in thoracic cavity now higher than outside air
mechanics of inspiration during exercise
internal intercostals relax
external intercostals contract
diaphragm contract
aided by sternocleodamastoid & scalenes & pectoralis minor
mechanics of expiration during exercise
internal intercostals contract
external intercostals relax
diaphragm relax
aided by abdominals
the respiratory muscles
- cartilage connects ribs to sternum
- lungs = in thoracic cavity sides = bounded by 12 pairs of ribs
- cartilage = softer & more pliable than bones = assists movement of rib cage during breathing
- 2 sets of antagonistic muscles are located between ribs and these are intercostal muscles whose actions move ribcage during breathing
pulmonary ventilation at rest
pulmonary = lungs
-involves contractions and relaxation of external intercostal muscles
-internal intercostal muscles active during exercise
diaphragm
powerful sheet of muscle, separates thorax from abdomen
dome shaped = relaxed
flattened = contracted
tidal volume (TV)
volume of air displaced from lungs during steady state inspiration and expiration
rest = 0.5L exercise = increase to 5L
breathing frequency (f)
number of breaths per minute
rest = 12-15 exercise = increase to 40-50
minute ventilation (VE) (v/min)
volume of air inhaled or exhaled per minute
rest = 6L exercise = increase 250L
VE = TV x f
inspiratory reserve volume (IRV)
volume of air inspired by force after a regular breath
decreases with exercise
expiratory reserve volume (ERV)
volume of air expired by force after a regular breath
decrease with exercise
residual volume
volume of air remaining in lungs after maximum expiration
stays same with exercise
vital capacity
volume of usable air in lungs
IRV + TV + ERV
total lung capacity
total volume of air in lungs including residual volume
impacts of exercise:
higher intensity = more significant changes
- increase inspiration= sternocleidomastoid, pectoralis minor, scalenes = increase thoracic cavity = lift sternum & ribcage
- increase expiration = internal intercostals (activated pulls ribs down & in more forcefully = force air out of lungs) , abdominals (contract & increasing intra-abdominal pressure force diaphragm -dome shape
regulation of breathing
receptors:
-chemo (pH change in aorta&MO = stimulate ICC= increase inspiration when CO2levels increase) (chemical)
-baro (BP decrease = increase in VE)
-proprio (joint movement stimulate ICC increase inspiration when moving)
(baro and proprio = neural control)
RCC & ICC & ECC
respiratory control centre
inspiratory control centre (external intercostals E.I.C (intercostal nerve) & diaphragm (phrenic nerve)
controls rate & depth of inspiration
receptors->medulla->phrenic nerve/intercostal nerve
->diaphragm/E.I.C.
expiratory control centre (internal intercostals I.I.C (intercostal nerve) & abdominals)
controls rate and depth of expiration
receptors->medulla->intercostal nerve->abdominals/I.I.C
stretch receptors
- impact inspiration
- stop alveoli being damaged, decrease size of alveoli = due to pressure reducing squeezed out
- detect bronchioles from over inflating
- stop inspiration & start expiration
- prevent the over inflation of lungs = send impulses to ECC and down intercostal nerve to expiratory muscles = expiration
- protective mechanism = Herring Bruer Reflex
Medulla oblongata
MO
where RCC located
factors affecting regulation of pulmonary ventilation during exercise:
- neural control
- chemical control
- hormonal control
sympathetic nervous system = always involved during exercise - increase breathing rate - prepare for exercise
parasympathetic nervous system = decrease breathing rate - prepare for retiring body to resting levels
herring bruer reflex
- protective mechanism
- increases breathing frequency
- prevents lungs and alveoli being damaged by reducing the pressure and forcing expiration (detect bronchioles over inflating)
- increase speed of expiration
- internal intercostals contract forcing air out quicker
control of breathing during exercise
rate & depth increases
- impulses ICC -> external intercostal muscles & diaphragm = more forceful depth of breathing
- stimulate accessory breathing muscles (sternocleidomastoid and scalene and pectoralis minor) = depth of inspiration increases
-impulses ECC -> internal intercostal muscles & abdominal muscles = expiration becomes an active process = increase rate of breathing
impact of poor lifestyle choices on the respiratory system
- smoking
- tar binds
- irritation of trachea and bronchi
- lung function & breathlessness
- cells lining the trachea, bronchi, bronchioles
- cilia are damaged = mucus = smokers cough
- damage alveoli = walls break join together = larger air spaces = reduces efficiency GE
- increases risk of chronic obstructive pulmonary disease (COPD) e.g. emphysema
effects of smoking
- smoking affect O2 transport
- carbon monoxide= high affinity for Hb (from cigarettes)= binds with Hb in RBCs much more readily than oxygen
- blood can carry less oxygen can lead to more breathlessness during exercise
COPD
chronic obstructive pulmonary disease
chronic/debilitating disease
collection of diseases such as emphysema
long term progressive disease of lungs = shortness of breath
