UNIT 3: Respiratory Physiology Flashcards
compare/contrast quiet inspiration vs forced inspiration
quiet inspiration –> aka rest breathing… diaphragm and external intercostals contract (and interchondral internal intercostals)… diaphragm accounts for 60% of inspiratory capacity
forced inspiration –> inc oxygen needs…. requires activation of the accessory muscles of inspiration… diaphragm contracts, abdomen protrudes
compare/contrast quiet expiration and forced expiration
quiet expiration —> involves passive forces only (no active forces)… gravity pulls ribs back to rest… the lungs are highly elastic, when stretched by inc thoracic volume they will return to original shape and size when released
forced expiration –> requires muscles contraction and passive forces, compresses abdominal viscera and thorax
what are the two diff elements that can be measures during respiration? how can they be measure?
- lung volume, w spirometry
- pressure, w manometery
what is respiratory rate?
- number of respiratory cycles per min (breaths per min, BPM)
what is volume? volume capacity?
- size or extent of a 3D space
- optimum or max volume
spirometer
- measures volume of water displaced by respiration
- measured in cubic cm (cc)
tidal volume (TV)
volume of air exchanged (inspired and expired) in one respiratory cycle
dependent on body/thorax size
450 cc for young adult female, 600cc for young adult male
inspiratory reserve volume (IRV)
- max volume of air that can be inspired above normal (i.e quiet) inspiratory tidal volume
- female = 1950cc, male = 3000cc
expiratory reserve volume (ERV)
- max volume of air that can be expired below normal expiratory tidal volume
- female = 800cc, male = 1200cc
residual volume (RV)
- volume of air remaining in lungs after a maximal forced expiration
- includes dead air in upper resp tract
- female = 1000cc, male = 1200cc
inspiratory capacity (IC)
- total amount of air that can be inspired after a tidal expiration
TV + IRV - approx 3000cc
functional residual capacity (FRC)
- amount of air remaining in lungs after tidal expiration
ERV +RV
Vital capacity (VC)
total amount of air that can be forcibly expired after a maximal inspiration
TV + IRV + ERV
- approx 4000cc
total lung capacity
total amount of air in the lungs after a maximal inspiration
TV+ IRV+ ERV+ RV
approx 5100cc
how does vital capacity change w age?
- inc 20 mL per year in adulthood to 20 years
- begins to decline at about 25 years old
All lung capacities except ___ decline because…
- Residual volume
- reduced elasticity: reduced ability to inflate the lungs, RV inc
- bronchiole diameter begins inc
- alveolar wall begins thickening
pressure
force exerted on walls of a chamber by gas molecules
manometer
measures number of cm or inch of water - cm/H2O
pressure is dependent on ____
- area
- pressure = force/area
- as area inc pressure dec
- as area dec pressure inc
atmospheric pressure
- what our lungs want to return to
- pressure arising from force of gravity on air molecules of atmosphere
alveolar pressure
pressure w/i the lungs
intrapleural pressure
- pressure bw visceral and parietal pleurae
- need to be neg to keep layers connected
subglottal pressure
pressure below vocal folds
intraoral pressure
pressure in oral cavity
inspiratory pressure
- when we inhale we stretch tissue
- tissue elasticity in lungs allows them to be stretched which is inspiratory pressure
- created by muscle contraction
relaxation pressure.. pos and neg?
- to return tissue to rest we rely on recoil and gravity which is relaxation pressure
- generated by relaxing muscle contraction
- the more you inspire the greater the positive relaxation pressure is generated
- the more you expire the greater the negative relaxation pressure is generated
- a restoring force
expiratory pressure
- when we forcefully exhale we distend tissue
- forceful exhalation forces the abdominal viscera superiorly, compressing the thorax which is expiratory pressure
- created by muscle contraction
tidal respiration
- quiet breathing
- entire cycle is about 10 sec
- approx 4 sec of inspiration and 6 sec of expiration
- balance bw inspiration and expiration varies based on activity level
what is the impact of aging on respiratory rate?
- bony thorax grows more than lungs - lungs stretch to fill space (semi inflated, dec work of breathing)
- number of alveoli inc from birth to adulthood, more SA which inc efficiency and dec work of breathing
what is the goal of speech breathing? how is uniform pressure achieved?
- to supply uniform source of pressure bw the vocal folds (subglottal pressure) of 6-10cm H2O
- variations in subglottal pressure will result in variations in vocal intensity
- higher intensity speech requires higher subglottal pressure
- uniform pressure is achieved thru balance bw active muscles forces and passive forces
- active: muscles of inspiration and expiration
-passive: elastic recoil, gravity
describe the steps of speech breathing (from speech beginning to as it continues)
as speech begins –> inspiratory muscles are activated to counteract or check passive forces
at mid range –> relaxation forces are sufficient to maintain subglottal pressure
as speech continues –> expiratory muscles compress abdomen and thorax to maintain subglottal below 40% VC
What percentage of VC do we inspire to for conversation speech? loud speech? when does the most efficient breathing for speech occur?
- 60% conversational
- 80% for loud
- typically fill the lungs about the same volume regardless of whether we are speaking or not
- more difficult to produce speech in the upper and lower ends of the VC range
- most efficient breathing for speech occurs in the middle of the curve
____ cm of H2O can be maintained across most of the VC range (10-90%)
7
summarize how the actions of the respiratory muscles control the air pressure in the lungs
- lungs are stretched to max inspiration
- generates an elastic recoil pressure = relaxation pressure
- inspiratory muscles are actively regulating subglottal pressure, preventing lung volume from dec too rapidly
- as lung volume dec, so does relaxation pressure, and less inspiratory muscle activity is needed
- as lung volume dec further, subglottal pressure becomes greater than relaxation pressure, and expiratory muscle activity is needed
how is respiration controlled neurally?
- via central pattern generators (CPGs) = neural control of rhythmic motor behaviours (basically are given a task and keep it going)
- pacemaker neurons in reticular formation of brainstem (medulla) called the pre-botzinger complex –> controls basic respiratory rhythm, but can be modidifed by sensory inputs
what sensory inputs is the pre-botzinger complex receiving? where are the receptors located? how does speech breathing come into play?
- chemoreceptors sensitive to blood O2 and CO2
- baroreceptors sensitive to blood pressure
- receptors located: in medulla, peripherally in aortic bodies (CN X) and carotid bodies (CN IX)
- descending cortical info and info from other brainstem nuclei override this rhythmic behaviour for speech breathing
what are the 4 respiratory defense mechanisms?
- coordination of breathing and swallowing
- mechanical clearance in conducting zone
- clearance of particles in respiratory zone
- clearance of liquids in respiratory zone
describe the coordination of breathing and swallowing as a defense mechanism…. what if it fails?
- highly coordinated, cant breath and swallow at the same time
- respiration is inhibited during a swallow (respiratory apnea, swallow-related apnea… apnea means pause)
- coordination can be altered in certain diseases
- if it fails to coordinate breathing and swallowing it can result in aspiration or aspiration pneumonia
aspiration
entry of foreign materials into airway below level of vocal folds
aspiration pneumonia
chest infection that results from aspiration of bacteria-laden material
describe the mechanical clearance in the conducting zone as a respiratory defense mechanism (2 ways)
- cough –> afferent inputs from CN X elicit motor response; expiratory airflow sweeps tracheal surface
- mucociliary action –> mucous and foreign particles are propelled toward major airways/trachea to be ejected via cough
describe the clearance of particles in the respiratory zone as a respiratory defense mechanism
- macrophages protect alveoli, provide phagocytosis (particle ingestion) and carry particles to conducting zone, lymph nodes, also kill pathogens
describe the clearance of liquids in the respiratory zone as a defense mechanism
- lymphatics = draining and filtering excess tissue fluids w/i the lymph system
- lung lymphatics normally clear 400-700ml a day
what are the impacts of respiratory issues?
- respiration is the energy supply for speech
- respiratory diseases affect lung volume, motor disorders affect resp control
- resp issues lead to: reduce VC, reduced pressure generation ability, reduced phrasing in speech, reduced vocal intensity, inc physical fatigue
COPD
- chronic obstructive pulmonary disease
- non-reversible respiratory disease
- laboured airflow, dec lung capacity
- two types: emphysema and chronic bronchitis
emphysema
- smoking or enviro related chronic inflammation leads to overactive response of macrophages in lungs
- breakdown of alveolar walls –> loss of SA and lung elasticity (air is trapped in alveoli clusters, leads to expanded thorax, flattened diaphragm, heavy lungs)
- symptoms: shortness of breath, shallow breathing (clavicular breathing), fatigue
- leads to weight loss and heart probs
- difficulty coordinating breathing and swallowing can lead to further impaired nutritional status
- speech: short phrasing, limited phonatory ability
chronic bronchitis
- exposure to smoking and other irritants leads to inflammation and fibrosis of bronchial passageway
- productive cough that lasts for 3 months or longer, twice in one year for 2 years
- affects 5% of adults, 6% of children worldwide
- 2.9 mill deaths annually
- results in: excessive mucus, cough, wheezing, shortness of breath, airway obstruction, frequent lung infections, cyanosis (blue appearance of lips)
- inc risk of airway obstruction during swallowing
- speech: reduced vocal intensity, short phrasing, fatigue during speech
amyotrophic lateral sclerosis (ALS)
- degenerative disease in which motor neurons are destroyed
- leads to weakness in all muscles, including resp
- forced respiration affected initially, then quiet resp
- for speech: mean length of utterance is dec
- for voice: less intense, aphonia (fatiguing to maintain subglottal pressure)
- for swallowing: weak cough, fatigue, pneumonia
