Respiratory System Flashcards
What is the upper and lower respiratory tract made up of?
Upper: nasal cavity, pharynx, nasopharynx, oropharynx, laryngopharynx, larynx
Lower: trachea, bronchi, bronchioles, alveolar sacs, alveoli
Describe the functions of upper respiratory tract?
Nasal cavity: air inhaled, warmed, humidified as it moves through nasal cavity
Scroll-shaped bones: nasal conchae protrude forming spaces where air passes, allows air to humidify, warm and be cleaned before entering lungs.
Epithelial cilia + mucous membrane: servo mucous and other glands produce mucous and cilia traps where unwanted large particles are coughed or swallowed.
Pharynx: connects nasal and oral cavities to larynx and oesophagus
Epiglottis: stays up so air can pass, when eating it closes and folds, covers larynx entrance (so food/liquid doesn’t enter trachea)
What is the pleura and pleural cavity
Pleura: a closed sac of serous membrane (contains serous fluid one for each lung).
Parietal pleura: the outer layer of pleura
Visceral pleura: the inner layer
Helps keep things lubricated to stop friction (which would result in inflammation)
What are the divisions and processes of lower respiratory tract
Air moves down trachea to conducting zone (bronchi,bronchioles, terminal bronchioles) no alveoli in this zone so no gas exchange.
- Alveoli (large SA) has two types of cells Type I (squamous, covers 90% permits gas exchange with capillaries)
Type II (cuboidal, 10% produce surfactant)
Macrophages line alveolar surface to phagocytose particles.
What protection does the lungs have
Epithelial lining (respiratory epithelium): has goblet cells and cilia (line from nasal cavity to largest bronchioles), this dusts other particles and are disposed to mucous layer/wafted towards pharynx where its coughed or swallowed.
At alveolar level goblet and cilia impede gas exchange so infection relies on antibodies and phagocytes.
Muscles used when breathing
Intercostal muscles: 11 pairs occupies spaces between 12 pairs of ribs two layers internal/external.
External IM: extend downwards and forward from lower border of rib to upper in inspiration
Internal IM: extend downwards and backwards from lower border of ribs to upper (crosses EIM fibres at right angles) used in active expiration eg exercise.
What are the functions of diaphragm and accessory muscles
Diaphragm: dome-shaped muscle supplied by phrenic nerve (separates thoracic and abdominal cavities, forms floor of thoracic and roof of abdominal).
Accessory muscles forced inspiration: assisted by STERNOCLEIDOMASTOID and scalene muscles, linking cervical vertebrae to first two ribs increasing ribcage expansion. Muscles contract pulling ribcage upwards.
Forced expiration: contraction of internal IM pull ribcage down and in compressing lungs aiding exhalation. (Rectus abdominis muscle sometimes used compression of abdominal organs increases pressure on diaphragm helping force air out of lungs.
What is the cycle of breathing
Inspiration: EIM (lifts ribcage up and out) and diaphragm contract simultaneously enlarges thoracic cavity in all directions. Perital pleura and visceral (PP) stuck to diaphragm is pulled out along with EIM (since the pleuras are held by negative intrapleural pressure) also causing lung tissue to be pulled up out and down towards diaphragm, causes negative pressure in thoracic cavity (venous return to heart this is called respiratory pump). Active process lasts 2 secs.
Expiration: EIM and diaphragm down and in as they relax causing elastic recoil of lungs increasing pressure in lungs to expel air. Lung still contains air to prevent complete collapse by intact pleura. Passive process lasts 3 secs.
Pause: everything relaxed respiration cycle paused (allows body to rest)
What are the physiological variables affecting breathing
Elasticity: amount of stretch lung has and ability to return to og shape
Compliance: how easy it is to stretch in first place (if diseased lungs r stiff making Work of Breathing (WOK) harder:
Airway resistance: how easy it is for air to move through airway
What is the role of surfactant
Produced by Type II alveolar cells (pneumocytes) reduces friction decreases surface tension so it’s easier for alveoli to expand and contract. Detergent like properties.
What is tidal volume
The amount of air that moves into lung in one single respiratory cycle
What is functional residual capacity
Amount of air left in lungs at end of expiration (required or else lungs will stick together causing collapse of lung)
What is inspiratory reserve volume
Extra volume of air one and above normal tidal volume that can be inhaled into lungs during maximal inspiration (tested using spirometer)
What is inspiratory capacity
Maximum amount of air inspired (both tidal and inspiratory reserve vol)
What is peak expiratory flow
Measured with peak flow meter generally between (400-700L/min) depends on dips meter of larger airways if constricted peak flow decreases. Regular in ppl with asthma.
