What are the main functions of the respiratory system?
GAS EXCHANGE
Oxygen in
Carbon dioxide out
HELPS REGULATE pH
OTHER
- smell
- filter
- vocal sounds
- excrete water & heat
What are the functions of the nose?
- warms & moistens air
Prevents dehydration by trapping water droplets - detects olfactory stimuli
- modifies speech
- paranasal sinuses
Mucous membranes
Conducting & respiratory portions of the lungs
CONDUCTING PORTION
- interconnection cavities & tubes
- conduct air into lungs
- filter, warm & moisten air
RESPIRATORY PORTION
- tissues where gas exchange occurs
What structures comprise the larynx?
- thyroid cartilage
- hyaline cartilage
- epiglottis
- cricoid cartilage
- arytenoid cartilage
How are vocal sounds produced?
Ventricular folds (false vocal cords)
Vocal folds (true vocal cords)
Vocal folds vibrate & produce sounds when stretched, narrowing the glottis.
What are the pleura?
- parietal pleura
Lines the thoracic cavity - visceral pleura
Covers the lungs
What are the structures of the lung lobule?
- lobules with terminal bronchioles
- terminal bronchioles….
- branch into respiratory bronchioles….
- subdivide into alveolar ducts
Which structures make up the alveoli sacs?
2 or more alveoli that share a common opening
Open to alveolar duct
Alveolar cells
- Type 1 gas exchange
- Type 2 secrete fluid
Alveolar macrophages
Respiratory membrane
Gas exchanged across the membrane by diffusion
Has 4 layers
What are the steps in respiration?
- Pulmonary ventilation
- in/out air from atmosphere & lungs - External respiration
- blood gains O2 & loses CO2 - Internal respiration
- blood in capillaries loses O2 & gains CO2
- tissue cells gain O2 & lose CO2 (cellular respiration)
How do we inhale?
- pressure in the lungs must be less than the atmosphere
- volume of lungs increases to lower lung pressure
- BOYLE’s LAW volume of gas varies inversely with pressure
- diaphragm muscle is extremely important
Lung pressures
INTRAPLEURAL PRESSURE
- pressure in pleural cavity
- caused by changes in the alveolar pressure
- important for the process of lung tissue expansion
ALVIOLAR PRESSURE
- active process due to use of muscular contractions
- alviolar pressure less than atmospheric pressure
- ain’t moves out of lungs
How do we exhale?
- lung pressure must be greater than the atmosphere
- passive process when resting or quiet breathing
- resulting from elastic recoil (elastic fibres)
- surface tension due to alviolar fluid (surfactant)
What are 2 important factors that contribute to the alveoli’s capacity to inflate?
-surface tension of alveolar fluid (surfactant reduces surface tension)
- compliance of the lung
Amount of effort needed to stretch lungs & thoracic wall
What factors alter ventilation capacity?
AIRWAY RESISTANCE
- Increased bronchi constriction
- Decreased dilation
MODIFIED RESPIRATORY MOVEMENTS
- Emotions
- Expel foreign bodies from lower air passage (cough, sneeze)
- Talking & singing
How do we measure lung function?
TIDAL VOLUME (VT) - volume of 1 breath
MINUTE VENTILATION (MV) - breathing rate X tidal volume
SPIROMETER
- measures resp rate
ALVEOLAR VENTILATION RATE
- volume of air/min that reaches the alveoli
Lung volumes
INSPIRATORY RESERVE
- extra amount inhaled
EXPIRATORY RESERVE
- extra a mound exhaled
RESIDUAL VOLUME
- amount of air in the lungs after expiratory reserve volume is exhaled
Lung capacities
INSPIRATORY CAPACITY
- VT + inspiratory reserve volume
FUNCTIONAL RESIDUAL CAPACITY
- residual volume + expiratory reserve volume
VITAL CAPACITY
- inspiratory reserve volume + tidal volume + expiratory reserve volume
What is internal respiration?
- systemic gas exchange
- occurs in tissues
- based on PO2 & PCO2 of tissues & blood in capillaries
What is external respiration?
PULMONARY GAS EXCHANGE
- diffusion of O2 to the alveoli in pulmonary capillaries
- diffusion of CO2 in the opposite direction
CONVERTS DEOXYGENATED BLOOD TO OXYGENATED BLOOD
What is DALTON’s law & HENRY’s law?
DALTON’s LAW
- partial pressure
- pressure of a specific gas in a mixture
- gases move down their pressure gradient regardless of the presence of other gases
HENRY’s LAW
- gases diffuse into a liquid base on their partial pressure & solubility into the liquid
- oxygen is less soluble than CO2
How do gases move across the respiratory membrane?
- partial pressure of the gas (difference)
- surface area available for gas exchange
- molecular weight & solubility of the gas
- diffusion difference
How is O2 transported in the blood?
- most O2 is transported by haemoglobin 98.5%
- oxyhemoglobin = Hb + O2
- deoxyhaemoglobin has a high affinity for O2
- ability to bind O2 depends on PO2
- percent saturation of Hb = average
What factors effect Hb affinity for O2?
ACIDITY (pH)
- pH decreases, affinity for O2 increases
- more O2 available to tissues
PCO2 EFFECTS Hb AFFINITY FOR O2
- PCO2 increases, Hb releases 9w easier
- acidity & PCO2 related
- buffer system (carbonic anhydrase)
