Respiratory system Flashcards
Upper respiratory tract
Moistens and filters inspired air
Nasal cavity, pharynx and larynx
Lower respiratory tract
Trachea, bronchi and bronchioles control air flow through lungs
Lung enables gaseous exchange
Anatomical difference between the right and left lung
Both have superior and inferior lobe
Right has a middle lobe, but not left because of position of heart
Trachea and respiratory airways have 3 layers
Outer layer - cartilage reducing from trachea to bronchi
Middle muscular layer
Inner epithelial layer with goblet cells
How does the ANS cause bronchodilation?
Sympathetic nerve tone results in adrenaline binding to beta 2 receptors in smooth muscle
How does the ANS cause bronchoconstriction?
Parasympathetic stimulation releases acetylcholine that binds to M3 receptors on smooth muscle
Epithelial layer of bronchi
Made up of pseudo-stratified columnar epithelium
Lined with cilia - removes dust and small particles
Aided by mucous secreted by Goblet cells
Type I alveoli
Form alveolar sac
Sites of gaseous exchange
Type II alveoli
Form surfactant
Exoctyose lipo-protein surfactant which reduces water tension
Create pressure needed by alveoli
Scavange debris
Pulmonary respiration and pressure
Movements in chest wall and lungs cause lungs to increase and decrease in volume - changes lung pressure relative to atmospheric pressure
Tidal volume
Amount of air breathed in and out at rest
Inspiratory reserve
Extra air that can be inhaled in a deep breath
Expiratory reserve
Extra air that can be expired in one breath
Residual volume
Air left in lungs after expiration (cant be exhaled)
Vital capacity
Amount of air that can be forcefully inhaled and exhaled
Functional residual capacity
Expiratory reserve + residual volume
External respiration
Oxygen diffuses from alveoli (p=100) to pulmonary capillary (p=40)
Carbon dioxide diffuses from capillary (p=45) to alveoli (p=40)
Role of haeomoglobin
- Oxygen carried in blood to haemoglobin
- Iron in subunit binds oxygen, promoted by increased partial pressure and increased pH
- When all 4 haemoglobin subunits have bound with oxygen, it is fully saturated
Oxygen saturation curve
- Oxygen partial pressure in blood drops as blood travels away from lung
- Haemoglobin drops oxygen as pressure decreases
- 75% saturated when it reaches tissue
Internal respiration
Oxygen diffuses from blood (p=95) to cells (p=40)
Carbon dioxide diffuses from cells (p=45) to blood (p=40)
Involuntary regulation of respiration
Moderated by medulla oblongata in response to carbon dioxide levels
Normal tiding breathing - Hering Breuer reflex s when expansion stretch receptors signal to the medulla to inhibit further expansion
Voluntary regulation of respiration
Cerebral cortex
Limbic system - emotions like fear and anger
SNS receptors
Beta 2
Adrenaline binds and causes bronchial relaxation
PSNS receptors
Muscarinic
Acetylcholine binds and causes bronchial constriction
