PSC1002/L14 Respiratory System Flashcards
Give two functions of the respiratory system.
Exchange of gases
Regulation of body pH
Protection from inhaled pathogens and irritants
Vocalisation
Which lung is divided into 3 lobes rather than 2?
Right lung
What are the conducting systems comprised of? (2)
Upper respiratory tract - nasal cavity, pharynx, larynx
Lower respiratory tract - trachea, bronchi, bronchioles
What is the respiratory zone comprised of?
Alveoli and capillary supply
Give 3 functions of the nose and nasal cavity.
Warm and humidify air
Filter debris
Secrete antibacterial substances
Houses olfactory receptors
Enhances resonance of voice
Give 3 functions of the pharynx.
Warm, humidify and filter air
Prevent food entering respiratory tract
Protects against mechanical stress
Give 2 functions of the larynx.
Prevents food and liquid entering respiratory tract (epiglottis)
Sound protection
How many secondary and tertiary bronchi are there?
5 secondary
18 tertiary
What are goblet cells?
Mucus-secreting cells that form a continuous layer over surface of respiratory tract
What are ciliated cells?
Cells that produce saline and sweep mucus upwards to pharynx
What does the mucociliary escalator do?
Removes noxious particles from lungs
Describe the saline secretion pathway in airway epithelial cells. (4)
NKCC brings Cl- into epithelial cells from ECF
Apical anion channels, including CFTR, allow Cl- to enter lumen
Na+ goes from ECF into lumen by paracellular pathway drawn by ECG
NaCl movement from ECF creates concentration gradient so water follows into lumen
What structures keep the trachea open?
C-shaped cartilage rings
What is the function of the posterior smooth muscle of the trachea?
Allows expansion of oesophagus during swallowing
What 3 main histological changes occur as bronchi divide and get smaller?
Cartilage changes to complete and fewer rings
Epithelium changes to columnar cells
Amount of smooth muscle increases
Describe the structure of a bronchiole. (3)
Non-ciliated epithelium
Smooth muscle layer
No cartilage
Describe the structure of alveoli. (3)
Single epithelial cell layer
Supported by elastic fibres
Large SA for gas exchange
Describe type I alveolar cells. (3)
90% of alveolar cells
Very thin
Gas exchange occurs
Describe type II alveolar cells. (3)
Smaller
Thicker
Produce surfactant
What is the function of macrophages with regards to alveoli?
Protect alveolar structures from non-filtered, small particles
Briefly describe quiet breathing.
Inhalation - active contraction of diaphragm
Exhalation - passive relaxation of diaphragm
Which muscles contract to raise the ribcage upwards and outwards? (2)
External intercostal muscles
Scalenes
Define Boyle’s Law.
As volume of the contained increases, the pressure that the gas exerts on the container decreases
Define atmospheric pressure.
Pull of gravity on air around us creates atmospheric pressure
Describe intrapulmonary pressure. (3)
Air pressure within alveoli
Rises and falls with inspiration and expiration
Always eventually equalises with atmospheric pressure
Define intrapleural pressure. (3)
Pressure found within pleural cavity
Rises and falls with inspiration and expiration
Does not equalise with atmospheric pressure
What are pleural sacs? (2)
Two membranes of elastic connective tissue and capillaries
Surrounds each lung
What is pleural fluid? (3)
Very thin film of fluid within cavity
Acts as lubricant to allow lung to move within thorax
Maintains lung inflation at rest
Describe the structure of the pleural sacs. (2)
Parietal pleura - outer layer fused to rib cage, diaphragm and other structures
At hilium, parietal pleura turns over to create visceral pleura continuous with lung surface
Why is intrapleural pressure less than atmospheric pressure?
The lungs and chest wall pull away from each other (elastic recoil)
