1/23
Looks like no tags are added yet.
Name | Mastery | Learn | Test | Matching | Spaced |
---|
No study sessions yet.
Structure of the nose/nasal cavity.
Structure
External nose:
made of hyaline cartilage and maxillary bone
covered externally by skin with sebaceous glands and nasal hairs
Nasal Vestibule:
lined with stratified squamous epithelium and big hairs for large particles
Main Nasal Cavity
lined with respiratory epithelium with goblet cells that secrete mucus
contains conchae (superior, middle and lower) that project into the cavity like shelves → increase SA and create turbulence in airflow (trappening of particles and moistening of inspired air and heat exchange)
has a rich vascular supply
Submucosa contains seromucous glands that moisten air and trap particles
Olfactory Region
found in the roof of the nasal cavity near the cribiform plate
contains olfactory epithelium with sensory neurons that detect smells
secretes mucus that dissolves odor molecules
Function of the nose/nasal cavity
Air Conduction:
Primary entry point for inhaled air.
Channels air to the pharynx and down to the lungs.
Air Conditioning:
Warming: Through heat exchange with blood vessels.
Humidifying: Via moisture from mucus and serous secretions.
Filtering: Hairs and mucus trap dust, pathogens, and debris.
Olfaction (Smell):
Specialized neurons in the roof of the nasal cavity detect odorants.
Resonance for Phonation:
The nasal cavity contributes to the resonance of the voice (tone quality).
Defense:
Mucus traps microbes; cilia sweep mucus to the pharynx to be swallowed or expelled.
Location of Nose and Nasal Cavity
The external nose is located centrally on the face, projecting from the face between the eyes and above the upper lip.
The nasal cavity is internal, lying posterior to the external nose and extending back to the pharynx.
It is separated:
Superiorly by the cribriform plate of the ethmoid bone (just below the brain).
Inferiorly by the hard and soft palate, which separates it from the oral cavity.
Medially by the nasal septum, formed by the vomer and perpendicular plate of the ethmoid bone.
Laterally by bones that form ridges called conchae (turbinates).
Paranasal Sinuses
boney chambers surrounding nasal cavity and lined by respiratory epithelium
air filled cavities in skull bones (frontal, maxillary, sphenoid, ethmoid)
lighten skin, add resonance to phonation and facilitate air conditioning
contains canals that drain mucus in the nasal cavity
Pharynx
connects nasal and oral cavities to the larynx and esophagus
functions in air conditioning, sound resonance, and food diversion during swallowing
has 3 regions: nasopharynx, laryngopharynx, and oropharynx
List the protective mechanisms of the respiratory system.
Protective Mechanisms
mucous and cilia
goblet cells that secrete mucous with defensins
nasal hairs
lysosome and enzymes in mucous
sneezing and coughing reflexes
immune surveillance
Conducting Zone
Conducting
laryngopharynx → terminal bronchioles
contains structures involved in phonation
includes larynx (primary organ of phonation), trachea, bronchi and bronchioles
superior limit is epiglottis
external structures made of hyaline cartilage linked by ligaments
mucosa lined by epithelia in regions of high turbulence and respiratory epithelia in other regions
submucosa contains seromucous glands
Respiratory Zone
Respiratory Bronchioles to aveoli
functions in gas exchange
Larynx
primary organ of phonation
superior → epiglottis
made of elastic cartilage + epithelia with taste buds
elevation of larynx allows epiglottis to cover larynx during swallowing
external structures made of hyaline cartilage linked by ligaments
internal structures include vocalis muscles and vocal folds
superior: vestibular fold (false vocal cord)
Inferior: vocal fold (true vocal cord)
forms slit like opening → glottis
width/stiffness determines pitch (narrow - high)
regulated by vocalis muscle
Trachea
connects the larynx to the bronchi as it goes downward
in front of esophagus
mucous lined with resp epithelia
submucosa contains C-shaped cartilage
shorten to decrease diameter during coughing
seromucous glands between C’s
inferior: carina
mucosa rich in sensory nerves → coughing
Bronchi/bronchioles
from trachea to resp bronchioles
one for each lung
primary → secondary → tertiary → bronchioles
3 for right and 2 for left
branching = small diameter
mucosal changes from trachea and bronchi → bronchioles
fewer mucous glands from bronchi to bronchiole
pseudostratified → columnar → cuboidal
decrease in goblet cells and cilia
submucosa → plates of cartilage instead of C shaped in bronchi
Bronchioles don’t have cartilage
major site for air flow/resistance
Respiratory Membrane + its function
Aveolar membrane (made of type 1 alveolar cells + basement cells)
inner lining of the air sacs in the lungs
consists of Type 1: thin, flattened cells that allow for easy diffusion + the majority of the alveolar surface
basement membrane: thin layer of connective tissue that provides support + structure for alveolar cells
thin interstitial space
small gap between aveolar membrane + capillary endothelium that contains fluid + CT fibers
capillary endothelium
lines capillaries that surrounds the alveoli + composed of a thin layer of cells + its own basement membrane
Function
designed for efficient gas exchange of oxygen in blood and CO2 out of blood
vast surface area
Surfactant → reduces surface tension in alveoli → preventing them from collasping
Respiratory Passageway Order
Nose → nasal cavity → pharynx → larynx → trachea → bronchi (primary, secondary, tertiary) → bronchioles → terminal bronchioles → respiratory bronchioles → alveolar ducts → alveolar sacs → alveoli
Lungs and Pleurae
Lungs
paired asymmetric organ within thoracic cavity
apex of lungs inferior clavicle and base rests upon diaphragm
bronchi,vessels and nerves penetrate lung at hilum forming lung root proximal to heart
right lung larger and with three lobes separated by fissures
left lung has two lobes with a fissure and cardiac notch
divided into connective tissue with bronchopulmonary segments
divided into lobules → main bronchiole → pulmonary artery/arteriole → branches → alveoli
thin connective tissue that forms capsule of organ and subdivides lobes, segments and lobules
Pleura
parietal → thoracic walls → simple squamous
visceral → lungs surface → simple squamous
thin layer of serous fluid between parietal and visceral
maintain capillary tension to adhere lungs to thoracic walls
allows frictionless movement of lung within thoracic cavity
inflammation of pleural → pleurisy
too much serous fluid via leaky capillaries → pleural effusion
Partial vacuum + importance
acts like a suction, preventing lung collapse and ensuring lungs expand during inhalation
negative pressure relative to aveolar pressure
during inhalation → the chest wall expands → increasing volume of thoracic cavity
creates a greater negative pressure + sucks lungs open → increases their volume and draws air in for gas exchange
Involves balance of forces → elastic recol of stroma and surface tension in aveoli + surface tension at pleura
Boyle’s Law and inspiration/expiration
PV = P2V2
pressure inversely changes to volume
during inspiration → thoracic cavity volume increases → pressure drops → air flows in
During expiration → volume decreases → pressure increases → air flows out
Inspiration
Inspiration
increase in lung volume mediated by changes in thoracic cavity volume
shortening of diaphragm → flattens out and moves inferiorly
shortening of external intercostal muscle → lifts rib cage + sternum to increase the diameter of thoracic cavity → thoracic volume increase
decrease Ppul to -1 mm Hg
involves other muscles that can raise the ribs to expand the thoracic cavity
Expiration
mostly passive relaxation of the inspiratory muscles and elastic recoil of lungs
inspiratory muscle relax → diaphragm rises, rib cage descend due to recoil of costal cartilage
thoracic cavity volume decreases
elastic lungs recoil passively → intrapulmon volume decreases
pressure rises
air flows out of the lungs and down the pressure gradient until intrapulmon pressure is 0
Lung Volumes
Tidal volume → normal relaxed breathing (500 mL)
Inspiratory Reserve → forced inhalation to maximum above TV (3100 ml)
Expiratory Reserve → forced exhalation to minimum below TV (1200 ml)
Residual Volume → volume remaining after forced exhalation → dead space of aveoli and conducting portion (1200 ml)
Capacity
total lung capacity: TLC = TV + IVR +EVR + RV (6000 ml)
Vital lung capacity: VC = TV + IVR + EVR = TLC - RV (4800 ml)
Inspiratory capacity: IC = TV + IVR (3600 ml)
Functional Residual capacity: FVR = EVR + RC (2400 ml)
Pulmonary Function Tests
type/effect of respiratory disease
classification of resp disease
easily measured with windmill type spirometer
FVC = vital capacity measured with volume spirometer
FEV = volume forcibly expired over a set time interval
diagnose obstructive and restrictive disease
Physical Factors Affecting Ventilation
friction, aveolar surface tension and lung compliance
Flow rate = pressure diff (boyle’ law) + friction (resistance via conducting zone)
Resistance varies (low in trachea, max in med-sized bronchi and min at terminal bronchi)
bronchi + bronchioles can modified by smooth muscle + inflammation
local effectors and autonomic system can modulate
para → bronchoconstriction, sym → bronchodilation
Surface tension of aveoli
wetted surface that sticks together via capillary action
Lung Compliance
stretchiness
change in volume by a change in pressure
determined by elastin and surface tension of alveoli
stretchibility of lungs and thoracic cage