Respiratory Tract Flashcards
What is internal/cellular respiration?
The use of oxygen in the metabolism of organic molecules
What is external respiration?
The exchange of oxygen and carbon dioxide between an organism and the external environment
What are 6 general functions of the respiratory system?
- Provide oxygen
- Eliminate CO2
- Form speech (phonation)
- Defend against microbes (host defense)
- Trap and dissolve blood clots arising from the systemic veins
- Modulate concentration of biologically active molecules
What is the principle muscle in the resp. system?
The diaphragm
What kind of epithelium makes up the respiratory epithelium? What does it rest on?
pseudostratified cilliated columnar epithelium resting on a thick basement membrane
What are the most abundant cells in the respiratory epithelium?
Cilliated columnar cells
What are most of the cells at the basement membrane making up 30% of the epithelium?
stem cells
what 3 other cell types (besides stem and CCC) are present in the resp. epithelium?
- mucous secreting goblet cells
- Intraepithelial lymphocytes
- Dendritic cells
What section makes up the upper airways? What is the function?
Nose to vocal cords
Humidify and warm inspired air
What happens to air as it passes through the nose? what structures exist in there to increase surface area?
Filtration and trapping of large particles
Nasal turbinates are 3 ridge like structures that project into the nasal passages
Where are neural endings associated with smell located in the nose? where do they go?
roof of the nose above the superior turbinate carry impulses through the cribriform plate to the
olfactory bulb.
what is the resistance to airflow like in the nose?
relatively high
What 3 cell types make up the olfactory epithelium?
- Basal cells
- Supporting cells
- Olfactory neurons
What kind of epithelium is olfactory epithelium?
pseudostratified
Paranasal sinuses are…?
4 air filled spaces surrounding the nasal cavity
What are the 4 paranasal sinuses? where are they?
- Frontal sinuses - above eyes
- Maxillary sinuses - below the eyes
- Ethmoidal sinuses - between the eyes
- Sphenoidal sinuses - behind the eyes
What are 2 functions of sinuses?
- lighten the skull
2. provide resonance to the voice
What type of cells line the sinuses?
cilliated epithelium
What is sinusitis?
Retention of secretions - in the maxillary sinus especially - that results in infection
What are the 3 major structures of the larynx?
- Epiglottis
- Arytenoids
- Vocal cords
What are the arytenoids?
pair of small 3 sided cartilage structures to which the vocal chords are attached
What do the epiglottis and arytenoids do during swallowing?
Cover the vocal chords and prevent the passage of food/drink into the lower resp. tract
the larynx is a short air passage between which two structures of the upper airway?
pharynx and the trachea
What makes the walls of the larynx rigid?
irregularily shaped cartilages
- hyaline and elastic
What holds the larynx together? what moves it?
held together by ligaments and moved by skeletal muscles
What guards the upper opening of the larynx?
the epiglottis
What effect do intrinsic vs extrinsic muscles have on the larynx?
Extrinsic muscles change larynx position in swallowing
Intrinsic muscles alter relative position (& tension) of vocal cords in production of sound (phonation)
How many lobes does each lung have? what separates them
right: 3
- oblique and horizontal fissures
left : 2
- just oblique fissure
Each lobe of the lung is further divided into..
segments
What covers both lungs?
thin membrane visceral pleura
What is the division of the lower airways starting at the trachea
- Trachea splits into two mainstem bronchi
- Mainstem bronchi divide into lobar bronchi
- Lobar bronchi divide into segmental bronchi
- Segmental bronchi to bronchioles
- Bronchioles terminate in alveoli
What are the 4 functions of the conducting zone airways? how do you differentiate between the conducting and the respiratory zone.
- pathway for airflow
- defend against microbes, toxic chemicals, other foreign materials
- mucocillary clearance - Warm and moisten air
- Phonation
know you have passed between the zones because of the outcroppings of alveoli
the trachea is lined with…
typical respiratory epithelium
What lies underneath the respiratory epithelium of the trachea? underneath that?
connective tissue of the lamina propria
seromucous glands in the lamina propria and submucosa
What else is found in the submucosa of the trachea besides seromucous glands?
hyaline cartilage rings
What do the seromucous glands and goblet cells produce? what does this accomplish?
layer of mucous that permits the propulsion of foreign material out of the respiratory system by cilliary movement
Do bronchi have smooth muscle? cartilage ?
yes to both
What two features are lost as the bronchi transition into bronchioles?
loss of supporting cartilage and glands
Large bronchioles have what kind of morphology?
folded respiratory epithelium, prominent smooth muscle, supported by fibrous connective tissue
Smaller bronchioles have what kind of morphology?
highly elastic smooth muscle
epithelium is simple columnar but still ciliated
What is the morphology of the smallest bronchioles?
simple cuboidal cells with cilia make up epithelia
Wall is made up mainly of several layers of smooth muscle
What are the terminal bronchioles?
the last section of the conducting airway
How many layers of smooth muscle does a terminal bronchiole have? what surrounds this? What kind of epithelium do they have?
only 1 or 2 layers of SM surrounded by connective tissue
epithelium is ciliated cuboidal cells and non-ciliated columnar
What differentiates the respiratory bronchioles and the terminal bronchioles?
the presence/absence of alveoli
What special cells are found in the terminal bronchioles
Clara cells
What kind of cells are clara cells?
non-ciliated and have bulging domes of apical cytoplasm
What are 3 functions of Clara cells?
- Secrete components of surfactant
- Detoxification through P450 system
- Produce secretory portion of IgA, lysozyme, cytokines to regulate inflammation
What else can be found among clara cells?
stem cells that give rise to call the cells within the bronchiolar epithelium
What is the result of the huge cross sectional area of the airways past the terminal bronchioles?
the flow velocity of air decreases and diffusion takes over as the dominant mechanism of air movement
What makes up the largest volume of the lung?
the distance between the terminal bronchioles and the alveoli
What is the branching order from terminal bronchioles to alveoli ?
Terminal bronchioles branch into respiratory bronchioles, which then branch further into alveolar ducts and individual alveoli.
units of gas exchange in the resp. system are the…
alveoli
which law governs gas exchange?
Fick’s law
What is Fick’s law?
VX=ADP/T
VX = volume of gas transferred per unit time; A = surface area; D = diffusion coefficient of that gas; P = partial pressure difference of the gas; T = thickness of the membrane
What are 3 important parameters for efficient gas exchange in the lungs?
- large driving force / partial pressure gradient
- Large surface area
- Small distance
Why is CO2 elimination not affected by diffusion problems?
Because Diffusion coefficient, D proportional to Sol/√MW
D for CO2 is approx 20 times higher than for
O2
What is different about type II alveolar cells? What % do they make up?
only about 3-4%
synthesize and release surfactant
What is the role of surfactant? why do we need it?
To increase SA and therefore gas exchange, you want to have more, smaller alveoli.
Smaller alveoli have a greater tendency to collapse though
Surfactant lowers the collapsing pressure
What law governs the surface tension of alveoli?
Law of Laplace: P = 2T/r
P = collapsing pressure on alveolus or pressure required to keep alveolus open (dynes/cm2) T = surface tension (dynes/cm) r = radius of the alveolus (cm)
Explain the relationship between pressure to collapse alveolus, surface tension, and radius
pressure tending to collapse an alveolus is directly proportional to the surface tension generated by the molecules of liquid lining the alveolus and inversely proportional to the alveolar radius
What is respiratory distress syndrome?
Newborn Type II alveolar epithelial cells do not mature until week 24 of gestation.
Babies born prematurely Before this do not have sufficient surfactant
to overcome the surface tension forces at alveolar air-liquid interface.
What is surfactant made from?
mixture of phospholipids and proteins
- including DPPC
What does DPPC do in surfactant?
DPPC molecules align themselves on alveolar surface, with hydrophobic portions attracted to each other and hydrophilic portions repelled
- Stabilizes alveoli and prevents them collapsing
What stimulates secretion of surfactant?
deep breathing which stretches the type II cells
What are the two distinct blood supplies to the lungs?
- Pulmonary circulation
2. Bronchial circulation
What does pulmonary circulation do?
brings deoxygenated blood from the right ventricle to the alveoli for
gas exchange- CO2 elimination, O2 pick-up.
Where does bronchial circulation arise? What does it achieve?
arises from aorta and provides nourishment to the lung tissue. Bronchial arteries provide oxygenated, systemic blood to the lungs
What are the two pleural membranes? Which one lines which part?
- Visceral pleural membrane covers the lobes of the lungs
2. Parietal pleural membrane lines the chest wall and mediasternum
What do the pleurae secrete?
viscous pleural fluid which lubricates them as they rub against each other during breathing
What is pressure like in the fluid filled pleural space?
slightly less than atmospheric
What is the term for inflammation of the pleura? What is the cause often?
Pleurisy
- often viral
What is pleural effusion?
excess of fluid in the pleural cavity
- form of pleurisy
What is the difference between transudates and exudates?
Transudate: Effusion from the pleural space with little protein
Exudate: contains protein
What is the histology of the pleurae like?
both consist of simple squamous mesothelium on a thin layer of connective tissue
- rich in collagen and elastin
What two muscle groups are involved in normal breathing?
- External intercostals
2. Diaphragm
What 4 groups of muscles are accessory and can be recruited for breathing?
- Sternocleidomastoid
- Scalenus
- Internal intercostals
- Abdominal muscles
The diaphragm divides..
the thoracic and abdominal cavities
What initiates inspiration? What other muscle movements keep it going?
- contraction of the diaphragm
- flattens abd. cavity and moves abdomen outward - Increased vert. dimension of ribcage sets up pressure gradient
- External intercostals pull ribcage up and forward.
What nerves innervate the diaphagm? The external intercostals?
Diaphragm innervated by phrenic nerves.
EI innervated by intercostal nerves
What are the most important accessory muscles for forced expiration?
abdominal wall muscles and internal intercostals
Where along the respiratory tract can you find cilliated cells?
From the trachea to the respiratory bronchioles
How many cilia approx. does each cell have
200
What is the arrangement of microtubules in cilia?
9 + 2
What key role do ciliated cells play?
host defense via mucocilary clearance
What is the ratio of goblet cells to ciliated cells?
1:5
When does the # of goblet cells increase? what effect can this have?
during disease which can increase the chance of small airways becoming blocked with mucous
Where are goblet cells present?
wherever there is cartilage
- ie from the trachea to the tertiary bronchi, maybe in the large bronchioles
What is the volume of the conducting zone of the airways?
150 mL
What is the volume of the alveolar range of the airway?
2.5-3 L
What is the difference in gas movement between the conducting and alveolar regions?
bulk flow vs. diffusion
