Respiratory System Flashcards
What is the surface of the external nose covered by?
keratinized stratified squamjous epithelium
What is present in varying amounts in the keratinized stratified squamous epithelium of a dog’s nose?
pigment
What is the shape of a nose determined by?
internal hyaline cartilage
What 2 parts can the respiratory system be subdivided into?
conductive part and respiratory part
What does the ‘conductive’ part of the respiratory system include?
all tubular organs in the tespiratory system:
- nose
- oropharynx
- larynx
- trachea
- primary bronchi
What is the function of the ‘conductive’ part of the respiratory system?
air way passage
- air is simply being let through to reach its final destination
What does the ‘respiratory’ part of the respiratory system include?
- respiratory bronchioles
- alveoli of the lungs
What is the function of the ‘respiratory’ part of the respiratory system?
most important function: GAS EXCHANGE!
carbon dioxide and oxygen exchange
State the composition of the external nose. Core? Covering? Distinctive feature?
core: hyaline cartilage
covering: keratinized stratified squamous epithelium
distinctive feature: thicker than skin –> grooves form
What is a nasal cavity?
a paired chamber seperated by a bony and cartilaginous septum
What is a nasal vestibule?
A dilated space of the nasal cavity just inside the nostrils.
lined by skin
What is the nasal vestibule lined by?
skin
What region is the largest part of the nasal cavities? What is it lined by?
Respiratory region!!
- inferior 2/3
- lined by respiratory mucosa
What region is the smaller part of the nasal cavities? What is it lined by?
Olfactory region!
- upper 1/3
- lined by specialized olfactory mucosa
What 3 parts is the nasal cavity divided into?
- nasal vestibule
- respiratory region
- olfactory region
What is the olfactory region known for?
- sensory function
- specific cells helping smell sensing
State the general function of the nasal vestibule.
- forms a part of the external nose
- communicated anteriorly with the external environment
State the composition (histological level) of the nasal vestibule.
- lined with stratified squamous epithelium (a continuation of the skin of the face)
- contains a variable number of vibrissae (entrap large particulate matter before it is carried in the air stream to the rest of the cavity)
- contains sebaceous glands (secretions assist the entrappment of particulate matter)
State the histological composition of the respiratory region of the nasal cavity.
- lined by respiratory mucosa containing a ciliated, pseudostratified columnar epithelium on its surface
pseudostratified columnar epithelium of the respiratory mucosa is composed of 5 cells:
- ciliated cells (tall columnar cells with cilia that project into the mucous covering the surface of the epithelium)
- goblet cells (synthesize and secrete mucous)
- brush cells (cells bearing short, blunt microvilli)
- basal cells (stem cells)
What 4 types of cells does the pseudostratified columnar epithelium of the respiratory mucosa consist of?
- ciliated cells (tall columnar cells with cilia that project into the mucous covering the surface of the epithelium)
- goblet cells (synthesize and secrete mucous)
- brush cells (cells bearing short, blunt microvilli)
- basal cells (stem cells)
What are ciliated cells?
tall columnar cells with cilia which projects into the mucous covering the surface of the epithelium
What are goblet cells?
cells synthesizing and secreting mucous
What are brush cells?
cells bearing short, blunt, microvilli
- carry the trapped mucous particle towards the outside of the organism
What are basal cells?
stem cells from which the other types of cells arise
- integrated with the basal lamina
What type of epithelium is the respiratory mucosa covered by?
ciliated pseudostratified columnar epithelium!
- simple not stratified! (all cells reach the basememnt membrane)
Why is mucous needed in the respiratory tract?
protect epithelial cells from infection by trapping small particles (pathogens, bacteria etc.)
What glands are present in the respiratory region of the nasal cavity? What secretions do they have? What is their function?
submucosal glands
- based on mucous or serous secretions
- humidifies air in the respiratory system
What network is present in the respiratory region? Where is it present? What is its function?
- rich network of blood vessels
- present in the underlying connective tissue
- necessary to warm the air entering the respiratory tract (equalizes body temperature with air temperature)
What is the olfactory region of the nasal cavity lined by?
specialized olfactory mucosa
What is the olfactory mucosa distinguished by?
- slight yellowish brown colour caused by the pigment in the olfactory epithelium and the associated olfactory glands
How does the total surface of olfactory mucosa compare between species?
Humans- 10 cm2
Dogs- 150 cm2
depending on the extent of the sense of smell: more extensive olfactory mucosa = acute sense of smell
What cells is the olfactory epithelium composed of?
- olfactory receptor cells (bipolar olfactory neurons that span the thickness of the epithelium and enters the central nervous system)
- supporting/sustentacular cells (columnar cells, similar to neuroglia cells, providing mechanical and metabolic support to the olfactory receptor cells) (synthesise and decrete odor-binding proteins)
- basal cells (stem cells)
- brush cells (cells bearing short, blunt microvilli)
What are olfactory receptor cells?
- bipolar olfactory neurons
- span the thickness of the epithelium
- enter the central nervous system
What are supporting cells? What is their other name? How do they look? What is their function? What do they secrete?
supporting cells = sustentacular cells
- columnar cells
- similar to neuroglia cells
- provide mechanical and metabolic support to the olfactory receptor cells
- synthesise and secrete odorant-binding proteins
What 4 types of cells are present in the olfactory epithelium?
- olfactory receptor cells
- supporting/sustentacular cells
- basal cells
- brush cells
What type of cells exist both in respiratory and olfactory epithelium?
- basal cells
- brush cells
What is the pharynx?
- connects the nasal cavity and oral cavity to the larynx and esophagus,
- passageway for air and food
- resonating chamber for speech
What lines the pharynx? What is present beneath?
- respiratory epithelium
- beneath: diffuse and aggregated lymphatic tissue
What are the different parts of the pharynx? What are they lined by?
- oropharynx= respiratory epithelium (same as nose)
- part associated with the digestive system
What is the larynx?
- connects the pharynx to the trachea
- contains vocal chords
What lines the larynx?
respiratory epithelium
State the histological composition of the larynx.
- respiratory epithelium (before reaching the trachea)
- lymphatic tissue (between epithelium and cartilage)
- elastic cartilage (forming the epiglottis and corniculate process of the arytenoid cartilage)
What are vocal folds? What do they produce? How?
- control the air flow through the larynx
- vibrate to produce sound
State the histological composition of vocal chords.
luminal surface is covered with stratified squamous epithelium
- more resistant to mechanical stress
- thicker
- protects vocal apparatus from being damaged
What is the epiglottis covered by?
stratified squamous epithelium
What is the function of the stratified squamous epithelium which covers the epiglottis and vocal chords?
Protects mucosa from abrasions caused by the rapidly moving air stream.
What is present beneath the epithelium in the entire respiratory system?
lymphoid nodules containing many lymphocytes:
- start immune response when infected
- protection
What is the wall of the trachea composed of?
1) Mucosa:
- ciliated pseudostratified epithelium,
- elastic, fiber-rich lamina propria
2) Submucosa:
- dense connective tissue (denser than lamina propria)
- elastic fibers
- seromucous glands (humidifying air)
- rich network of blood vessels (warms air)
3) Cartilaginous layer:
- C-shaped hyaline cartilages
4) Adventitia:
- connective tissue
- binds trachea to adjacent structures
What is the mucosa of the trachea composed of?
- ciliated, pseudostratified epithelium
- elastic, fiber-rich lamina propria
What is the submucosa of the trachea composed of?
- dense connective tisse (Denser than the lamina propria within the mucosa)
- elastic fibers
- mixed serous-mucous glands (humidifying the inhaled air)
- rich network of blood vessels (warms air)
What is the cartilaginous layer of the trachea composed of? What are their functions? What closes the rings off?
- C-shaped hyaline cartilages
- ensures that the trachea remains open while allowing for elasticity of the passage way
- C-shape is closed by muscle cells
What is the adventitia of the trachea composed of? What is its function?
loose connective tissue which binds the trachea to adjacent structures
What is the specific role of the elastic fibers in the lamina propria of the tracheal mucosa?
inspiration and expiration function (gives teh structure elastic properties)
What is the most distinctive feature of the trachea?
hyaline cartilage
- most species occurs as C or U shaped
- dorsal free ends of the cartilages are bridged by the trachealis muscle (A band of smooth muscle)
- some species it is fused to form a continuum
one layer has 2 structures/tissues (cartilage and msucle)
State the composition of the trachealis muscle.
band of smooth muscle
On entering the hilium of the lung, what does each main bronchus divide into?
lobar bronchi (secondary bronchi)
What are lobar bronchi divided into?
lobar bronchi (secondary bronchi) –> bronchi segments (tertiary bronchi)
What are bronchopulmonary segments subdivided into? What are those supplied by?
subdivided into pulmonary lobules
- each lobule is supplied by a bronchiole
What partially seperates adjacent lobules? How may it be represented?
- delicate connective tissue septa
- represented on the lung sirface as a faintly outlined polygonal area
What makes up the lobules?
pulmonary acini (smaller units of structure)
What is the last component of the conductive portion of the lung?
terminal bronchiole
What is the smallest functional unit of the pulmonary bronchiole? What does it consist of?
- respiratory bronchiolar unit
- consists of a single respiratory bronchiole and the alveoli
What portions are present in the entire bronchi system?
respiratory and conductive portions
What does the functional part of the lung include? What is it called?
respiratory bronchiolar units
- consist of respiratory bronchioles and alveoli
What lines the bronchioles?
larger diameter bronchioles:
- ciliated, pseudostratified columnar epithelium
smaller diameter bronchioles:
- ciliated, simple columnar epithelium
- simple cuboidal epithelium
State the overview of the structures present in the conducting respiratory system.
- epithelium
- goblet cells
- ciliated cells
- glands
- hyaline cartilage
- smooth muscle
- elastic fibers
State the overview of the structures present in the respiratory respiratory system.
- epithelium
- ciliated cells
- smooth muscle
- elastic fibers
What does not dramatically change between the conducting and respiratory parts of the respiratory system? Why?
elastic fibers
- lung changes all the time, it must have elastic properties to facilitate the movement of air and pressure changes
How can bronchi be identified?
- cartilage plates
- circular layer of smooth muscle
Why can the wall of the bronchus be regarded as having 5 layers?
the smooth muscle forms a seperate layer called a muscularis
What are the 5 layers of the wall of the bronchus?
1) Mucosa:
- pseudostratified epithelium (same cellular composition as the trachea) (height of cells decreases as the bronchi decrease in diameter)
2) Muscularis:
- smooth muscle layer (large bronchi = continuous ; small bronchi = discontinuous (due to spiral course and loose arrangement)
3) Submucosa:
- loose connective tissue
- glands
- adipose tissue (larger bronchi)
4) Cartilage layer:
- discontinuous cartilage plates (become smaller as the bronchial diameter decreases)
5) Adventitia:
- dense connective tissue (continuous with adjacent structures: pulmonary artery, lung parenchyma)
What is the muscularis layer composed of in the bronchioles? Why, in teh bronchioles, to we mention it as being a whole new layer (and not part of mucosa)?
Muscularis:
- smooth muscle layer (large bronchi = continuous ; small bronchi = discontinuous (due to spiral course and loose arrangement)
- much thicker than usual, therefore referred to as a full layer
What is the function of the muscular layer of the bronchiles?
Contracts for the expiration phase to help the expulsion of air from the lungs.
How does the cartilage layer of the bronchioles compare to that of the trachea?
trachea: C or U shaped (from 1 full ring to an increasing amount of small fragments)
bronchiole: cartilage plates (not full ring, only fragments present)
What are bronchioles?
- smaller types of bronchi
- air conducting ducts that measure <1mm
What do brinchioles give rise to?
smaller terminal bronchioles
What do smaller terminal bronchioles give rise to?
respiratory bronchioles
What is not present in bronchioles?
cartilage plates!!!
glands!!!
What are the characteristic features of clara cells?
- non-ciliated cells
- characteristic rounded or dome shaped apical surface projection
What is the function of clara cells?
- secrete a surface-active agent = lipoprotein
- lipoprotein= surface active agent= prevents the luminal adhesion during expiration (in case the lung collapses, for the opposite walls not to stick to each other)
What structure is present in bronchioles? What is their function?
smooth muscles!
- regulates size of bronchiole lumen
What is asthma heavily related to?
- bronchioles
- smooth muscle cells regulating bronchiole lumen
When does an asthma attack occur?
when bronchiles collapse (fully close furing expiration)
What cells are present in bronchioles? What do they replace?
Clara cells
- replace seromucous glands
What is the alveolar epithelium composed of which playes a defensive and protective role?
several specialized cells:
- type I alveolar cells
- type II alveolar cells
State the characteristic features of type I alveolar cells.
- also known as type I pneumocytes
- extremely thin squamous cells
- comprise 40% of the entire alveolar lining
- line 95% of the surface of the alveoli
What cells line most of the surface of the alveoli?
type I pneumocytes
State the characteristic features of type II alveolar cells.
- also known as type II pneumocytes or septal cells
- secretory cells
- cuboidal cells
- account for 60% of alveolar lining cells
- cover about 5% of the alveolar air surface
- rich in phospholipids, neural lipids, and proteins which are secreted by exocytosis to form an alveolar lining, surface-active agent called surfacant.
What is the location of type II alveolar cells?
- interspersed among type I cells
- tend to congregate at septal junctions
What is the function of type II alveolar cells?
- secrete an alveolar lining,* surface-active agent* called surfacant
- rich in phospholipids, neural lipids, and proteins
- secrete by EXOCYTOSIS
What is teh function of surfacant?
- decreases alveolar surface tension
- actively paricipates in the clearance of foreign materials
Fact: At what time does surfacant play a crucial role of opening alveoli?
upon birth!!
What is the function of alveolar macrophages? Where are they present? What is their other name?
location:
- connective tissue of the septum
- air spaces of the alveolus
function:
- scavenge the surface of air spaces to remove inhaled particulate matter (dust/pollen)
- act as part of the immune system (antigen rpesenting cells
- activate an immune response
name:
dust cells
What inhaled substances can be phagocytized by microphages?
inorganic substances (eg. silicone)
Under a microscope, why do some alveolar macrophages appear as having a darker colour?
- filled with inorganic matter (ie. silicone)
- clearing lungs of inhaled particulate matter
- the more dark spots there are, the less functional the lungs are
What does the ‘air-blood barrier’ refer to?
The cells and cell products across which gases must diffuse between the alveolar and capillary compartments.
What is the thinnest air-blood barrier? What does it consist of?
- thin layer of surfacant
- type I epithelial cell
- basal lamina (type I epithelial cell)
- capillary endothelial cell
- basal lamina (of capillary endothelial cell)
(usually the basal lamina’s (basement membranes) are fused –> makes the structure thinner –> produces a narrow gap through which gas exchange occurs)
–> 4 LAYERS
Where does gas exchange occur?
in the narrow gap between the fused basal laminas (basement membranes)
of the capillary endothelial cell and the type I epithelial cell
