Histology Flashcards
f: the respiratory system
Supplies oxygen to the blood for delivery to cells throughout the body.
Removes carbon dioxide that has been accumulated in the blood from the tissues of the body.
Phonation.
Olfaction (smelling)
Lungs function in blood pressure control via renin-angiotensin system
describe the path of inhaled air
. Air enters the nose or mouth travels via the pharynx and larynx into the trachea which branches into the principal bronchi to convey the air to the lungs. In the lung each bronchus divides into smaller bronchi which divide into smaller bronchioles. These bronchioles terminate in the alveolar sacs where gaseous exchange occurs
f: nasal cavity
Warming
2. Moistening
3. Filtering
the inspired air.
In addition in the roof it contains an area of specialised olfactory epithelium.
what is the initial part of the nasal cavity called and lined by?
vestibule
keratinised stratified squamous epithelium
name the components of the respiratory epithelium
Pseudostratified columnar epithelium ciliated with goblet cells
what is under the respiratory epithelium (RE) ?
lamina Propria
what is the lamina propria composed of?
loose connective tissue
seromucous glands
thin-walled venous tissues
How do sinuses block the nose?
thin-walled venous sinuses (V) which can quickly engorge with blood and ‘block’ the nose.
why is the oropharynx lined by non-keratinized stratifies squamous epithelium?
the oropharynx transmits both air and swallowed food, it must resist abrasion
what are the walls of the larynx made up of and what is the exception?
made up of cartilage and muscles with respiratory epithelium lining its surfaces with the exception of the vocal folds
what are the vocal folds covered with?
stratified squamous epithelium
how many cartilages does the trachea have on avg?
15-20
what muscle is the open side of the cartilage spanned by?
fibroelastic tissue and smooth muscle (trachealis muscle).
what shape is the cartilage?
c shaped
name the layers and the components of the trachea wall
The wall of the trachea includes a lining of respiratory epithelium backed by a basal lamina, a lamina propria of connective tissue with abundant elastic fibres and a submucosa of connective tissue that includes numerous seromucous glands
at what size of the bronchus is the cartilage lost? what is this airway called?
when the airway is 1mm in diameter
bronchioles
what does the epithelium change to as you move from the bronchus to the bronchioles?
from columnar to cuboidal
d:terminal bronchioles
The smallest bronchioles that lack respiratory (gas exchange) function
what type of stimulation does the SM in the bronchioles respond to?
respond to parasympathetic innervation, histamine and other factors by contracting and constricting the diameter of the bronchiole
what lines the terminal bronchioles?
cuboidal ciliated epithelium and contain non-ciliated club cells
f: club cells
Stem cells
Detoxification
Immune modulation
Surfactant production
what is the low cuboidal epithelium replaced by when it moves to alveoli?
replaced by discontinuous squamous type I alveolar cells.
where does gas exchange occur?
in the alveoli
respiratory bronchioles
what do alveoli look like?
resemble thin-walled pockets similar to a honeycomb
d: pneumocytes
alveolar cells
what does alveolar epithelium consist of?
Type I alveolar cells and Type II alveolar cells
how much of the alveolar surface is covered by type 1 alveoli?
90%
what is the composition of alveoli type 1 cells?
simple squamous epithelium
what does the type 1 alveolar cells allow?
provide a barrier of minimal thickness that is permeable to gases
gas exchange
what shape are type 2 alveolar cells?
polygonal in shape
describe the structure of the type 2 alveolar cells
the free surface is covered by microvilli and the cytoplasm displays dense membrane bound lamellar bodies which contain surfactant
how is the surfactant released?
exocytosis
f: surfactant
is released by exocytosis and spreads over the pulmonary surface to reduce the surface tension at the air-fluid interface
what does the surfactant reduced the chance of happening?
alveolar collapse at the end of expiration
apart from type 1 + 2 alveolar cells, what other cell is present in the alveoli?
alveolar macrophages - dust cells
what happens to the dust cells and how do they arise?
free cells either in the septa or migrating over the luminal surfaces of the alveoli, phagocytosing inhaled particles that may have escaped entrapment by the mucous lining of the airway. They typically will migrate up the bronchial tree, transported by ciliary action, to the pharynx where they are swallowed or will move into the septal connective tissue where they will remain
what is the thin tissue at the septa of the alveoli referred to as?
air-blood barrier
what does the air-blood barrier consist of?
consists of the Type I cell, the endothelial cell and the basal lamina of each
what does the visceral pleura consist of?
an outer layer of simple squamous epithelium called mesothelium backed by layers of fibrous and elastic connective tissue
