Anatomy and Cell Biology 3309 Lecture Notes - Lecture 23: Pseudostratified Columnar Epithelium, Respiratory Epithelium, Cilium
22 May 2018
School
Department
Professor
Histology 3309
Respiratory Passages
Learning Objectives
1. Identify major functions of the respiratory systems and the components of the conducting
portion
2. List the cells comprising respiratory epithelium and their various functions
3. Describe the function of olfactory epithelium and how it differs from respiratory epithelium
4. Distinguish the unique histological features of the trachea, bronchi and bronchioles
Conducting System
- The conducting system is where gas exchange does not take place
- Extends from nasal cavities down the pharynx/larynx into the
trachea to the bronchi to the left and right bronchus to terminal
bronchioles
- Conducting system is important for the preprocessing of air before
oxygen exchange happens
- Functions;
o Filtration
▪ The air also contains pollutants and we don’t want
these trapped in our alveoli so the conducting
system will trap and remove some of those particles
o Humification and Warming
▪ Air is coming from cold environments so the
conducting system will warm and humidify the air so
that we don’t damage the delicate surfaces of our lungs (like alveoli
o Speech
▪ This happens in the larynx
o Olfaction
▪ Happens in the nasal cavity
Respiratory Epithelium
- Respiratory epithelium lines the conducting system
- Pseudostratified Columnar Epithelium with Goblet Cells
- Lines conducting system all the way from the trachea down into the
bronchi and then the bronchioles
Respiratory Epithelium
- Goblet cells
- Basal cells that don’t reach the lumen
(pseudostratified)
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find more resources at oneclass.com
Cell Types found in a Respiratory Epithelium
- Goblet cells:
o Mucous secreting cells
o Secrete mucous to the surface of the epithelium
o The dust and particles that enter through the air get trapped in the mucous and they will
dissolve into the mucous
- Ciliated cell:
o Have big cilia
o The cilia are motile (able to beat in a rhthymic motion together)
o This allows the respiratory tract to be a mucociliary escalator
o The cilia will beat the mucous up the respiratory tract so that it can be swallowed down
the esophagus
- Basal cell:
o Cuboidal in appearance
o Lay at the base of the epithelium
o Can differentiate and mature into the other cells of the respiratory epithelium
o So these are important for turnover and maintenance of the epithelium over time
- Brush cell:
o Cant identify under slide
o Sensory cell
o They contact with nerve afferents below (nerve terminals lying underneath the
epithelium) and they provide some sensory info from the respiratory epithelium
- Enteroendocrine cell:
o Cant identify under slide
o Respond to nervous input
o Secrete hormones across the basal side
o Help with management and turnover of the epithelium
o Also help with healing and paracrine signaling bw neighboring cells
o But the function of these is not well understood
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find more resources at oneclass.com
- In the EM image, you can see the granules of mucous in the goblet cells that will be secreted
- We can see the nucleus of the cell below at eh basal aspect
- Can also see some RER
- At the top you can also see some cilia
Nasal Passages
- Olfaction is an important function of the respiratory system
- Olfaction takes place at the roof of our nasal cavity
- Olfactory bulbs lie at the roof of your nose
- Inside the nose, we have 3 turbinates and in the upper roof is where olfaction takes place
- So the turbinate areas will all be covered by respiratory epithelium but there will be a unique
epithelium at the roof of the nasal cavity where olfaction is taking place
- That epithelium is called olfactory epithelium bc its specific function is olfaction
- the roof of our bone is formed by the ethmoid bone
- the nerves of the olfactory bulb penetrate through the ethmoid bone and reach the surface of the
olfactory epithelium (which would be the roof of the nasal cavity – this is where the odour is
going to make contact with the nerve cells)
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
The conducting system is where gas exchange does not take place. Extends from nasal cavities down the pharynx/larynx into the trachea to the bronchi to the left and right bronchus to terminal bronchioles. Conducting system is important for the preprocessing of air before oxygen exchange happens. Lines conducting system all the way from the trachea down into the bronchi and then the bronchioles. Basal cells that don"t reach the lumen (pseudostratified) Goblet cells: mucous secreting cells, secrete mucous to the surface of the epithelium, the dust and particles that enter through the air get trapped in the mucous and they will dissolve into the mucous. Basal cell: cuboidal in appearance, lay at the base of the epithelium, can differentiate and mature into the other cells of the respiratory epithelium, so these are important for turnover and maintenance of the epithelium over time.
