Anatomy and Cell Biology 3309 Lecture Notes - Lecture 11: Pseudostratified Columnar Epithelium, Respiratory Epithelium, Goblet Cell
15 May 2018
School
Department
Professor
Lecture 11 – Respiratory Passages
Conducting system
- Where gas exchange does NOT occur
- Extends from nasal cavities or mouth to terminal bronchioles
o Down pharynx or larynx in the back of throat to trachea and bronchi
o One trachea splits into a bronchus in each lung (left and right primary bronchus)
o Bronchi further divide into bronchioles
- Important for the pre-processing of air before oxygen exchange occurs
- When air enters respiratory system, it comes from cold environments → warms and
humidifies air so we do not damage the delicate alveoli
- Air contains pollutants (chemicals + particles) → don’t want these getting trapped in alveoli
- Larynx is part of the conducting system
o Respiration is necessary for speech production
- Functions:
o Filtration
o Humidification
o Warming
o Speech
o Olfaction (smell)
Respiratory epithelium
- Most of the conduction system is lined by pseudostratified columnar epithelium with goblet
cells
- Lines conducting system from
o Nose, back of larynx and trachea until the bronchi and bronchioles
o Changes occur in the epithelium as we move towards respiratory and gas exchange
surfaces
find more resources at oneclass.com
find more resources at oneclass.com
- Pseudostratified with goblet cells: not all cells reach the apical surface/lumen
o Do not have nice rows of cells
- This is somewhere along the respiratory tract
- Goblet cell: secretes mucous that is then released to the surface of the epithelium
o Dust and particles that enter from the air get dissolved in the mucous
o Works in conjugation with ciliated cells
- Ciliated cells: have cilia on the apical surface
o Cilia are motile and beat in rhythmic motion together
o Function: mucociliary escalator
▪ Cilia beat upwards and beat the mucous up the respiratory tract so it can be
swallowed down the esophagus
o Functions to clear dust and particles that are trapped in mucous out of the
respiratory system
- Basal cell: cuboidal in appearance and lie at base of epithelium on the upper surface of
basement membrane
o Differentiate and mature into other cells of the respiratory epithelium
o Important for turnover and maintenance of epithelium over time
- Brush cell:
o Hard to find histologically
find more resources at oneclass.com
find more resources at oneclass.com
o Considered a sensory cell
o Make contact with nerve afferents below
o Nerve terminals lie under epithelium and the cells provide some sensory
information from the respiratory epithelium
- Enteroendocrine cell:
o Respond to nervous input and secrete hormones across basal aspect
o Hormones help with management and turn over of epithelium, healing, paracrine
signalling between neighbouring cells
- Goblet cells contain granules of mucous
o Granules are secreted up to the epithelial surface
- Nucleus of the goblet cell is seen at the basal aspect
- Rough ER (squiggly lines): for protein production
- Cilia have dot like appearance when they come in and out of the plane of the section
Nasal passages
- Respiratory epithelium covers most of the conducting system
find more resources at oneclass.com
find more resources at oneclass.com
