Cilia, Ciliary Movement, and Mucociliary Transport
Cilia are extensions of the apical membranes. The cilium itself is characterized by a 9 + 2 axonemal structure. An active, coordinated ciliary beating is essential for mucociliary transport. Ciliary beating depends on the ATPase activity in the dynein arm
- PDF / 1,207,374 Bytes
- 11 Pages / 504.57 x 720 pts Page_size
- 85 Downloads / 198 Views
Cilia, Ciliary Movement, and Mucociliary Transport Mark Jorissen and Martine Jaspers
Keywords
Cilia • Dynein • PCD • SCD • Mucociliary transport • Ciliary beating
Core Messages
• Cilia are extensions of the apical membranes and are characterized by a 9 + 2 axonemal structure. • Ciliary beating depends on the ATP-ase activity in the dynein arms and is characterized by a specific beating pattern. • Structural and functional ciliary abnormalities can be the results of external factors (secondary ciliary dyskinesia) or inherited (primary ciliary dyskinesia). • An active, coordinated ciliary beating is essential for mucociliary transport. Mucociliary transport is the final result of the functional and ultrastructural organization of the cilia at different levels.
M. Jorissen, MD, PhD (*) • M. Jaspers, MSc ENT Department, University Hospitals Leuven, Herestraat 49, Leuven B-3000, Belgium e-mail: [email protected]; [email protected]
2.1
Cilia
2.1.1
General Description
Cilia are tiny hairlike cell organelles, found on the surface of most cell types in the vertebrate body (Ferkol and Leigh 2012). There are two types of cilia: motile cilia and non-motile or primary cilia. Primary cilia or non-motile sensory cilia transmit signals to the interior of the cell. A second type of cilia, the motile cilia, is important for the movement of extracellular fluids. Motile cilia are found in the apical surface (ciliated epithelium) of the upper and lower respiratory tract, the oviducts of the female reproductive system, and ependymal cells lining the ventricles of the brain. These epithelial cells contain hundreds of motile cilia that beat together in a concerted manner to propel substances over the epithelial surface. Failure of these cilia to perform their normal function results in respiratory disease, sterility, or hydrocephalus.
Cilia, which line both the upper and lower airways, are covered by a thin layer of mucus and beat in a coordinated fashion propelling particles trapped in the mucus layer to the pharynx. Cilial defects may be either primary or secondary.
T.M. Önerci (ed.), Nasal Physiology and Pathophysiology of Nasal Disorders, DOI 10.1007/978-3-642-37250-6_2, © Springer-Verlag Berlin Heidelberg 2013
15
M. Jorissen and M. Jaspers
16 Fig. 2.1 m microvillar cell, s secretory cell, t ciliated cell, b basal cell, bm basal membrane
t s
m
b
bm
2.1.1.1 Ciliated Cells The respiratory epithelium consists mainly of four cell types: ciliated columnar cells, nonciliated columnar cells or brush cells with microvilli (m), goblet cells secreting mucin (s), and basal cells (b). The different cells types of the respiratory epithelium are illustrated in Fig. 2.1. A ciliated cell has a diameter of 5 μm at its apex and carries 100–200 cilia at a density of 6–8/μm2, interspersed with ±400 short microvilli (Rhodin 1966). The length of a cilium in the nose is 5 μm, in the larger airways 6–7 μm, and 5 μm in the smaller bronchiole (Jafek 1983). The diameter of the shaft or axoneme measures approximately 0.
Data Loading...