HSCI 4950- Histology Apical Modification

Summary

This video explores the unique apical modifications of epithelial cells: cilia and microvilli. Cilia, with their 9+2 microtubule arrangement, are motile organelles that move mucus in the respiratory tract, facilitated by axonemes. In contrast, microvilli lack axonemes and are non-motile, serving to increase the absorptive surface area of cells. Both structures play crucial roles in epithelial function, with cilia aiding in mucus transport and microvilli enhancing absorption efficiency.

Takeaways

• 🔬 Epithelial cells are polarized, having distinct apical and basal surfaces.
• 🌟 Cilia are hair-like extensions on the apical surface of epithelial cells that are motile organelles.
• 🔬 Cilia are supported by an axoneme, which has a 9+2 arrangement of microtubules and motor proteins.
• 🚀 The movement of cilia helps to create a current in the mucus layer, aiding in the transport of mucus.
• 🍽️ Goblet cells secrete mucus which is moved by cilia towards the pharynx for swallowing.
• 📚 Cilia contain axonemes and are specialized for movement, unlike other structures.
• 🌿 Microvilli are thin structures found on the apical surface of epithelial cells that increase surface area.
• 🔬 Unlike cilia, microvilli do not have axonemes and are not motile.
• 🧽 Microvilli function to increase the surface area for absorption in absorptive epithelial cells.
• 🌱 The presence of microvilli enhances the efficiency of absorption by increasing the plasma membrane exposure.
• 📖 The script differentiates between the functions of cilia and microvilli, highlighting their unique roles in epithelial cells.

Q & A

What is the main characteristic that distinguishes epithelial cells from many other types of cells?

Epithelial cells are polarized, which means they have distinct basal and apical surfaces.

What are cilia and where are they typically found on epithelial cells?

Cilia are hair-like extensions that are found on the apical surface of epithelial cells and are involved in movement.

What is the structural support for cilia and what is its special arrangement?

Cilia are supported by an axoneme, which has a special 9+2 arrangement of microtubules along with motor proteins.

How do cilia contribute to the movement of mucus in the upper respiratory tract?

Cilia beat in a wave-like motion that moves mucus up the respiratory tract into the pharynx for swallowing.

What is the primary function of cilia in terms of their movement?

The primary function of cilia is to impart motion, facilitating the movement of substances like mucus.

What is the difference between cilia and microvilli in terms of motility?

Cilia are motile organelles, while microvilli are not motile and serve a different function.

What is the main function of microvilli on the apical surface of epithelial cells?

Microvilli function to increase the surface area of the apical surface of epithelial cells, enhancing absorption efficiency.

How do microvilli differ structurally from cilia?

Microvilli lack axonemes and are not involved in movement; they are thin structures that increase surface area.

In what type of epithelial cells are microvilli typically found and why?

Microvilli are typically found in absorptive epithelial cells to increase the plasma membrane exposure for absorption.

What role do goblet cells play in relation to cilia?

Goblet cells secrete mucus, which is then moved by the beating action of cilia in the respiratory tract.

What is the significance of the 'come hither' motion of cilia?

The 'come hither' motion of cilia helps to move substances, such as mucus, in a specific direction, aiding in clearance from the respiratory tract.