Fibers in Pharmacognosy: Quiz and Flashcards

What is the main component of the cell walls of natural fibers?

Which process, involving the tips of elongating cells pushing past one another, is facilitated by a modification in the middle lamella?

Which part of the fiber initial grows rapidly during development in the axial direction?

What is a common characteristic of fibers found in higher plants at maturity?

What is the purpose of fibers in the biology of plants?

Which characteristic distinguishes fibers from other plant cells like sclereids?

What type of fibres are commonly found outside the xylem in plants?

Which type of fibres are found in the xylem of plants?

Which of the following is NOT an example of animal fibre?

What is the main component of synthetic fibres?

Which fibre type is secreted by glands of insects during the preparation of cocoons?

Where are mineral fibres like glass and asbestos derived from?

Characteristics of Fibres

Fibres are thin, long, and flexible structures that are indigestible by the human body.
They are elongated thick-walled cells with pointed ends, consisting of cellulose and may or may not contain lignin.
Fibres are developed from a single cell, the fibre initial, which grows rapidly in the axial direction.
They are often found in groups or clumps or patches and are often dead at maturity, lacking a nucleus and cytoplasm.

Properties of Fibres

Fibres are long and tapered at the end.
They can be as long as 1-8 mm in length.
They contain thick secondary walls with fewer pits than sclereids.
Fibres have uniformly thickened lignified cell walls in plants.

Types of Fibres

Natural fibres: biodegradable, produced by plants, animals, and geological processes.
Vegetable fibres: elongated, needle-like pointed sclerenchyma cells.
Intraxylary fibres: found in the xylem, including libriform fibres and fibre tracheids.
Extraxylary fibres: found outside the xylem, including cortical fibres, pericyclic fibres, and phloem or bast fibres.
Seed fibres: e.g., cotton.
Leaf fibres: e.g., sisal.
Nut fibres: e.g., coconut.
Fruit fibres: e.g., oil palm.
Stem or stalk fibres: e.g., rice, flax.

Animal Fibres

Examples include sheep wool, mink, alpaca hair, horse hair, and silk.
Avian fiber: from birds' feathers and feather fibers.
Goat hair, alpaca hair, horse hair, and angora wool.
Tendon or sinew, catgut, and fur.

Mineral Fibres

Glass and asbestos.

Synthetic Fibres

Generally come from synthetic materials such as petrochemicals and natural carbohydrates.
Examples include rayon, cellulose wadding, acetate rayon, nylon, and terylene.

Explore the biological origin and structure of plant fibres, including natural and synthetic fibres. Learn about the characteristics of plant fibres such as cotton and their cell wall composition in Pharmacognosy.