Class 9th Tissues Lecture Overview

Comprehensive vocabulary flashcards covering plant and animal tissues, their structures, and specific cellular functions based on the lecture transcript.

Tissue

A group of cells having similar shape and function acting together to perform a specific function.

Meristematic Tissue

Plant tissues that have the capacity to divide, featuring small, isodiametric cells with thin walls and usually lacking vacuoles.

Apical Meristem

Tissues found at the tips of stems and roots that help shoots and roots grow longer, known as primary growth.

Intercalary Meristem

Found at the base of leaves or between nodes on branches, helping parts like the internode or leaves grow longer.

Lateral Meristem

Found in roots or stems, it helps the plant become thicker through a process known as secondary growth.

Permanent Tissue

Tissues composed of cells that have lost their capability to divide and have attained a definite shape, size, and thickness.

Cell Differentiation

The process where developing cells change from simple forms to more complex forms to become specialized for specific functions.

Parenchyma

Small, unspecialized living cells with thin walls and large intercellular spaces that form basic packing tissue and store food.

Chlorenchyma

Type of parenchyma tissue that contains chlorophyll and is capable of performing photosynthesis.

Aerenchyma

Parenchyma tissues in aquatic plants with large air spaces that provide buoyancy to help the plant float.

Collenchyma

Living, elongated cells with thick corners found in leaf stalks that provide flexibility and mechanical support.

Sclerenchyma

Dead, long, and narrow cells with thick walls containing lignin; they provide hardness and stiffness to plants.

Lignin

A chemical cementing substance found in the cell walls of sclerenchyma that makes them stiff and hard.

Xylem

A vascular and mechanical tissue (wood) that conducts water and minerals unidirectionally from roots to apical parts.

Tracheids

Elongated, angular, dead cells in xylem involved in the conduction of water and minerals, mainly in gymnosperms.

Vessels

Advanced cylindrical tube-like structures in xylem forming a continuous channel for efficient water conduction in angiosperms.

Phloem

Vascular tissue that conducts organic solutes or food materials bidirectionally throughout the plant.

Sieve Tubes

Slender tube-like structures made of elongated, thin-walled cells with perforated end walls called sieve plates.

Companion Cells

Cells with dense cytoplasm and prominent nuclei that originate from the same mother cell as sieve cells and assist in their function.

Epidermis

The outermost protective layer of plants that protects against injury, pathogens, and water loss.

Suberin

A chemical substance found in the cell walls of dead cork tissue that prevents water loss and infection.

Epithelial Tissue

Protective tissue that covers organs and lines hollow cavities, resting on a non-cellular basement membrane.

Squamous Epithelium

Cells found in the inner surface of the mouth, esophagus, and blood vessels; specialized for protection and transport.

Muscular Tissue

Long, fiber-like cells called muscle fibers capable of contraction and relaxation to bring about movement.

Striated Muscles

Voluntary muscles that are multinucleated, unbranched, and attached to the skeleton; they get tired and need rest.

Sarcolemma

The thin membrane that encloses each striated muscle fiber.

Cardiac Muscle Fibres

Involuntary, branched, and uninucleated fibers found only in the heart that show rhythmic contraction throughout life.

Smooth Muscles

Involuntary, non-striated, spindle-shaped cells found in the walls of the stomach, intestine, and bronchi.

Connective Tissue

Tissue with widely spaced cells embedded in an intercellular matrix that provides structural framework and connects body parts.

Plasma

The fluid part of blood, making up $55\%$ of its volume, consisting of water, proteins, and inorganic salts.

Erythrocytes (RBCs)

Cells containing hemoglobin that help in the transportation of oxygen throughout the body.

Leukocytes (WBCs)

Irregular, amoeboid cells called 'soldiers of the body' that protect by engulfing bacterial and foreign particles.

Thrombocytes

Spindle-shaped cells also known as blood platelets involved in the clotting of blood.

Tendons

Non-elastic, tough, white connective tissues that attach muscles to bones.

Ligaments

Elastic, strong, yellow connective tissues that attach bone to bone.

Bone

Hard, non-flexible, and porous tissue with a matrix made of protein and mineral salts.

Cartilage

Flexible, non-hard, and non-porous tissue with a matrix composed solely of proteins.

Areolar Tissue

The most widely distributed connective tissue that fills spaces inside organs and is found between skin and muscles.

Adipose Tissue

Tissue made of adipocytes filled with fat globules; it stores nutrients and helps in temperature regulation.

Neuron

The longest cell in the body and the structural and functional unit of the nervous system.

Cyton

The cell body of a neuron, containing the nucleus and other organelles, covered by a plasma membrane.

Dendrites

Branched structures of a neuron that collect information and pass it to the cell body.

Axon

A tube-like structure that carries information from the cell body to the nerve endings.