Specialised Cells and Their Functions

Specialised Cells

• Unicellular organisms: One cell performs all life functions.

• Multicellular organisms (e.g., plants, animals): Made up of many cells with different specializations.

Types of Cells in Multicellular Organisms

• Animals: Approximately 50 trillion cells and over 200 cell types.

Muscle Cells

• Skeletal Muscles: Voluntary, attached to bones, control movement (e.g., biceps, triceps).

• Involuntary Muscles: Control automatic functions (e.g., diaphragm for breathing, gut movements).

• Cardiac Muscles: Involuntary, located in the heart, striped appearance, fatigue-resistant due to high mitochondria counts.

Nerve Cells

• Transmit messages between the brain and other body parts.

• Long extensions called axons allow long-distance communication.

Blood Cells

• Red Blood Cells: Carry oxygen and remove carbon dioxide; no nucleus, constantly replenished.

• White Blood Cells: Part of the immune system, combat infections.

Fat Cells

• Brown Fat Cells: Generate heat (important for newborns and hibernating animals).

• White Fat Cells: Store energy and insulate the body.

Specialised Plant Cells

• Plants also have specialised cells, although fewer types than animals.

Key Plant Cell Types

• Guard Cells: Regulate gas exchange in leaves by opening and closing stomata.

• Conducting Cells: Transport water and food; elongated structure.

• Photosynthetic Cells: Contain chlorophyll for photosynthesis, present in leaf surfaces.

• Structural Cells: Provide support; cell walls are thick and strong.

• Root Hairs: Increase surface area for water absorption from soil.