FOR YOUR NOTEBOOK:

What is a Tissue?

A tissue is a group of similar cells that work together to perform a specific function.

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Biological Organization Reminder

Cells → Tissues → Organs → Organ Systems → Organism

An organ contains multiple types of tissues working together.

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The Four Major Types of Human Tissue

1. Epithelial Tissue

Function:

• Covers surfaces

• Protects underlying tissues

• Absorbs substances

• Secretes substances

Locations:

• Skin

• Lining of the digestive tract

• Lining of blood vessels

• Respiratory passages

Key idea:

Epithelial tissue acts like a covering or barrier.

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2. Connective Tissue

Function:

• Supports

• Connects

• Protects

• Stores materials

• Transports substances

Examples:

• Bone

• Cartilage

• Blood

• Fat (adipose)

• Tendons

• Ligaments

Key idea:

Connective tissue supports and connects different parts of the body.

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3. Muscle Tissue

Function:

• Contracts to produce movement

There are three major types:

Skeletal muscle

• Attached to bones

• Produces voluntary movement

Cardiac muscle

• Found in the heart

• Produces heart contractions

Smooth muscle

• Found in organs such as the stomach and intestines

• Controls involuntary movements

Key idea:

Muscle tissue contracts and creates movement.

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4. Nervous Tissue

Function:

• Receives information

• Processes information

• Sends electrical signals

Locations:

• Brain

• Spinal cord

• Nerves

The primary cells are neurons, which transmit electrical signals.

Key idea:

Nervous tissue communicates and coordinates body activities.

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Tissue → Organ Example

The heart contains several types of tissue:

• Cardiac muscle tissue → contracts the heart

• Connective tissue → provides support

• Epithelial tissue → lines internal surfaces

• Nervous tissue → helps regulate heart activity

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These tissues work together to form an organ.

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