Hierachy of Organization and Tissue Types

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Specialized Cells

Cells that perform a specific function. They have structures that allow them to perform their specific function.

Tissues

Groups of specialized cells

Epithelial Tissue

Tightly packed cells that line the surfaces of the body.

Types:

1. Exterior (skin epithelia)

2. Interior (columor epithelia)

   1. Lining of stomach, intestine, mouth, lungs, etc

Connective tissue

Tissues that build support structures for organs. They often form external matrixes of collagen fibres.

Types

1. Bone

2. Cartilage, Tendons, Ligaments

3. Fat

4. Blood

Muscle Tissue

Long fibrous tissue that can contract and provide movement. They are attached to bones and surrounds the digestive tract, blood vessels, and forms the heart.

Types:

1. Skeletal

2. Smooth

3. Cardiac

Nervous Tissue

Tissue that allows for the respone to internal and external stimuli. It forms the brain and nerves, and connects to the sensory receptors and muscles.

Epithelial (skin) cells

Tightly packed - Protects against foreign invaders from entering and prevents important molecules from escaping.

Layered - for protective barrier

Thin - so many layers can form since these cells wear away easily

Inner epithelial cells

Cilia (respiratory) - Sweeps out toxins/dirt out of trachea

Golgi-rich - To secrete mucous to help the digestive and respiratory system

Red blood cells

Cells that contain hemoglobin to carry oxygen in the blood.

Smooth - easily passes through vessels

Concave shape - to increase surface area so more oxygen can be transported

No nucleus or membranes - to maximize space for oxygen; thinning of the cell

White blood cells

Cells that are able to engulf/swallow invading bacteria to fight infection by digesting them with enzymes. They can destroy damaged old cells in the body.

Flexible cell membrane - to consume invaders

Ribosome rich - To form proteins to attack invaders

Lysosome rich - to break down substances absorbed

Nerve cells

Cells that conduct electrical impulses to coordinate body activities.

Long body (axon) - to rapidly carry nerve impulses to the brain

Dendrites - allows for communication between cells

Mitochondria rich - to fuel the rapid impulses

Sperm cells

Cells that carry DNA of the male parent to join with DNA of the female parent

Head - pointed to pierce egg wall

Cap on head (acrosome) - contains digestive material to break down egg membrane

Mitochondria rich tail - to fuel propulsion of tail

Tail - long and thin to propel forward

Small - so more of them can be produced

Muscle cells

Three types:

1. Skeletal (connects to bones and joints)

2. Cardiac (heart)

3. Visceral/smooth (inside blood vessels and internal organs)

Produces movement and maintains posture due to muscles contracting and relaxing.

• They form long fibres that have a striped/striated appearance

Fat cells

Cells that store extra materials from food that can be turned into energy later.

• Provides insulation

• Surrounds vital organs and tissues

• Fills sharp angles between bones and muscle

Goblet cells

Column shaped cells that secrete mucus. They are found in intestinal and respiratory tracks.