Animal Tissues, Dental Anatomy, and Digestion

Four Types of Animal Tissues

1. Epithelial Tissue

• Squamous:
  • Simple: One cell thick; forms solid layers of cells.
  • Stratified: Multiple layers; forms the epidermis.
• Cuboidal:
  • Simple: One cell thick, roughly cube-shaped. Lines ducts where absorption and secretory activities take place.
• Columnar:
  • Simple: One cell thick, column-shaped. Lines the digestive tract.
  • Pseudostratified: Gives the appearance of more than one layer of columnar epithelial organs.

2. Connective Tissue

• Adipose: Honeycomb or chicken wire appearance. Stores energy, insulates, and supports and protects organs.
• Dense: Forms ligaments and the outer protective covering for bone.
• Bone: Tree ring-like appearance. Supports and protects, stores minerals and fat, and aids in blood cell production.
• Cartilage: Supports while providing flexibility. Absorbs compression between bones in joints and holds open respiratory passages.
• Blood: Composed of plasma and cells. Plasma is made up of water and dissolved substances.

3. Muscle Tissue

• Skeletal Muscle: Muscular fibers are long, parallel, and cylindrical with many nuclei sections. Features striated, tubular, multinucleated fibers. Usually attached to the skeleton and is voluntary.
• Smooth Muscle: Cells are spindle-shaped with only one central nucleus, found in the walls of hollow organs. Features narrow, tapered, non-striated, uninucleated fibers. Occurs in the walls of internal organs and blood vessels and is involuntary.
• Cardiac Muscle: Only found in the heart wall and is not under conscious control (involuntary). It has cross-striations, a nucleus, and one or more branches. Features striated, tubular, branched, uninucleated fibers.

4. Nervous Tissue

• Excitable: Branching cells (neurons) with many long prolongations and a large central nucleus. Transmits impulses from one area of the body to another.
• Non-excitable: Supports the neuron.

Dental Health and Tooth Structure

• Dental Decay: Brushing your teeth regularly and using an alkaline toothpaste helps to minimize the harmful activity of bacteria. Key components of tooth structure include the gum, pulp cavity, enamel, dentine, plaque, cement, and nerve.
• Fluoride: A naturally occurring mineral that is known to strengthen enamel.

The Digestive Process

• Physical Breakdown: Breaking large lumps of food into smaller lumps by the teeth and the churning of the gut.
• Chemical Digestion: Breaking of large, insoluble molecules into smaller, soluble molecules by enzymes.
• Absorption: The process through which nutrients enter the blood through the villi.