Tissues- Human Bio

Organization and Regulation of Body Systems

Tissue Overview

  • Definition of Tissue: A collection of cells of the same type that perform a common function and form a discrete region of an organ.

  • Functionality: Various tissues come together to form organs, which are specialized for particular functions. The organs work together in organ systems.

Major Tissue Types

  1. Connective Tissue

    • Binds and supports body parts.

  2. Muscular Tissue

    • Moves the body and its parts.

  3. Nervous Tissue

    • Receives stimuli and conducts nerve impulses.

  4. Epithelial Tissue

    • Covers body surfaces and lines body cavities.

Components of Tissues

  • All tissues consist of:

    • Cells

    • Matrix: Composed of fibrous proteins and ground substance (extracellular fluid).

Connective Tissue

  • Functions:

    • Binds and supports parts of the body.

    • Storage of energy.

    • Heat production.

    • Transport (e.g., blood).

  • Components: All connective tissues have specialized cells, a ground substance, and protein fibers including collagenous, elastic, and reticular fibers.

  • Ground Substance: Noncellular, varying from solid to fluid, forms the matrix of the tissue.

Types of Connective Tissue

  1. Fibrous Connective Tissue

    • Types:

      • Loose: Supports and binds organs, contains more ground substance.

      • Dense: Contains closely packed fibers, found in tendons and ligaments.

  2. Supportive Connective Tissue

    • Cartilage: Solid, flexible matrix, includes:

    • Hyaline Cartilage: Fine collagen fibers; found in nose, ends of long bones.

    • Elastic Cartilage: More elastic fibers; found in outer ear.

    • Fibrocartilage: Strong collagen fibers; found in disks between vertebrae.

    • Bone: Solid, rigid matrix made of collagen and calcium salts; includes compact and spongy types.

  3. Fluid Connective Tissue

    • Blood: Composed of plasma and formed elements (red blood cells, white blood cells, and platelets).

Muscle Tissue

  • Functions: Allows for movement in the body.

  • Components: Made of muscle fibers/cells containing protein fibers (actin and myosin).

  • Types:

    • Skeletal Muscle: Voluntary movement, striated, attached to bones.

    • Smooth Muscle: Involuntary, spindle-shaped, located in viscera (intestines, blood vessels).

    • Cardiac Muscle: Involuntary, branched cells, found in the heart.

Nervous Tissue

  • Function: Allows communication between cells.

  • Components:

    • Neurons: Carry information to/from the brain.

      • Dendrites carry signals to the cell body.

      • Axons carry signals away from the cell body.

    • Neuroglia: Support, nourish neurons, outnumber neurons 9:1.

Epithelial Tissue

  • Function: Covers body surfaces, lines cavities, avascular, and forms glands.

  • Structure: Tightly bound cells, anchored by a basement membrane.

  • Types:

    • Simple: One cell layer; Stratified: More than one cell layer; Pseudostratified: Appears to have layers but is one layer.

    • Shapes: Cuboidal, columnar, squamous.

Transition from Tissues to Organs

  • Definition: An organ consists of two or more tissue types working together towards a specific function.

  • Organ System: A combination of organs that work together to carry out particular functions.

Body Cavities Overview

  1. Ventral Body Cavity: Front side.

    • Thoracic Cavity: Contains heart and lungs.

    • Abdominal Cavity: Contains digestive organs.

    • Pelvic Cavity: Contains reproductive organs.

  2. Dorsal Body Cavity: Backside.

    • Cranial Cavity: Contains the brain.

    • Vertebral Cavity: Contains the spinal cord.

Organ Systems of the Human Body

  1. Integumentary System: Protects body, senses environment, regulates temperature.

  2. Cardiovascular System: Transports blood, nutrients, defends against disease.

  3. Lymphatic System: Controls fluid balance, absorbs fats, defends against disease.

  4. Digestive System: Ingests and digests food, absorbs nutrients.

  5. Respiratory System: Allows breathing, gas exchange.

  6. Urinary System: Excretes waste, maintains fluid balance.

  7. Skeletal System: Supports the body, protects organs, produces blood cells.

  8. Muscular System: Moves body and maintains posture.

  9. Nervous System: Integrates sensory input, coordinates actions.

  10. Endocrine System: Produces hormones, regulates functions.

  11. Reproductive System: Produces gametes, supports offspring.

Functions of Integumentary System

  1. Protection against trauma and pathogens.

  2. Temperature regulation.

  3. Sensory awareness.

  4. Synthesis of melanin and vitamin D.

Skin Structure

  • Epidermis:

    • Outermost layer, made of epithelial tissue, contains keratin.

    • Langerhans cells fight pathogens and melanocytes produce melanin.

  • Dermis:

    • Inner layer made of dense connective tissue with blood vessels, nerves, and glands.

Skin Color

  • Melanin: Produced by melanocytes.

  • Carotene: Contributes yellow-orange color.

  • Hemoglobin: Red pigment in blood.

Accessory Organs of the Skin

  • Nails and Hair: Derived from epidermis and dermis respectively, provide protection.

  • Oil Glands: Lubricate hair and skin.

  • Sweat Glands: Help regulate temperature.

Skin Cancer

  • Types:

    • Basal Cell Carcinoma: Most common.

    • Melanoma: Most deadly but less common.

  • Prevention:

    • Avoid sun exposure, wear sunscreen, protective clothing.