Body Tissues & Nervous System Notes

Disciplines of Anatomy and Physiology

  • Anatomy: Study of the body's internal and external structures, and their relationships.

  • Physiology: Study of how these structures work as an integrated whole.

Self Regulation

  • Homeostasis: Maintaining a constant, stable internal environment.

  • Negative Feedback: A form of regulation where the result of a process inhibits that same process.

    • Example: Maintenance of temperature in a room using a thermostat and AC system.

  • Positive Feedback: When something is increasing, the body is saying to increase more

    • Example: Breast milk

  • Thermoregulation in the human body:

    • Components:

      • Set point: 37 degrees Celsius

      • Stimulus: body temperature

      • Sensor: temperature on skin

      • Control center: Brain

      • Response: Construction of the blood vessel, shivering (when body temperature is low)

Levels of Physical Organization

  • Complexity increases at each level.

  • Internal organization allows for:

    • Transport of nutrients and wastes

    • Movement

    • Support

  • Multicellularity allows for division of labor:

    • Tissues: Groups of cells.

    • Organs: Groups of different tissues with distinct functions.

    • Systems: Several organs working together.

    • Organism: Several organ systems. Humans have 11 systems.

Human Body's Four Basic Tissue Types

  • Epithelial

  • Connective

  • Muscle

  • Nervous

Epithelial Tissue

  • Cells always in contact with the external environment.

  • Functions:

    • Protection: Keeps body heat, waterproof.

    • Secretory:

      • Exocrine glands: Sweat glands (sweat), salivary glands (saliva).

      • Endocrine glands: Produce hormones to regulate growth/metabolism (e.g., thyroid).

    • Connection to other tissues

  • Cell Organization:

    • Simple (single layer)

    • Stratified (multiple layers)

  • Types:

    • Squamous

      • Simple: lines of blood vessels

      • Stratified: Skin, mouth, vagina

    • Cuboidal

      • Simple: small kidney

      • Stratified: sweat glands

    • Columnar

      • Simple: lining of small intensives

      • Stratified: mammary glands

  • Basement membrane: Supporting non-cellular layer that anchors to connective tissue.

  • Junctions:

    • Tight: Leak-proof (e.g., digestive tract).

    • Desmosomes: Flexibility (e.g., skin, heart).

    • Gap: Exchange of ions/water (e.g., epithelium of liver, heart, pancreas).

Connective Tissue

  • Cells produce ground substance (e.g., proteins & calcified material in bone).

  • Types:

    • Fibrous (loose, dense, elastic, reticular)

    • Specialized (cartilage, bone, blood, adipose)

  • Functions:

    • Flexibility

    • Insulation

    • Cushion

    • Energy storage

    • Strength

    • Transport

  • Fibrous:

    • Loose: Collagen & elastin, most common, provides flexibility.

    • Dense: Collagen, found in tendons, ligaments, lower skin layers, strongest.

    • Elastic: Organs that change shape (e.g., stomach), elastic fibers for stretch & recoil.

    • Reticular or Lymphoid: Internal framework of soft organs (e.g., liver, spleen, tonsils), collagen.

  • Specialized:

    • Cartilage: Protects/cushions joints, collagen & chondroblasts in lacunae, no capillaries (chondrocytes feed by diffusion through ground substance from capillaries located outside), slow to heal.

    • Bone: Few living cells, mostly mineral deposits of calcium & phosphate, contains blood vessels.

    • Blood: Cells suspended in plasma, RBC carry oxygen/CO2, WBC involved in immunity, platelets involved in clotting.

    • Adipose: Adipocytes, almost no ground substance, provides protection, insulation.

Muscle Tissue

  • Powers movement; contractile proteins within cells allow them to shorten.

  • Types:

    • Skeletal: Striated (stripe-like), regular arrangement of actin and myosin fibers, voluntary control, connects to tendons which attach to bones, fused young cells into one long cell, peripherally-located nuclei.

    • Cardiac: Found only in the heart, striated but under influence of its own pacemaker cells, involuntary, short, blunt-ended cells with one nucleus/cell, connected by gap junctions for electrical connections.

    • Smooth: Surrounds hollow organs & tubes (blood vessels, digestive tract, uterus), non-striated, involuntary, small, parallel cells with one nucleus, tapered cells, gap junctions.

Nervous Tissue

  • Generates and transmits electrical impulses.

  • Located in brain, spinal cord, and nerves.

  • Two cell types:

    • Neurons: Transmit nerve signals; 3 basic parts: cell body contains nucleus, dendrites are several cytoplasmic extensions from the cell body & receive signals from other neurons, and axons, which are long extensions that transmit electrical impulses over long distances.

    • Neuroglia: Non-neuronal cells surround neurons and hold them in place; for support, nourishment, insulation, & to destroy pathogens.

Organization of the Nervous System

  • Signal transduction from the stimulus to the spinal cord and back to the muscle that responds to such stimulus.