Unit 5-8 Study Guide

Unit 5: Tissues and Integumentary System

Four Categories of Tissues

  • Epithelial: Covers body surfaces and lines cavities.
  • Connective: Supports, protects, and binds other tissues.
  • Muscle: Contracts to produce movement.
  • Nervous: Receives stimuli and transmits impulses.

Epithelial Tissue

  • Function: Protection, absorption, secretion, and filtration.
  • Types:
    • Simple squamous: diffusion/filtration (lungs, vessels)
    • Simple cuboidal: secretion/absorption (kidneys)
    • Simple columnar: absorption/secretion (digestive tract)
    • Stratified squamous: protection (skin, mouth)
    • Pseudostratified columnar: secretion/movement (respiratory)
    • Transitional: stretch (bladder)
  • Homeostasis: Maintains barriers and controls permeability.

Connective Tissue

  • Functions: Support, protection, insulation, storage, transport.
  • Types:
    • Loose: areolar, adipose, reticular
    • Dense: dense regular, dense irregular, elastic
    • Supportive: hyaline cartilage, fibrocartilage, elastic cartilage, compact bone
    • Fluid: blood, lymph

Examples and Locations

  • Areolar: under epithelia (cushions organs)
  • Reticular: lymph nodes, spleen (supports soft tissue)
  • Adipose: under skin, around organs (stores fat)
  • Dense regular: tendons, ligaments
  • Hyaline cartilage: nose, trachea, ends of long bones
  • Compact bone: skeleton
  • Blood: within blood vessels

Muscle Tissue

  • Skeletal: voluntary movement; attached to bones
  • Cardiac: involuntary, pumps blood; heart wall
  • Smooth: involuntary, moves substances; walls of hollow organs

Nervous Tissue

  • Neurons: transmit impulses (brain, spinal cord)
  • Neuroglia: support and protect neurons

Embryonic Origins

  • Ectoderm: skin, nervous system
  • Mesoderm: muscles, bones, blood, kidneys
  • Endoderm: lining of GI and respiratory tracts

Skin Layers and Cells

  • Epidermis: keratinocytes, melanocytes, Langerhans, Merkel
  • Dermis: fibroblasts, collagen, elastin
  • Hypodermis: adipose tissue

Functions of Skin

  1. Protection
  2. Sensation
  3. Thermoregulation
  4. Metabolic functions (vitamin D)
  5. Blood reservoir
  6. Excretion

Thick vs Thin Skin

  • Thick: palms/soles, 5 layers, no hair
  • Thin: covers rest of body, 4 layers, has hair

Skin Receptors

  • Meissner's corpuscles: light touch
  • Pacinian corpuscles: pressure/vibration
  • Merkel discs: steady pressure
  • Ruffini endings: stretch
  • Free nerve endings: pain, temperature
  • Krause end bulbs: cold

Skin Appendages

  • Hair: protection, sensory
  • Arrector pili: goosebumps, insulation
  • Nails: protect fingertips
  • Sudoriferous glands:
    • Eccrine: temperature control
    • Apocrine: emotional sweating
  • Sebaceous glands:
    • Secrete sebum
    • Lubricate skin/hair, antibacterial

Skin Cancer

  • Basal cell carcinoma: least dangerous, basal layer
  • Squamous cell carcinoma: may metastasize, stratum spinosum
  • Melanoma: most dangerous, melanocytes

Wound Healing

  • Regeneration: replaces with same tissue
  • Fibrosis: replaces with scar tissue