Zoology Animal Tissues Quiz

Animal Tissues Overview

• Animal tissues are classified into four basic types: epithelial, connective, muscle, and nervous tissue.
• Histo​logy is the study of the microscopic anatomy of cells and tissues.

Epithelial Tissues

• Epithelial tissues cover body surfaces, form glands, and line hollow organs, cavities, and ducts.
• Classification is based on layers (simple vs. stratified) and shape (squamous, cuboidal, columnar).
• Shapes of epithelial cells:
  • Simple squamous: single layer of flat cells; functions in diffusion (e.g., alveoli in lungs).
  • Simple cuboidal: single layer of cube-shaped cells; involved in secretion and absorption (e.g., kidney tubules).
  • Simple columnar: taller cells may have microvilli or cilia; functions in absorption and secretion (e.g., digestive tract).
  • Pseudostratified columnar: appears stratified, but all cells contact the basement membrane; common in respiratory tract.
  • Stratified squamous: multiple layers for protection against abrasion; found in skin.
  • Transitional: cells change shape based on tissue stretch; found in urinary bladder.

Connective Tissues

• Connective tissues are the most abundant and widely distributed, classified as either embryonic or mature.
• Key functions include binding tissues, supporting organs, insulating fat, and transporting substances (e.g., blood).
• Main cell types:
  • Fibroblasts: secrete proteins and maintain the extracellular matrix.
  • Chondrocytes: produce cartilage.
  • Osteocytes: form bone tissue.
  • Adipocytes: store fat.

Types of Connective Tissues

• Loose Connective Tissue:
  • Areolar tissue: widely distributed, provides cushioning.
  • Adipose tissue: stores energy and insulates.
  • Reticular tissue: forms a supportive framework for organs (e.g., lymph nodes).
• Dense Connective Tissue:
  • Dense irregular: collagen fibers arranged in various directions for multidirectional strength (e.g., dermis).
  • Dense regular: collagen fibers aligned; found in tendons and ligaments for unidirectional strength.
  • Elastic: contains elastin fibers, allows tissue to stretch (e.g., aorta).
• Cartilage:
  • Hyaline: smooth surface for joint movement; found in joints, ribs, and respiratory tract.
  • Fibrocartilage: tough, supports heavy loads (e.g., intervertebral discs).
  • Elastic: flexible cartilage found in structures like the ear and epiglottis.
• Bone:
  • Composed of a calcified matrix; osteocytes develop from chondrocytes as maturity increases.

Muscle and Nervous Tissues

• Muscle and nerve tissues are the final two types of the basic tissue group.
• Neurons and muscle fibers are excitable cells that generate electrical signals (action potentials).
• Types of Muscle Tissue:
  • Skeletal: striated, multinucleated, voluntary control; nuclei located peripherally.
  • Cardiac: striated, single centrally located nucleus, involuntary; contains intercalated discs and branches.
  • Smooth (Visceral): non-striated, involuntary; has a single central nucleus and tapered ends.

Summary of Nerve Function

• Action potentials propagate along neuron and muscle membranes due to voltage-gated ion channels, enabling cell communication and contractions.