Overview
This lecture introduces the four major tissue types in the body - epithelial, connective, muscle, and nervous tissues - covering their structure, function, and main locations.
Major Types of Body Tissues
- The four main tissue types are epithelial, connective, muscle, and nervous tissue.
- Tissues are groups of specialized cells organized by structure and function.
- Tissues make up organs and body parts like skeleton, muscles, and vasculature.
Epithelial Tissue
- Lines body cavities, blood vessels, and organ surfaces; forms protective sheets.
- Simple squamous: single thin cell layer, allows filtration/exchange; found in alveoli, capillaries, serous membranes.
- Simple cuboidal: one cube-shaped cell layer, filtration/exchange; found in glands, bile ducts, kidney tubules, ovary surface.
- Simple columnar: single tall cell layer, absorption/secretion; found in digestive tract, mucous membranes.
- Stratified epithelium: multiple layers for durability; squamous in mouth/skin/oesophagus, cuboidal/columnar in gland ducts.
- Glandular epithelium: covers glands, for secretion; found in endocrine and exocrine glands.
- Pseudostratified columnar: appears layered, actually single layer; secretion/absorption; lines trachea, reproductive organs.
Connective Tissue
- Widely distributed throughout the body; cells are suspended in extracellular matrix (ECM).
- Bone: osteocytes in hard matrix, provides protection and support.
- Cartilage: chondrocytes, more flexible than bone; types are fibrocartilage (strong, absorbs shock), hyaline (glassy, flexible), elastic (very flexible).
- Dense connective: mainly collagen fibers; forms tendons (muscle-to-bone) and ligaments (bone-to-bone).
- Loose connective: supports organs/vessels, links tissues; areolar (cushions organs), adipose (stores fat, insulates), reticular (supports lymphoid organs).
- Blood: connective tissue with cells in plasma; transports nutrients, gases, wastes; includes erythrocytes (RBCs), leukocytes (WBCs), platelets, plasma.
Muscle Tissue
- Specialized for contraction and movement, includes skeletal, cardiac, and smooth muscle.
- Skeletal muscle: attached to bones by tendons, voluntary, striated, multinucleate.
- Cardiac muscle: only in heart, involuntary, striated, uninucleate, cells fit tightly together.
- Smooth muscle: walls of blood vessels, digestive tract, bladder, uterus; involuntary, non-striated.
Nervous Tissue
- Functions in sensing, processing, and transmitting information.
- Composed of neurons (conduct impulses) and glial cells (support, insulate, protect neurons).
- Neurons: have cell body (soma), dendrites (receive signals), axon (sends signals), axon terminal.
- Glial cells: produce myelin, defend against pathogens, form blood-brain barrier.
Key Terms & Definitions
- Epithelial tissue — tissue covering body surfaces and lining cavities.
- Connective tissue — tissue supporting and connecting other tissues.
- Muscle tissue — tissue able to contract for movement.
- Nervous tissue — tissue for electrical impulse transmission.
- Osteocyte — bone cell.
- Chondrocyte — cartilage cell.
- Extracellular matrix (ECM) — substance around cells in connective tissues.
- Neuron — nerve cell conducting impulses.
- Glial cell — support cell of the nervous system.
Action Items / Next Steps
- Review the structure, location, and function of each tissue type.
- Complete the accompanying quiz to assess understanding.