Unit 4: Multicellular Organization Quiz

Unit 4: Multicellular Organization

• This unit covers major tissue types and their subcategories.
• It details the locations of various tissue types in the body.
• The process of tissue repair is also discussed.

Lesson 4.1: Tissues

• Covers Epithelial Tissue, Connective Tissue, Muscular Tissue, and Nervous Tissue.

Lesson 4.2: Organs and Systems

• Details on organs and systems.

Lesson 4.3: Body Plan and Multicellular Animals

• Details about body plans and multicellular animals.

Grades of Organization in Animals

• There are five grades of animal organization:
  • Protoplasm
  • Cell
  • Tissue
  • Organ
  • Organ System

Tissue Definition

• A tissue is a group of similar cells, with shared embryonic origins, that work together for specialized functions.
• A pathologist studies cells and tissues to aid in diagnoses.

Histology

• Histology is the study of tissues.

Biopsy

• A biopsy is a medical procedure where a small sample of tissue or cells is removed for examination under a microscope.

Types of Tissues

• Body tissues are categorized into four types:
  • Epithelial tissue: lines body cavities, covers surfaces and forms glands
  • Connective tissue: protects, supports, binds and stores energy
  • Muscular tissue: generates force for movement
  • Nervous tissue: detects changes and transmits signals for coordinated body functions

Epithelial Cells

• Epithelial cells have apical (free) surfaces exposed to exterior or body cavities.
• Lateral surfaces face adjacent cells.
• Basal surfaces are attached to the basement membrane.
• The basement membrane is an extracellular structure, mainly proteins, separating epithelium from underlying connective tissues.

Avascular Concept

• Epithelial cells rely on diffusion of oxygen and nutrients from blood vessels in the connective tissue beneath, limiting their thickness.

Epithelium Renewal

• Epithelial tissue can regenerate or repair itself through cell division.

Classification of Epithelium:

• Classified by number of layers (simple or stratified) and cell shape (squamous, cuboidal, columnar).
  • Simple: single layer
  • Stratified: multiple layers

Epithelial Tissue Types

• Simple Squamous Epithelium: single layer of flat cells, found in air sacs of lungs and capillary walls. Primary function: transport
• Simple Cuboidal : single layer of cube-shaped cells, found in glands and ducts, function in secretion and absorption
• Simple Columnar : single layer of elongated cells. Found in lining of the digestive tract. Involved in secretion and absorption.
• Stratified Squamous : multiple layers of flat cells, commonly found in areas subject to friction such as skin and mouth; protect against abrasion
• Stratified Cuboidal: two or more layers of cube-shaped cells. Found in larger glands.
• Stratified Columnar : multiple layers of column-shaped cells. Rare in the body, found in ducts of large glands.
• Transitional Epithelium: shape changes depending on stretch. Found in urinary bladder to allow for expansion.
• Glandular Epithelium: specialized for secretion. Composed of single cells or groups of cells.

Connective Tissue

• Connects body parts.
• Most abundant and widely distributed tissue type.
• Types include bone, cartilage, dense connective tissues, loose connective tissues, adipose tissue, reticular connective tissue, and blood/vascular tissue.

Bone (Osseous Tissue)

• Composed of bone cells (osteocytes) sitting in cavities (lacunae).
• Compact or spongy.

Cartilage

• Less hard and more flexible than bone.
• Hyaline (most widespread), elastic, and fibrocartilage
• Has abundant collagen fibers.

Dense Connective Tissue

• Dense fibrous tissue with collagen fibers.
• Forms strong rope-like structure, tendons, and ligaments.

Loose Connective Tissue

• Softer and contains more cells than other connective tissue types.
• Includes areolar, adipose, and reticular tissues.

Areolar Tissue

• Soft, pliable, “cobwebby” tissue.
• Cushions and protects organs.
• Universal packing tissue.
• Lamina Propria

Adipose Tissue

• Commonly called "fat".
• Fat cells predominate.
• Forms subcutaneous tissue beneath skin
• Insulates body.

Reticular Tissue

• Delicate network of reticular fibers and cells
• Forms stroma(support tissue framework) in lymphoid organs like lymph nodes, spleen, bone marrow.

Blood (Vascular Tissue)

• Consists of blood cells.
• Surrounded by non-living, fluid matrix (blood plasma).
• Transport vehicle for the cardiovascular system.

Muscular Tissue

• Highly specialized to contract or shorten, producing movement.
• Types: skeletal, cardiac, and smooth.

Nervous Tissue

• Consists of neurons (nerve cells) and neuroglia.
• Neurons are sensitive to stimuli. They convert stimuli into nerve impulses and transmit them to other neurons, muscles, or glands.
• Neuroglia support neurons.

Tissue Repair

• Process that replaces damaged, worn-out, or dead cells.
• Regenertaion happens when tissue is replaced by the same kind of cells.
• Fibrosis happens when tissue is replaced by dense connective tissue, resulting in scar tissue.

Inflammation

• A generalized body response to injury that attempts to prevent further damage.
• The body mounts a specific immune response to contain invaders (bacteria, viruses, toxins).