Question

Which of these is not a type of epithelial tissue? a. simple cuboidal and stratified columnar b. bone and cartilage c. stratified squamous and simple squamous d. pseudostratified and transitional e. All of these are epithelial tissues.

Short answer

The correct answer is option b: bone and cartilage are not types of epithelial tissue, but are types of connective tissue.

Step-by-step solution

Understand Epithelial Tissue Types

There are several types of epithelial tissue in the human body, and they are primarily classified by the number of layers of cells (simple or stratified) and the shape of the cells (squamous, cuboidal, columnar). Additionally, two special types are transitional and pseudostratified. Therefore, options a, c, and d in this exercise list legitimate epithelial tissues.

Identify Non-epithelial Tissues

Looking at option b which states bone and cartilage, these are not epithelial tissues. They are, in fact, types of connective tissues, another major tissue class in the body alongside epithelial tissues. Therefore, the correct answer is option b.

Check the "All of these" Option

Finally, it's always necessary to look at the option that states 'all of these are epithelial tissues' in this type of question. In this case, option e cannot be correct because option b is not a type of epithelial tissue. So, the correct answer to the exercise is option b: bone and cartilage are not types of epithelial tissue, but are types of connective tissue.

Key concepts

Types of Epithelial Tissue

Epithelial tissue is a crucial component of human anatomy, lining the cavities and surfaces of structures throughout the body. It serves as a barrier against microbial invasion, regulates permeability, and is responsible for secretion and sensation. Classification of epithelial tissue is based on cell layers and cell shapes. The simplest classification includes simple epithelium, which is just one layer thick, and stratified epithelium, comprising multiple layers. Cell shape further categorizes epithelial tissue into squamous (flat and thin), cuboidal (cube-like), and columnar (taller than wide).

Specialized epithelial tissues hold additional classifications. Pseudostratified epithelium gives the illusion of multiple layers due to the varied cell height, but it's actually a single layer. Transitional epithelium can stretch and change its appearance; it's found lining the bladder. Each type plays a unique role and is adapted to its function, such as protection, absorption, filtration, and secretion.

Connective Tissue

As the name implies, connective tissue supports and structures other tissues in the body. It is the most abundant and widely distributed tissue type. Unlike epithelial tissue, connective tissue typically has sparse cells scattered throughout an extracellular matrix, which is rich in fibrous proteins and can vary in density and composition. Major categories include:

• Loose connective tissue - Provides flexibility and cushioning; examples include areolar, adipose, and reticular tissues.
• Dense connective tissue - Offers strength and rigidity; found in tendons and ligaments.
• Cartilage - A semi-rigid structure that maintains shape and provides smooth surfaces for movement.
• Bone - The rigid, mineralized connective tissue that forms the skeleton.
• Blood - Consists of cells surrounded by a liquid matrix (plasma), which transports substances throughout the body.

Connective tissue also has specialized cells, such as fibroblasts that produce fibers, and adipocytes which store fat. It is integral to providing structure, storing energy, transporting substances, and protecting organs.

Human Tissue Classification

Human tissue classification serves as a foundation for understanding the complex structure and function of the body. Tissue types are broadly divided into four primary categories:

• Epithelial tissue - Covers body surfaces, lines cavities and ducts, forms glands.
• Connective tissue - Supports and integrates different parts of the body.
• Muscle tissue - Enables movement through contraction; types include skeletal, cardiac, and smooth muscle.
• Nervous tissue - Conducts electrical impulses, processes information, and controls responses to the environment.

Each category encompasses various sub-types and specializes to fulfill distinct physiological roles. The harmonious interaction between these tissue groups is what allows for the complex functionality of an organism. Anatomy and physiology courses dissect these classifications further to give students an in-depth understanding of the structure and function of the human body.