Questions: Epithelial Tissue, Connective Tissue Proper, and Body Membranes

Flashcards covering epithelial tissue classification, specialized apical structures, exocrine/endocrine gland development, connective tissue proper sub-types, fibers, cellular characteristics, and body membranes based on BIOL 430 Lab #2 material.

What are the four primary types of tissues in the human body?

Epithelia, Connective, Muscle, and Nervous tissues.

What two criteria are used to classify epithelial tissues?

The number of cell layers (simple vs. stratified) and the shape of the cells at the apical surface (squamous, cuboidal, or columnar).

What is the main structural difference between simple and stratified epithelium?

Simple epithelium consists of a single layer of cells attached directly to the basement membrane, whereas stratified epithelium consists of two or more cell layers with only the deepest layer attaching directly to the basement membrane.

What are the two layers that compose the basement membrane deep to epithelial tissue?

The basal lamina and the reticular lamina.

What does polarity mean in the context of epithelial tissue characteristics?

Epithelial tissue has two asymmetrical surfaces: an apical surface exposed to a space, lumen, or environment, and a basal surface next to underlying connective tissue.

What are three specialized surface features that can be found at the apical surface of epithelia?

Microvilli, cilia, and keratinization.

What is the structural and functional difference between microvilli and cilia?

Microvilli are non-motile tiny protrusions that increase surface area for absorption and secretion (forming a brush border), while cilia are hair-like projections that actively propel mucus and debris across the apical surface.

What is endothelium?

A simple squamous epithelial layer that lines structures exposed to blood or blood products, such as the heart, blood vessels, and lymphatic vessels.

What is mesothelium?

The simple squamous epithelial layer of serous membranes lining closed body cavities, such as the pericardium, pleura, and peritoneum.

How do exocrine glands and endocrine glands differ structurally and functionally during development?

Exocrine glands retain a duct formed by connecting cells to release their secretions onto an apical surface, whereas endocrine glands lose their connecting duct cells and secrete hormones directly into surrounding blood vessels.

What is a goblet cell and where is it commonly found?

A unicellular exocrine gland that secretes mucus; it is commonly found scattered within simple columnar and ciliated pseudostratified columnar epithelia.

What are the primary functions and key locations of simple squamous epithelium?

Functions: Rapid diffusion, filtration, and secretion of lubricating serous fluid. Locations: Kidney glomeruli (Bowman's capsule), air sacs of lungs (alveoli), endothelium of blood and lymph vessels, and mesothelium of serous membranes.

What are the primary functions and key locations of simple cuboidal epithelium?

Functions: Absorption and secretion. Locations: Kidney tubules, ducts and secretory portions of small glands, ovary surface, and thyroid gland follicles.

What structural features distinguish nonciliated simple columnar epithelium, and where is it located?

Structure: Single layer of cells taller than wide with oval nuclei, apical microvilli (brush border), and goblet cells. Locations: Most of the digestive tract (stomach to rectum), gallbladder, and excretory ducts of some glands.

What is the function and location of ciliated simple columnar epithelium?

Functions: Absorption, secretion of mucus, and propulsion of mucus by ciliary action. Locations: Small bronchi, uterine tubes, and some regions of the uterus.

What are the key characteristics and locations of ciliated pseudostratified columnar epithelium?

Structure: Single layer of cells of varying heights (all attached to basement membrane, but not all reach apical surface) with nuclei at different levels, bearing cilia and goblet cells. Functions: Secretion of mucus and propulsion of mucus by ciliary action. Locations: Larger airways of the upper respiratory tract (nasal cavity, pharynx, larynx, trachea, bronchi).

Where is non-ciliated pseudostratified columnar epithelium located and what is its primary function?

Function: Protection. Locations: Lines male sperm-carrying ducts (epididymis and urethra) and ducts of large glands.

What distinguishes keratinized stratified squamous epithelium from nonkeratinized stratified squamous epithelium?

Keratinized stratified squamous epithelium has superficial apical layers of dead, flat cells filled with keratin protein without visible nuclei to form a dry protective barrier (epidermis of skin). Nonkeratinized stratified squamous epithelium contains moist, living surface cells with visible nuclei (lining mouth, oral cavity, pharynx, esophagus, vagina, anus).

Where is stratified cuboidal epithelium located and what is its function?

Functions: Protection and strengthening duct walls of exocrine glands. Locations: Largest ducts of sweat glands, mammary glands, salivary glands, and regions of the male urethra.

Where is stratified columnar epithelium found in the human body?

It is a rare tissue located in small amounts in the male urethra and in large ducts of some glands, such as salivary gland ducts.

What unique functional capability defines transitional epithelium?

It stretches and distends readily to accommodate changing urine volume (cells transition from polyhedral/rounded umbrella cells when relaxed to flattened squamous-like cells when distended) in the urinary bladder, ureters, and part of the urethra.

What are the three main structural components of all connective tissues?

Cells (e.g., fibroblasts, adipocytes, immune cells), ground substance (gelatinous matrix), and extracellular fibers (collagen, reticular, elastic).

What are the characteristics and functions of collagen fibers in connective tissue?

Long, strong, flexible fibers produced by fibroblasts that provide high tensile strength, durability, and resistance to stretching.

What are reticular fibers and where are they primarily utilized?

Thin, glycoprotein-coated collagenous fibers that form a net-like scaffolding (stroma) to support immune cells in lymphoid organs (spleen, lymph nodes, bone marrow, thymus).

What protein composes elastic fibers, and what physical property do they impart to tissues?

Elastin; they allow tissues to stretch under tension and recoil passively back to their original shape.

What structural and functional differences exist between a fibroblast and a fibrocyte?

A fibroblast is in an activated state with a large size, irregular shape, large ovoid nucleus, and basophilic cytoplasm that actively produces matrix. A fibrocyte is in a less active state with a smaller size, spindle shape, small nucleus, and acidophilic cytoplasm.

What is the cell composition, fiber content, and function of loose areolar connective tissue?

Composition: Fibroblasts, macrophages, mast cells, and leukocytes dispersed in gel-like ground substance with all three fiber types (collagen, elastic, reticular). Functions: Wraps and cushions organs, binds epithelia to deeper tissue, holds tissue fluid, phagocytizes bacteria, and plays a role in inflammation.

What are the three types of fat in the human body, and how do white fat and brown fat differ functionally?

The three types are White Fat, Brown Fat, and Beige Fat. White fat contains single large lipid droplets for lipid/energy storage and organ cushion. Brown fat contains numerous small lipid droplets and high mitochondrial content to burn fat and generate heat (non-shivering thermogenesis).

What tissue type forms the stroma of lymphoid organs like the spleen and lymph nodes?

Reticular connective tissue, consisting of a network of reticular fibers and reticular cells supporting white blood cells (lymphocytes), mast cells, and macrophages.

What structural arrangement allows dense regular connective tissue to withstand high tensile stress in a single direction?

Densely packed, parallel organization of collagen fiber bundles with fibroblasts squeezed between fiber rows and scarce ground substance.

What are three primary anatomical structures composed of dense regular connective tissue?

Tendons (attach muscle to bone), ligaments (attach bone to bone), and aponeuroses (flat, wide sheet attachments).

How does dense irregular connective tissue differ structurally and functionally from dense regular connective tissue?

Dense irregular connective tissue contains collagen fibers arranged randomly/irregularly in multiple directions, allowing it to withstand tension applied from many directions (e.g., in the dermis of skin, submucosa of digestive tract, and fibrous joint capsules).

Where is elastic connective tissue located, and why is it essential in large blood vessels like the aorta?

Located in the walls of large arteries (aorta), certain ligaments associated with the vertebral column, and bronchial tube walls; it allows high-pressure blood vessels to stretch during heart contraction and recoil passively to maintain pulsatile blood flow.

What epithelial and connective tissue layers compose the cutaneous membrane?

Keratinized stratified squamous epithelium (epidermis) supported deep by loose areolar connective tissue and dense irregular connective tissue (dermis).

What tissue components make up a mucous membrane (mucosa)?

An epithelial layer (e.g., nonkeratinized stratified squamous, simple columnar, or ciliated pseudostratified columnar epithelium) resting on a layer of loose areolar connective tissue called the lamina propria.

What tissue components constitute a serous membrane (serosa)?

A simple squamous epithelium (mesothelium) resting on a thin layer of loose areolar connective tissue.

How do the body locations of mucous membranes compare to serous membranes?

Mucous membranes line body cavities that are open to the exterior (digestive, respiratory, urinary, and reproductive tracts). Serous membranes line body cavities that are closed to the exterior (pleural, pericardial, and peritoneal cavities).