Labs 1-8 Flashcards
Simple Squamous Epithelium
Locations: Mesothelia lining ventral body cavities; endothelia lining heart and blood vessels; portions of the kidney tubules (thin sections of nephron loops); inner lining of cornea; alveoli of lungs.
Function: Reduces friction; controls vessel permeability; performs absorption and secretion.
Definition: is a thin tissue that in a superficial preparation appears as a sheet of cells that look like ceramic floor tiles. In serous membranes this tissue is called mesothelium. In locations where it lines blood vessels and the heart chambers it’s endothelium. Simple squamous epithelium also constructs the thin walls of air sacs in the lungs, where gas exchange occurs. Squamous epithelial cells are irregularly shaped, flat, and scale-like. These cells depending on how they are organized, function either in protection or in secretion and diffusion.
Simple Cuboidal Epithelium
Locations: Glands; ducts; portions of the kidney tubules; thyroid gland
Function: Limited protection, secretion, absorption.
Definition: lines kidney tubules, the thyroid and other glands, and ducts. On slides of cuboidal epithelium from the kidney, the tubules sectioned longitudinally appear as two rows of square cells; in transverse sections, the cuboidal cells are arranged in a ring to form the round wall of the tubule. Typically the basal lamina is conspicuous in simple cuboidal epithelium. Cuboidal epithelial cells are cubic (that is, their cross section is approximately square) and have a large nucleus.
Simple Columnar Epithelium
Locations: Lining of stomach, intestine, gallbladder, uterine tubes, and collecting ducts of kidneys.
Function: Protection, secretion, and absorption.
Definition: lines most of the digestive tract, the uterine tubes, and the renal collecting ducts. In the small intestine, the wall is folded and covered with simple columnar epithelium to increase the surface area available for digestion and absorption of nutrients. In the uterine tubes, the cilia transport released eggs to the uterus. These have Microvilli.
Stratified Squamous Epithelium
Location: Surface of the skin; lining of the mouth, throat, esophagus, rectum, anus, and vagina.
Function: Provides physical protection against abrasion, pathogens, and chemical attack.
Has squamous superficial cells and stem cells.
Definition: forms the superficial region of the skin, called the epidermis. Stem cells produce new cells at the basal lamina and are pushed toward the free surface by the next group of new cells. The cells manufacture the protein keratin, which toughens the cells but also kills them. The cells then dehydrate and interlock into a broad sheet, forming a dry protective barrier against abrasion, friction, chemical exposure, and even infection. Stratified squamous epithelium of the skin is thus said to be keratinized and has a dry surface.
Stratified squamous epithelium also lines the tongue, mouth, pharynx, esophagus, anus, and vagina. The epithelium in these regions is kept moist by lining cells on the tissue surface. This moist tissue is described as being nonkeratinized (mucosal type) stratified squamous epithelium.
Stratified Epithelia
Multilayered tissues with only the bottom layer of cells in contact with the basal lamina and only the upper cells exposed to the free surface. Stratified Epithelia are found in areas exposed to abrasion and friction, such as the body surface and upper digestive tract. When a stratified epithelium contains more than one type of epithelial cell, the type at the free surface determines the classification of the tissue.
Stratified Cuboidal Epithelium
Location: Lining of some ducts (rare).
Function: Protection, secretion, and absorption.
Definition: is uncommon. It is found in the ducts of certain sweat glands.
Stratified Columnar Epithelium
Location: Small areas of the pharynx, epiglottis, anus, mammary gland, salivary gland ducts, and urethra.
Function: Protection.
Definition: is found in parts of the mammary glands, in salivary-gland ducts, and in small regions of the pharynx, epiglottis, anus, and urethra.
Pseudostratified Ciliated Columnar Epithelium
Location: Lining of nasal cavity, trachea, and bronchi; portions of male reproductive tract.
Function: Protection, secretion.
Definition:lines the nasal cavity, the trachea, bronchi, and parts of the male reproductive tract. The tissue has columnar cells and smaller stem cells, which replenish the tissue. It appears stratified but is not because every cell touches the basal lamina. Typically the columnar cells are ciliated, and the tissue is called pseudostratified ciliated columnar epithelium. Large goblet cells interspersed among the columnar cells secrete mucus onto the epithelial free surface. The mucus traps dust and other particles in the inhaled air. Cilia at the free surface sweep the mucus to the throat, where it is swallowed and disposed of in the digestive tract.
Transitional Epithelium
Location: Urinary bladder; renal pelvis; ureters.
Function: Permits expansion and recoil after stretching.
Definition: lines organs, such as the urinary bladder, that must stretch and shrink. The cells have a variety of shapes and sizes, and not all of them touch the basal lamina. Most transitional tissue slides are prepared from relaxed transitional tissue, and the tissue appears thick, with many cells stacked one upon another. If the organ is stretched, the transitional epithelium gets thinner.
Simple Epithelium
The main functions of simple epithelium are diffusion, absorption, and secretion. At the free surface, microvilli on the epithelial cell membrane increase the surface area available for absorption. To protect the tissue at the free surface, cells called goblet cells secrete mucus that coats the cells. Other cells in a simple epithelial layer have cilia that sweep the mucus along the free surface to remove debris.
Collagen fibers
Give strength
Elastic fibers
Provide flexibility
Reticular fibers
Interwoven proteins found in reticular connective tissue; they provide a framework for support of internal soft organs, such as the liver and spleen.
Connective Tissue Proper
Has a thick liquid matrix and a variety of cell types. Connective tissue proper is divided into 2 categories Loose (areolar, adipose, reticular), Dense (dense regular, dense irregular, and elastic).
Fluid Connective Tissue
Liquid tissues that flow through blood vessels and lymphatic vessels.
Blood- Contained in cardiovascular system
Lymph-Contained in lymphatic system.
