4.1, 4.2, 4.3, 5.1, 5.2: Checkpoint Questions Flashcards
Define histology.
the study of tissues
Identify the four major types of tissues in the body.
1) epithelial
2) connective
3) muscle
4) neural
List five important characteristics of epithelilial tissue.
Cellularity, polarity, attachment, avasularity, regeneration
Identify four essential functions of epithelial tissue.
- provides physical protection
- controls permeability
- provides sensation
- produces specialized secretions
What is the probable function of an epithelial surface whose cells bear many microvilli?
involved in absorbtion or secretion (the microvilli greatly increase the surface area available for absorbtion and secretion)
Identify the various types of epithelial cell junctions.
tight junctions, gap junctions, hemidesmosomes, and spot desmosomes
What is the functional significance of gap junctions?
Gap junctions allow small molecules and ions to pass from cell to cell; they help coordinate such functions as the beating of cilia; in cardiac and smooth muscle tissues, they are essential to the coordination of muscle cell contraction
identify the three cell shapes characteristic of epithelial cells.
- squamous (flat)
- cuboidal (cube-like)
- columnar (cylindrical)
When classifying epithelial tissue, the number of layers of cells etermines whether it is simple of stratified. A single layer of cells is termed _____, whereas multiple layers of cells are known as _____.
simple; stratified
Using a light microscope, a tissue appears as a simple squamous epithelium. Can this be a sample of the skin surface? Why or why not?
No. A simple squamous epithelium does not provide enough protection against infection, abrasion, or dehydration. The skin surface has a stratified squamous epithelium.
Why do the pharynx, esophagus, anus, and vagina have a similar epithelial organization?
All of these regions are subject to mechanical trauma and abrasion- by food (pharynx and esophagus), by feces (anus), and by intercourse or childbirth (vagina).
Name the two primary types of glandular epithelia.
endocrine glands and exocrine glands
The secretory cells of sebaceous glands fill with secretions and then rupture, releasing their contents. Which mode of secretion is this?
Sebaceous glands exhibit holocrine secretion.
Which type of gland releases its secretions directly into the extracellular fluid?
endocrine gland
Identify the layers of the epidermis.
stratum basale, stratum spinosum. stratum granulosum. stratum lucidum, and stratum corneum
Dandruff is caused by excessive shedding of cells from the outer layer of skin in the scalp. Thus, dandruff is composed of cells from which epidermal layer?
stratum corneum
A splinter that penetrates to the third layer of the epidermis of the palm is lodged in which layer?
stratum granulosum
Why does swimming in fresh water for an extended period cause epidermal swelling?
fresh water is hypotonic with respect to skin cells, so water moves into the cells by osmosis, causing them to swell
Some criminals sand the tips of their fingers so as not to leave recognizable fingerprints. Would this practice permanently remove fingerprints? Why or why not?
No, the ridges of the fingerprints are formed in layers of the skin that are constantly regenerated, so these ridges will eventually reappear.
Name the two pigments contrained in the epidermis.
carotone (an orange-yellow pigment) and melanin (a brown, yellow-brown, or black pigment)
Why does exposure to sunlight or sunlamps darken skin?
melanocytes in the epidermis and dermis synthesize the pigment melanin when exposed to UV radiation, darkening the skin
Why does the skin of a fair-skinned person appear red during exercise in hot weather?
When skin gets warm, arriving oxygenated blood is diverted to the superficial dermis for the purpose of eliminating heat. The oxygenated blood imparts a reddish coloration to the skin.
