4.1, 4.2, 4.3, 5.1, 5.2: Checkpoint Questions

Question 1

Define histology.

Answer 1

the study of tissues

Question 2

Identify the four major types of tissues in the body.

Answer 2

1) epithelial
2) connective
3) muscle
4) neural

Question 3

List five important characteristics of epithelilial tissue.

Answer 3

Cellularity, polarity, attachment, avasularity, regeneration

Question 4

Identify four essential functions of epithelial tissue.

Answer 4

• provides physical protection
• controls permeability
• provides sensation
• produces specialized secretions

Question 5

What is the probable function of an epithelial surface whose cells bear many microvilli?

Answer 5

involved in absorbtion or secretion (the microvilli greatly increase the surface area available for absorbtion and secretion)

Question 6

Identify the various types of epithelial cell junctions.

Answer 6

tight junctions, gap junctions, hemidesmosomes, and spot desmosomes

Question 7

What is the functional significance of gap junctions?

Answer 7

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

Question 8

identify the three cell shapes characteristic of epithelial cells.

Answer 8

• squamous (flat)
• cuboidal (cube-like)
• columnar (cylindrical)

Question 9

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 _____.

Answer 9

simple; stratified

Question 10

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?

Answer 10

No. A simple squamous epithelium does not provide enough protection against infection, abrasion, or dehydration. The skin surface has a stratified squamous epithelium.

Question 11

Why do the pharynx, esophagus, anus, and vagina have a similar epithelial organization?

Answer 11

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).

Question 12

Name the two primary types of glandular epithelia.

Answer 12

endocrine glands and exocrine glands

Question 13

The secretory cells of sebaceous glands fill with secretions and then rupture, releasing their contents. Which mode of secretion is this?

Answer 13

Sebaceous glands exhibit holocrine secretion.

Question 14

Which type of gland releases its secretions directly into the extracellular fluid?

Answer 14

endocrine gland

Question 15

Identify the layers of the epidermis.

Answer 15

stratum basale, stratum spinosum. stratum granulosum. stratum lucidum, and stratum corneum

Question 16

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?

Answer 16

stratum corneum

Question 17

A splinter that penetrates to the third layer of the epidermis of the palm is lodged in which layer?

Answer 17

stratum granulosum

Question 18

Why does swimming in fresh water for an extended period cause epidermal swelling?

Answer 18

fresh water is hypotonic with respect to skin cells, so water moves into the cells by osmosis, causing them to swell

Question 19

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?

Answer 19

No, the ridges of the fingerprints are formed in layers of the skin that are constantly regenerated, so these ridges will eventually reappear.

Question 20

Name the two pigments contrained in the epidermis.

Answer 20

carotone (an orange-yellow pigment) and melanin (a brown, yellow-brown, or black pigment)

Question 21

Why does exposure to sunlight or sunlamps darken skin?

Answer 21

melanocytes in the epidermis and dermis synthesize the pigment melanin when exposed to UV radiation, darkening the skin

Question 22

Why does the skin of a fair-skinned person appear red during exercise in hot weather?

Answer 22

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.