*Exercise 6A: Classification of Tissues
Group of cells that are similar in structure and function
lines body cavities and covers the body's external surface
pumps blood, flushes urine out of body, and allows one to swing a bat.
transmits electrochemical impulses
anchors, packages, and supports body organs
cells may absorb, secrete and filter, synthesizes hormones
most involved in regulating and controlling body functions
major function is to contract
the most durable tissue type
abundant nonliving extracellular matrix
most widespread tissue in the body
forms nerves and the brain
Describe five general characteristics of epithelial tissue.
Polarity, Cellularity, Supported by Connective tissue, Avascularity and Regeneration
On what basis are epithelial tissues classified?
arrangement or relative number of layers and cell shape
List five major functions of epithelium in the body, and give examples of each.
1. protection; epithelium covering body surface protects against bacterial invasion and chemical damage.
2. absorption; epithelium specialized to absorb substances lines the stomach and small intestines.
3. filtration; in kidney tubules, epithelium filters (and absorbs and secretes)
4. excretion; Sweat is excreted from the body by epithelial cells in the sweat glands
5. secretion; In glands, epithelial tissue is specialized to secrete specific chemical substances such as enzymes, hormones and lubricating fluids
How does the function of stratified epithelia differ from the function of simple epithelia?
Simple means that there is only one layer of these cells, not as much protection as stratified which indicates several layers of cells. Stratified epithelia are named according to the cells at the apical surface of the epithelial membrane, not those resting on a basement membrane like the simple epithelia.
Where is ciliated epithelium found? What role does it play?
Can be found in the lining of the trachea, most of the upper respiratory tract. There role is to keep mucus and any other debris from entering the lower reaches of the lung tissue by moving in a upward direction.
Transitional epithelium is actually stratified squamous epithelium with special characteristics. How does it differ structurally from other stratified squamous epithelia? How does the structural difference support its function?
its structure is different in that it is rounded, or "plump" cells. Its structural difference supports in function in that it has the ability to slide over one another to allow the organ to be stretched.
How do the endocrine and exocrine glands differ in structure and function?
Endocrine glands are ductless, and there function is to release all hormones into the extracellular fluid where they enter blood stream and lymphatic vessels. But Exocrine glands have ducts, and they secrete through the ducts to an epithelial surface.
Lining of the esophagus
Lining of the stomach
Alveolar Sac of Lungs
Tubules of the kidney
Epidermis of the skin
Lining of bladder; peculiar cells that have the ability to slide over each other
Forms the thin serous membranes; a single layer of flattened cells.
What are three general characteristics of connective tissues?
1. With a few exceptions, connective tissues have a rich supply of blood vessels.
2. Connective tissues are composed of many types of cells.
3. There is a great deal of noncellular, nonliving material (matrix) between the cells of connective tissues.
What functions are performed by connective tissue?
protection, support, and bind together tissues of the body.
How are the functions of connective tissue reflected in its structure?
there is a wide variety in the structures of connective tissue. This is relected in the wide variety of functions they perfrom. Also, the large amount of nonliving matrix seen provides the strength needed to protect the body and carry out the normal functions of the body.
attaches bones to bones and muscles to bones
dense connective tissue
acts as a storage depot for fat
the dermis of the skin
makes up the intervertebral discs
forms the hip bone
composes basement membranes; a soft packaging tissue with a jellylike matrix
forms the larynx the costal cartilages of the ribs and the embryonic skeleton
provides a flexible framework for the external ear
firm structurally amorphous matrix heavily invaded with fibers; appears glassy and smooth
matrix hard owing to calcium salts; provides levers for muscles to act on
insulates against heat loss
adipose connective tissue
walls of large arteries
Why do adipose cells remind people of a ring with a single jewel?
they contain a large fat-filled vacuole occupying most of the cell volume. The nucleus is pushed to the periphery, giving the cell a "signet ring" appearance.
What two physiological characteristics are highly developed in neurons, nerve cells?
irritablility and conductivity
In what ways are neurons similar to other cells?
they constain a nucleus and the usual organelles.
How are neurons and other cells different?
their cytoplasm is drawn out into long processes.
Describe how the unique structure of a neuron relates to its function in the body
neurons conduct impulses over relatively long distances in the body. This is facilitated by their long cytoplasmic extensions.
Muscle tissue: voluntarily controlled
Muscle tissue: involuntarily controlled
Muscle tissue: striated
Muscle tissue: has a single nucleus in each cell
tissue: has several nuclei per cell
tissue: found attached to bone
tissue: allows you to direct your eyeballs
Muscle tissue: found in the walls of the stomach, uterus and arteries
tissue: contains spindle-shaped cells
tissue: contains branching cylindrical cells
tissue: contains long, nonbranching cylindrical cells
Muscle tissue: has intercalated discs
Muscle tissue: concerned with locomotion of the body as a whole
Muscle tissue: changes the internal volume of an organ as it contacts
Muscle tissue: tissue of the heart