22 Chapter 1
Test Your Knowledge
- Glands are derived from
a. nervous tissue. c. muscle tissue.
b. connective tissue. d. epithelial tissue.- Cells joined tightly together are characteristic of
a. nervous tissue. c. muscle tissue.
b. connective tissue. d. epithelial tissue.- Cells are separated by large extracellular spaces in
a. nervous tissue. c. muscle tissue.
b. connective tissue. d. epithelial tissue.- Blood vessels and nerves are usually located within
a. nervous tissue.
b. connective tissue.
c. muscle tissue.
d. epithelial tissue.Review Activities
- Most organs are composed of
a. epithelial tissue.
b. muscle tissue.
c. connective tissue.
d. all of these. - Sweat is secreted by exocrine glands. This means that
a. it is produced by endocrine cells.
b. it is a hormone.
c. it is secreted into a duct.
d. it is produced outside the body. - Which of these statements about homeostasis is true?
a. The internal environment is maintained absolutely constant.
b. Negative feedback mechanisms act to correct deviations
from a normal range within the internal environment.
c. Homeostasis is maintained by turning effectors on and off.
d. All of these are true.
1.3 The Primary Tissues 10
A. The body is composed of four types of primary tissues:
muscle, nervous, epithelial, and connective tissues.
- There are three types of muscle tissue: skeletal, cardiac,
and smooth muscle.
a. Skeletal and cardiac muscle are striated.
b. Smooth muscle is found in the walls of the internal
organs. - Nervous tissue is composed of neurons and neuroglial
cells.
a. Neurons are specialized for the generation and
conduction of electrical impulses.
b. Neuroglial cells provide the neurons with anatomical
and functional support. - Epithelial tissue includes membranes and glands.
a. Epithelial membranes cover and line the body
surfaces, and their cells are tightly joined by
junctional complexes.
b. Epithelial membranes may be simple or stratified, and
their cells may be squamous, cuboidal, or columnar.
c. Exocrine glands, which secrete into ducts, and endocrine
glands, which lack ducts and secrete hormones into the
blood, are derived from epithelial membranes. - Connective tissue is characterized by large intercel lular
spaces that contain extracellular material.
a. Connective tissue proper is categorized into subtypes,
including loose, dense fibrous, adipose, and others.
b. Cartilage, bone, and blood are classified as connective
tissues because their cells are widely spaced with
abundant extracellular material between them.
1.4 Organs and Systems 18
A. Organs are units of structure and function that are composed of
at least two, and usually all four, of the primary types of tissues.
1. The skin is a good example of an organ.
a. The epidermis is a stratified squamous keratinized
epithelium that protects underlying structures and
produces vitamin D.
b. The dermis is an example of loose connective tissue.
c. Hair follicles, sweat glands, and sebaceous glands
are exocrine glands located within the dermis.
d. Sensory and motor nerve fibers enter the spaces
within the dermis to innervate sensory organs and
smooth muscles.
e. The arrector pili muscles that attach to the hair
follicles are composed of smooth muscle.
2. Organs that are located in different regions of the body
and that perform related functions are grouped into
systems. These include, among others, the circulatory
system, digestive system, and endocrine system.
3. Many organs contain adult stem cells, which are able to
differentiate into a number of related cell types.
a. Because of their limited flexibility, adult stem cells
are described as multipotent, rather than as totipotent
or pluripotent.
b. For example, the bulge region of a hair follicle
contains stem cells that can become keratinocytes,
epithelial cells, and melanocytes; the loss of the
melanocyte stem cells causes graying of the hair.
B. The fluids of the body are divided into two major
compartments.
1. The intracellular compartment refers to the fluid within
cells.
2. The extracellular compartment refers to the fluid outside
of cells; extracellular fluid is subdivided into plasma (the
fluid portion of the blood) and tissue (interstitial) fluid.