Chapter 20
Unifying Concepts of Animal Structure and Function
I. The
Structural Organization of Animals
1. In
animals, individual cells are grouped into tissues, which are in turn grouped
into organs, which participate in systems, which together make up the entire
organism.
2.
Parts of the body at each level of the hierarchy act together to perform the
functions of life.
3.
Anatomy is the study of the structure of an organism,
while physiology is the study of the
functions an organism performs.
4.
Structure and function are
correlated at all levels of biological organization.
5.
Tissues are groups of
cells with a common structure and function.
(1)
Epithelial tissue
(epithelium; plural form epithelia) covers the outside of the body, and
linings of organs and cavities within the body.
1)
Simple squamous epithelium (lining the air sacs of the lung)
2)
Simple cuboidal epithelium (forming a tube in the kidney)
3)
Simple columnar epithelium (lining the intestines)
4)
Stratified squamous epithelium
(lining the esophagus)
(1)
Connective tissue
functions mainly to bind and support other tissues.
1)
Loose connective tissue:
the most widespread
2)
Fibrous connective tissue:
tendons and ligaments
3)
Adipose tissue: fat
storage
4)
Cartilage: secreted by
chondrocytes
5)
Bone (skeleton)
6)
Blood
(2)
Muscle tissue functions in
movement.
Muscle tissue is composed
of muscle fibers that are capable of contracting when stimulated by nerve
impulses.
1) Skeletal muscle
(striated muscle)
2) Cardiac muscle: wall of
the heart
3) Smooth muscle
(non-striated muscle)
(3)
Nervous tissue
forms a communication network.
Nervous tissue
senses stimuli and transmits signals.
The functional unit of nervous tissue is the neuron (nerve cell),
containing dendrite, soma and axon.
6.
Organs are made up of tissues.
An organ consists of two
or more tissues packaged into one working unit that performs a specific
function, for example, heart, brain, and intestine.
7.
Organ system is a group of organs that work together in performing vital body
functions.
(1)
Circulatory system
(2)
Respiratory system
(3)
Integumentary system
(4)
Skeletal system
(5)
Muscular system
(6)
Urinary system
(7)
Digestive system
(8)
Endocrine system
(9)
Lymphatic system
(10)
Immune system
(11)
Nervous system
(12)
Reproductive system
II.
Exchanges with the
External Environment
1.
Organisms contain open
systems that interact continuously with their environments.
2.
In complex animals, it
requires exchange between the external environment and the internal environment.
III.
Regulating the Internal Environment
1.
Homeostasis is a dynamic
state and means internal balance, steady state or constant internal environment,
for example,
2.
Homeostasis is maintained
by negative and positive feedbacks.