Page 37 - Anatomy and Physiology of Farm Animals, 8th Edition

22 / Anatomy and Physiology of Farm Animals

Learning Objectives was called protoplasm. The protoplasm of
the cell has since been further defined to
VetBooks.ir • Define and be able to explain the contain cytoplasm and the organelles nec­

essary for cellular function.
significance of the bold italic terms in
this chapter. In 1839 Matthias Schleiden, a German
• Briefly outline the basic properties of a botanist, and Theodor Schwann, an animal
cell and how the organization of the cell anatomist, formulated the cell theory, which
contributes to each basic property. set forth the concept that “the elementary
• Describe the chemical composition of parts of all tissues are formed of cells in an
cells and how these chemicals contribute analogous, though very diversified, manner,
to homeostasis. so that it may be asserted that there is one
• Be able to differentiate between the use universal principle of development for the
of light microscopy and electron micros­ elementary parts of organisms, however
copy when studying the cell and its different, and that this principle is the
components. formation of cells.”
• Describe how transport is achieved across The word cell comes from the Latin
a cell membrane. Differentiate between cella meaning small chamber. In biology,
the rate of transport and the need for particularly animal biology, the term cell
energy to achieve transport. refers more specifically to the individual
• Which cells are capable of an action units of living structure rather than the
potential and how is it achieved in a compartments that may contain them.
cell? With the exception of bone and cartilage,
• What is the function of each of the there are actually no compartments in
organelles? most tissues. The living units of an organism,
• What are the primary differences between the cells, are found in groups, which we
a cell surface receptor and a cytoplasmic then classify into tissues or organs and
or nuclear receptor? classify into systems.
• Be able to characterize the type of ligand,
type of receptor, speed of the biological
response, and whether that response is Properties of Life
associated with gene transcription, second
messengers, or both. It is difficult to give a satisfactory defini­
• What is the central dogma of molecu­ tion of life. However, the cell is the func­
lar biology? Can you describe each of tional unit of all animal life. It is the unit
these steps and where they occur in the that makes up all tissues, organs, and
cell? systems, which in turn make up the total
• What is the difference between mitosis animal. Therefore, the properties of the
and meiosis? cell are equated with those of life. These
properties include homeostasis, growth,
reproduction, absorption, metabolism,
iscovery of living cells would have secretion, irritability, conductivity, and
Dbeen difficult, if not impossible, contractility. The last two characteristics,
before Zacharias Jansen of the Netherlands however, are not properties of all cells.
invented the compound microscope in 1590. Conductivity is an important functional
Robert Hooke of England used the term characteristic of both nerve and muscle
cell to describe the cavities he saw in sec­ cells, whereas contractility is a property
tions of cork. In 1665, Hooke published a of only muscle cells.
description of cork cells based on a study Homeostasis is the tendency for living
done with his improved compound micro­ things to attempt to maintain a state of
scope. As early as 1772, Corti observed relative stability. At the whole‐animal level
the jellylike material in the cell that later or at the cellular level, all living things