31

CHAPTER

2

Overview of Cellular

Physiology in

Medical Physiology

OBJECTIVES

After studying this chapter, you should be able to:

■

Name the prominent cellular organelles and state their functions in cells.

■

Name the building blocks of the cellular cytoskeleton and state their contributions

to cell structure and function.

■

Name the intercellular and cellular to extracellular connections.

■

Define the processes of exocytosis and endocytosis, and describe the contribution

of each to normal cell function.

■

Define proteins that contribute to membrane permeability and transport.

■

Describe specialized transport and filtration across the capillary wall.

■

Recognize various forms of intercellular communication and describe ways in which

chemical messengers (including second messengers) affect cellular physiology.

■

Define cellular homeostasis.

INTRODUCTION

The cell is the fundamental working unit of all organisms. In

humans, cells can be highly specialized in both structure and

function; alternatively, cells from different organs can share

features and function. In the previous chapter, we examined

some basic principles of biophysics and the catabolism and

metabolism of building blocks found in the cell. In some of

those discussions, we examined how the building blocks

could contribute to basic cellular physiology (eg, DNA repli-

cation, transcription, and translation). In this chapter, we will

briefly review more of the fundamental aspects of cellular and

molecular physiology. Additional aspects that concern spe-

cialization of cellular and molecular physiology are consid-

ered in the next chapter concerning immune function and in

the relevant chapters on the various organs.

FUNCTIONAL MORPHOLOGY

OF THE CELL

A basic knowledge of cell biology is essential to an under-
standing of the organ systems in the body and the way they
function. A key tool for examining cellular constituents is the
microscope. A light microscope can resolve structures as close
as 0.2
μ
m, while an electron microscope can resolve structures
as close as 0.002
μ
m. Although cell dimensions are quite vari-
able, this resolution can give us a good look at the inner work-
ings of the cell. The advent of common access to fluorescent,

confocal, and other microscopy along with specialized probes

for both static and dynamic cellular structures further expand-

ed the examination of cell structure and function. Equally rev-

olutionary advances in the modern biophysical, biochemical,

and molecular biology techniques have also greatly contribut-

ed to our knowledge of the cell.

The specialization of the cells in the various organs is consid-

erable, and no cell can be called “typical” of all cells in the body.

However, a number of structures

(organelles)

are common to

most cells. These structures are shown in Figure 2–1. Many of

them can be isolated by ultracentrifugation combined with