Human Physiology, 14th edition (2016)

The Study of Body Function 17

Figure 1.18 Dense regular connective tissue. In this
photomicrograph, the collagen fibers in a tendon are packaged
densely into parallel groups. The ground substance is in the tiny
spaces between the collagen fibers.

Collagen fibers

Fibroblast nucleus

Figure 1.19 Adipose tissue. Each adipocyte contains
a large, central globule of fat surrounded by the cytoplasm of the
adipocyte. ( a ) Photomicrograph and ( b ) illustration of adipose
tissue.

Fat

globule

Nucleus of

adipocyte

Cytoplasm

Cell

membrane

(a)

(b)

Figure 1.20 The structure of bone. ( a ) A diagram of

a long bone, ( b ) a photomicrograph showing osteons (haversian

systems), and ( c ) a diagram of osteons. Within each central

canal, an artery (red), a vein (blue), and a nerve (yellow) is

illustrated.

(b)

(c)

(a)

Lamellae

Central canal

Osteocyte

within a

lacuna

Canaliculi

alive because they are nourished by “lifelines” of cytoplasm
that extend from the cells to the blood vessels in canaliculi
(little canals). The blood vessels lie within central canals,
surrounded by concentric rings of bone lamellae with their
trapped osteocytes. These units of bone structure are called
osteons, or haversian systems ( fig. 1.20 ).