Essentials of Anatomy and Physiology

fat, rather it is part of the complex systems that ensure
we are nourished properly or that protect us from
pathogens that get through the skin.

FIBROUS CONNECTIVE TISSUE

Fibrous connective tissueconsists mainly of parallel
(regular) collagen fibers with a few fibroblasts scat-
tered among them (Fig. 4–5). This parallel arrange-
ment of collagen provides great strength, yet is
flexible. The locations of this tissue are related to
the need for flexible strength. The outer walls of arter-

ies are reinforced with fibrous connective tissue,

because the blood in these vessels is under high pres-

sure. The strong outer wall prevents rupture of the

artery (see also Box 4–2: Vitamin C and Collagen).

Tendons and ligaments are made of fibrous connective

tissue. Tendons connect muscle to bone; ligaments

connect bone to bone. When the skeleton is moved,

these structures must be able to withstand the great

mechanical forces exerted upon them.

Fibrous connective tissue has a relatively poor

blood supply, which makes repair a slow process. If

you have ever had a severely sprained ankle (which

Tissues and Membranes 77

Table 4–2 TYPES OF CONNECTIVE TISSUE

Type Structure Location and Function

Blood

Areolar (loose)

Adipose

Fibrous

Elastic

Bone

Cartilage

Within blood vessels

• Plasma—transports materials


• RBCs—carry oxygen


• WBCs—destroy pathogens


• Platelets—prevent blood loss
  Subcutaneous


• Connects skin to muscles; WBCs destroy pathogens
  Mucous membranes (digestive, respiratory, urinary,
  reproductive tracts)


• WBCs destroy pathogens
  Subcutaneous


• Stores excess energy


• Produces chemicals that influence appetite, use
  of nutrients, and inflammation
  Around eyes and Kidneys


• Cushions
  Tendons and ligaments (regular)


• Strong to withstand forces of movement of joints
  Dermis (irregular)


• The strong inner layer of the skin
  Walls of large arteries


• Helps maintain blood pressure Around alveoli in lungs


• Promotes normal exhalation
  Bones


• Support the body


• Protect internal organs from mechanical injury


• Store excess calcium


• Contain and protect red bone marrow
  Wall of trachea


• Keeps airway open
  On joint surfaces of bones


• Smooth to prevent friction
  Tip of nose and outer ear


• Support
  Between vertebrae


• Absorb shock

Plasma (matrix) and red blood cells,

white blood cells, and platelets

Fibroblasts and a matrix of tissue

fluid, collagen, and elastin fibers

Adipocytes that store fat (little matrix)

Mostly collagen fibers (matrix) with

few fibroblasts

Mostly elastin fibers (matrix) with few

fibroblasts

Osteocytes in a matrix of calcium

salts and collagen

Chondrocytes in a flexible protein

matrix