Animal Form and Function: Animals are multicellular organisms with their specialized cells grouped...

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Animal Form and Function:

• Animals are multicellular organisms with their specialized cells grouped into tissues.

• In most animals, combinations of various tissues make up functional units called organs, and groups of organs that work together form organ systems.

Fig. 41.13

Anatomy and Physiology

Anatomy is the study of the structure of an organism.

Physiology is the study of the functions an organism performs.

1. Epithelial tissue: covers the outside of the body and lines organs and cavities within the body.

2. Connective tissue: functions mainly to bind and support other tissues.

3. Nervous tissue: senses stimuli and transmits signals from one part of the animal to another.

4. Muscle tissue: is composed of long cells called muscle fibers that are capable of contracting when stimulated by nerve impulses.

Epithelial Cells:

– The epithelium functions as a barrier protecting against mechanical injury, invasive microorganisms, and fluid loss.

– The free surface of the epithelium is exposed to air or fluid, and the cells at the base of the barrier are attached to a basement membrane, a dense mat of extracellular matrix.

• Epithelia are classified by the number of cell layers and the shape of the cells on the free surface.

• A simple epithelium has a single layer of cells, and a stratified epithelium has multiple tiers of cells.

• The shapes of cells may be cuboidal (like dice), columnar (like bricks on end), or squamous (flat like floor tiles).

Fig. 40.1

Fig. 41.19

The free epithelial surfaces of some mucous membranes have beating cilia that move the film of mucus along the surface.In the respiratory tubes, this traps dust and particles.

Connective tissue

–Connective tissues have a sparse population of cells scattered through an extracellular matrix.

–The matrix generally consists of a web of fibers embedding in a uniform foundation that may be liquid, jellylike, or solid.

–In most cases, the connective tissue cells secrete the matrix.

• Three kinds of connective tissue All of which are all proteins:

1. Collagenous fibers are made of collagen.– Collagenous fibers are nonelastic and do not

tear easily when pulled lengthwise.

2. Elastic fibers are long threads of elastin.– Elastin fiber provide a rubbery quality.

3. Reticular fibers are very thin and branched.– Composed of collagen and continuous with

collagenous fibers, they form a tightly woven fabric that joins connective tissue to adjacent tissues.

• The major types of connective tissues in vertebrates are loose connective tissue, adipose tissue, fibrous connective tissue, cartilage, bone, and blood.– Each has a

structure correlated with its specialized function.

Fig. 40.2

Loose Connective Tissue

Adipose Tissue

Fibrous Connective Tissue

Cartilage

The microscopic structure of hard mammalian bones consists of repeating units called osteons.

Each osteon has concentric layers of mineralized matrix deposited around a central canal containing blood vessels and nerves that service the bone.

Bone Tissue

• There are three types of muscle tissue in the vertebrate body: skeletal muscle, cardiac muscle, and smooth muscle.

Fig. 40.4

• skeletal muscle

Fig. 40.4

• cardiac muscle

Fig. 40.4

• smooth muscle

Fig. 40.4

cytoplasm dendron

cell membrane

nucleus

nucleus of cell which makes the myelin sheath

direction of nerve

impulses

neurone

Animal Form and Function: Animals are multicellular organisms with their specialized cells grouped...

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