Fig. 1.8

Levels of Organization

Cellular Level of Organization

• the basic unit of life

• Cells are semi-autonomous.– increasing differentiation

/ decreasing autonomy

Tissue Level of Organization

• histology = study of tissues

• collection of similar cells and associated extracellular materials

• organization– sheets (e.g., linings of skin, respiratory and

digestive tracts)– masses (e.g., skeletal muscle tissue,

cardiac muscle tissue)– masses of sheets (e.g., liver tissue)

Organ Level of Organization

• 2 or more tissues joined together to perform a specific function or functions– e.g., liver

• liver epithelial tissue• bile duct epithelial tissue• blood vessel epithelial tissue, smooth muscle• connective tissue

– e.g., stomach• glandular epithelial tissue• smooth muscle• connective tissue

• Most organs have a distinct, recognizable shape (including bones), but each major blood vessel is also an organ.

Organ System Level of Organization

• different organs that have a related function– often connected

• e.g., respiratory and digestive systems

– but not always• e.g., endocrine system

Fig. A.1

head

neck

trunkupperlimbs

lower limbs

Major Body Regions

Know terms on Fig. A.5

• Head– caput (Latin), cephal- (Greek)

• skull– cranium – face

• Neck– cervix (Latin)

• Trunk– thorax– abdomen

Fig. A.6

Fig. A.5

Fig. A.18

• Upper Limbs (arms)– shoulder

– axilla (-ae, plural)

– brachium

– elbow • (cubit)

– antebrachium

– hand • (manus) Fig. A.5

• Lower Limbs (legs)– groin

• inguinal region

– thigh– knee– (lower) leg– ankle– foot

• (pes, ped-)Fig. A.5

Body Cavities

Fig. A.7

coelom

BodyPlans

Wallace, et al., Biosphere, The Realm of Life

ectoderm

mesoderm

Tube-within-a-tubeBody Plan

serous serous membranesmembranes

visceralvisceral____________________

parietalparietal____________________

endoderm

The coelom is a potentialspace. Serous fluid provides lubrication.

coelom