animal body

Copyright © 2005 Brooks/Cole — Thomson Learning

Biology, Seventh Edition Solomon • Berg • Martin

The Animal Body: The Animal Body: Introduction to Introduction to

Structure and FunctionStructure and Function


Biology, Seventh Edition CHAPTER 37 The Animal Body

• Tissue consists of a group of closely associated, similar cells that carry out specific functions

• Tissues associate to form organs, such as the heart

• Groups of tissues and organs form organ systems



• Main types of animal tissue• Epithelial

• Connective

• Muscle

• Nervous

• Classification depends on structure and origin



• Epithelial tissue forms a continuous layer or sheet covering a body surface or lining a body cavity• Protection• Absorption• Secretion• Sensation



• Connective tissue consists of fewer cells separated by intercellular substance, fibers in a matrix• Collagen fibers

• Elastic fibers

• Reticular fibers



• Connective tissue contains specialized cells• Fibroblasts

• Macrophages

• Functions of connective tissue• Joins other tissues

• Supports the body and its organs

• Protects underlying organs



• Muscle tissue consists of cells specialized to contract• Each cell is an elongated muscle

fiber containing contractile units called myofibrils



• Nervous tissue• Elongated cells called neurons

–Specialized for transmitting impulses

• Glial cells–Support and nourish neurons



• Types of epithelial cell shapes• Squamous

• Cuboidal

• Columnar

• Type of epithelial tissue• Simple

• Stratified

• Pseudostratified



• Simple squamous epithelium• Lines blood vessels and air sacs

in the lungs

• Exchange of materials by diffusion



Simple squamous epithelium



• Simple cuboidal and columnar epithelium• Lines passageways

• Specialized for secretion and absorption



Simple cuboidal epithelium



Simple columnar epithelium



• Stratified squamous epithelium• Outer layer of skin

• Lines passageways into the body

• Provides protection

• Pseudostratified epithelium• Lines passageways

• Protects underlying tissue



Stratified squamous epithelium



Pseudostratified epithelium



• Glands are formed from epithelial tissue• Goblet cells

–Unicellular glands that secret mucus–Exocrine glands secrete onto an

epithelial surface

• Endocrine glands–Release hormones into interstitial fluid or

blood



Glands



• Epithelial membrane• Sheet of epithelial tissue and a • Layer of underlying connective tissue

• Mucous membrane• Lines a cavity that opens to the

outside of the body

• Serous membrane• Lines a cavity that does not open to

the outside of the body



• Types of connective tissue• Loose connective tissue• Dense connective tissue• Elastic connective tissue• Adipose tissue• Cartilage• Bone• Blood



• Loose connective tissue• In the subcutaneous tissue

• Between many body parts

• Fibers in a semifluid matrix

• Cartilage cells (chondroctyes)• In lacunae, small cavities in the

cartilage matrix



Loose connective tissue



Cartilage



• Osteocytes• Secrete and maintain the matrix

of bone• Compact bone consists of

spindle-shaped units called osteons–Central blood vessel through a

Haversian canal surrounded by lamellae



Bone



• Skeletal muscle• Striated

• Under voluntary control

• Each elongated, cylindrical muscle fiber has several nuclei



• Cardiac muscle• Striated

• Contraction is involuntary

• Elongated, cylindrical fibers branch and fuse

• Each fiber has one or two nuclei



• Smooth muscle• Contracts involuntarily

• Elongated, spindle-shaped fibers lack striation

• Each fiber has a central nucleus

• Responsible for movement of food through the digestive tract



Muscle tissues



• Elongated neurons receive and transmit information• Dendrites receive signals and

transmit them to the cell body• Axon transmits signal to other

neurons, a muscle, or a gland• Synapse is a junction between

neurons



Nervous tissue



•Organ systems• Integumentary• Skeletal• Muscular• Nervous• Endocrine• Circulatory



•Organ systems• Lymphatic

• Respiratory

• Digestive

• Urinary

• Reproductive



• Homeostasis• Automatic tendency to maintain a

balanced internal environment

• Dynamic equilibrium maintained by negative feedback systems

• Regulators respond to counteract changes caused by stressors



Homeostasis



• Thermoregulation• Homeostatic mechanisms for

regulating body temperature

• Physiological

• Structural

• Behavioral



• Ectotherms• Body temperature varies with the

environment

• Very little energy used

• Less food needed

• Activity may be limited by daily and seasonal temperatures



• Endotherms• Mechanisms to maintain body

temperature in a narrow range

• Increased enzyme activity

• Activity even in low winter temperatures

• High energy cost



• Acclimatization• Process of adjustment to seasonal

changes• Torpor

–Adaptive hypothermia• Hibernation

–Long-term torpor in winter cold• Estivation

–Torpor caused by lack of food or water in summer heat

animal body

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