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Chapter 37. The Animal Body: Introduction to Structure and Function. 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.
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Chapter 37 The Animal Body: Introduction to Structure and Function
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 cuboidal and columnar epithelium • Lines passageways • Specialized for secretion and absorption
Stratified squamous epithelium • Outer layer of skin • Lines passageways into the body • Provides protection • Pseudostratified epithelium • Lines passageways • Protects underlying tissue
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
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
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
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
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
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
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