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Structure and Function. Chapter 20. Hierarchy of Structure (A Review). From most exclusive to most inclusive Cells : structural and functional unit of a living organism Muscle fibers, neurons and erythrocyte Tissues : integrated group of cells with a common function
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Structure and Function Chapter 20
Hierarchy of Structure (A Review) • From most exclusive to most inclusive • Cells: structural and functional unit of a living organism • Muscle fibers, neurons and erythrocyte • Tissues: integrated group of cells with a common function • 4 main types: Epithelial, connective, muscle, and nervous • Organs: 2+ tissue types that work to perform a task • Heart, lungs, kidneys, brain, and liver • Organ systems: multiple organs that perform a vital function • Circulatory, nervous, reproductive, and respiratory • Organism: a number of organ systems with different functions to form 1 coordinated unit • Interaction between systems to facilitate life • Example of emergent properties
Similarity in Body Plans • Results from convergent evolution • Similar environmental challenges face diverse organisms • E.g water resistance • Can decerase by streamlining shape • Can revise earlier theories • Speed of Tyrannosaurus rex
Epithelial Tissue (epithelium) • Covers body surfaces and lines internal organs and cavities • Basal (connecting base) and apical (free) ends • Classified by cell layer and shape • Simple or stratified • Squamous, cuboidal, and columnar • Pseudostratified • Shape and layer reflect function • Simple layers facilitate diffusion • Stratified for abbrasive surfaces • Cells move basal to apical while sloughing off old
Connective Tissue • Sparse cells spread throughout a matrix they created • Liquid, jelly, or solid • 6 major types • Loose connective: most common, matrix of collagen (strength) and elastic (resilient) fibers • Fibrous connective: dense packing of collagen fibers; tendons and ligaments • Adipose: stores fat in cells; fat droplet swell or shrink with storage • Cartilage: dense collagen fibers (strong and flexible) • Bone: collagen in mineralized Ca2+, Mg2+, and P • Blood: matrix is plasma containing water, salts, and dissolved proteins
Cells called muscle fibers Most abundant tissue in most animals Contractile proteins, actin and myosin, within cytoplasm 3 Types Muscle Tissue
Senses stimuli and transmits information throughout the body Structural, functional unit is a neuron Tissue contains neurons and other supporting cells CellBody Nucleus Nervous Tissue
Each of the 4 tissue types perform different functions Together contribute to the functioning of an organ Bioengineers have created artificially in the lab for replacements from a recipients cells Organs
Anatomical Terminology Posterior Sagittal plane Anterior
Organ Systems • All interdependent and work together • 12 found in vertebrate animals • Endocrine: controls hormones • Skeletal: bones for structure, support, and shape • Circulatory: nutrients and oxygen to body • Respiratory: exchange gases in body with environment • Muscular: produces movement and heat; produces heat • Integument: skin for protection and fluid retention • Lymphatic: lymph nodes to return excess fluid; immunity role • Immune: defense against infections • Urinary: bladder to excrete nitrogenous wastes and regulation • Digestive: ingest and breaks down food to obtain nutrients • Reproductive: gametes and gonads to preserve the species • Nervous: coordinates body activities and cell signaling
Integument System • Skin, hair, and nails • Structure • Epidermis (5 layers) of stratified squamous • Dermis contains accessory structures • Hypodermis contains adipose tissue; injection sites • Functions • Tightly joined cells for protection • Sensory receptors for environmental information • Produce vitamin D, necessary for absorbing calcium • Adequate sunlight necessary • Hair and nails • Oil secretion lubricate hair and inhibit bacterial growth • Insulation, goose-bumps are remnants • Nails for manipulation and scratching
Molecular Exchange • O2 and nutrients must enter cells • CO2 and wastes must exit • Larger organisms have smaller outer surfaces than inner • All cells must be in an aqueous environment • Folds and alternate structures within to facilitate
Homeostasis and Feedback • Responses minimize internal changes due to large external ones • Most homeostatic controls due to negative feedback • One variable change causes a reverse change • Interaction of stimulus, receptor, control center, and effector, and response