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Transcript
Chapter 3 Cells and Tissues Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 1 CELLS Size and shape Human cells vary considerably in size; all are microscopic Cells differ notably in shape Composition Cells contain cytoplasm—substance found only in cells Organelles—specialized structures within the cytoplasm Cell interior—surrounded by plasma membrane Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 2 CELLS (cont.) Structural parts Plasma membrane (Figure 3-1) • Forms outer boundary of cell • Composed of thin, two-layered membrane of phospholipids • Embedded with proteins • Selectively permeable Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 3 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 4 CELLS (cont.) Cytoplasm (Figure 3-2) • All cell substance from the nucleus to the plasma membrane • Cytoskeleton—internal framework of cell Made up of microfilaments and microtubules Provides support and movement of cell and organelles • Other cell parts Ribosomes – Made of two tiny subunits of mostly ribosomal RNA (rRNA) – May attach to rough endoplasmic reticulum or lie free in cytoplasm – Manufacture enzymes and other proteins; often called protein factories Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 5 CELLS (cont.) • Other cell parts (cont.) Endoplasmic reticulum (ER) – Network of connecting sacs and canals – Carry substances through cytoplasm – Rough ER collects, folds, and transports proteins made by ribosomes – Smooth ER synthesizes chemicals; makes new membrane Golgi apparatus – Group of flattened sacs near nucleus – Collect chemicals into vesicles that move from the smooth ER outward to the plasma membrane – Called the chemical processing and packaging center Mitochondria – Composed of inner and outer membranous sacs – Involved with energy-releasing chemical reactions (cellular respiration) – Often called power plants of the cell – Each mitochondrion contains one DNA molecule Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 6 CELLS (cont.) • Other cell parts (cont.) Lysosomes – Membrane-enclosed packets containing digestive enzymes – Have protective function (eat microbes) – Formerly thought to be responsible for apoptosis (programmed cell death) Centrosome – Microtubule-organizing region of the cytoskeleton near the nucleus – Centrioles—paired organelles that lie at right angles to each other within the centrosome and function in moving chromosomes during cell reproduction Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 7 CELLS (cont.) Other cell parts (cont.) Cell extensions (Figure 3-3) – Microvilli—short extensions of the plasma membrane that increase surface area and produce slight movements that enhance absorption by the cell – Cilia—Hairlike extensions with inner microtubules found on free or exposed surfaces of all cells; serve sensory functions but some are also capable of moving together in a wavelike fashion to propel mucus across a surface – Flagella—single projections (much longer than cilia) that act as “tails” of sperm cells Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 8 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 9 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 10 CELLS (cont.) Nucleus • Controls cell because it contains most of the genetic code (genome)—instructions for making proteins, which in turn determine cell structure and function • Component structures include nuclear envelope, nucleoplasm, nucleolus, and chromatin granules • DNA molecules become tightly coiled chromosomes during cell division • 46 nuclear chromosomes contain DNA, which contains the genetic code Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 11 CELLS (cont.) Relationship of cell structure and function Every human cell has a designated function— some help maintain the cell; others regulate life processes Specialized functions of a cell depend on number and types of organelles Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 12 MOVEMENT OF SUBSTANCE THROUGH CELL MEMBRANES Passive transport processes do not require added energy and result in movement “down a concentration gradient” Diffusion (Figure 3-4) • Substances scatter evenly throughout an available space, with particles moving from high to low concentration and moving through channels or carriers in a membrane to reach an equilibrium (equality of concentration) • Passive process—it is unnecessary to add energy to the system • Osmosis is diffusion of water (when some solutes cannot cross the membrane) • Dialysis is diffusion of small solute particles Filtration—movement of water and solutes caused by hydrostatic pressure on one side of membrane Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 13 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 14 MOVEMENT OF SUBSTANCE THROUGH CELL MEMBRANES (cont.) Active transport processes occur only in living cells; movement of substances is “up the concentration gradient”; this requires energy from ATP Ion pumps (Figure 3-5) • An ion pump is a protein complex in the cell membrane • Ion pumps use energy from ATP to move substances across cell membranes against their concentration gradients • Examples: sodium-potassium pump, calcium pump • Some ion pumps work with other carriers so that glucose or amino acids are transported along with ions Phagocytosis and pinocytosis • Phagocytosis (“cell eating”)—engulfs large particles in a vesicle as a protective mechanism; destroys bacteria or debris from tissue damage (Figure 3-6) • Pinocytosis (“cell drinking”)—engulfs fluids or dissolved substances into cells • Both are active transport mechanisms because they require cell energy (from ATP) to move the cytoskeleton in a way that engulfs material and pulls it into the cell Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 15 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 16 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 17 CELL REPRODUCTION DNA structure Large molecule shaped like a spiral staircase; sugar (deoxyribose) and phosphate units compose sides of the molecule; base pairs (adenine-thymine or guanine-cytosine) compose “steps” Base pairings are always the same (complementary base pairing), but the sequence of base pairs differs in different DNA molecules • A gene is a specific sequence of base pairs within a DNA molecule • Genes dictate formation of enzymes and other proteins by ribosomes, thereby indirectly determining a cell’s structure and functions; in short, genes determine heredity (Figure 3-7) Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 18 CELL REPRODUCTION (cont.) Genetic code Genetic information—stored in base-pair sequences on genes; expressed through protein synthesis RNA molecules and protein synthesis • DNA—contained in cell nucleus • Protein synthesis—occurs in cytoplasm, thus genetic information must pass from the nucleus to the cytoplasm • Process of transferring genetic information from nucleus to cytoplasm where proteins are produced requires completion of transcription and translation (Figure 3-8) Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 19 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 20 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 21 CELL REPRODUCTION (cont.) Genetic code (cont.) Transcription • Double-stranded DNA separates to form messenger RNA (mRNA) • Each strand of mRNA duplicates a particular gene (base-pair sequence) from a segment of DNA • mRNA molecules pass from the nucleus to the cytoplasm where they direct protein synthesis in ribosomes and ER Translation • Involves synthesis of proteins in cytoplasm by ribosomes • Requires use of information contained in mRNA • Codon—a series of three nucleotide bases that act as a code for specific amino acid Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 22 CELL REPRODUCTION (cont.) Cell division—reproduction of cell involving division of the nucleus (mitosis) and the cytoplasm Two daughter cells result from the division Interphase—period when cell is not actively dividing DNA replication—process by which each half of a DNA molecule becomes a whole molecule identical to the original DNA molecule; precedes mitosis Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 23 CELL REPRODUCTION (cont.) Mitosis—process in cell division that distributes identical chromosomes (DNA molecules) to each new cell formed when the original cell divides; enables cells to reproduce their own kind; makes heredity possible (Figure 3-9) • Prophase—first stage Chromatin granules become organized Chromosomes (pairs of linked chromatids) appear Centrioles move away from nucleus Nuclear envelope disappears, freeing genetic material Spindle fibers appear • Metaphase—second stage Chromosomes align across center of cell Spindle fibers attach to each chromatid Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 24 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 25 CELL REPRODUCTION (cont.) Mitosis (cont.) • Anaphase—third stage Centromeres break apart Separated chromatids are called chromosomes Chromosomes are pulled to opposite ends of cell Cleavage furrow develops at end of anaphase • Telophase—fourth stage Cell division is completed Nuclei appear in daughter cells Nuclear envelope and nucleoli appear Cytoplasm is divided (cytokinesis) Daughter cells become fully functional Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 26 CELL REPRODUCTION (cont.) Results of cell division • Two identical cells result from cell division, growing tissues or replacing old damaged cells • Differentiation—process by which daughter cells can specialize and form different kinds of tissue • Abnormalities of mitotic division can produce benign or malignant neoplasms Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 27 TISSUES (Tables 3-5 through 3-7) Epithelial tissue Covers body and lines body cavities Cells packed closely together with little matrix Classified by shape of cells (Figure 3-10) • Squamous • Cuboidal • Columnar • Transitional Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 28 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 29 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 30 TISSUES (cont.) Epithelial tissue (cont.) Also classified by arrangement of cells into one or more layers: simple or stratified Simple squamous epithelium—single layer of scalelike cells adapted for transport (e.g., absorption) (Figure 3-11) Stratified squamous epithelium—several layers of closely packed cells specializing in protection (Figure 3-12) Simple columnar epithelium—tall, column-like cells arranged in a single layer; contain mucus-producing goblet cells; specialized for absorption (Figure 3-13) Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 31 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 32 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 33 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 34 TISSUES (cont.) Epithelial tissue (cont.) Stratified transitional epithelium—up to 10 layers of roughly cuboidal-shaped cells that distort to squamous shape when stretched; found in body areas that stretch, such as urinary bladder (Figure 3-14) Pseudostratified epithelium—single layer of distorted columnar cells; each cell touches basement membrane Simple cuboidal epithelium—single layer of cubelike cells often specialized for secretory activity; may secrete into ducts, directly into blood, and on body surface (Figure 3-15) Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 35 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 36 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 37 TISSUES (cont.) Connective tissue Most abundant and widely distributed tissue in body, with many different types, appearances, and functions Relatively few cells in intercellular matrix Types • Areolar (loose connective) tissue—fibrous glue (fascia) that holds organs • • • • • • together; collagenous and elastic fibers, plus a variety of cell types Adipose (fat) tissue—lipid storage, metabolism regulation; brown fat produces heat (Figure 3-16) Reticular tissue—delicate net of collage fibers, as in bone marrow Dense fibrous tissue—bundles of strong collagen fibers; example is tendon (Figure 3-17) Bone tissue—matrix is calcified; functions as support and protection (Figure 3-18) Cartilage tissue—matrix is consistency of gristle-like gel; chondrocyte is cell type (Figure 3-19) Blood tissue—matrix is fluid; functions are transportation and protection (Figure 3-20) Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 38 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 39 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 40 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 41 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 42 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 43 TISSUES (cont.) Muscle tissue (Figures 3-21 to 3-23) Types • Skeletal muscle tissue—attaches to bones; also called striated or voluntary; control is voluntary; striations apparent when viewed under a microscope (Figure 3-21) • Cardiac muscle tissue—also called striated involuntary; composes heart wall; ordinarily cannot control contractions (Figure 3-22) • Smooth muscle tissue—also called nonstriated (visceral) or involuntary; no cross striations; found in blood vessels and other tube-shaped organs (Figure 3-23) Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 44 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 45 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 46 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 47 TISSUES (cont.) Nervous tissue (Figure 3-24) Function—rapid communication between body structures and control of body functions Neurons • Conduction cells • All neurons have cell body and two types of processes: axon and dendrite Axon (one) carries nerve impulse away from cell body Dendrites (one or more) carry nerve impulse toward cell body Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 48 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 49