Chapter 3 Cells and Tissues. Mosby items and derived items © 2008 by Mosby, Inc., an affiliate of...

Chapter 3Chapter 3Cells and TissuesCells and Tissues

Mosby items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 2

CELLSCELLS

Size and shapeSize and shape Human cells vary considerably in size; all are Human cells vary considerably in size; all are

microscopicmicroscopic Cells differ notably in shapeCells differ notably in shape

CompositionComposition Cytoplasm containing specialized organelles Cytoplasm containing specialized organelles

surrounded by a plasma membranesurrounded by a plasma membrane Organization of cytoplasmic substances Organization of cytoplasmic substances

important for lifeimportant for life


CELLSCELLS

Structural partsStructural parts Plasma membrane forms outer boundary of Plasma membrane forms outer boundary of

cell (Figure 3-1)cell (Figure 3-1)• Thin, two-layered membrane of phospholipids Thin, two-layered membrane of phospholipids

containing proteinscontaining proteins

• Is selectively permeableIs selectively permeable



CELLSCELLS

Cytoplasm (Figure 3-2)Cytoplasm (Figure 3-2)• OrganellesOrganelles

RibosomesRibosomes– May attach to rough ER or lie free in cytoplasmMay attach to rough ER or lie free in cytoplasm

– Manufacture proteins; often called Manufacture proteins; often called protein factoriesprotein factories Endoplasmic reticulum (ER)Endoplasmic reticulum (ER)

– Network of connecting sacs and canalsNetwork of connecting sacs and canals

– Carry substances through cytoplasmCarry substances through cytoplasm

– Rough ER collects and transports proteins made by ribosomesRough ER collects and transports proteins made by ribosomes

– Smooth ER synthesizes chemicals; makes new membraneSmooth ER synthesizes chemicals; makes new membrane Golgi apparatusGolgi apparatus

– Group of flattened sacs near nucleusGroup of flattened sacs near nucleus

– Collect chemicals that move from the smooth ER in vesicles Collect chemicals that move from the smooth ER in vesicles and process them: called the and process them: called the chemical processing and chemical processing and packaging centerpackaging center



CELLSCELLS

Cytoplasm Cytoplasm • Organelles (cont.)Organelles (cont.)

MitochondriaMitochondria– Composed of inner and outer membranes; contains one DNA Composed of inner and outer membranes; contains one DNA

moleculemolecule

– Involved with energy-releasing chemical reactions; called Involved with energy-releasing chemical reactions; called power power plantsplants of the cell of the cell

LysosomesLysosomes– Membrane-enclosed packets containing digestive enzymesMembrane-enclosed packets containing digestive enzymes

– Have protective function (eat microbes)Have protective function (eat microbes)

– Formerly thought to be responsible for apoptosis (programmed Formerly thought to be responsible for apoptosis (programmed cell death)cell death)

CentriolesCentrioles– Paired organelles that lie at right angles to each other near Paired organelles that lie at right angles to each other near

nucleusnucleus

– Function in cell reproductionFunction in cell reproduction


CELLSCELLS

Cytoplasm Cytoplasm • Organelles (cont.)Organelles (cont.)

CiliaCilia– Fine, hairlike extensions found on free or exposed Fine, hairlike extensions found on free or exposed

surfaces of some cellssurfaces of some cells– Capable of moving in unison in a wavelike fashionCapable of moving in unison in a wavelike fashion

FlagellaFlagella– Single projections extending from cell surfaces; much Single projections extending from cell surfaces; much

larger than cilialarger than cilia– ““Tails” of sperm cells only example of flagella in humansTails” of sperm cells only example of flagella in humans


CELLSCELLS

NucleusNucleus• Controls cell because it contains the genetic code—Controls cell because it contains the genetic code—

instructions for making proteins, which in turn instructions for making proteins, which in turn determine cell structure and functiondetermine cell structure and function

• Component structures include nuclear envelope, Component structures include nuclear envelope, nucleoplasm, nucleolus, and chromatin granulesnucleoplasm, nucleolus, and chromatin granules

• 46 chromosomes contain DNA, which contains the 46 chromosomes contain DNA, which contains the genetic codegenetic code


CELLSCELLS

Relationship of cell structure and functionRelationship of cell structure and function Regulation of life processesRegulation of life processes Relationship of structure to function apparent in Relationship of structure to function apparent in

number and type of organelles seen in different number and type of organelles seen in different cellscells


MOVEMENTS OF SUBSTANCES MOVEMENTS OF SUBSTANCES THROUGH CELL MEMBRANESTHROUGH CELL MEMBRANES

Passive transport processes do not require added Passive transport processes do not require added energy and result in movement “down a energy and result in movement “down a concentration gradient”concentration gradient” Diffusion (Figure 3-3)Diffusion (Figure 3-3)

• Substances scatter themselves evenly throughout an Substances scatter themselves evenly throughout an available space, the particles moving from high to low available space, the particles moving from high to low concentrationconcentration

• Passive process—not necessary to add energy to the Passive process—not necessary to add energy to the systemsystem

• Osmosis is diffusion of water (some solutes cannot cross Osmosis is diffusion of water (some solutes cannot cross the membrane during osmosis)the membrane during osmosis)

• Dialysis is diffusion of small solute particlesDialysis is diffusion of small solute particles Filtration—movement of water and solutes caused by Filtration—movement of water and solutes caused by

hydrostatic pressure on one side of membranehydrostatic pressure on one side of membrane


MOVEMENTS OF SUBSTANCES MOVEMENTS OF SUBSTANCES THROUGH CELL MEMBRANESTHROUGH CELL MEMBRANES

Active transport processes occur only in living cells; Active transport processes occur only in living cells; movement of substances is “up the concentration gradient”; movement of substances is “up the concentration gradient”; this requires energy from ATPthis requires energy from ATP Ion pumps (Figure 3-4)Ion pumps (Figure 3-4)

• An ion pump is a protein complex in the cell membraneAn ion pump is a protein complex in the cell membrane• Ion pumps use energy from ATP to move substances across cell Ion pumps use energy from ATP to move substances across cell

membranes against their concentration gradientsmembranes against their concentration gradients• Examples: sodium-potassium pump, calcium pumpExamples: sodium-potassium pump, calcium pump• Some ion pumps work with other carriers so that glucose or amino Some ion pumps work with other carriers so that glucose or amino

acids are transported along with ionsacids are transported along with ions Phagocytosis and pinocytosisPhagocytosis and pinocytosis

• Both are active transport mechanisms because they require cell Both are active transport mechanisms because they require cell energyenergy

• Phagocytosis is a protective mechanism often used to destroy Phagocytosis is a protective mechanism often used to destroy bacteriabacteria

• Pinocytosis is used to incorporate fluids or dissolved substances Pinocytosis is used to incorporate fluids or dissolved substances into cellsinto cells


CELL REPRODUCTIONCELL REPRODUCTION

DNA structure—large molecule shaped like a DNA structure—large molecule shaped like a spiral staircase; sugar (deoxyribose) and spiral staircase; sugar (deoxyribose) and phosphate units compose sides of the molecule; phosphate units compose sides of the molecule; base pairs (adenine-thymine or guanine-cytosine) base pairs (adenine-thymine or guanine-cytosine) compose “steps”; base pairs always the same but compose “steps”; base pairs always the same but sequence of base pairs differs in different DNA sequence of base pairs differs in different DNA molecules; a gene is a specific sequence of base molecules; a gene is a specific sequence of base pairs within a DNA molecule; genes dictate pairs within a DNA molecule; genes dictate formation of enzymes and other proteins by formation of enzymes and other proteins by ribosomes, thereby indirectly determining a cell’s ribosomes, thereby indirectly determining a cell’s structure and functions; in short, genes are structure and functions; in short, genes are heredity determinants (Figure 3-5)heredity determinants (Figure 3-5)



Genetic codeGenetic code Genetic information—stored in base-pair Genetic information—stored in base-pair

sequences on genes; expressed through sequences on genes; expressed through protein synthesisprotein synthesis

RNA molecules and protein synthesisRNA molecules and protein synthesis• DNA—contained in cell nucleusDNA—contained in cell nucleus• Protein synthesis—occurs in cytoplasm, thus genetic Protein synthesis—occurs in cytoplasm, thus genetic

information must pass from the nucleus to the information must pass from the nucleus to the cytoplasmcytoplasm

• Process of transferring genetic information from Process of transferring genetic information from nucleus to cytoplasm where proteins are produced nucleus to cytoplasm where proteins are produced requires completion of requires completion of transcriptiontranscription and and translationtranslation (Figure 3-5).(Figure 3-5).




Genetic code (cont.)Genetic code (cont.) TranscriptionTranscription

• Double-stranded DNA separates to form messenger Double-stranded DNA separates to form messenger RNA (mRNA)RNA (mRNA)

• Each strand of mRNA duplicates a particular gene Each strand of mRNA duplicates a particular gene (base-pair sequence) from a segment of DNA(base-pair sequence) from a segment of DNA

• mRNA molecules pass from the nucleus to the mRNA molecules pass from the nucleus to the cytoplasm where they direct protein synthesis in cytoplasm where they direct protein synthesis in ribosomes and ERribosomes and ER

TranslationTranslation• Involves synthesis of proteins in cytoplasm by Involves synthesis of proteins in cytoplasm by

ribosomesribosomes• Requires use of information contained in mRNARequires use of information contained in mRNA



Cell division—reproduction of cell involving division of the Cell division—reproduction of cell involving division of the nucleus (mitosis) and the cytoplasm; period when the cell is nucleus (mitosis) and the cytoplasm; period when the cell is not actively dividing is called not actively dividing is called interphaseinterphase

DNA replication—process by which each half of a DNA DNA replication—process by which each half of a DNA molecule becomes a whole molecule identical to the original molecule becomes a whole molecule identical to the original DNA molecule; precedes mitosisDNA molecule; precedes mitosis

Mitosis—process in cell division that distributes identical Mitosis—process in cell division that distributes identical chromosomes (DNA molecules) to each new cell formed chromosomes (DNA molecules) to each new cell formed when the original cell divides; enables cells to reproduce when the original cell divides; enables cells to reproduce their own kind; makes heredity possibletheir own kind; makes heredity possible



Stages of mitosis (Figure 3-6)Stages of mitosis (Figure 3-6) Prophase—first stageProphase—first stage

• Chromatin granules become organizedChromatin granules become organized

• Chromosomes (pairs of linked chromatids) appearChromosomes (pairs of linked chromatids) appear

• Centrioles move away from nucleusCentrioles move away from nucleus

• Nuclear envelope disappears, freeing genetic Nuclear envelope disappears, freeing genetic materialmaterial

• Spindle fibers appearSpindle fibers appear

Metaphase—second stageMetaphase—second stage• Chromosomes align across center of cellChromosomes align across center of cell

• Spindle fibers attach themselves to each chromatidSpindle fibers attach themselves to each chromatid




Stages of mitosis (cont.)Stages of mitosis (cont.) Anaphase—third stageAnaphase—third stage

• Centromeres break apartCentromeres break apart

• Separated chromatids then called Separated chromatids then called chromosomeschromosomes

• Chromosomes are pulled to opposite ends of cellChromosomes are pulled to opposite ends of cell

• Cleavage furrow develops at end of anaphaseCleavage furrow develops at end of anaphase



Stages of mitosis (cont.)Stages of mitosis (cont.) Telophase—fourth stageTelophase—fourth stage

• Cell division is completedCell division is completed

• Nuclei appear in daughter cellsNuclei appear in daughter cells

• Nuclear envelope and nucleoli appearNuclear envelope and nucleoli appear

• Cytoplasm is divided (cytokinesis)Cytoplasm is divided (cytokinesis)

• Daughter cells become fully functionalDaughter cells become fully functional


TISSUES (Tables 3-6 through 3-8)TISSUES (Tables 3-6 through 3-8)

Epithelial tissueEpithelial tissue Covers body and lines body cavitiesCovers body and lines body cavities Cells packed closely together with little matrixCells packed closely together with little matrix Classified by shape of cells (Figure 3-7)Classified by shape of cells (Figure 3-7)

• SquamousSquamous

• CuboidalCuboidal

• ColumnarColumnar

• TransitionalTransitional



TISSUESTISSUES

Epithelial tissue (cont.)Epithelial tissue (cont.) Also classified by arrangement of cells into one or more Also classified by arrangement of cells into one or more

layers: simple or stratifiedlayers: simple or stratified Simple squamous epithelium—single layer of scalelike Simple squamous epithelium—single layer of scalelike

cells adapted for transport (e.g., absorption) (Figure 3-8)cells adapted for transport (e.g., absorption) (Figure 3-8) Stratified squamous epithelium—several layers of Stratified squamous epithelium—several layers of

closely packed cells specializing in protection (Figure 3-closely packed cells specializing in protection (Figure 3-9)9)

Simple columnar epithelium—tall, column-like cells Simple columnar epithelium—tall, column-like cells arranged in a single layer; contain mucus-producing arranged in a single layer; contain mucus-producing goblet cells; specialized for absorption (Figure 3-10)goblet cells; specialized for absorption (Figure 3-10)


TISSUESTISSUES

Epithelial tissue (cont.)Epithelial tissue (cont.) Stratified transitional epithelium—up to 10 layers of Stratified transitional epithelium—up to 10 layers of

roughly cuboidal-shaped cells that distort to squamous roughly cuboidal-shaped cells that distort to squamous shape when stretched; found in body areas that stretch, shape when stretched; found in body areas that stretch, such as urinary bladder (Figure 3-11)such as urinary bladder (Figure 3-11)

Pseudostratified epithelium—single layer of distorted Pseudostratified epithelium—single layer of distorted columnar cells; each cell touches basement membranecolumnar cells; each cell touches basement membrane

Simple cuboidal epithelium—single layer of cubelike Simple cuboidal epithelium—single layer of cubelike cells often specialized for secretory activity; may secrete cells often specialized for secretory activity; may secrete into ducts, directly into blood, and on body surface into ducts, directly into blood, and on body surface (Figure 3-12)(Figure 3-12)


TISSUESTISSUES

Connective tissueConnective tissue Most abundant and widely distributed tissue in body, Most abundant and widely distributed tissue in body,

with many different types, appearances, and functionswith many different types, appearances, and functions Relatively few cells in intercellular matrixRelatively few cells in intercellular matrix TypesTypes

• Areolar—glue that holds organs togetherAreolar—glue that holds organs together• Adipose (fat)—lipid storage is primary function (Figure 3-Adipose (fat)—lipid storage is primary function (Figure 3-

13)13)• Fibrous—strong fibers; example is tendon (Figure 3-14)Fibrous—strong fibers; example is tendon (Figure 3-14)• Bone—matrix is calcified; functions as support and Bone—matrix is calcified; functions as support and

protection (Figure 3-15)protection (Figure 3-15)• Cartilage—chondrocyte is cell type (Figure 3-16)Cartilage—chondrocyte is cell type (Figure 3-16)• Blood—matrix is fluid; function is transportation (Figure 3-Blood—matrix is fluid; function is transportation (Figure 3-

17)17)


TISSUESTISSUES

Muscle tissue (Figures 3-18 to 3-20)Muscle tissue (Figures 3-18 to 3-20) TypesTypes

• Skeletal—attaches to bones; also called striated or Skeletal—attaches to bones; also called striated or voluntaryvoluntary; control is voluntary; striations apparent ; control is voluntary; striations apparent when viewed under a microscope (Figure 3-18)when viewed under a microscope (Figure 3-18)

• Cardiac—also called Cardiac—also called striated involuntarystriated involuntary; composes ; composes heart wall; ordinarily cannot control contractions heart wall; ordinarily cannot control contractions (Figure 3-19)(Figure 3-19)

• Smooth—also called Smooth—also called nonstriated (visceral)nonstriated (visceral) or or involuntaryinvoluntary; no cross striations; found in blood ; no cross striations; found in blood vessels and other tube-shaped organs (Figure 3-20)vessels and other tube-shaped organs (Figure 3-20)

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