Anatomy & Physiology: The Unity Of Form & Function, 8th Edition (Ch. 3: Cellular Form and, Exams of Physiology

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Anatomy & Physiology: The Unity Of Form & Function, 8th Edition (Ch. 3:

Cellular Form and Function) Questions & Answers 202 3 /

cytology - ANSWER-scientific study of cells

cell theory - ANSWER-the theory that cells form the fundamental structural and functional units of all living organisms

cells - ANSWER--functions: fight disease, store nutrients, connect things, line things, gather information and control body functions, involved in reproduction

-structure:

*nuclear envelope -> nucleus -> nucleolus

*plasma membrane

*cytoplasm -> cytoskeleton, organelles, inclusions, cytosol

intracellular fluid - ANSWER-fluid within cells; cytosol

extracellular fluid - ANSWER-fluid outside the cell; tissue fluid (ex. blood plasma, lymph, and cerebrospinal fluid

cytoplasm - ANSWER-fluid between the nucleus and surface membrane; contains the cytoskeleton, organelles, and inclusions

plasma (cell) membrane - ANSWER--stick cells together to form tissues; regulates exchange of materials that go in and out of a cell; involved in intracellular communication; gives cell its shape

-made of proteins, lipids, & carbohydrates; phospholipids are major components; semi-permeable membrane

cytoskeleton - ANSWER--supportive framework of protein filaments and tubules

-network of protein filaments and cylinders that structurally support a cell, determine its shape, organize its contents, direct the movement of materials within the cell, and contribute to movements of the cell as a whole

-composed of microfilaments, intermediate filaments, and microtubules

organelles - ANSWER-diverse structures that perform various metabolic tasks for the cell

inclusions - ANSWER--highly variable - fat droplets, glycogen granules, protein crystals, dust, bacteria, viruses; never enclosed in membranes

-foreign matter retained in cytoplasm

-(function) storage products or other products of cellular metabolism

phospholipids - ANSWER-75% of membrane molecules of the plasma membrane; drift laterally from place to place, spin on their axes, and flex their tails

glycolipids - ANSWER-5% of membrane lipids molecules of the plasma membrane; phospholipids with short carbohydrate chains on the extracellular face of the membrane; help form the glycocalyx

cholesterol - ANSWER-20% of membrane lipids molecules of the plasma membrane; molecules found near the membrane surfaces amid the phospholipids; interact with phospholipids and hold them still and stiffen the membrane; high concentrations can increase membrane fluidity by preventing phospholipids from becoming packed closely together

integral proteins - ANSWER-membrane protein; penetrate into the phospholipid bilayer or all the way through it

transmembrane proteins - ANSWER-membrane proteins that pass completely through

peripheral proteins - ANSWER-membrane proteins; do not protrude into the phospholipid layer but adhere to one face of the membrane

glycoproteins - ANSWER-most transmembrane proteins; bound to oligosaccharides on the extracellular side of the membrane

membrane proteins - ANSWER-receptors, second messenger systems, enzymes, channel proteins, carriers, cell identity markers, cell adhesion molecules

leak channels - ANSWER-always open and allow materials to pass through continually

gated channels - ANSWER-open and close under different circumstances and allow solutes through at some times, but not others; respond to stimuli

ligand-gated channels - ANSWER-respond to chemical messengers

voltage gated channels - ANSWER-respond to electrical potential across the plasma membrane

mechanically gated channels - ANSWER-respond to physical stress on a cell

membrane receptors - ANSWER-binds to a transmembrane receptor on the outside of the plasma membrane because it cannot get across

G proteins - ANSWER-get their energy from GTP; relays the the signal to adenylate cyclase when activated by the receptor

adenylate cyclase - ANSWER-removes two phosphate groups from ATP and converts it to cAMP

cyclic adenosine mono phosphate - ANSWER-the second messenger; activates kinases

kinases - ANSWER-cytoplasmic enzymes that add phosphate groups to other cellular enzymes

glycocalyx - ANSWER-a bacterial capsule that is made of a fuzzy coat of sticky sugars

functions:

-protects the plasma membrane from physical/chemical injury

-enables the immune system to recognize and selectively attack foreign organisms

-defense against cancer

-forms the basis of compatibility of blood transfusions, tissue grafts, and organ transplants

-cell adhesion (binds cells together so tissues do not fall apart)

-enables fertilization

-guides embryonic development

microvilli - ANSWER--extensions of the plasma membrane that serve primarily to increase the cell's surface area, developed in cells specialized for absorption

-(function) increase absorptive surface area; widespread sensory roles

-some appear as a fringe called the brush border at the atypical cell surface

-show little internal structure, but some have a bundle of stiff filaments of a protein called actin, which attach to the inside of the plasma membrane at the tip of the microvillus, and at its base they extend a little way into the cell and anchor the microvillus to a protein mesh called the terminal web

cilia - ANSWER--long hairlike projections of apical cell surface; axoneme with a usually 9+2 array of microtubules

-(function) move substances along cell surface; widespread sensory roles; secrete mucus

-each bends stiffly and produces a power stroke that pushes along the mucus or other matter

-recovery stroke restores it to the upright position

-responsible for several hereditary diseases called ciliopathies

-beat within a saline layer at the cell surface

-chloride pumps in the apical plasma membrane produce the saline layer by pumping Cl- into the extracellular fluid; sodium ions follow by electrical attraction and water follows by osmosis

-structural basis for movement is a core called the axoneme, which consists of an array of thin projection cylinders called microtubles

flagellum - ANSWER-whiplike tail of a sperm is the only function in humans; much longer than the cilium and has an identical axoneme, but between the axoneme and plasma membrane; long hair like extensions

pseudopods - ANSWER-cytoplasm-filled extensions of the cell varying in shape from fine, filamentous processes to blunt fingerlike ones; change continually (ex. amoeba, neutrophils, macrophage)

selective permeability - ANSWER-allows some substances to cross it (like nutrients and wastes) more easily than others (like proteins and phosphates)

passive mechanisms - ANSWER-requires no ATP; filtration, diffusion (simple and facilitated), osmosis

active mechanisms - ANSWER-require ATP; active (primary and secondary) and vesicular transport

carrier-mediated transport - ANSWER--movement of material through a cell membrane by carrier proteins

-carrier exhibits specificity for its ligand

-carrier exhibits saturation; as solute concentration rises, its rate of transport increases

-carriers don't chemically change their ligands, they simply pick them up on one side of the membrane and release them, unchanged, on the other

membrane transport - ANSWER--transport without carriers (filtration, simple diffusion)

-carrier mediated transport (facilitated diffusion, primary active transport, secondary active transport, cotransport, countertransport)

-vesicular transport (endocytosis, exocytosis)

filtration - ANSWER--movement of water and solutes through a selectively permeable membrane from higher pressure to lower pressure as a result of hydrostatic pressure

-transport without carriers

simple diffusion - ANSWER-diffusion of dissolved particles (nonpolar and lipid-soluble) from a higher concentration gradient (outside cell) to a lower concentration gradient (inside cell), without the aid of membrane carriers

factors that affect the rate:

-temperature (warmer substance = rapid diffusion)

-molecular weight (small molecules move quickly, large ones move slowly)

-steepness of the concentration gradient (greater difference = rapid diffusion)

-membrane surface area

-membrane permeability

osmosis - ANSWER-diffusion of water through semipermeable membrane from higher concentration to lower concentration; impermeable to solute molecules; large enough for water and sugar molecules (hypotonic, hypertonic, isotonic solutions)

aquaporins - ANSWER-water channel proteins

nonpermeable solute - ANSWER-solute that cannot pass through the membrane pores because of its size or other properties (ex. proteins)

reverse osmosis - ANSWER-process of applying mechanical pressure to override osmotic pressure and drive water through a membrane against its concentration gradient; capillary filtration

hydrostatic pressure - ANSWER-force exerted by a fluid against the container wall

osmotic pressure - ANSWER-pressure that must be applied to prevent osmotic movement across a selectively permeable membrane

osmolarity - ANSWER-solute concentration expressed as molarity

tonicity - ANSWER-ability of a solution to affect fluid volume and pressure in a cell

hypotonic solution - ANSWER-solution has a lower solute concentration than the intracellular fluid; cells absorb water, swell, and may burst

hypertonic solution - ANSWER-solution has higher solute concentration of non permeating solutes than the ICF; causes cell to lose water and shrivel; may die of torn membranes and cytoplasmic loss

isotonic solution - ANSWER-total concentration of nonpermeating solutes is the same as the ICF; cause no change in cell volume or shape

uniport - ANSWER-carries only one type of solute

cotransport - ANSWER-simultaneous transport of two or more solutes in the same direction through a membrane by a carrier protein called symport, using either facilitated diffusion or active transport

countertransport - ANSWER-transport of two or more solutes in opposite directions through a membrane by a carrier protein called antiport, using either facilitated diffusion or active transport

facilitated diffusion - ANSWER--transport of particles through a selectively permeable membrane, down their concentration gradient, by a carrier that does not directly consume ATP

-transports solutes that cannot pass through the membrane unaided

1. solute particle enters channel of a membrane protein
2. solute binds to a receptor site on carrier, which changes conformation
3. carrier releases the solute on the other side of the membrane

primary active transport - ANSWER--transport of solute particles through a selectively permeable membrane, up their concentration gradient, by a carrier that consumes ATP, which transfers a phosphate group to the transport protein

-calcium pump uses this mechanism

secondary active transport - ANSWER--transport of solute particles through a selectively permeable membrane, up their concentration gradient, by a carrier that does not itself use ATP but depends on concentration gradients produced by primary active transport elsewhere in the membrane

sodium potassium pump - ANSWER-good example of primary active transport; transmembrane protein; binds three NA+ simultaneously on the cytoplasmic side of the membrane, releases these to the ECF, binds two K+ simultaneously from the ECF, and releases these into the cell; each cycle consumes one ATP and exchanges three Na+ for two K+; keeps K+ concentration higher and Na+ concentration lower

functions:

-secondary active transport

-regulation of cell volume

-maintenance of membrane potential

-heat production

vesicular transport - ANSWER-movement of fluid and particles through a plasma membrane by way of membrane vesicles; consumes ATP

endocytosis - ANSWER-vesicular transport of particles into a cell (phagocytosis, pinocytosis, receptor- mediated)

exocytosis - ANSWER-process of eliminating material from a cell by means of a vesicle approaching the cell surface, fusing with the plasma membrane, and expelling its contents; used to release cell secretions, replace worn-out plasma membrane, and replace membrane that has been internalized by endocytosis

phagocytosis - ANSWER-process of engulfing large particles by means of pseudopods; "cell-eating"

pinocytosis - ANSWER-process of imbibing extracellular fluid in which the plasma membrane sinks in and pinches off small vesicles containing droplets of fluid; "cell-drinking"

receptor-mediated endocytosis - ANSWER-phagocytosis or pinocytosis in which specific solute particles bind to receptors on the plasma membrane, and are then taken into the cell in clathrin-coated vesicles with a minimal amount of extraneous matter

transcytosis - ANSWER-transport of material across a cell

microtubles - ANSWER--made up of tubulin

-(function) form axonomes of the cilia and flagella, basal bodies, centrioles, and mitotic spindles; enable motility of cell parts, form trackways that direct organelles and macromolecules to their destinations within a cell

microfilaments - ANSWER--thin protein filaments often in parallel bundles or dense networks in cytoplasm

-(function) support microvilli and plasma membrane; involved in muscle contraction and other cell motility, endocytosis, and cell division

-made of a protein called actin

-widespread throughout the cell but especially concentrated in a fibrous mat called the terminal web on the cytoplasmic side of the plasma membrane

-web provides physical support, lipids provide a permeability barrier

intermediate filaments - ANSWER--thicker protein filaments (8 to 10 nm thick) extending throughout the cytoplasm or concentrated at cell to cell junctions

-(function) give the cell its shape, resist stress, and participate in junctions that attach cells to their neighbors

-made of keratin in epidermal cells and fibrous things

nucleus - ANSWER--largest organelle in most cells, surrounded by a double membrane of nuclear pores

-(function) genetic control center of cell; directs protein synthesis; shelters the DNA

-enclosed in a double membrane called the nuclear envelope, which is perforated with nuclear pores formed by a ring of proteins known as the nuclear pore complex

-inside the nuclear envelope is a narrow but fibrous zone called the nuclear lamina, composed of a web of intermediate filaments; it supports the nuclear envelope and pores, provides points of attachment and organization for the chromosomes inside the nucleus, and plays a role in regulating the cell life cycle

-material in the nucleus is called the nucleoplasm, which includes chromatin (fine, threadlike matter composed of DNA and protein) and one or more dark-staining masses called nucleoli, where ribosomes are produced

endoplasmic reticulum (ER) - ANSWER-system of interconnected channels called cisterns enclosed by a unit membrane; cisterns are parallel, flattened sacks covered with ribosomes in rough ER; in smooth ER, cisterns are more tubular, branch more extensively, and lack ribosomes

rough ER - ANSWER--extensive sheets of parallel membranes with ribosomes on the outer surface

-(function) protein synthesis and manufacture of cellular membranes

smooth ER - ANSWER--branching network of tubules with smooth surface (no ribosomes); usually broken into numerous small segments in TEM photos

-(function) lipid synthesis, detoxification, calcium storage

ribosomes - ANSWER--small dark granules free in cytosol or on surface of rough ER and nuclear envelope

-(function) interpret the genetic code and synthesize polypeptides

golgi complex - ANSWER--several closely spaced, parallel cisternae with thick edges, usually near nucleus, often with many golgi vesicles nearby

-(function) receives and modifies newly synthesized polypeptides, synthesizes carbohydrates, adds carbohydrates to glycoproteins; packages cell products into golgi vesicles

golgi vesicles - ANSWER--round to irregular sacs near golgi complex, usually with light, featureless contents

-(function) become secretory vesicles and carry cell products to apical surface for exocytosis, or become lysosomes

lysosomes - ANSWER--round to oval sacs with single enclosing membrane, often a dark featureless interior but sometimes with protein layers or crystals

-formed by golgi

-(function) contain enzymes for intracellular digestion, autophagy, programmed cell death, and glucose mobilization

autophagy - ANSWER-lysosomal breakdown of a cell's own components

autolysis - ANSWER-destruction of cells by enzymes within the cells

peroxisomes - ANSWER--similar to lysosomes; often lighter in color

-formed by rough ER

-(function) contain enzymes for detoxification of free radicals, alcohol, and other drugs; oxidize fatty acids

proteasomes - ANSWER--small cytoplasmic granules composed of a cylindrical array of proteins

-(function) degrade proteins that are undesirable or no longer needed by a cell

mitochondria - ANSWER--round, rod-shaped, bean-shaped, or threadlike structures with double- enclosing membrane and shelflike infoldings called cristae

-(function) ATP synthesis; powerhouse of the cell

centrioles - ANSWER--short, cylindrical bodies, each composed of a circle of nine triplets of microtubules

-(function) form mitotic spindle during cell division; unpaired centrioles form basal bodies of cilia and flagella

centrosome - ANSWER--clear area near nucleus containing a pair of centrioles

-(function) organizing center for formation of microtubules of cytoskeleton and mitotic spindle

basal bodies - ANSWER--unpaired centriole at the base of a cilium or flagellum

-(function) point of origin, growth, and anchorage of a cilium or flagellum; produces axoneme

nuclear lamina - ANSWER-composed of proteins and maintains the shape of the nucleus

secretory vesicles - ANSWER-secrete substances outside the cell by exocytosis

unicellular - ANSWER-made of one cell

multicellular - ANSWER-made of many cells

cell junctions - ANSWER-connections between one cell and another

tight junctions - ANSWER-completely encircles each cell and provides seal that prevents passage of materials between cells

desmosomes - ANSWER-holds cells together

gap junctions - ANSWER-provide cytoplasmic channels between adjacent animal cells; formed by a connexon

enzymes - ANSWER-carry out the final stages of starch and protein digestion in the small intestine, help produce second messengers, and break down hormones and other signaling molecules

receptors - ANSWER-binds to chemical messengers sent by other cells

channel proteins - ANSWER-passages that allow water and hydrophilic solutes to move through an individual membrane or protein tunnel

cell identity markers - ANSWER-bodies are enabled to tell which cells do and don't belong in our bodies

cell adhesion molecules - ANSWER-membrane proteins that cells adhere to one another and to extracellular material

second messengers system - ANSWER-when a messenger binds to a surface receptor, it may trigger changes within the cell that produce a second messenger in the cytoplasm

carrier proteins - ANSWER-transmembrane proteins that bind to glucose, electrolytes, and other solutes and transfer them to the other side of the membrane; come carriers, called pumps, consume ATP in the process

nucleolus - ANSWER-makes ribosomes and forms mRNA