Human A&P Chapter 3

Squamous

Squamous

Thin, flat, scaly shape, often with a bulge where the nucleus is

Cuboidal

Squarish-looking in frontal sections and about equal in height and width

Columnar

Distinctly taller than wide

Polygonal

Having irregular angular shapes with 4, 5, or more sides

Stellate

Having multiple pointed processes projecting from the body of a cell

Spheroidal to ovoid

Round to oval, as in egg cells and white blood cells

Discoidal

Disc-shaped

Fusiform

Spindle-shaped; elongated, with a thick middle and tapered ends

Fibrous

Long, slender, and threadlike

The relationship between volume and surface area

Cell sized is limited by…

Phospholipids

Make up 75% of the plasma membrane, keeps the membrane fluid

Cholesterol

Hold the phospholipids still

Glycolipids

Phospholipids with short, carbohydrate chain. Contributes to glycocalyx—carbohydrate coating on cell surface

Transmembrane proteins

Pass completely through the phospholipid bilayer

Peripheral proteins

Don’t protrude into the phospholipid layer but adhere to either the inner our outer face of the membrane

Functions of membrane proteins

Receptors, enzymes, channel proteins, carriers, cell-identity markers, and cell-adhesion molecules

Glycocalyx

A layer of carbohydrate molecules covalently bonded to the phospholipids and proteins of a plasma membrane; forms a surface coat on all human cells

Microvilli

Extensions of the plasma membrane that serve primarily to increase a cell’s surface area

Cilia

Hairlike processes. Plays many roles such as serving as the cell’s “antenna” for monitoring nearby conditions, play a role in the sense of balance in the ear, and more

Flagella

Tail of sperm is the only functional example in humans, move in a corkscrew fashion

Pseudopods

Cytoplasm-filled extensions of the cell varying in shape from fine, filamentous processes to blunt fingerlike ones

Selectively permeable membrane

A membrane that allows some substances to pass through while excluding others

Factors that affect diffusion

Temperature, molecular weight, “steepness” on concentration gradient, membrane surface area, and membrane permeability

Passive mechanisms of transport (don’t use ATP)

Filtration, diffusion, and osmosis

Active mechanisms of transport (use ATP)

Active transport and vesicular transport

Filtration

A process in which a physical pressure (hydrostatic pressure) forces fluid through a selectively permeable membrane

Simple diffusion

The net movement of particles from a place of high concentration to a place of lower concentration (down concentration gradient)

Osmosis

The net flow of water from one side of a selectively permeable membrane to the other

Tonicity

The ability of a solution to affect the fluid volume of a cell

Hypotonic solution

Has a lower concentration of nonpermeating solutes than the intracellular fluid (ICF). Cells absorb water and may burst (lyse)

Hypertonic solution

Has a higher concentration of nonpermeating solutes than the intracellular fluid (ICF). Cells lose water and shrivel (crenate)

Isotonic solution

Concentration of nonpermeating solutes is the same as the intracellular fluid (ICF). No change occurs

Carrier-mediated transport

Any process of transporting solutes across a cell membrane. Solute binds to a receptor site on carrier protein

Uniport

Carries only one solute at a time

Symport

Can carry two or more solutes through a membrane simultaneously in the same direction (cotransport)

Antiport

Carries two or more solutes in opposite directions

Facilitated diffusion, primary active transport, secondary active transport

Three mechanisms of carrier-mediated transport

Facilitated diffusion

The carrier-mediated transport of solute through a membrane down its concentration gradient (no ATP consumed)

Primary active transport

Carrier-mediated transport of a solute through a membrane up (against) its concentration gradient (uses ATP)

Secondary active transport

A mechanism in which solutes are moved through a plasma membrane by a carrier that does not itself use ATP but depends on a concentration gradient established by an active transport pump elsewhere in the cell

Vesicular transport

Transport of large particles or fluid droplets through a membrane in vesicles of membrane

Exocytosis

Vesicular transport out of cell

Endocytosis

Vesicular transport into cell

Phagocytosis

Form of endocytosis in which a cell engulfs large particles

Pinocytosis

Form of endocytosis in which a cell takes in fluid droplets

Receptor-mediated endocytosis

Form of endocytosis in which a cell takes in specific molecules from the extracellular fluid

Cytoskeleton

A 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

Microfilaments

Part of the cytoskeleton. Supports membrane and microvilli, produces cell movement

Intermediate filaments

Part of the cytoskeleton. Thicker and stiffer than microfilaments. Give the cell its shape, resist stress, and form junctions that attach to their neighbors

Microtubules

Part of the cytoskeleton. Hold organelles in place and maintain cell shape, inside cilia and flagellum

Organelles

Any structure within a cell that carries out one of its metabolic roles

Nucleus

Contains the cell’s chromosomes and is therefore the genetic control center of the cell

Nucleolus

Inside nucleus, plays a role in ribosome synthesis

Endoplasmic reticulum

System of interconnected channels called cistern

Rough endoplasmic reticulum

Cisternae are parallel and covered with ribosomes, synthesize proteins

Smooth endoplasmic reticulum

Cisternae are tubular and lack ribosomes, steroid (and other lipid) synthesis, detoxifies alcohol and drugs

Ribosomes

Small granules of protein and RNA, read the nucleotide sequence of messenger RNA and assemble amino acids into proteins, protein synthesis

Golgi complex

System of cisternae; synthesize carbohydrates and modify and package newly synthesized proteins, indirect role in protein synthesis

Lysosomes

A package of catabolic enzymes bounded by a membrane. Have a variety of intracellular and extracellular roles in digesting foreign matter, pathogens, and expire organelles. Autophagy (digest worn out organelles/phagocytized bacteria), autolysis (cell suicide), and glucose mobilization (break down glycogen)

Peroxisomes

Resemble lysosomes but contain different enzymes. Use O₂ to oxidize organic molecules, neutralize free radicals, and detoxify alcohol, drugs, and toxins. Breaks down fatty acids, produces hydrogen peroxide (H₂O₂)

Proteasomes

Protein disposal, breaks down proteins into short peptide bonds and free amino acids

Mitochondria

Synthesizes ATP, surrounded by double membrane, powerhouse of the cell, inner membrane has folds=cristae

Centrioles

A short cylindrical assembly of microtubules, arranged in 9 groups of 3 microtubules each, organize chromosomes during cell division

Inclusions

Various nutrients or pigments that can be found within the cell. Two types: stored cellular products and disease markings. Not essential for cell survival