Chapter Three: Cells and Tissues

gene

a DNA segment that carries the information for building one protein

selective permeability

a barrier that allows some substances to pass through it while excluding others

plasma membrane

a fragile, transparent barrier that contains the cell contents and separates them from the surrounding environment.

solution

a homogenous mixture of two or more components

lamina propria

a soft layer of areolar connective tissue that underlies all mucous membranes

DNA replication

always precedes cell division during the end of interphase; the DNA "unzips" and becomes two nucleotide chains, which are then each used as a template to create two copies of identical DNA

adipose connective tissue

an areolar tissue in which adipose (fat) cells dominate; forms the subcutaneous tissue beneath the skin where it insulates and protects the body

solute

components or substances that are present in small amounts in a solution

dense connective tissue

connective tissue surrounded by collagen fibers and rows of fibroblasts (fiber-forming cells) that manufacture the building blocks of the fibers; forms strong, ropelike structures like tendons and ligaments that can withstand tension in one direction; also called dense regular fibrous tissue

blood

considered a connective tissue because it consists of blood cells surrounded by a nonliving, fluid matrix called blood plasma; also called vascular tissue

the generalized cell

contains a nucleus near the center of the cell surrounded by the semifluid cytoplasm and enclosed by the plasma membrane (the outer cell boundary)

ligaments

dense connective tissue that attaches bones to bones at joints; more stretchy and contain more elastic fibers than tendons

tendons

dense connective tissue that attaches skeletal muscles to bones

endocrine glands

ductless glands whose secretions (all hormones) diffuse directly into the blood vessels; include the thyroid, adrenals, and pituitary

prophase

duplicated chromosomes form sister chromatids

skeletal muscle

form the muscular system; it is consciously or voluntarily controlled; consist of long, cylindrical, and multinucleate cells with obvious striations (stripes); also called muscle fibers

cardiac muscle

found only in the heart wall, it contracts to pump the heart and propel blood through the blood vessels; consist of striated tissue made of relatively short, branching cells that fit together tightly like clasped fingers at junctions called intercalated discs that allow ions to pass freely from cell to cell; it cannot consciously be controlled

exocrine glands

glands that secrete through ducts to the epithelial surface

muscle tissues

highly specialized to contract, or shorten, which generates the force required to produce movement

simple epithelia

made of only one layer of cells; concerned with absorption, secretion, and filtration

stratified epithelia

made of two or more cell layers; function primarily as protection

dense irregular connective tissue

makes up the lower layers of the skin (dermis) where it is arranged in sheets and withstands tension in many directions

nervous tissue

mostly consist of cells called neurons, which receive and send electrochemical impulses from one part of the body to another

smooth (visceral) muscle

muscles that lack visible striations found in the walls of hollow organs such as the stomach, uterus, and blood vessels; its contraction are longer and slower than the other two muscle types as it propels and mixes substances along a specific pathway

gland

one or more cells that make and secrete a particular product

bone

osseous tissue composed of osteocytes sitting in cavities called lacunae, which are surrounded by layers of a very hard matrix that contains calcium salts and a large number of collagen fibers

secretion

protein molecules in an aqueous (water-based) fluid

facilitated diffusion

provides passage for certain needed substances (notably glucose) that are both lipid-insoluble and too large to pass through the membrane pores, or charged

fibrosis

repair by dense (fibrous) connective tissue aka the formation of scar tissue

metaphase

sister chromatids line up along the metaphase plate of the mitotic spindle

anaphase

sister chromatids split apart and travel to opposite poles of the cell

organelles

specialized cellular compartments that are the metabolic machinery of the cell; each are specialized to carry out a specific function of a cell, much like organs in the body

the principle of complementarity

structure determines function

cytoplasm

the "factory floor" of the cell; the cellular material outside the nucleus and inside the plasma membrane; the site of most cellular activities

inclusions

the "pantry" of the cell; chemical substances that are kept on hand until needed

endocytosis

the ATP-requiring processes that take up or engulf extracellular substances by enclosing them in a vesicle

solute pumps

the carrier proteins that transport amino acids, some sugars, and most ions against concentration gradients using ATP for energy

telophase

the cell splits in two and becomes two identical cells

nucleus

the control center of the cell, which contains the DNA

osmosis

the diffusion of water through a selectively permeable membrane

solvent

the dissolving medium in a solution

cytokinesis

the division of the cytoplasm; the second step of cell division

mitosis

the division of the nucleus of a cell; the first step of cell division; prophase, metaphase, anaphase, and telophase are the four main steps

epithelial tissue

the lining, covering, and glandular tissue of the body; covers and lines all free body surfaces both inside and out; also called the epithelium; functions to protect, absorb, filtrate, and secrete

interphase

the longest phase of the cell cycle wherein the cell grows and carries on its usual metabolic activities while preparing for cell division; also called the metabolic phase

exocytosis

the mechanism that cells use to actively secrete hormones, mucus, and other cell products or to eject certain cellular wastes

connective tissue

the most abundant and widely distributed tissue in the body; consist of living cells surrounded by a nonliving extracellular matrix; connects body parts and functions to protect, support, cushion, and insulate other body tissues

areolar connective tissue

the most widely distributed connective tissue variety in the body; a soft, pliable, "cobwebby" tissue that cushions and protects the body organs it wraps; holds internal organs together and in their proper place; provides a reservoir of water and salts for surrounding tissues where cells obtain nutrients and release wastes

passive transport

the movement of substances across a cell membrane without the use of energy by the cell, such as through diffusion and filtration

cell division

the period of the cell's life cycle when it reproduces itself

diffusion

the process by which molecules (and ions) move away from areas where they are more concentrated (more numerous) to areas where they are less concentrated (with fewer of them)

filtration

the process by which water and solutes are forced through a membrane by fluid, or hydrostatic, pressure; occurs only across capillary walls

cells

the structural units of all living things

simple diffusion

the unassisted diffusion of lipid-soluble solutes (such as fats, oxygen, and carbon dioxide) through the plasma membrane

active transport

when a cell uses ATP to move substances across the cell membrane