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