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This membrane seperates the cell contents from the dilute saltwater solution called interstitial fluid or tissue fluid, that bathes every cell in the body. It also incloses the cytoplasm and forms the outer boundary of the cell. Selectively permeable or semi permeable membran, meaning certain substances can move through the membrane but others are barred from entery, also identifies a cell as being part of one particular individual. Each cell in the body is surrounded by a thin membrane, forming its outer boundary. It is made up mostly of phospholipids. The most important part is the proteins embedded in the phospholipids. Also important roles such as the nervous or endocrine systems.
is the internal living material of cells. It fills the space between the plasma membrane and the nucleus. A spherical structure in the center of the cell. Numerous small structures are part of it, with the fluid that serves as the interior environment of each cell. Is all the living material inside the cell (except the nucleus) or living matter.
tiny organs, they digest or destroy. They are contained within the cytoplasm of each cell. As a group, the small structures that make up much of the cytoplasm.
A small, circular body called the ________ is also inside the cell. It is a large, membrane-bound structure in most cells that contains the genetic code.
Two layers of phosphate containg fat molecules called______. Form a fluid framework for the plasma membrane. Cholesterol is also a component of the plasma membrane.
All of which are found in the cytoplasm
organelles called________ are very tiny particles found throughout the cell. Some ribosomes are found temporarily attached to a network of membranous canals called endoplasmic reticulum (ER). Ribosomes also may be free-floating in the cytoplasm. Perform a very complex function.
endoplasmic reticulum (ER)
is a system of membranes forming a network of connecting sacs and canals that wind back and forth through a cell's cytoplam, from the nucleus almost to the plasma membrane. The tubular passageways or canals in the ER carry proteins and other substances through the fluid cytoplasm of the cell from one area to another. There are two types of ER rough and smooth.
many ribosomes are attached to its outer surface, giving it a rough texture similar to sandpaper. Ribosomes make their proteins, they attach to the rough ER and drop the protein into the interior of the ER.
The absence of attached ribosomes gives this type of ER a smooth texture. Fats, carbohydrates, and proteins that make up cellular membrane materials are manufactured in smooth ER. Sum up rough ER recieves folds, and transports newly made proteins and smooth ER manufactures new membrane.
consist of tiny flattened sacs stacked on one another near the nucleus. Sac's break off the smooth ER and carry new proteins and other compounds to the sacs of the Golgi apparatus. These sacs are also called vesicles. ex. product is the slippery substance called mucus. it is also the chemical processing and packaging center.
within a mitochondrion's fragile walls, complex, energy-releaseing chemical reactions occur continnuously. Has been nicknamed the "power plant". The survival of cell and therefore of the body depends on mitochondrial chemical reactions. Enzymes, which are found in mitochondrial walls and the mitochondrial fluids, use oxygen to break down glucose and other nutrients to release energy required for cellular work.
are membranous-walled organelles that in their active stage look like small sacs, often woth tiny particles in them. Because lysosomes contain enzymes that can digest food compounds, they have the nickname digestive bags. Lysosomal enzymes also can digest substances other than foods. EX. they can digest and thereby destroy microbes that invade the cell. Thus lysosomes can protect cells against destruction by microbes
are small finger like projections of the plasma membrane of some cells. they increase the surface area of the cell and thus increase its ability to absorb substances. EX. cells that line the small intestine are covered with the microvilli that increase the absorbtion rate of nutrients into the blood.
are extremely fine, almost hairlike extensions on the exposed or free surfaces of some cells. Are organelles capable of movement. lines the respatory tract.
is a single projection extending from the cell surface. much larger than cilia. In the human the only example of a flagellum is the tail of the male sperm cell.
made up of two separate membranes. the nuclear envelope has many tiny openings called nuclear pores that permit large molecules to move into and out the nucleus.
the nucleolus is critical in protein formation because it prgrams the formation of ribosomes in the nucleus.
Chromatin and Chromosomes
Chromatin granules in the nucleus are threadlike structures made of proteins and hereitary molecules called DNA or deoxyribonucleic acid. DNA is the genetic material often described as the chemical "cookbook" of the body.
short, rodlike structures and are called_________. Each cell of the body contains a total of 46 different DNA molecules in its nucleus and the one copy 47th DNA molecule in each of its mitochondria
A number of processess allow this mass movement of substances into and out of cells. They are classified under two general headings:
1. Passive transport processes
2. Active transport processes
active transport processes
require the expenditure of energy by the cell. the energy required for this is obtained from very important chemical substance called adenosine triphosphate (ATP) Is the uphill movement of a substance through a living cell membrane. (lower to a higher concentration)
passive transport processes
does not require the expenditure of energy by the cell. scientist describe the movement of substances in passive systems are going down a concentration gradient. (high to low concentration)
(ATP) adenosine triphosphate
is produced in the mitochondria using energy from nutrients and is capable of releasing that energy to do work in the cell.
passive transport processses
The primary passive transport processes that move substances through the cell membranes include the following:
a good example of a passive transport process, is the process by which substances scatter themselves evenly throughout an available space. the system does not require additional energy for this movement
osmosis and dialysis
are specialized examples of diffusion. in both cases, diffusion occurs across a selectively permeable membrane. The plasma membrane of a cell is said to be selectively permeable because it permits the passage of certain substances but not others. osmosis is the diffusion of water, but not solutes across a selectively permeable membrane.
is the movement of water and solutes through a membrane as a result of a pushing force that is grater on one side of the membrane that on the other side. The force is called hydrostatic pressure. Filtration is the process responsible for urine formation in the kidneys; wastes are filtered out the blood into the kidneys tubles because of a difference in hydrostatic pressure.
is another example of how a cell can actively move an object or substance through the plasma membrane and into the cytoplasm. The term phagocytosis comes from a greek word meaning to eat. The word is appropriate because this process permits a cell to engulf and literallyeat foreign material. certain white blood cells destroy bacteria in the body by phagocytosis. During this process the cell membrane forms a pocekt around the bacterium, by expenditure of energy from ATP. then it is moved to the interior of the cell. Once inside the cytoplasm, the bacterium fuses with a lysosome and is destroyed.
is an active transport mechanism used to incorporate fluids or dissovled substances into cells by trapping them in a pocket of plasma membrane that pinches off inside the cell.
all human cells that reproduce do so by a process called_________ during this process a cell divides to multiply; that is, one cell divides to form two cells. Cell reproduction and ultimately the transfer of heritable traits is closely tied to the production of proteins. Two nucleic acids, ribonucleic acid, or RNA, in the cytoplasm and DNA in the nucleus play crucial roles in protein synthesis.
The double-stranded DNA molecule separates or unwinds, and a special type of RNA called messenger RNA or mRNA is formed. Each strand of mRNA is a duplicate or copy of a particular gene sequence along one of the newly separated DNA spirals.
is the synthesis of a protein by ribosomes, which use the information contained in an mRNA molecule to direst the choice and sequencing of the appropriate chemical building blocks called amino acids.
transfer RNA (tRNA)
molecules assist the process by bringing specific amino acids in to dock at each condon along the mRNA strand. A condon is a series of three nucleotide bases that act as a code representing a specific amino acid.
messenger RNA (mRNA)
each strand of this is a duplicate or copy of a particular gene sequence along one of the newly separated DNA spirals. the messenger RNA is said to have been "transcribed" or copied from its DNA mold template.It passes from the nucleus to the cytoplasmto direct protein synthesis in the ribosomes and the ER.
includes the inital growing stages of a newly formed cell, followed by a period during which the cell prepares for possible cell divsion.
the first stage of mitosis. The chromatin becomes "organized". Chromosomes in the nucleus have formed two strands called chromatids. the two chromatides are held together by a beadlike structure called centromere. In the cytoplasm the centrioles are moving away from each other as a network of tubules called spindle fibers forms between them.
begins the nuclear envelope and nucleolus have disappeared. Also the centrioles have migrated to opposite ends of the cell, and spindle fibers are attached to each chromatid
begins the beadlike centromeres, which were holding the paired chromatides together, to break apart. As a result, the individual chromatids, identified once again as chromosomes, move away from the center of the cell.
cell division is completed. Two nuclei appear, and chromosomes become less distinct and appear to break up. As the nuclear envelope forms around the chromatin, the cleavage furrow completely divides the cell into two parts.
sometimes cells respond to change in the internal enviornment by increasing their rate of reproduction. Like hypertrophy, hyperplasia causes an increase in the size of a tissue or organ. However, hyperplasia is an increase in the number of cells rather than an increase in the size of each cell.
If the body loses its ability to control mitosis, abnormal hyperplasia may occur. The new mass of cells formed are called _________.
Many neoplasmas also exhibit a characteristic called __________. Is a condition in which cells change in orientation to each other and fail to mature normally; that is they fail to differentiate into a specialized cell type.
covers the body and many of its parts. it also lines various parts of the body. the are packed close together so they have little or no intercellular material between them, they form continuous sheets that contain no blood vessels.
consist of a single layer of very tiny thin and irregularly shaped cells. because of its structure, substances can readily pass through simple squamous epithelial tissue, making transport its special function.EX. takes place through the simple squamous epithelium that forms the tiny air sacs in the lungs.
stratified squamous epithelium
consist of several layers of closely packed cells, an arrangement that makes this tissue especially adept at protection. Protects the body against invasion by microorganisms.
simple columnar epithelium
can be found lining the inner surface of the stomach, intestines, and some areas of the respiratory and reproductive tracts.
stratified transitional epithelium
is typically found in body areas subjected to stress and must be able to stretch; EX. the wall of the urinary bladder.
typical of that which lines the trachea or windpipe. Each cell actually touches the gluelike basement membrane that lies under all epithelial tissues. This is the reason that it is called pseudo (or false) stratified epithelium. The cilia that extend from the cells are capable of moving in unison. In doing so, they move mucus along the lining surface of the trachea, thus affording protection against entry of dust or other foreign particles into the lungs.
simple cubodial epithelium
forms tubules or other groupings specialized for secretory activity. These secretory cuboidal cells usually function in clusters or tubes of secretory cells commonly called glands.
_________ of the body may be classified as excocrine if they release their secretion through a duct or as endocrine if they release their secretion directly into the bloodstream.
areolar connective tissue
is the most widely distributed of all connective tissue types. it is the "glue" that gives form to the internal organs.
Fibrous connective tissue
consist mainly of bundles of strong, white collagen fibers arranged in parallel rows. It does not stretch.
is one of the most highly specialized forms of connective tissue. The matrix of bone is hard and calcified. it forms numerous structural building blocks called osteons. they are a storage area for calcium and provide support and protection for the body.
differs from bone in that its matrix is the consistancy of a firm plastic or a gristle-like gel. cartilage cells, which are called chondrocytes are located in many tiny spaces distributed throughout the matrix.
is perhaps the most unusual form of connective tissue. It has transportation and protective functions in the body. Red and white blood cells are the cell types common to blood.
is the bloodlike connective tissue found in the re marrow cavities of bones and in organs such as the spleen, tonsils, and lymph nodes.
skeletal muscle tissue
striated and called voluntary because willed or voluntary control of skeletal muscle contractions is possible. Individual cells are long and threadlike and are often called fibers. Skeletal muscles are attached to bones and when contracted, produce voluntary and controlled body movements.
cardiac muscle tissue
cardiac muscle forms the walls of the heart, and the regular but involuntary contractions of cardiac muscle produce the heartbeat. have fainted cross striations, thicker dark bands called intercalated disks. cardiac muscle fibers branch and reform to produce an interlocking mass of contractile tissue.
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