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Summary BIOL 235/BIOL235 Review for Midterm-1: Human Anatomy and Physiology: Biology (Athabasca University)
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BIOL 235/BIOL235 Review for Midterm-1: Human Anatomy and Physiology: Biology (Athabasca University)
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lOMoARcPSD|5079866lOMoARcPSD|5079866FINAL BIO 235 REVIEW FOR MIDTERM 1
Medical Uses of Isotonic, Hypertonic, and Hypotonic Solutions
RBCs and other body cells may be damaged or destroyed if exposed to hypertonic or hypotonic solutions. For this reason, most intravenous (IV) solutions, liquids infused into the blood of a vein, are isotonic. Examples are isotonic saline (0.9% NaCl) and D5W, which stands for dextrose 5% in water. Sometimes infusion of a hypertonic solution such as mannitol (sugar alcohol) is useful to treat patients who have cerebral edema, excess interstitial fluid in the brain. Infusion of such a solution relieves fluid overload by causing osmosis of water from interstitial fluid into the blood. The kidneys then excrete the excess water from the blood into the urine. Hypotonic solutions, given either orally or through an IV, can be used to treat people who are dehydrated. The water in the hypotonic solution moves A. SIMPLE SQUAMOUS EPITHELIUMlOMoARcPSD|5079866
from the blood into interstitial fluid and then into body cells to rehydrate them. Water and most sports drinks that you consume to “rehydrate” after a workout are hypotonic relative to your body cells.
4.Cell division of the somatic cells; the phases of somatic cell division;
reviewthe main events occurring in each phaseandmore specifically
see what happens in interphase.
5.Main features of simple and stratified cuboidal epithelium (see where
these two types of epitheliumaremostly found in the body; table 4.1 may help.
Description Simple squamous epithelium is a single layer of flat cells that resembles a tiled floor when viewed from apical surface; centrally located nucleus
that is flattened and oval or spherical in shape.
LocationMost commonly (1) lines the cardiovascular and lymphatic system (heart, blood lOMoARcPSD|5079866
A. SIMPLE SQUAMOUS EPITHELIUM
vessels, lymphatic vessel linings), where it is known as endo t heliu m (en′-dō- THĒ-lē-um; endo- = within; -thelium = covering), and (2) forms the epithelial layer of serous membranes (peritoneum, pleura, pericardium), where it is
called mesotheliu m (mez′-ō-THĒ-lē-um; meso- = middle). Also found in air sacs of lungs, glomerular (Bowman's) capsule of kidneys, inner surface of
tympanic membrane (eardrum).
FunctionPresent at sites of filtration (such as blood filtration in kidneys) or diffusion (such as diffusion of oxygen into blood vessels of lungs) and at site of secretion in serous membranes. Not found in body areas subject to mechanical stress (wear and tear).
B. SIMPLE CUBOIDAL EPITHELIUM
Description Simple cuboidal epithelium is a single layer of cube-shaped cells; round, centrally located nucleus. Cuboidal cell shape is obvious when tissue is sectioned and viewed from the side. (Note: Strictly cuboidal cells could not form small tubes; these cuboidal cells are more pie-shaped but still nearly as high as they are wide at the base.)
LocationCovers surface of ovary; lines anterior surface of capsule of lens of the eye; forms pigmented epithelium at posterior surface of retina of the eye; lines kidney tubules and smaller ducts of many glands; makes up secreting portion of some glands such as thyroid gland and ducts of some glands such as pancreas.
FunctionSecretion and absorption.
C. NONCILIATED SIMPLE COLUMNAR EPITHELIUM
Description Nonciliated simple columnar epithelium is a single layer of nonciliated columnlike cells with oval nuclei near base of cells; contains (1) columnar epithelial cells with microvilli at apical surface and (2) goblet cells. Microvilli, fingerlike cytoplasmic projections, increase surface area of plasma membrane (see
Figure 3.1), thus increasing cell's rate of absorption. Goblet cells are modified columnar epithelial cells that secrete mucus, a slightly sticky fluid, at their apical surfaces. Before release, mucus accumulates in upper portion of cell, causing it to bulge and making the whole cell resemble a goblet or wine glass.
LocationLines gastrointestinal tract (from stomach to anus), ducts of many glands, and gallbladder.
FunctionSecretion and absorption; larger columnar cells contain more organelles and thus are capable of higher level of secretion and absorption than are cuboidal cells.
Secreted mucus lubricates linings of digestive, respiratory, and reproductive tracts, and most of urinary tract; helps prevent destruction of stomach lining by acidic gastric juice secreted by stomach.
D. CILIATED SIMPLE COLUMNAR EPITHELIUM lOMoARcPSD|5079866
A. SIMPLE SQUAMOUS EPITHELIUM
Description Ciliated simple columnar epithelium is a single layer of ciliated columnlike
cells with oval nuclei near base of cells. Goblet cells are usually interspersed.
LocationLines some bronchioles (small tubes) of respiratory tract, uterine (fallopian) tubes, uterus, some paranasal sinuses, central canal of spinal cord, and ventricles of brain.
FunctionCilia beat in unison, moving mucus and foreign particles toward throat, where they can be coughed up and swallowed or spit out. Coughing and sneezing speed up movement of cilia and mucus. Cilia also help move oocytes expelled from ovaries through uterine (fallopian) tubes into uterus.
E. PSEUDOSTRATIFIED COLUMNAR EPITHELIUM
Description Pseudostratified columnar epithelium appears to have several layers because cell nuclei are at various levels. All cells are attached to basement membrane in a single layer, but some cells do not extend to apical surface. When viewed from side, these features give false impression of a multilayered tissue (thus the name pseudostratified; pseudo = false).
Pseudostratified ciliated columnar epithelium contains cells that extend to surface and secrete mucus (goblet cells) or bear cilia.
Pseudostratified nonciliated columnar epithelium contains cells without cilia and lacks goblet cells.
LocationCiliated variety lines airways of most of upper respiratory tract; nonciliated variety lines larger ducts of many glands, epididymis, and part of male urethra.
FunctionCiliated variety secretes mucus that traps foreign particles, and cilia sweep away mucus for elimination from body; nonciliated variety functions in absorption and protection.
F. STRATIFIED SQUAMOUS EPITHELIUM
Description Stratified squamous epithelium has two or more layers of cells; cells in apical layer and several layers deep to it are squamous; cells in deeper layers vary from cuboidal to columnar. As basal cells divide, daughter cells arising from cell divisions push upward toward apical layer. As they move toward surface and away from blood supply in underlying connective tissue, they become dehydrated and less metabolically active. Tough proteins predominate as cytoplasm is reduced, and cells become tough, hard structures that eventually die. At apical layer, after dead cells lose cell junctions they are sloughed off, but they are replaced
continuously as new cells emerge from basal cells.
Keratinized stratified squamous epithelium develops tough layer of keratin in apical layer of cells and several layers deep to it (see Figure 5.3). (Keratin is a tough, fibrous intracellular protein that helps protect skin and underlying tissues from heat, microbes, and chemicals.) Relative amount of keratin increases in cells as they move away from nutritive blood supply and organelles die.
Nonkeratinized stratified squamous epithelium does not contain large amounts of keratin in apical layer and several layers deep and is
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