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| Frage | Antworten |
| Tome | to cut |
| Ana | Apart |
| Anatomical Position | The body is erect and facing forward, arms are at the side, the palms are facing forward, and the toes are pointing forward. |
| Anterior (Ventral) | Toward the front of the body (belly side) |
| Posterior (dorsal) | toward the back of the body |
| Superior (cranial) | above, or toward the head end of the body. |
| Inferior (caudal) | below, or toward the feet. |
| Lateral | farther from the midline of the body |
| Medial | nearer to the midline of the body. |
| Internal (deep) | deeper within the body, away from the surface of the body. |
| External (superficial) | nearer the surface of the body |
| Proximal | nearer to the midline of the body or to the origin of a part. |
| Distal | farther from the midline of the body or from the origin of a part. |
| Parietal | refers to the walls of a cavity |
| Visceral | refers to the organs found in a cavity |
| Ipsilateral | refers to structures that are on the same side of the body. |
| Contralateral | refers to structures that are on opposite sides of the body. |
| Cephalic | Head |
| Frontal | Forehead |
| Orbital | Eye cavity |
| Buccal | Cheek |
| Mental | Chin |
| Sternal | Breast bone |
| Pectoral | Chest |
| Umbilical | Navel |
| Inguinal | Groin |
| Coxal | Hip |
| Sural | Calf |
| Crural | Leg |
| Pedal | Foot |
| Otic | Ear |
| Nasal | Nose |
| Oral | Mouth |
| Cervical | Neck |
| Acromial | Point of Shoulder |
| Axillary | Armpit |
| Mammary | Breast |
| Brachial | Arm |
| Antecubital | Front of elbow |
| Abdominal | Abdomen |
| Antebrachial | forearm |
| Carpal | wrist |
| palmar | palm |
| digital | finger |
| genital | reproductive organs |
| patellar | front of knee |
| tarsal | instep |
| digital | toe |
| occipital | back of head |
| vertebral | spinal column |
| dorsum | back |
| cubital | elbow |
| lumbar | lower back |
| sacral | between hips |
| gluteal | buttocks |
| perineal | area between the anus and the reproductive organ |
| femoral | thigh |
| popliteal | back of knee |
| plantar | sole |
| Sagittal Plane | this plane runs anterior to posterior and divides the body into right and left portions |
| Median (midsagittal) Plane | runs through the midline of the body and divides it into right and left halves |
| Parasagittal Plane | Plane that runs on either side of the midline of the body and divides it into unequal right and left sides |
| Coronal (or frontal) Plane | This plane runs vertically to the ground and divides the body into a front (anterior or ventral) and a back (posterior or dorsal) portion. *Both the sagittal and coronal planes result in a longitudinal section of the body |
| Transverse | This plane runs parallel to the ground and divides the body into superior and inferior portions. *The term cross section is frequently used. This refers to any section cut perpendicular to the long axis of an organ or structure. |
| Serous Membranes | Thin, double-layered membrane that lined walls of cavity and outer surfaces. Provide protection and lubrication for organ movement |
| Pleural Membranes (pleura) | - The membranes surrounding the lungs are the visceral and parietal PLEURAL MEMBRANES (PLEURA) - Parietal and visceral membranes |
| Pericardial Membrane (Pericardium) | - The membranes surrounding the heart are the visceral and parietal pericardial membrane (pericardium) |
| Peritoneal membranes (Peritoneum) | The membranes enclosing the organs in the abdominopelvic cavity are the visceral and parietal peritoneal membranes (peritoneum) |
| The major body cavities | 1) Cranial Cavity 2) Vertebral Cavity 3) Ventral Cavity |
| Cranial Cavity | houses the brain |
| Spinal Cavity (or canal) | formed by the vertebral foramina, houses the spinal cord |
| Dorsal Cavity | The cranial and vertebral cavities |
| Ventral Cavity | *Formed by the space enclosed by the ribs, sternum, muscles, and pelvic bone. *Large cavity that includes the thoracic cavity and the abdominopelvic cavity. *These two cavities are separated by the diaphragm. |
| Thoracic Cavity | Located above the diaphragm and includes three smaller cavities and a space: 1) Pleural cavity 2) pericardial cavity 3) mediastinum |
| Pleural cavity | located between the visceral and parietal pleural membranes around each lung |
| Pericardial cavity | located between the visceral and parietal pericardial membranes around the heart. |
| Mediastinum | The space between the lunges, houses the thymus, trachea, bronchi, esophagus, and the large blood vessels entering and leaving the heart. Also houses the heart. |
| Abdominopelvic Cavity | Located below the diaphragm and includes three smaller cavities: 1) Abdominal Cavity 2) Pelvic Cavity 3) Peritoneal Cavity |
| Abdominal Cavity | Houses the stomach, liver, gallbladder, pancreas, spleen, and most of the small and large intestines. *Kidneys, ureters, and adrenal glands are also in this cavity area, but lie behind the peritoneal lining and are RETROPERITONEAL. |
| Pelvic Cavity | Houses the urinary bladder, ovaries, oviducts, uterus, vas deferens, seminal vescicle, prostate glad, Cowper's gland, the lower part of the small intestine, and the lower part of the large intestine, including the cecum, appendix, sigmoid colon, and rectum. |
| Peritoneal Cavity | Located between the visceral and parietal peritoneal membranes, which line the abdominopelvic cavity. |
| Vertebral Cavity | spinal cord and backbone |
| Oral Cavity | Teeth and tongue |
| Nasal Cavity | Nose divided into right/left nasal septum |
| Orbital Cavities | Eyes; associated with skeletal muscles and nerves |
| Middle Ear Cavities | middle ear bones |
| Parietal | membrane attached to wall of cavity |
| Visceral | membrane attached to internal organ |
| Serous Fluid | watery fluid separating parietal and visceral membranes |
| Axial | head, neck, and trunk |
| Appendicular | Upper and lower limbs |
| Bilateral | paired structures, one of each side |
| Superficial | situated near the surface |
| Deep | more internal than superficial parts |
| Filtration | the passage of materials under pressure (or gravity) through a semipermeable membrane on the basis of size. Example: formation of tissue fluid by forcing water and dissolved substances out of blood capillaries |
| Permeable | To pass through the openings |
| Passive Diffusion | the spontaneous passage of molecules from an area of high concentration to an area of low concentration until equilibrium is reached |
| Passive Mechanisms | - Do not require energy -> Diffusion -> Facilitated Diffusion -> Osmosis -> Filtration |
| Active Mechanisms | - Require cellular energy -> active transport -> endocytosis -> exocytosis |
| Diffusion | Molecules or ions in liquid or air solution move from regions of higher concentration → lower concentration |
| Facilitated Diffusion | *Used when substances are not able to pass through lipid bilayer without help of membrane proteins *Uses carrier molecules to transport substances in/out of cell |
| Osmosis | Type of diffusion in which water moves from an area of high water concentration to an area of low water concentration through a membrane selectively permeable ONLY to water *Impermeable to the solute |
| Osmotic Pressure | Ability of osmosis to generate enough pressure to ↑ water volume |
| Active Transport | Process that moves particles through membranes from region of lower concentration to higher concentration |
| Exocytosis | Moves particles out of cell (export) |
| Endocytosis | *Moves particles into cell *Includes: Pinocytosis & Phagocytosi |
| Pinocytosis | “cell drinking” Engulfs liquid droplets |
| Phagocytosis | “cell eating” Engulfs solids |
| Transcytosis | Selectively transports substance from one end of cell to other end of cell |
| Isotonic | any solution w/ same osmotic pressure as body fluids |
| Hypertonic | solutions w/ higher osmotic pressure than body fluids *Cell will shrink |
| Hypotonic | solution w/ lower osmotic pressure than body fluids *Cell will appear swollen |
| Tonicity | The osmotic pressure or tension of a solution. |
| Receptor-mediated endocytosis | endocytotic mechanism in which specific molecules are ingested into the cell |
| Edema | *occurs when an excessive volume of fluid accumulates in the tissues *Causes: eating too much sugar or salt, water imbalance |
| Fluid Compartments | Intracellular and extracellular |
| Intracellular | liquid (fluid) contained inside the cell membranes |
| Extracellular | Fluid outside our cells. *Consists of: plasma (or intravascular fluid), interstitial fluid, and lymph fluid |
| Plasma (Intravascular fluid) | Fluid that is found in blood vessels. *The blood vessels wrap around the cells, bringing oxygen and nutrients and removing waste |
| Interstitial Fluid | Fluid that surrounds the cells |
| Lymph Fluid | *The clear fluid found outside the cells which bathes the tissues. *It is collected, filtered, and transported by the lymphatic system from around the tissues to the blood circulatory system. |
| Gross | Large body structures |
| Regional | particular structures in area |
| systemic | system by system |
| surface | topographical or superficial |
| microscopic | small body structures |
| cytology | the study of cells |
| histology | the study of tissues |
| developmental | progressive structural changes |
| embryology | the study of changes before birth |
| What is anatomy? | The study of structure of living organisms |
| What is Physiology? | the study of the function of living organisms |
| Renal Physiology | Kidney function and urine production |
| Neurophysiology | nervous system |
| cardiovascular physiology | heart and blood vessels |
| Levels of Organizations of the Body | 1) Atom 2) Molecule 3) Macromolecule 4) Organelle 5) Cell 6) Tissue 7) Organ 8) Organ System 9) Organism |
| What is at the chemical level? | Atoms, Molecules, & Macromolecules |
| What is at the cellular level? | cells: smallest unit of living things |
| Tissues | group of similar cells |
| Organ | - discrete structure composed of at least 2 tissue. - complex functions become possible |
| Organ system | organs that work together to accomplish common goal |
| Organism | sum total of all structural levels working together |
| Characteristics of Life | There are nine: Movement, Responsiveness, Growth, Reproduction, Boundaries, Metabolism, Development, Digestion, Excretion |
| What is homeostasis? | ability to maintain relatively stable internal conditions even though outside environment changes |
| Homeostatic Mechanisms | 3 components of self-regulating system: 1) Receptors 2) Control Center/Set Point 3) Effectors |
| Homeostatic Mechanisms: RECEPTORS | Sensor that responds to stimulus by sending input to control center (afferent) |
| Homeostatic Mechanism: CONTROL CENTER/SET POINT | analyzes input and determines response |
| Homeostatic Mechanism: EFFECTORS | provides means for control center's response to stimulus (efferent) |
| Negative Feedback System | - response acts against the stimulus - receptors measure deviation from set point - effectors activate & return conditions towards normal - as conditions return to normal, deviation from set point lessons & effectors shut down - decreasing the stimulus can be either raining or lowering the level - Examples: Home heating system; body temperature; insulin/glucagon regulation |
| Positive Feedback System | - response acts to amplify stimulus - result of response enhances original stimulus so activity is accelerated - change that occurs proceeds in same direction as initial disturbance - usually control infrequent events that do not require continuous adjustments - examples: blood clotting |
| Chemistry | branch of science that considers composition of matter and how this composition changes |
| What is matter? | anything that occupies space and has mass |
| Elements | - fundamental substances that compose matter - example: carbon, hydrogen, oxygen, iron *human body requires approx. 20% elements: 95% are O, C, H, N |
| Atoms | - building blocks of elements - atoms w/in element are similar but differ from other atoms in different elements - atoms vary in size, weight, and interactions |
| What does an atomic structure consist of? | Nucleus, Protons, Neutrons, and Electrons |
| Proton | single positive electrical charge |
| Neutron | uncharged (neutral) |
| Electrons | single negative electrical charge |
| Atomic Number | # of protons in atom |
| Atomic Weight | Number of protons & neutrons in the nucleus |
| What is an isotope? | - atoms of an element with different atomic weights due to an unusual # of neutrons |
| Ions | atoms that gain or lose electrons become charged |
| Chemical Bond | atoms attache to other atoms by gaining, losing, or sharing electrons |
| Ionic Bond | chemical bond between atoms formed by the transfer of one or more electrons from one atom to the other *example: Sodium Chloride (NaCl) |
| Covalent Bond | Chemical bond in which atoms share electrons equally (single, double, or triple) |
| Polar Covalent Bond | covalent bond in which the electrons are not shared equally, creating a slightly negative end and a slightly positive end *Example: Water |
| Hydrogen Bond | weak attraction between polar ends of molecules |
| Molecule | two or more atoms held together by a chemical bond (same or different element) |
| Compound | two or more atoms of different elements held together by a chemical bond *example: water - molecule of a compound always consist of definite kinds and numbers of atoms |
| Electrolytes | substances that release ions in water |
| Acids | electrolytes that release hydrogen ions (H+) in water (example: HCl --> H+ + Cl- |
| Bases | electrolytes that release ions that bond with hydrogen ions (ex: NaOH --> Na+ + OH-) |
| pH | value that measures hydrogen ion concentration |
| pH Scale | - ranges from 0 to 14 - pH of 7 is neutral b/c has equal # of hydrogen and hydroxide ions - pH less than 7 is acidic, more than 7 is basic (alkaline) - each whole number differs by a factor of 10 *ex/ 4.0 is 10 times more acidic than 5.0 |
| Inorganic Compounds | molecules that do NOT contain carbon (exceptions: CO, CO2) |
| Organic Compounds | - molecule that include both carbon and hydrogen atoms -can dissolve in water but usually do NOT release ions - organic compounds in cells: carbohydrates, lipids, proteins, nucleic acids |
| Carbohydrates | - macronutrient supplying energy for cells - contains elements C, H, & O - most common: glucose |
| Categories of Carbohydrates | 1) Monosccharides (glucose, fructose, glactose) 2) Disaccharides (sucrose, maltose, lactose) 3) Polysaccharides (starch, fiber, glycogen) |
| Monosaccharides | - simple sugar units |
| Glucose | - blood sugar - found in fruits and vegetables - used for: cell energy, stored as glycogen in muscles and liver, converted to fat for energy storage |
| Fructose | - "fruit sugar" - found in fruit, honey, corn syrup |
| Galactose | found as part of lactose in milk |
| Disaccharides | two monosaccharides |
| Sucrose | - Glucose + Fructose - commonly known as table sugar |
| Lactose | - milk sugar - glucose + galatose |
| Maltose | - Glucose + Glucose - Honey |
| Polysaccharides | 3 or more simple sugars combined |
| Animal Polysaccharides | - Glycogen: ranges in size from few hundred to thousands of glucose molecules linked together like sausage links *storage form of glucose |
| Lipids | Fats, phospholipids, steroids |
| Neutral fats (aka triglyceride) | - contains C, H, & O - most common & plentiful fat in body - supply energy (9 kcal/gram) - more than 95% of body fat is triglyceride (primary storage form) - composed of 2 different atom clusters |
| Fatty Acids | - give each fat unique qualities of flavor & texture - Two types: Saturated & Unsaturated - differ in: *length of carbon chain *bonding of carbon atoms and arrangement of hydrogen atoms along carbon chain |
| Saturated Fatty Acids | contain only SINGLE BONDS between C atoms; all remaining bonds attach to hydrogen - the fatty acid molecule holds as many H+ atoms as possible -- thus the term saturated |
| Unsaturated Fatty Acids | - contain one or more double bonds along the main C chain - the fatty acid is unsaturated with respect to H+ |
| Mono-unsaturated | 1 double bond (olive, canola, and peanut oil) |
| Poly - unsaturated | 2 or more double bonds (safflower, sunflower, soybean, corn oil) |
| Phospholipids | modified triglyceride with a glycerol backbone, 2 fatty acid chains, and a phosphate group - component of ALL cells - modulate fluid movement across cells walls - important in blood clotting |
| Steroids | - ring structured lipids - example: Cholesterol *component of cell membranes * precursor to other substances (sterol hormones {sex hormones}, vitamin D, bile salts) |
| Functions of Proteins | - Anabolism - structural proteins - enzymes - DNA, RNA - Blood Plasma - Vitamin Precursor - 1 g = 5.65 kCal |
| Protein Organization | - Chemical organization similar to fats & CHO, except protein also contain Nitrogen - Basic unit --"building blocks" -- of protein are Amino Acids (AA) |
| Amino Acids | - organic compounds that combine to form proteins. Amino acids and proteins are the building blocks of life. - The human body uses amino acids to make proteins to help the body: Break down food, grow, repair body tissue, perform many other body functions |
| Structural Levels of Protein | -bonding of atoms in different parts of the polypeptide chain give protein distinctive 3-dimensional shape=conformation *conformation determines proteins functions - Levels: Primary, secondary, tertiary, quaternary |
| Primary | linear sequence of amino acids |
| Secondary | Alpha helix or beta pleated |
| Tertiary | bends superimposed on the alpha helix |
| Quaternary | joining of 2 or more polypeptide chains |
| Nucleic Acids: RNA & DNA | composed of C, O, H, N, and P are the largest molecules in the body - form genes - take part in protein synthesis - structural units are nucleotides |
| RNA | ribonucleic acid - located chiefly outside nucleus - carries out orders of for protein synthesis |
| DNA | deoxyribonucleic acid - found in nucleus - constitues genetic material or genes - provides instructions for building every protein in body |
| The Composite Cell | - all cells composed mainly of C, H, N, & O - Cells 3 main components: 1) Plasma Membrane 2) Cytoplasm 3) Nucleus |
| Plasma Membrane | - outer boundary of cell; serve as external barrier - act in transport of substances into/out of cell - proteins in membrane act as receptors to detect signals - helps cells attach to certain other cells (important for tissue formation) - helps body recognize that it's your body's cell |
| Plasma Membrane: General Traits | -thin, flexible, and elastic - selectively permeable - microvilli (not common in all cells), found in small intestines - composed of double layer (bilayer) of phospholipid molecules with proteins dispersed throughout *proteins float in fluid bilayer creating a constantly changing mosaic pattern = fluid mosaic model |
| Microvilli | finger-like extensions that project and increase surface area (in absorptive cells) |
| Plasma Membrane Structure | -bilayer of phospholipid molecules w/ proteins - water soluble phosphate "heads" form surfaces of membrane (hydrophilic) - water insoluble "tails" form interior of membrane (hydrophobic) - 2 parallel sheets of phospholipid molecules lying tail to tail w/ polar head facing exterior and interior of cell |
| Plasma Membrane Proteins | - proteins embedded in membrane - variety of functions and shapes - 2 main types: integral proteins & peripheral proteins |
| Plasma Membrane Proteins: INTEGRAL | -firmly inserted into lipid bilayer - may protrude from 1 or both faces of membrane - have hydrophobic & hydrophilic regions allowing them to interact w/ non-polar lipid tails and w/ water inside/outside cell - Ex/ transmembrane & non- transmembrane |
| Transmembrane | mainly used for transport - form channels - act as carriers (bring something in/out of cell) - receptors that relay info to cell inferior |
| Plasma Membrane Proteins: PERIPHERAL | - associate mainly w/ 1 side of membrane (NOT embedded into lipid membrane) - attach loosely to integral proteins or membrane lipids - easily removed w/o disturbing cell membrane - Functions: enzymes, change cell shape, link cells - NOT USED FOR TRANSPORTATION |
| Plasma Membrane Functions | - Transport - enzymatic activity - receptors for signal transduction - intercellular joining - cell-cell recognition - attachment to the cytoskeleton and extracellular matrix (CAM) |
| Plasma Membrane: Selective Barrier | - allows mvmt. of substance in/out of cell *"traffic" is continuous but selective - Two types: Passive Mechanisms and Active Mechanisms |
| Cytoplasm | - gel-like substance where organelles & membranes are suspended in cytosol - makes up most of cell's volume - includes protein rods & tubules that form cytoskeleton or "cell skeleton" *protein connects to rods & tubules to create shape and function - most of cell activities occur here |
| Cytoskeleton | Contain two main structures: - microfilaments - Microtubules |
| Microfilaments | - tiny rods of protein called actin - form bundles - provide cell movement |
| Microtubules | - long, rigid, slender tubes - composed of tubulin (globular protein) - important in cell division - help determine overall shape of cell & shape distribution of organelles |
| Organelle: Endoplasmic Reticulum | - extensive system of interconnected tubes & parallel membranes enclosing fluid filled cavities - coils and twists through cytosol - continuous w/ nuclear membrane - 2 variations: rough ER & smooth ER |
| Rough ER | - studded w/ ribosomes - ribosomes manufacture all proteins secreted from cell - manufactures integral proteins and phospholipids - closer to nucleus |
| Smooth ER | - closer to plasma membrane of cell - ribosomes sparse - enzymes important in lipid synthesis, fat absorption, metabolism of drugs - abundant in liver |
| Organelle: Golgi Apparatus | "traffic director" - stacked and flattened membranous sacs - refines, packages, & transport proteins synthesized on ribosomes of Rough ER - proteins arrive at Golgi Apparatus enclosed in vesicles & fuse w/ GA membrane - proteins pass through layers & are modified chemically - proteins packaged & delivered through exocytosis to sites in cell or exported out of cell |
| Organelle: Mitochondria | - power plant of cell, providing most of its ATP supply and where ATP is created - elongated, fluid filled sacs w/ out and inner layer - inner layer folds extensively into partitions called cristae - contain own RNA & DNA; can reproduce themselves - active cells (muscle cells) have thousands of mitochondria |
| Organelle: Lysosomes | - "garbage disposals" of the cell - tiny membranous sacs that contain digestive enzymes - highly acidic interior |
| Lysosomes Functions | - digest particles taken in by endocytosis - degrades worn out, injured, or non-functioning organelles - metabolic functions such as glycogen breakdown - breaks down non-useful tissue (ex: uterine lining during menstruation) - breaks down bone to release calcium ions into blood - works close with immune system |
| Organelle: Peroxisomes | - most abundant in liver & kidney cells - contain enzymes, peroxidases that catalyze metabolic reactions that release hydrogen peroxide - contain enzyme, catalase, which decomposes hydrogen peroxide |
| Organelle: Centrosome | - near GA and nucleus - microtubules organizing center - contains paired centrioles |
| Organelle: Centrioles | - composed of microtubules in 9 groups of 3 - at right angles to each other - distribute chromosomes to newly forming cells (will separate) |
| Cilia | - fringe surface of epithelial cells - tiny, hair-like, and attached beneath cell membrane - move in "to and fro" manner - waves move fluid over surface of certain tissues |
| Flagella | - longer than cilia - cell usually only has one - moves in undulating wave - ex: sperm tail |
| Nucleus | - houses genetic material (DNA) which directs all cell activities - large, spherical structure - contains nucleoplasm |
| Nuclear Envelope | - encloses nucleus - double layered; inner & outer lipid bilayer membrane - protein lined channel called nuclear pores |
| Nucleolus | - small, dense body composed of RNA & protein - site where ribosome subunits are assembled |
| Chromatin | loosely coiled fibers of DNA & protein that condense to form chromosomes |
| Cell Life Cycle | - series of changes cell undergoes from creation to reproduction/division - 3 phases: 1) interphase 2) Mitotic Phase 3) cytokinesis - disruption can affect health *cell division too infrequent, no healing *cell division too frequent, cancer |
| Interphase | - period of cell formation to cell division - active period of synthetic activity *obtains/utilizes new living organism *maintains usual functions * duplicates membranes, ribosomes, lysosomes, mitochondria * replicates DNA - 3 phases: G1, S, G2 |
| Interphase: G1 | (Gap 1) - cell metabolically active - synthesizing proteins & growing rapidly - Variable phase: minutes to hours or days to years |
| Interphase: S | (Synthetic) - DNA replicates - histones are assembled into chromatin |
| Interphase: G2 | (Gap 2) - very brief phase - enzymes/proteins needed for division are synthesized & moved - centriole replication is complete - cell ready to divide |
| Mitosis | - 4 Phases: Prophase, Metaphase, Anaphase, & Telophase - duration varies, but usually 1 hour or less |
| Prophase | - first of four mitotic phases - chromatic threads coil & condense to form chromosomes - chromatids of each chromosome held together by centromere - nucleoli disappears & cytoskeleton disassembles - centrioles move away from each other - mitotic spindle forms from new assembly of microtubules - mitotic spindle occupies center of cell between the centrioles |
| Metaphase | - 2nd out of 4 mitotic phase - chromosomes line up at middle of cell - centromeres aligned at exact center - spindle fibers attach to centromeres of each chromosome - fiber from 1 centriole contacts 1 centromere and fiber from other centriole contacts other centromere. |
| Anaphase | - 3rd of 4th mitotic phase - centromeres pulled apart - as chromatids separate, they become individual chromosomes - spindles shorten & pull attached chromosomes towards their centrioles at opposite ends of cell - cell elongates - shortest stage of mitosis |
| Telophase | - 4 out of 4 mitotic phase - like prophase in reverse - chromosomes uncoil & resume chromatin form - nuclear envelope forms around each chromatin mass - nucleoli appear w/in new nuclei - spindle breaks down - brief moment, cell has 2 nuclei - mitosis ends |
| Cytokinesis | - cytoplasmic division - cell membrane constricts around cell middle creating a cleavage furrow - contraction of ring of microfilaments divides the cytoplasm - ring pinches inward, separating 2 nuclei & distributing half of organelles into each cell |
| Control of Cell Division | - cell division controlled/varied w/ cell type - most human cells divide between 40-60 times - basis for mitotic clock = DNA at tips of chromosomes, telomeres |
| On telomeres | - same 6 nucleotide sequence repeats hundreds of times - each mitosis removes 1200 nucleotides - at certain point, signals cell to cease dividing |
| Control of Cell Division: External | - hormones - growth factor (ex: epidermal) - space availability (contact inhibition) *division will not occur if there is inhibition) |
| Control of Cell Division: Internal | - levels of proteins, kinases & cyclins - cell size -- ratio between surface area cell membrane provides & cell volume * if volume is larger than cell membrane, cell will divide |
| Tumors: Malignant | - too frequent mitosis - unabated mitosis producing abnormal growth |
| Oncogenes | - abnormal variants of genes normally in control of cell cycle - over-expressed, increasing cell division rate |
| Tumor supressor gene | - normally hold mitosis in check - if removed or inactive, control of cell cycle gone & uncontrolled cell division results |
| Cell Death | - apoptosis = programmed cell death - fast, continuous, orderly, contained destruction - packages cellular remnants into membrane enclosed pieces & are removed - begins w/ "death receptor" on cell's membrane *becomes activated w/ dying cell * ex: sunburn |
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