Anatomy Chapter 3 Cells and Tissues PDF

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Cells and Tissues Cells - smallest unit of living things - made up primarily of 4 elements: carbon, oxygen, hydrogen and nitrogen- plus much smaller amounts of other elements Interstitial Fluid – derived from the blood; exchanges between cells and blood are made through this fluid Cells have 3 main regions: Nucleus, Cytoplasm, Plasma Membrane *Fats and Carbohydrates have similar components* ~ Calcium is needed for blood clotting ~ ~ Iron is needed to make hemoglobin ~ ~ Iodine is needed to make thyroid hormone that controls metabolism ~ ~ Sodium and potassium are essential if nerve impulses are to be transmitted and muscles are to contract ~ Nucleus - located near the center of the cell - DNA (deoxyribonucleic acid) containing - has 3 regions: Nuclear envelope, nucleoli, chromatin *RNA (ribonucleic acid) - produces proteins - is around the nucleus* - the actual sites of protein synthesis in the cell DNA (deoxyribonucleic acid) - has the instructions for building proteins - necessary for cell production Nuclear Envelope (Nuclear Membrane) - a double membrane barrier that bounds the nucleus Nucleoplasm - jellylike fluid enclosed by the nuclear membrane in which other elements are suspended Nucleoli - one or more small dark-staining essentially round bodies contained in the nucleus - are sites were ribosomes are assembled Ribosome - actual sites of protein synthesis ~ When a cell is not dividing, its DNA is combined with protein and forms a loose network of bumpy threads called chromatin ~ ~ When a cell is dividing to form 2 daughter cells, the chromatin threads coil and condense to form dense, rodlike bodies called chromosomes Plasma membrane - is a fragile transparent barrier that contains the cell contents and separates them from surrounding environment ~ The structure of the plasma membrane consists of 2 lipid(fat) layers arranged "tail to tail" in which protein molecules float ~ ~ Most of the lipid portion is phospholipids (some with attached sugar groups), but substantial amount of cholesterol is also found in plasma membranes ~ Hydrophilic - water loving i.e. polar head Hydrophobic - water hating i.e. polar tails Specializations of the plasma membrane: Microvilli – are tiny fingerlike projections that greatly increase the cell’s surface area for absorption so that the process occurs more quickly Membrane Junctions – vary structurally depending on their roles Membrane Junctions: a. Tight Junctions - are impermeable junctions that bind cells together into leak proof sheets b. Desmosomes - are anchoring junctions that prevent cells subjected to mechanical stress (such as skin cells from being pulled apart c. Gap Junctions - commonly seen in the heart and between embryonic cells, function mainly to allow communication Cytoplasm - the cellular material outside the nucleus and inside the plasma membrane Cytoplasm’s 3 Major Elements: Cytosol, Organelles, Inclusions Cytosol - is a semitransparent fluid that suspends the other elements Organelles - metabolic machinery of the cell Inclusion - chemical substances that may or may not be present, depending on the specific cell type Cytoplasmic Organelles (little organs) - specialized cellular compartments each performing its own job to maintain life of the cell Mitochondria - powerhouse of the cell Ribosomes - tiny, bilobed dark bodies made of proteins and one variety of RNA called ribosomal RNA Endoplasmic Reticulum (ER) - a system of fluid-filled cisterns (tubules or canals) that coil and twist through the cytoplasm ~ Rough ER is also called because it is studded with ribosomes (protein synthesis) ~

~ Smooth ER communicates with the rough variety but it plays no role in protein synthesis; fat production; degasification ~ Golgi Apparatus - a stack of flattened membranous sacs, associated with swarms of tiny vesicles; modifies and package proteins; stimulate the sacs; pinches of sacs containing proteins and phospholipids destined for "home" Secretory Vesicles - formed from swollen ends of proteins of Golgi Apparatus Lysosomes (breakdown bodies) - appear in different sizes, and are membraneos bags containing powerful digestive ~ When lysosomal membrane becomes fragile he cell is injured or deprived of oxygen and when excessive amounts of vitamin A are present ~ Peroxisomes - sacs containing powerful oxidase enzymes that use molecular oxygen to detoxify a number of harmful or poisonous substance; convert free radicals to hydrogen peroxide, a function indicated in their naming The enzyme catalase then converts excess hydrogen peroxide to water *Enzyme catalysts that regulate chemical reactions * Free Radicals - unpaired electrons that can scramble the structure of proteins and nucleic acids * - product of normal metabolism of the body * Cytoskeleton - acts as cell bones and muscles; framework of cell Microfilaments – such as actin and myosin are most involved in cell motility and in producing changes in cell shape Centrioles - generates microtubules and during cell division, it directs the formation of mitotic spindle Cilia - move substances along the cell surface Flagella - i.e. is the sperms tail 1. Cells that connect body parts: Fibroblast - elongated shape Erythrocyte (red blood cell) - carries oxygen in the bloodstream 2. Cells that covers and lines body organs: Epithelial cell – honeycomb of a beehive shape; allows epithelial cells to pack together in sheets; abundant intermediate filaments that resist tearing when the epithelium is rubbed or pulled 3. Cells that stores nutrients: Fat Cell - huge spherical shape of a fat cell is produced by a large lipid droplet in its cytoplasm 4. Cell that fights disease: Macrophage (phagocyte cell) - extends long pseudopods(false feet) to crawl through tissue to reach infection 5. Cell that gathers information and controls body functions: Nerve cell (neuron) - has long processes for receiving messages and transmitting them to other structures in the body 6. Cells of reproduction: Oocyte (female) - largest cell in the body, this egg contains several copies of organelles Sperm (male) - is a long and streamlined, but built for swimming to the egg for fertilization Solution - homogenous mixture of 2 or more components Solvent - largest amount in a solution; dissolving medium Solute - components or substances present in smaller amounts Intracellular fluid (inside the cell) - a solution containing small amounts of gases, nutrients, and salts, dissolved in water Interstitial fluid (outside the cell) - fluid that continuously bathes the exterior of our cells Selective Permeability -allows nutrients to enter the cell but keeps many undesirable substances out Passive transport - substances that are transported across the membrane without energy input from the cell Active transport - cell provides the metabolic energy (ATP) that drives the transport process Diffusion - molecules (and ions) move away from a region where they are more concentrated to a region where they are less concentrated The hydrophobic core of the plasma membrane is a physical barrier to diffusion. However, molecules will diffuse through the plasma membrane if (1) they are small enough to pass through its pores (2)they can dissolve in the fatty portion (phospholipid) of the membrane is called simple diffusion Osmosis - water will move the solute from lesser concentration to greater concentration; attracts water Filtration - process in which water and and solutes are forced through a membrane by fluid or hydrostatic pressure Pressure Gradiant – pushes solute – containing fluid from the higher-pressure area to the lower pressure area. Active Transport – solute pumping; require protein carriers that combine reversibly with the substances to be transported across the membrane; against the gradient; uses ATP to energize its protein carriers, which are called solute pumps

Sodium Potassium pump - simultaneously carries sodium ions (Na+) out of and potassium ions into the cell is absolutely necessary for normal transmission of impulses by nerve cells Vesicular Transport – involves help from ATP, moves substancesinto or out of cells without actually crossing the plasma membrane. 2 types of Vesicular transport: Exocytocis - moves substances out of the cell Endocytosis - includes those ATP-requiring processes that take up or engulf, extracellular substances by enclosing them in a small membranous vesicle; into the cell Phagocytosis - cell eating Pinocytosis - cell drinking; gulps droplets of extracellular fluid Cell life cycle - series of changes a cell goes through from the time it is formed until it divides 2 Major periods of cycle: Interphase - cell grows and carries on its usual metabolic activities; between division Cell Division - reproduces itself Cell Division consists of 2 events: Mitosis - division of the nucleus occurs first Cytokinesis - division of cytoplasm in which begins when mitosis is nearly completed ~ When each nucleus divides, each daughter cell ends up and exactly the same genetic info. as the original mother cell ~ 4 Stages of Mitosis: Prophase - cell division begins, the chromatin threads coil and shorten so that visible barlike bodies called chromosomes appear ~ Each chromosome is actually made up of to strands each called a chromatid, held together by a small buttonlike body called a centromere~ Mitotic Spindle – composed of microtubules Metaphase - chromosomes are alike Anaphase - splitting of chromatids Telophase - becomes chromatid again Gene - defined as a DNA segment that carries the information for building one protein or polypeptide chain 3 varieties of RNA Transfer RNA (tRNA) - molecules are small cloverleaf-shaped molecules Ribosomal RNA (Rrna) - helps form the ribosomes, where proteins are built Messenger RNA (mRNA) - single nucleotide strand that resemble half of a DNA molecule and carry the 'message' containing instructions for protein synthesis from the DNA Transcription - transfer of information from DNA's base sequence into the complementary base sequence of mRNA Epithelial Tissue (epithelium) - doesn't have blood supply (avascular); lining covering and glandular tissue of the body - its functions include: protection, absorption, filtration and secretion Simple epithelium (one layer cell) and stratified epithelium are classifications by cell arrangements Squamous Cell - flattened like fish scales Cuboidal Cell - cube-shaped like dice Simple Squamous Epithelium- sinlge layer of thin squamous cells resting on a basement membrane Simple Cuboidal Epithelium - one layer of cuboidal cell resting on a basement membrane Simple Columnar Epithelium - made up of single layer of tall cells that fit closely together Goblets cells - produce lubricating mucus Stratified Squamous Epithelium - most common epithelium in the body Transitional Epithelium - highly midified, stratified squamous epithelium that forms the lining of only few organs the urinary bladder Endocrine Glands - lose their connection to the surface (duct), thus they are often called ductless Exocrine Glands - retain their ducts, and their secretions empty through the ducts to the epithelial surface Connective Tissue - connects body parts; protecting, supporting, and binding together Types of connective tissues: Bone (Osseous Tissue) - bone cells sitting in the cavities called lacunae

Cartilage - less hard and more flexible than the bone; hyaline cartilage has abundant collagen fiber hidden by a rubbery matrix with glassy blue-white appearance; fibrocartilage forms cushionlike diss between the vertebrae of the spinal column Dense Connective Tissue (Dense Fibrous Tissue) - has collagen fibers as its main matrix element ~ Tendons attach skeletal muscles to bone ligaments connect bones to bones at joint ~ Lose Connective Tissue - softer and have more cells and fewer fibers Areolar tissue the most widely distributed connective tissue Adipose Tissue - commonly fat Reticular Connective Tissue - consist of delicate network of interwoven reticular fibers associated with rerticular cells which resembles fibroblasts Types of Muscle Tissue: Skeletal Muscle - can be controlled voluntarily; attached to the skeleton; has striations Cardiac Muscle - found only in the heart; has junctions called intercalated disks that contains gap junctions that allow ions to pass freely from cell to cell; has striations Smooth Muscle - also called visceral muscle because no striations are visible Peristalsis - wavelike motion that keeps food moving through the small intestine Regeneration -replacement of destroyed tissue by the same kind of cell Fibrosis - repair by dense connective tissue that is the formation of a scar Keloid – overproducing of fibers

Tissue a. b. c.

injury sets series of events into motion: The capillaries become very permeable Granulation tissue forms The surface epithelium regenerates

Tumor - growth

Benign - kindly

Hypertrophy - increase in number

Malignant - bad Hyperplasia - increase in size

Carcinogens - cancer-causers Atrophy - decrease in size...