BIOLOGY 315 1st Edition Lecture 3 Outline of Last Lecture I. Light Microscopy vs Electron MicroscopyII. The Cella. The Parts of the Average Celli. 3 basic partsOutline of Current Lecture I. Cytoplasmic Components (continued)II. The NucleusIII. The Human Body PlanIV. Medical Imaging TechniquesCurrent LectureI. Cytoplasmic Components (continued)a. Centrioles1. Structure:a. Short barrels, usually adjacent to the cell nucleusb. Occur in pairs, each lies perpendicular to each otherc. Wall of centriole made of 27 microtubules (looks like straws)d. Surrounded by cloud of proteins: Centrosome2. Function:a. Form the mitotic spindles during cell divisionb. Lies in the cell center b. Cytoskeleton (cell skeleton)1. Act like muscular and skeletal system in the cell2. None have unit membrane3. Consists of 3 classes of protein rodsa. Microfilaments (actin filaments)i. Thin rods (5-7 nanometers in diameter)ii. NOT hollowiii. Made of protein actiniv. Work with myosin to generate contractile forcesv. Constantly forming, breaking down, and reformingvi. Organelles move along actin filamentsvii. Myosin moves organelles around within the cellsviii. Actinomyosin: myosin + actin1. acts like muscles within a cellb. Intermediate Filaments:i. NOT hollowii. 8-10 nanometers in diameter (Thickest filament)iii. Highly stable iv. Structural role: resisting tension within the cellv. Analogous with the tension-resisting ligaments in our bodyc. Microtubulesi. HOLLOW rodsii. About 20 nanometers in diameteriii. Radiate from the cytosoliv. Stiff and resist compression, maintain cell shapev. Highways along which organelles and molecules are movedvi. Kinesins and dynein pull organelles along microtubules vii. Framework for organelles to attach toviii. Form the walls of centrioles and cilia c. Cytoplasmic inclusions1. Occupy the cytoplasm2. NOT organelles3. Most are food stores4. Glycosomesa. Dense, twice the diameter of ribosomes b. Cluster together in rosette pattern c. Consist of glycogen (long chain of sugar moleculesd. Contains enzymes that build and break down the glycogene. Serves as a stored fuel in highly active cells5. Lipid Droplets:a. Drops of fatb. Highly concentrated stores of nutrientc. Grey or black spots in cytoplasmd. No unit membraneII. The Nucleusa. Control centeri. Controls protein synthesis and synthesis of other moleculesii. DNA does the controllingb. Chromatini. DNA occurs within chromosomesii. Chromatin: DNA + proteinsiii. Diagrammed as rods, but only neatly organized when tightly coilediv. Uncoils to expose DNA for transcriptionc. Nuclear Envelopedi. Membranous envelope surrounding nucleusii. Continuous with RER of the cytoplasm iii. Has pores to pass messenger RNA, histones, and other molecules1. not found in RERd. Nucleolus i. Dark rounded body within the nucleusii. Several per nucleusiii. Function: make most ribosomal RNAiv. Part of 10 different chromosomesv. 2 subunits of ribosomes are manufactured hereIII. Human Body Plan (pg 10 in textbook)a. Body is divided into several regionsi. Axial Region (head, neck, trunk)1. Trunk (thorax, abdomen, pelvis, and perineum { around the anus})ii. Limbsb. Vertebratesi. Tube-within-a-tube body1. Digestive tube inside tube-shaped trunkii. Dorsal, hollow nerve cord (spinal cord and brain)iii. Notochord: stiffening rod just ventral to the spinal cord in the backiv. Pharynx or throatv. Segmentation= segmented outer-body1. Structures that are repeated along the body length a. Examples) vertebrae, spinal nerves, and ribsvi. Head with eyes, ears, nose and brainvii. Heart (located within the ventral thorax)viii. Underlined above are the 6 characteristics of vertebrate: need to know!IV. Medical Imaging Techniquesa. X-raysi. Discovered in 1985ii. Very short wavelength electromagnetic waves , some absorbed when shot at a body, amount absorbed depends on density of the matteriii. Bones absorb better than tissues b/c made of heavier elements (C and P)iv. 4 different substances in human body (darkest to lightest)1. Air, fat, soft tissue, bonev. Limitations1. Blurry images of soft tissues2. Flatten the 3-D structure of the body onto a 2-D image so organs appear to overlap3. Can damage tissue, cause mutations, and cause cancerb. CT: An Advanced X-Ray Technique i. CT (computed tomography) or CAT (computed axial tomography)ii. Patient lies in the tubeiii. Ring rotates to take 12 successive x-rays at equal intervals around the body’s full circumferenceiv. X-ray beam very thinv. Computer translates all the information into very detailed picture of the body sectionvi. Soft structures show up better than X-rayvii. Presented as cross-sectionsviii. View from the feet of the patientix. Cheap enough for small hospitals to affordx. Dose of radiation is lessc. PET Scansi. PET: Positron emission tomography ii. Locating radioactive isotopes that have been injected into the bloodstreamiii. Messages about the chemical processes iv. Prior to, the patient is injected with a short-lived radioisotope that has been included in biological molecules1. Isotopes break down and emit positrons, producing gamma rays2. Machine like CT scanner3. Sensors pick up the emitted gamma rays, translated into electrical impulses, and then sent to the computer which constructs an image with vivid colorsv. If the PET scan fails to find the dye, means there is not adequate blood flow to that areavi. Often used to identify brain damage by a strokevii. Relatively safeviii. Expensiveix. Rather blurry and is a slow process to produced. Sonographyi. Inexpensive and compactii. Safe form of energy, high frequency sound wavesiii. No known harmful effects on living tissues iv. Causes echoes and a computer analyzed these echoes v. Not useful for viewing air-filled structures or structures surrounded by bonee. MRIi. MRI (Medical Resonance Imaging)ii. Produced detailed, high contrast images of soft tissuesiii. Maps element H in bodyiv. Differentiates tissues based on the differences in their water contentv. Exposes patient to magnetic fields, lies within a huge magnet, the nuclei of the body’s hydrogen line up parallel to the strong magnetic fieldvi. Body’s protons return to alignment, detected by sensors and translated into a MRI imagevii. Joints image very wellviii. Disadvantages1. The magnets can get suck metal objects (implants)2. Magnets bang loudly, which can be stressful for the patient3. Very expensive to use and maintain4.