Chapter 4 - Tissues
Chapter 4 - Tissues BIOL 243 001
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This 10 page Class Notes was uploaded by Kaitlin Notetaker on Sunday February 14, 2016. The Class Notes belongs to BIOL 243 001 at University of South Carolina taught by Lewis Bowman in Spring 2016. Since its upload, it has received 75 views. For similar materials see Human Anatomy and Physiology I in Biology at University of South Carolina.
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Date Created: 02/14/16
Monday, February 15, y Translation (end of Ch. 3) Process of Translation (occurs in cytoplasm) • there are 3 RNAs involved in decoding the messenger RNA 1. ribosomal RNA (rRNA) forms part of the ribosome • remember ribosomes = RNA + protein 2. messenger RNA (mRNA) contains the information for the sequence of amino acids for a specific protein • the code is a 3 nucleotide base code 3 nucleotides is a codon • each arrangement decodes into a specific amino acid 64 possible codons but only 20 amino acids (not a 1 1 correspondence • 61 code for specific AA, 3 code for a stop signal for translation and the peptide will fall off (like a period at the end of the sentence) codes are degenerate more than one codon can code for the same amino acid table of amino acid possibilities for each codon figure 3.36 (slides) 3. transfer RNA (tRNA) has a cloverleaf structure • two important regions of the tRNA 1. anticodon complimentary to the codon • its the complimentary base (codon is A anticodon is U) to form base pair 2. place where amino acid is attached 1 Monday, February 15, y • different tRNA for different codons • how does it work? tRNA with attached growing polypeptide is bound to the ribosome next tRNA (with its appropriate amino acid) will bind to adjacent site peptide bond is formed ribosome moves down the mRNA when the ribosome comes to a stop sequence, there is no tRNA to bind to it, and the peptide will be released • only one specific tRNA works for each codon, no other tRNA will fit (like cinderella’s slippers) 2 Monday, February 15, y Tissues (Chapter 4) - Epithelial Tissue • located on “free surfaces” not in contact with other cells - inside of digestive tract, blood vessels, respiratory tract and skin • functions for protection, secretion of mucus and glands, and absorption for digestion • characteristics - free surfaces top layer of the cells basement - membrane located directly below the cells • extracellular made of proteins and carbohydrates - serves as a barrier to separate epithelial tissue and what is underneath - litt intercellular space cells are very close and touching - no blood vessels no capillaries passing through, capillaries instead are located near basement membrane • nutrients diffuse through basement membrane to supply epithelial tissue • Classification of Epithelia • each has two names to be classified by: cell layers, shape - based on cell layers: • 1. simple one layer thick - all cells come in contact with basement membrane and free surface 2. stratified the cells are in layers (thicker, stronger) - some cells touch the basement membrane, some touch surface, some come in contact with neither 3 Monday, February 15, y • 3. pseudostratified some cells do not reach the surface, but all come in contact with the basement membrane - based on cell shapes at the free surface • 1. squamous flat • 2. columnar taller than wide, like a column • 3. cuboidal shaped like a cube • Classification Types imple squamous one layer thick of flat cells (very thin) • function: diffusion and filtration where protection is not important • location: in the air sacs of the lungs where gas exchange occurs - capillaries small thin blood vessels so blood can diffuse • two special types: endothelium found in the lining of blood vessels mesothelium found in serous membranes and covering organs imple columnar one layer with tall cells, lots of cytoplasm • function: secretion and absorption; ciliated type propels mucus • location: the digestive tract, gallbladder, excretory ducts of glands; ciliated lines bronchi, uterine tubes and uterus imple cuboidal one layer and cells shaped like a cube, lots of cytoplasm • function: secretion and absorption • location: in the salivary glands, sweat glands, ovaries and kidney tubules tratifie squamous thick epithelium where the top layer is flat • function: protection where friction takes place 4 Monday, February 15, y • location: skin, mouth, vagina, anus pseudostratified columnar ciliated, • function: secrete mucus and propulsion of mucus • location: in respiratory tract (sinuses) ransitional can change shape, stretch (resembles stratified squamous and cuboidal) • location: the bladder and ureter • function: stretches and permits swelling of the bladder for/by urine • Classifying by Function or Location ndothelium found in the lining of blood vessels • simple squamous cells cus membranes secretes mucin (slimy stuff that enables surface to be moist and slippery ) • goblet cells found here synthesize and secrete mucin taneous membrane found in the “skin” rous membrane combination of connective and epithelial tissues • like a water balloon • outer wall is made up of simple squamous and • surrounds heart, stomach, intestines, liver andular epithelium • 1. endocrine glands not connected to a free surface, secretions are absorbed into the blood stream - when they are absorbed into the blood, then transported through the rest of the body 5 Monday, February 15, y • 2. exocrine glands directly connected to a free surface, act locally sweat - glands connected to skin and deposit sweat onto skin but doesn't affect eye balls (local) - 3 classifications according to mode of secretion merocrine secretions pass through the membrane (exocytosis) and cell is not harmed - ex: sweat glands, salivary glands, pancreas (with digestive juices), etc holocrine accumulate secretion and basically die and release the substance - ex: sebaceous glands secretes seban (fatty, oil like substance) apocrine a part of the cell will bud off - ex: mammary glands Classifying by structure - • duct structure - 1.simple duct does not branch • intestinal glands - 2.compound duct branches • stomach glands • structure of the secretory parts - 1.tubular does not branch • oil glands - 2.alveolar duct branches • mammary and salivary glands - Connective Tissue 6 Monday, February 15, y • general characteristics: location : found in many places • fat, tendons, fills body spaces, attaches skin to the rest of the body unction : varied • protection, support (skeletal system), binds things together, storage of fat characteristics • very abundant lots in our bodies • cells are not close together, widely spaced • good blood supply lots of blood vessels going through the tissue keup : • cells different types of cells in the different types of connective tissue • extracellular matrix - ground substance could be very watery or very hard - fibers different types of connective tissues have different amounts of each type of fibers • 1. collagenous fibers made of collagen, large, strong, white • 2. reticular fibers relatively short and branched • 3. elastic fibers can stretch and coil • A) Connective Tissue Proper class of connective tissue with subclasses - made up of fibroblast cells which makes and secretes the proteins that make up the fibers (or extracellular matrix) - 1.loose connective tissue few, widely spread fibers • 1. areolar has a watery, brown substance and relatively few fibers (very abundant) 7 Monday, February 15, y - most of the fibers are collagenous fucntions - : binds the skin to underlying tissues, surrounds blood vessels, fills body spaces • 2. adipose tissue basically fat, has watery brown substance • 3. reticular high concentration (large amounts) or reticular fibers function - : forms skeleton and serves as a base for other cells - location: lymphoid organs (lymph nodes, bone marrow, and spleen) - 2.dense connective tissue dense, closer together • 1. regular primarily collagen fibers which are parallel, few elastic fibers, very strong - does not heal very well because does not have good blood supply - function: attaches muscles to bones and bones to bones - location: tendons, ligaments • 2. irregular contains collagen fibers which are interwoven irregularly function - : withstands tension in different directions for structural strength - location: organ/joint fibrous capsules, dermis • 3. dense connective tissue large amounts of elastic fibers - function: allows recoil, maintains blood flow through arteries (pulsatile), aids recoil of lungs - location: vocal cords, surrounding large arteries, aorta • B) Cartilage cells: chondroblasts (more immature, just developing) - characteristic: • has a little bit of “give” unlike bones (hyaline) • cells: 8 Monday, February 15, y - chondroblasts are more immature and just developing ch - ondrocytes are more mature • extracellular matrix ground substance is made of chondrin firm, hard but pliable - holes in the cartilage lacunae • contains the cells • no direct blood supply there is a membrane surrounding known as the perichondrium which contains blood vessels - nutrients must diffuse into the cartilage and waste diffuses out three - types of cartilage 1. hyaline cartilage firm but pliable, contains closely packed collagenous fibers and glassy appearance - function : supports and reinforces resilient and cushioning, resists compressive stress - location : • costal cartilage involved in attaching the ribs to sternum • reticular cartilage at the ends of bones, provides smooth surface for the joints • in trachea so when we breathe in, the air comes in without collapsing 2. fibrocartilage more elastic fibers than hyaline so it is compressible (like a mattress if you push down it springs back) - location : intervertebral discs if you jump, the fibrocartilage will compress then go back to its normal shape 3. elastic cartilage very high concentration of elastic fibers - function : allows flexibility but still maintains shape/structure 9 Monday, February 15, y - location: external ear, epiglottis 10
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