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179 Cards in this Set
- Front
- Back
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Name some of the common attributes of a typical cell
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It contains a cell membrane that surrounds the cytoplasm and nucleus.
is composed of cytosol (protein, carb and electrolyte solution) and is divided into compartments (organelles) contain various non membrane bound inclusions the cell shape is determined by intermediae filaments, microfilaments and microtubules that mke up the cytoskeleton at the light microscopic levek you cannot see the full detail of the cell membrane |
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what are some generl characterictics of the cell membrane
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is about 7.5 nm thick. exhibits a trilminar structure. is composed of a phospholipid bilayer and associated proteins, cholesterol, glycolipids/proteins. envelopes the cell and maintains its structural/functional integrety.
is a sensory devie that allows the cell to recognize other cells and molecules |
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what is the fluid mosaic model of the cell membrane?
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it says that the cell membrane exhibits a fluid like structure that allows any associted structure to move around and also to flip from one side of the layer to the other. nothing has a particular fixed position within the cell membrane.
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what are the types of membrane proteins and what are some of their characteristics?
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integral- pass through or are attched to the inner part of the membrane. usually have hydrophobic groups sequestered there.
peripheral- are attached to one side or the other but do not cross the membrane. transmembrane- cross from one side of the membrane to the other side |
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where are cell membrane proteins synthesized?
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they are synthesized in the rER and are then modified and packed in the golgi complex
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what is the cell membrane structure based on?
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on both phospholipid bilayer and proteins.
it is freely permeable to water, O2, and small nonpolar lipid soluable molecules but it impermeable to charged ions nd most polar substances. any breaks or tearsare sealed spontaneously. |
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what are some of the funstoins of membrane proteins?
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transport, cell communication, enzyme activity and cell attachment
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what are the components of the lipid bilayer?
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phospholipids (50%)
cholesterol (2%) glycolipids |
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what are phospholipids?
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they are an amphipathic molecule with a hydophilic (polar) head and two hydrophobic (nonpolar) fatty acids tails.
the polar head of the phospholipid faces the membrne surface (water) and the tails face inward. the two layers fatty acid tails form weak bonds (hydrophobic interaction) that attach each side (leaflet) to each other. |
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What is cholesterol?
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is located in BOTH leaflets of the plasma membrane.
constitutes about 2% of plasmalemma lipids. assists in maintaining the structural intergrity of the plasma membrane limits the movement of adjacent phospholipids and makes the membrane less fluid and more mechanically stable. |
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what are glycolipids and how are they important for the cell membrane?
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the are present ONLy in the OUTER leaflet. they have a polar carbohydrate residue that attaches from the outer leaflet out into extracellular space forming part of the glycocalyx.
is important for extracellular communication. |
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what are some characteritics of membrane proteins?
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they cary out most of the specialized membrane functions. they transport molecules in and out of the cell. they act as receptors for chemical signaling between cells. they posess specific enzyme activity. they attach cytoskeletal filaments to the cell membrane and they attach cells to extracellular matrix
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what are the two types of transporter proteins?
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open channels: creates water filled pore that allows molecules to pass through due to diffusion
carriers: never forms a open channel from one side to the other. either opens or closes. |
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what is an example of a protein receptor?
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acetylcholine receptor sites, and also G-linked proteins.
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what are G linked proetins?
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they alter the activity on the inner surface on the plasma membrane.
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what are some example of peripheral proteins?
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do not extend into the lipid bilayer. located on the inner leaflet in most cells. can bind to phospholipids or to intergral proteins of the outer leaflet. usually function as part of the cytoskeleton or of an intracellular secondary messenger systems.
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what is glycocalyx?
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it is the "cell coat" and is commonly associated with the OUTER leaflet. my be up to 50nm in thickness. consists of oligosaccharide side chains (polar) linked to glycolipids/proteins of PM. contains cell surface proteoglycans which are integral proteins that bind to gags.
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what are functions of the glycocalyx?
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aids in cellular attachment to extracullar matrix components.
binds antigens and enzymes. facilitates cell/cell recognition and interaction. |
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what are some ways that molecules can be transported by the cell?
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they can move in/out via diffusion or they my be transported in/out via a protein.
can move one moleule in one direction (uniport) or can move two molecule in the same (symport) or opposite (antiport) directions. |
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what is endo/exocytosis?
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endocytosis: invagination of moluecules form the extracellular space tht may be incorported into the cell
exocytosis: transport of substances into the extracellular space. |
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what is passive transport?
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NO ENERGY REQUIRED. includes simple diffusion and facilitated diffusion. both involve passage through the plasma membrane. moves down a concentration gradient without the use of energy. lipid soluable molecules do not require a protein carrier. facilitated diffusion uses transport proteins but DOES NOT requir any energy and moves until it reaches equilibrium.
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What is carrier mediated transport?
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can be passive or active. can be uniport or cotransport. (either symport or antiport)
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What is active transport?
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is an energy REQUIRING process that move a substance AGAINST THE CONCENTRATION GRADIENT. divided into primary and secondary active transport.
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What is primary active transport?
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example: sodium/potssium pump. uses theenergy from moving one molucule out to move anothe rmolucle in.
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what is secondary active transport?
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cotransports molecule the same way across a membrane and uses the diffusion gradient of one molecule to move the other. cannot move one wthout the other and makes it energetically favorable.
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what is transcytosis?
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movement of material from one side of the cell to the other
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what is phagocytosis?
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internalization of foregin body by the formation of a vessicle that is then destroyed by lysosomal activity.
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explain exocytosis
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vesicle secretions accumulate in the cell and need to be expelled. they are sent to the golgi for modification and fuse with the cell membrane and their contents are expelled.
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what is cell-to-cell communication?
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it uses signalling molecules that are secreted by the cell and function in communicating wiht other cells. these incluse neurotransmitter substances (synaptic cleft) , horomones ( bloodstream to target cell)
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what are paricrines and autocrines?
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signalling molecules
paracrine: works on a neighboring cell autocines: works on itself |
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what are some hyrophilic signaling molecules?
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neurotransmitters and various horomones. bind and activate cell surface receptors and have divers physiological effects.
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what is cell recoognition?
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allows cells to identify one another and other molecules.
use glycoproteins and glycolipids. example: immune system and sperm/egg recogition |
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What are some characteristics of the cytoplasm?
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it contains 4 main structural components; the nucleus, the organelles, inclusion and the sytoskeleton.
the fluid component is called the cytosol. |
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what are some basic organelles and their finctions?
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nucleus- contains DNA.
mitochondria- energy production golgi- packaging and processing ER- lipid and proetin production vesicles- packging of biosynthetic materials lysosomes- digestion of intracellulr materials perixosomes- fatty acid metabolism and H2O2 turnover proteosomes- protein breakdown |
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What is the nucleus?
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it is the largest membrane bound organelle. it stains bsic with dyes such as hematoxin. includes the nuclear envelope, nucleoplasm, chromatin and nucleolus. contains DNA. directs prtein synthesis via rRNA, mRNA and tRNA which are synthesized in the nucleus.
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What is the nuclear envelope?
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surrounds nuclear material and consists of two parallel unit membrane separated by a perinuclear cisterna. is perforated at intervals by nuclear pores. the inner membrane has proteins that attach to lamins (filamentous proteins) that give the nucleus its shape and support. the inner membrane face the nuclear material but is separted from it and is supported by the nuclear lamina (is composed of lamins A,B,C) the outer membrane faces the cytoplasm and has ribosomes attached to it. the perinuclear space is continuous with the rER cisternae.
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what are nuclear pores?
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it is the only way to enter or leave the nucleus. they averane 80nm in diameter. permits ONLY certain molecules in either direction. formed by the fusion of the inner and out nuclear membrane. make cylindrical aqeuous channels that permits the passage of WATER SOLUABLE molecules.
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What is chromatin?
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a double stranded DNA complexed with histones and acidic proteins. is responsible for RNA synthesis.
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what is heterochromatin?
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appears in dense clumps of nucleoprotein. found at the periphery of the nucleus and around the nucleolus. is TRANSCRIPTIONALLY INACTIVE. appears as dark staining clumps of chromatin.
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what is euchromatin?
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appears as lightly stained and dispersed within the nucleus. IS TRANSCRIPTIONALLY ACTIVE!
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what are chromosomes?
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a collection os chromosomes in various stages of coiling or uncoiling. become visible durning mitosis and meiosis when they are condensed.
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what is the nucleuolus?
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it is a well defined but not membrane bound nuclear inclusion present in cells synthesizing proteins. it increases in size with active gene transcription (1-3 um). detectable when the cell is in interphase. rRNAs aquire proteins ans are assembled into ribosomal subunits and are transported to the cytoplasm from here.
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what are ribosomes?
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they consist of a small (40s) ad a large (60s) subunit. and are made up of rRNA, histones and other proteins. they are non membrane bound. they my exist freely in the cytoplams or my be bound to a membrane or the rER or nuclear envelope or to a short strand os mRNA (polysomes)
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what are polysomes?
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they are a cluster of ribosomes on mRNA that translate mRNA into proteins for intracellular use.
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what is the rough endoplasmic reticulum?
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the rER is a system of mambraneous sacs whose outer surfaces are studded with ribosomes and whose internal surfaces are called custernae. this is the ste where non cytosolic proteins are synthesized and inculde secretory, plasa-membrane and lysosomes. ribosomes attach to ribophprin receptors on the ER membrane. phospholipid are also formed here.
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what is the smooth ER?
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sER is an irregular network os membrane bound channels that lack ribsomes on the membrane surfaces. usually appear as branching tubules whose membranes do not contain ribophorin receptors. usually less extensive that rER but predominates in cells that are synthesizing steroids, triglycerides and cholesterol (lipids).
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how are lipids synthesized?
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for lipid synthesis the lipid synthetic enzymes are located on the outer fce of the sER with rady access to lipid percursors then are flipped into the inner part by flipase enzymes
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what are some functions of the sER?
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steriod horomone synthesis- (testes) make testerone and adrenal glands make cortisol
drg detoxification- metabolizes drugs such as phenolbarbitol. mucles contraction and relaxation- involves release and recapture of calcium ions in the sarcoplasmic reticulum. lipid synthesis- for cell membranes and other uses. |
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what is the mitochondria?
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a cylindrical organelle that is about 0.5-2 um long. posses an outer membrane and an inner membrane arranged in cristae. subdivided into innermembraneous space (between the two membranes) and an inner matrix. contains enzymes for oxidation of fatty acids and pyruvate as well as the citric acids cycle (TCA).
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what is the function of the mitochondria?
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it is the primary source of ATP production in cells via oxidative phosphorylation coupled with the electron transport chain. posess their own DNA, mRNA, tRNA and rRNA. proliferate by division nd have about a 10 day life span. can activate cell death by release of proteins. may have originted through symbiosis (intracellualr parisites). maternally derived!
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what is the golgi complex?
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consists of several disk-shaped cisternae arranged in a stack. organized into cis, medial and trans faces. has a distinct polarity across the stacks.
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what is the function of each face of the golgi complex?
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cis (entry) face- comprises forming cisternae at side of stack facing the rER and small ER transport vesicles.
trans face- maturing cisterne located at the side of the stack facing the vesicle and secretory granules. |
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what are lysosomes?
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dense, membrane bounded organelle that function as an intracellular digestion system posessing material ingested by the cell or worn out cellular components. are considered to be part of the acid-vesicle system (have H-ATPase that can decrease the lumen pH to bout 5)
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what is a primary/secondary lysosome?
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a primary lysosome- comes from the golgi complex and then fuses with the cell membrane and expelles its contents.
secondary- comes from the golgi and then binds with another lysosome carrying a material and is then either expelles, destroyed or remains as a residual body. |
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what are the functions of a lsosome?
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forms when a golgi hydrolase fuses with an endosome to form a primary lysosme. my be identified by acid hydrolsis staining. posess special membrane proteins and posess ATP-powered proton pumps in their membrane that maintin their pH at about 5.
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what is a perioxisome?
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a small membrane bound organelle that contin oxidative enzymes that oxidize substarte to H2O2. functons vary from beta oxidation of fatty acids to detoxification of sunstances such as ethanol. may be stained by a chemical reaction for catalase. originate from prexisting peroxisomes which grow form cytosolic proteins and then divide.
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what is a proeteosome?
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ubiquitin combines via lysine and effects the cytoplasm and then is destroyed by proteosome proteases via a proteosome
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what are centrioles?
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they exist as a pair of cylindical rods oriented at right angle sto each othe.r located at the centrosome (cell center). orgainze the spindle in mitosis (self replicate) and also ar in non dividing cells as a microtubule organzing center. have a wall composed of 9 triplets of mictotubules
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what are inclusion?
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"lifeless" accumulations of materials that are metabolically inactive and are oftern temporary in the cell.
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what are lipid droplets?
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INCLUSIONS- vary in size and appearance. are often NOT BOUND to the membrane. are storage of triglycerides and cholesterol.
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what are glycogen inclusion?
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INCLUSIONS- appear as small clusters or as larger aggregates of electron dense and look like, but are larger than ribosomes. not bound to the membrane. serves as a stored energy source that can be degraded to glucose and enter the bloodstream.
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what are lipofuscin granules?
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INCLUSIONS- membrane-bound and often contain lipid droplets. represent a risidual od undigested material present in risidual bodies. ind=creases with age and are called age pigments. most common in undividing cells and in hepatocytes.
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what is melanin?
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INCLUSIONS- appears as small clusters or as larger aggregate sin keratinocytes. produced by melanocytes and are injected into other cells. give cells pigment.
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what are secretory granules?
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INCLUSIONS- appear as membrane bound, granular material. seen in secretory cells such as salivary glands and swaet glands. destined for extracellular sites.
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what is the cytoskeleton?
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a structural framework within the cytosol. functions in maintaining the cell shape and stabilizes the cell attachments. includes intermediate filaments, microtubules, and microfilaments.
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what are microtubules?
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straight hollow tubules, 25nm in diameter and several micrometers long. have a rigid wall mad eof 10 proteofilaments composed of alpha and beta dimers. maintians the cell shape. aids in the transport of macromolecules within the cytosol. promote movement of cilia, flagella and chromosomes. anchors cells together. make up centriols (9 triplets of micrtubules), cillium and flagellum have 9 doublets and two center microtubules (9+2)
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whata re microfilaments?
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also known as F-actin and actin filaments. actin accounts for about 5% of total protein in the cell. 6nm in diameter. composed of globular (g-actin) monomers that are polymerized and linked into a fiberous double helix. involved in: sol/gel transformation in the cytoplasm, endocytosis and exocytosis and mocomotion of nonmucles cells.
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what are intrmediate filaments?
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8-11 nm in diameter. anchored to transmembrane proteins at special sites on the cell membrane ( desmosomes and hemidesmosome). provide mechanical strength to the cell. critical in diagnosis and treatment in some tumors.
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how can some tumors be diagnosed?
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is based on immunochemical identification of intermediate filaments in tumor cells. since the type of intermediate filament identifies the tissue from which the metastatic cancer cells originat it dictates the treatment.
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name the types/locations of intermediate filaments
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keratins- epithelial cells
desmins-fibroblasts, chrondoblasts, muscle (smooth and striated) GFAP- astrocytic glial cells neurofilaments- neurons nuclear lamin- nucleus of cells vimentin- CT, endothelial cells and vascular smooth muscle |
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what is the general structure of epithelia?
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line internal and cover external surfaces of the body. consist of a sheet pf cells with very little intracellular space. each cell has 3 surfaces: apical (free), lateral (abut to neighboring cells) and basal (attaches to basal lamina). named with respect to the number of cell layers and the shape of the surface cells. functions in protection, secretion, abosrption and cellular transport. rest on a extra cellular basal lamina that separtes cells from underlying CT (lamin propria) continuousle renewed and replaced (replace from the bottom up). they are avascular and recieve nourishment by diffusion through the basal lamina from bv.
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what is simple squamous epithelium?
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single layer of flattened cells.
examples include: endothelium (lining of b.v.) mesothelium (peritoneum and peaura) all cells are in contact with the underlying extracellular matrix. covers orgns with some form of base structure. |
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what is simple cudal epithelium?
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cells are cuboidal in shape with a centrically placed nucleus. the height, width and depth are approximatly the same.
examples: distal tubules in kidneys and surface of ovaries. |
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what is simple columnar epithelium?
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cells are columnar in shapr and the height is about 2-3xs greater than the width and often have cilia or microvilli.
examples: lining of the gastrointestinal tract. functions include secretion and absorption simplest if the goblet cell. |
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what is pseudostratified cilliated columnar epithelium?
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cells rest on basal lamin but many do not reach the lumen so it gives the effect of them being stacked and falsely stratified.
examples: trachea, bronchi and nasal cavity often is called respiratory epithemlium |
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what is stratified squmous nonkeratinized epithelium?
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mltiple layers with cells of various shapes but the UPPER layer is flattened cells being NUCLEATED.
examples: esophagus, vagina, oral mucosa and vocal cords. |
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what is stratified squamous nonkerainzed epithelium?
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multiple layers with cells of various shapes with the UPPER layer of flattened NON-NUCLEATED cells. forms a barrier against friction, abrasion, infection and water loss.
examples: epidermis of the skin, maticatory mucosa |
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what is stratified cuboidal epithelium?
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2 or 4 layers os cuboidl cells.
examples: dects of sweat glands. |
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what is stratified columnar epithelium?
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multiple layers of cells in the columnar shape
examples: excretory ducts, cavernous urethra and conjunctiva |
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what is transitional epithelium?
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cells appear dome shaped when relaxed and flattened when stretched. facilitates distension of organs. found ONLY in urinary system.
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what is the embryonic origin of epithelium?
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derived from ectoderm, mesoderm and endoderm. ectoderm- gives rise to the skin (kertininzed strat. sqam. epi) sweat glands (simple and strat. cuboidal) and lining of the vaginal and oral cavities (nonkeratinized strat. squamous).
mesoderm: gives rise to the endothelium lining blood vessels (simple squamous) and lining of genitalia and urinary ducts (transitional and pseudo. columnar and simple colum/cub) endoderm: lines the esophagus (nonkert. strat squa) gastrointestinal tract ( simple colum) and respiratory system (pseudo cilliated colum) |
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what are the functions of epithelium?
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transcellular transport- movement of molecules fromone epithelium to another:
1)diffusion of O2 and CO2 2)carier of protein mediated transport of amino acids 3)vesicle mediated transport of IIgA and other molecules absorption- occurs via endocytosis secretion- occurs via exocytosis protection (speaks for itself) |
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what are junctional complexes?
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they are a comboination of varous intracellular junctions. (lie near the apex). 3 components: zonula occludens (occluding junctions)
zonula adherens (anchoring junctions) and macula adherens (desmosomes) |
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what is the difference between zonula and macula?
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zonula: belt-like and completely encircle the cell
macula: disk-like and attach two cells at a spot |
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what are zonula occludens?
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they form a imermeable barrier. AKA "tight junctions" is a zone around th entire apical perimerter od adjacent cells formed by fusion of the outer leaflets of their plasma membrane. reembles a quilting pattern by fusion by tight junction proteins (occludin and claudin). seals off the intracellular space, allowing the epithelium to isolate certin body compartments.
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what are zonla adherens?
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these are anchoring junctions that link cytoskeleton cells to other cells. AKA "belt desmosome or intermediate junction". extends completely around the perimeter of epithelial cells just below the zonula occludens. has a 10-20 nm separation between the cell membranes.
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what are macula adherins?
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AKA "desmosomes". characterized by a dense plaque of intracellular attachment proteins (desmoplakins). has intermediate keratin filaments looping in/out from the cytoplasm. they are stable but do not prevent the flow of subtances between cells. cadherins insert into the cytoplasmic plaques and mediate cell-to-cell attchments.
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what are gap junctions?
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AKA "nexus" or communicating junction. 6 clyndircal subunits called connexons with a central canal. produces cell-to-cell channel that allows the passage of ions and small molecules. connects cells metabolically and electrically and also allows for select diffusion and cell communication.
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what are basal epithelial surfaces?
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epithelial cells from the basal lamina portion of the basement membrane. is the surface closest to the underlying blood supply which contains receptors for horomones and oher blood borne factors. have hemidesmosomal attachments to the underlying CT
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what is a basement membrane?
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separates epithelium from the subjacent CT
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what is the basal lamina?
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extracellular supportive structure that underlies all true epithelial cells. sheetlike structure that is composed os type IV collagen, laminin (helps bind cell to basal lamina) entaactin (associated with laminin) and proteoglycans. domponents are contributed by the epithelial cells and connective tissue. consists of two zones: lamina rra which lies next to the plasma membrane and the lamina densa which lies next to the reticular lamina of the CT (type III collagen). if the reticular lamina is added to the basal lamina then it is BASEMENT MEMBRANE. forms a barier between epithelium and CT.
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what are hemidesmosomes?
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specialized junctions that resemble 1/2 of a desmosomes. mediate adhesion of epithelial cells to the underlying ECM. are present on the basal surfces of epithelial cells and myoepithelial cells adjacent to the basal lamina.
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what are ion-transporting cells?
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cells specialized for transcellular transport (ion pumps). form active barriers to control ion and water concentration in the body. has hihly infolded basal plasma membranesand numerous mitochondria. basal infoldings bring ion pumps in the plasma membrane close to their energy supply.
examples: Na/K brings NA out and K into the cells. |
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what are cells that are specialized of transport through transcytosis?
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have tight junctions and abundant pinocytotic vesicles. vesicles transport substances across the cell from luminal to basal surfaces and vica versa found in cells lining the blood vessels where transport is rapid.
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wht are epithelial cells that are specilized for absorption?
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they line the digestive tract and the kidneys. have many apicl microvilli that increase surface area.
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what are epithelial cells specialized for secretion?
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have abundant basophilic rER and well developed golgi complexes. proteins that are secreted are digestive enzymes, alumbin and horomones.
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what are mucous cells?
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unicellular (goblet cells) or may occur in sheets as solid glands. hae a lightstaining foamy appearance and have a large mucous containing vesicle concentrated near the cell apex.
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what ar polypeptide secreting cells?
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have a small amount of rER, a supranuclear golgi complex and secretory granules
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what are microvilli?
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finger-like projections of epithelia that increase the surface area of the cells luminal surface. most developeed in absorptive cells such as kidney tubules and small intestine. characterized by a glycocalyx and enzymes on their eterior surface. constitiute the brush border of the proximal tubule cells and the striated border of the intestine. have an actin (microfilament) core.
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What are cilia?
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activley motile processes extending from certain epithelia (where they move mucous). highly specialized extentions of the cytoskeleton. contain a core of microtubules (9 doublets+2 centermicrotubules; aconeme) that arises from a basal body during ciliogenesis. are bound together with various proteins to produce an energy dependent movement that result in a BEATING movement.
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what is a axoneme?
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consists of nine doublet microtubules, made of tubulin, soaced around two central microtubules (9+2) in the central sheath. contains dyneinarms with dynein ATPase. contains radial spokes which etxend from each of the doublets toward the central sheath which regulate the ciliary beat. nexin is a linking elastic protein thats connects adjacent doublet microtubules.
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what are stereocilia?
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very long microcilli (not cilia) that are locted in the epididymis and vas deferens. are sensors of cochlear hair cells.
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what is glandular epithelium?
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originates from an epithelium that invoginates into the connective tissue and forms secretory units. consists of a functional portion of secretory and ductal epithelial cells. are named based on the secretory epithelium.
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what are connective tissues?
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occupy the intercellular space nd forms the extracellular matrix. composed of an amorphous ground sunstances, fibers and cells. all molecules must pass through this to reach the cells. provide structural support for organs and cells. serve as a medium as exchange of nutrients and wastes between the blood and tissues. aids in protection. repairs in damaged tissues. used in fat storage.
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what is ground substance?
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a colorless, transparent material that fills the space among cells and fibers of the CT. acts as a lubricant and helps prevent penetration by foregin microbes. synthesized by CT cells. complex mixture of glycosaminoglycans (GAGS), proteoglycans and glycoproteins that facilitates diffusion of sucstances through the extracellular sace and into and out of cells and blood vessels and supplying those cells
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what is the part of the CT matrix that gives it its strucutral integrity?
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chondroytin sulfate. it still allows for diffusion.
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What are GAGS?
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Glycosaminoglycans. unbranched polysaccharide polymers os repeating amino sugars made of hexamine and a uronic acid. form a hydrated gel matrix which helps resist compressive forces and regulates the diffusion of substances. there are four different types of GAGS: hyaluronic acid, chondroitin sulfate and dermatin sulfate, herparin sulfate and heparin and keratn sulfate.
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what are proeteoglycans?
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have a protein core to which GAGs are bound to form a large macromolecule in the extracellular matrix. (more crbohydrate than protein) are very hydrophilic and form huge macromolecules in the exttracellular space and fills the introcellular space.
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what are glycoproteins?
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proteins to which shorter, branched, sugar chains are covalently bound. much smaller than proteoglycans. fibronectin which mediates cell adhesion to the extracellular matrix. laminin is basal lamina component that mediates epithelial cell adhesion. for both of these linkages between the cytoskeleton and matrix occurs by intregrins.
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what is fibronectin?
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a glycoprotein that mediates cellular adhesion between a wide range of cells and EC matrix components. exists in 3 main forms: circ. plasma protein, transiently attached to the surface of many cells and as insoluable fibrils that form part of the ECM when dimers crosslink via disulfide bonds. is thought to play a role in organizing the deposition of early collagen fibrils
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what is laminin?
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a glycoprotein that is the major component of the basement membrane. is produced by most epithelial and endothelial cells. is cross shaped molecule with binding sites specific receptors for heparan sulfate and type IV collagen. mediates the interaction btwn epithelum and ECM by anchoring cells to the basal lamina.
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what is entactin?
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a glycoprotein that is a component of all basal membranes and binds to laminin.
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what is tenascin?
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extracellular glycoprotein involved in cell adhesion and important in cell migration in the developing nervous system.
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what is osteonectin?
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found in bone, links minerals to type I collagen and influences calcification by inhibiting crystal growth.
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what are collagen fibers?
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ubiquitous in distribution: bone, skin, cartlidge, tendon/
are produced in two stages invilving intracellular and extracellular events. |
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what are elastic fibers?
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coiled, branched fibers which can form in loose networks and sheets. composed of microfibrils of fibrillin embedded in elastin. mechanical properties are due to the presence of desmosine and isodesmosine and cross links via lysine to give it a coil formation. synthesis is carried out by fibroblasts in elastic ligments, smooth muscle cells and chrondocytes. found in arterial walls, respiratory system and loose and dense CT
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how are elastic fibers made?
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fibrillin proteins and proelastin are synthesized on rER and secreted separatly. microfibrillr proteins contain hydrophilic a.a. proelastin molecules polymerize to form elastin chains. elastin protein subsequently associates with many microfibrils to form elastic fibers. requires elastase enzyme to form and cross links via desmosomes.
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what are reticular fibers?
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extremely thin and are formed of loosly packed tropocollagen fibrils. are composed mainly of type III collagen and have a higher sugar content than any other collagen fiber. the supportive fiber network allows motile cells to move in loosly arranged tissues.
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what is connective tissue proper?
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found throughout the body where blood vessels and nerves have to travel. characterized by the predominance of typeI collgen fibers. binds cells and tissues into organsnd organ systems.
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what is loose connective tissue?
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AKA "areolar tissue". appears disorganized and posses relativly fewer fibers but more cells than dense connective tissue. is well vascularized, flexible and not very resistant to stress. is more abundant tha dense CT. surrounds and suspends vessels an nerves and underlies and supports most epithelia. conveys oxygen amd nutrient to the avascular epithelia. cells function in immune suvellince and is a collection of collagen, elastic and reticular fibers and ground substance and cells.
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what is dense irregular connective tissue?
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contains fiber bundles that have no definite orientation. constitutes most dense CT. covers fragile tissues and organs and protects ythem from mechanical stresses. is characteritic of the dermis and capsules of many organs. has fewer cells and more coarse fibers than loose CT. type I collagen fibers predominate. is classified by the orientation of its fiber bundles into either regular or irregular dense CT.
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what is dense regular CT?
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contains fibers that are arranged in a uniform parallel fashion. posses attenuated fibroblasts which occupy the narrow space in between. is present in TENDONS AND LIGAMENTS.
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what are myofibroblasts?
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look like fibroblasts, found in healing tissue and can contract to shrink the size of scar tissue. contain aggregates of actin filaments associated with myosin to provide contractile function. develope during the repair of damaged tissues and produce collagen.
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what is reticular CT?
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contains a network of branched reticular fibers in which macrophages are dispersed. invests liver sinusoids and smooth muscle cells.
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what is elastic tissue?
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contains course, branching elastic fibers with a sparse network of collagen fibers and some fibroblasts filling hte interstitial space. is present in the dermis, lungs, blood vessels and ligaments of the back and neck.
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what is adipose tissue?
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is the primary site for storage of energy (triglycerides) and has a rich neurovascular supply. has receptors for growth horome, insulin, glucocorticoids and thyroid horomones that uptake and release fat. unilocular fat= white and multilocular fat= brown fat.
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what is whartons jelly?
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mucous CT in embryo and pulps of teeth. have active fibroblsts and extensive matrix of collagen and ground substance.
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what are fibroblasts?
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arise from undifferentiated mesenchymal cells. are the predominant cells located in CT proper. have an oval nucleus and two nuclioli. synthesize and secretes and maintains all mjor matrix components- collagen, elastin and GAGs.
"workhorse" of the CT. |
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what are macrophages?
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second only to fibroblasts in CT proper. orgiginate in the bone marrow as monocytes and migrate into the CT where they differentiate into macrophages. they are phagocytosing cells and are responsible for removing large particles and assisting the immune response. they also secrete substances that function in wound healing. many macrophages can unitw to form foreign-body giant cells that are multinucleated cells that surround and phagocytose large foreign molecules. have a jagged look which is the cells pseudopodia.
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what are giant cells?
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a synticium of many cells that creates one large multinucleated cell that can phagocytose a large foreign body.
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what are plasma cells?
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derived form B-lymphocytes in the blood that originate in the bone marrow. smal oval shaped cell with an eccentric clock face nucleus and an extensive rER.
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what is a mast cell?
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arise from the myeloid stem cells during hemaotpoesis. posess a small, ovoid, pale staining nucleus and deeply staining metachromatic granules.display a surface with folds, well develope golgi complex, scant rER. contain heparin, histamne, leukotrienes and other vasoavtive substances. mediate immediate anaphylactic reactions
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how do anaphylactic reactions occur?
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the first exposure to an allergen leads to the production of IgE antibodies, which bind to receptors on the surface of the mast cells causing them to become sensitized. during a second exposure to the same allergen, the IgE binds to the allergen triggering release of various mediators (heparin, esionphil chemotactic factor (ECF), histamine and leukotriene C). histamine increases the permeability of blood vessels. leukotriene C induces slow contraction of smooth muscle.
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what are adipose cells and adiposcytes?
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arise form undifferentiuated mesenchymal cells and are surrounded by basal lamina. are responsible for the synthesis and storage of fat. accomadate a large fat droplet (WHITE FAT) and generally do not increase in number after birth. only forms in loose connective tissue. and the nucleus is puched to the periphery.
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what are pericytes, perivascular cells or adventitial cells?
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re derived form undifferntiated mesenchymal cells and may retain the pluriptential role of the embryonc mesenchymal cells. are smaller than fibroblasts and are located along capillaries. display few mitochondira and little rER.
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what are plasma cells?
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derived form B-lymphocytes in the blood that originate in the bone marrow. smal oval shaped cell with an eccentric clock face nucleus and an extensive rER.
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what is a mast cell?
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arise from the myeloid stem cells during hemaotpoesis. posess a small, ovoid, pale staining nucleus and deeply staining metachromatic granules.display a surface with folds, well develope golgi complex, scant rER. contain heparin, histamne, leukotrienes and other vasoavtive substances. mediate immediate anaphylactic reactions
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how do anaphylactic reactions occur?
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the first exposure to an allergen leads to the production of IgE antibodies, which bind to receptors on the surface of the mast cells causing them to become sensitized. during a second exposure to the same allergen, the IgE binds to the allergen triggering release of various mediators (heparin, esionphil chemotactic factor (ECF), histamine and leukotriene C). histamine increases the permeability of blood vessels. leukotriene C induces slow contraction of smooth muscle.
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what are adipose cells and adiposcytes?
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arise form undifferentiuated mesenchymal cells and are surrounded by basal lamina. are responsible for the synthesis and storage of fat. accomadate a large fat droplet (WHITE FAT) and generally do not increase in number after birth. only forms in loose connective tissue. and the nucleus is puched to the periphery.
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what are pericytes, perivascular cells or adventitial cells?
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re derived form undifferntiated mesenchymal cells and may retain the pluriptential role of the embryonc mesenchymal cells. are smaller than fibroblasts and are located along capillaries. display few mitochondira and little rER.
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what are the parts of the central and perpheral nervous system?
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central: brain, brain stem, and spinal cord
peripheral: nerve fibers and their cell bodies (ganglia) |
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what are afferent/efferent neurons?
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afferent: information coming in. always found in the posterior horn
efferent: information going out. always found in the anterior horn. |
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what is an excitable cell?
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has the potential to create an action potential. the cell wall conducts the action potential and not the cytoplasm.
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what are the functions of the nervous system?
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subconscience: 1)homeostasis- normalization of vital parameters like temp and b.p. 2) behavioral patterns- feeding, reproduction, defense and breathing
conscience: cognition, thinking, reasoning, emotions. only the crust of the brain ]if you loose conscience function then you are in a coma and are considered brain dead. |
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what are the three neurons and their parts?
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dendrites (input), cell body (nutriton and protein synthesis), and axon (output).
unipolar: only has one input multipolar: has multiple inputs pseudounipolar: in all sensory ganglia the cell body is also called the trophic center. |
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where are the cell bodies located?
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in the CNS: they are locate din the gray matter. (white matter consists of axons)
in the PNS: they are located in the ganglia. |
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what is the neuronal cell body?
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it contains the nucleus. is the trophic center of the cell (nutrition and repair). has aggregates of parallel rER with collections of ribosomes (basophilic bodies).
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what are dendrites?
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short and branching. needed for reception and processing. one purkinji cell recieves communications from 200,000 neurons.
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what are dendrite spines?
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small membranous protrusions from the dendrite. recieves input from a single synapse. thousands oer neuron especially in the hippocampus and the cerebellum. has to do with learning and memory. change in shapr and number,
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what are axons?
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the ONLY signal outlet from the neuron. originate at the axon hillock. has axoplasm (cytoplasm of the axon). running inside the axolemma (cell membrane). the initial segemt is where all the incoming signalsare analyzed to decide weather or not an AP should be sent down the axon. the AP runs in only one direction. are insulated by layers of myelin. the myelin sheeth is not part of the axon, but belongs to the supporting cells (schwann cells in periphery and oligodendrocyts on the CNS). during development the cells roll around the axon.
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what is the name of the point at which two schwann cells meet?
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nodes of ranvier. AP jumps from node to node.
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what is a synapse?
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unidirectional link between teo nerve cells. transmits the AP from one cell to another. and can be form nerve to muscle. AP reaches the presynaptic terminal and causes an influx of calcium which then opens neurotransmitter stores. neurotransmitters are release into the synaptic cleft where it binds to the receptors on the post synaptic terminal. a cascade of events leasds to a AP in the post synaptic terminal.
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what is the difference between pre and post synaptic inhibition/excitation?
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presynaptic= inhibits the axon of the incoming axon before it has a chance to synapse with the next neuron
post synaptic= inhibits the next neuron after it has synapsed with the incoming neuron |
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what is an electical synapse?
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there is no synaptic cleft. the pre and post synaptic terminals are connected via gap junctions. ions pass directly frm the pre to the post terminals generating the action potential.
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what are schwann cells?
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supporting cell for the peripheral nerve.
each schwann cell wraps itself inlayers around a segment of one axon, forming a think layer of myelin. |
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what are oanceligodendrocytes?
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supports axons in the CNS. each oligodendrocyte provides a myelin sheath to segments in several axons. the axolemma shows a thickening where the cell membrane of the oligodendrocytes comes into contact with it.
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what is myelin?
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80% lipid 20% protein. main component is glycolipid strengthened by the interwining of the sphinogomyelin chains.
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functions of the myelin sheath?
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increases propagation speed: the current bounces between the NOR.
increases electrical resistance: helps prevent the current from leaving the axon. decreases capacitation: prevents the loss of energy within the axon. the myelin sheath provides a track along which regrowth can occur. unmyelinated fibers and myelinated fibers in the mammalian CNS do not regenerate. |
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what are unmyleinated nerve fibers?
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in CNS: bundles of uncovred axons.
InPNS: inclosed in the cytoplasm of th eschwann cells but they do not roll themselves around the axon. |
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what are glial cells?
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non-neuronal cells in the CNS.
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what are astrocytes?
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most numerous glial cells in the CNS. star shaped (more like spider). fibrous astrocyes= white matter and proteoplasmic astrocytes= gray matter, supports the connection to blood vessels. forms scar tissue after brain danage.
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what atre microglia?
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flat nucleus that becomes a phagocyte when attacked. dense elongate nuclei w. branched cytoplasm. involved in MS and HIV dementia
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what are Ependymal cells?
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columnar epithelium that line the CNS cavities. some are ciliated cavities to guide the flow of CSF. may be the source of neuronal stem cells.
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what are satellite cells?
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flattened schwann cells that surround neuron cell bodies on the PNS. these help regulate the external chemical environment. similar to astrocytes. highly sensitive to injury and inflammation. and contribute to chronic pain.
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what is a dermatome?
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an area of the skin supplied mainly by a single cutaneous nerve. also called the perceptive field.
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how do the first, seconf and third motor neurons work?
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the sensory neuron (all pseudounipolar) will send a signal and will synapse with a itnerneuron (secondary neuron) which crosses over in the spinal cord and sctivates the third motor neuron.
motor neuron cross over in the brain stem. |
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what are the parts of the CNS?
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the brain: the cerebral hemisphere and the cerebellum. the brainstem: the midbrain, the pons, and the medulla oblongata. the spinal cord.
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what is the pia, arachnoid and the dura mater?
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together called the menegies.
the pia mater: on the brain surface. between the pia and the arachnoid mater, (subarachnoid space) the arachnoid space: the middle layer. the dura mater: the external part of the meninges. |
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what is the cerebral cortex?
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neuronal cell bodies and unmyelinated fibers. consciousness, memory, attention and perception. forms the outer crust of the cerbral hemispheres. has six layers of neuronal cell bodies. convoluted surface pattern of gyri (elevations) and sulci (grooves)
the executive branch of the brain. has the first segment of the unmyelinated neuronal cell bodies. |
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what is the blood brain barrier?
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the functional barrier preventing the passage of some substances between the plasma and the brain. the capillaries of the CNS have decreased permeability with occluding junctions between endothelial cells. astrocytes may play a role in selectivity.
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what is the cerebellar cortex?
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three layers of cells. outer molecular layer, central layer of purkinje cells and an inner grnaular layer.
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what are purkinje cells?
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cell bodies with extensive fan-shaped dendrites. their dendrites occupy the outer molecular layer. recieves over 200,000 signals.
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what is the white matter?
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myleinated axons with no cell bodies. ascending, descending or communicating tracts. commissural fibers connect similar zones in the two hemispheres. is white because of all the myelin. myelin is 80% fat.
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what are the peripheral nerves?
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each axon is covered by the endoneurium ( a membrane of reticular fibers within a myelin sheath). axonsa are packed to form bundles covered by the perineurium (layers of packed epithelium like cells) the nerve is formed of several bundles are enclosed within the epineurium.
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whats is the schmidt-lanternan clefts?
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clefts of schwann cells cytoplams trapped within the layers of myelin during development. no one knows the purpose of these.
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what is the ultrastructure of the node of ranvier?
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loose interdigitated processes of schwann cells. axolema acts as a barrier to diffusion. covering the nerve fiber is a connective tissue layer
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how do we feel pain?
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stimulus-->receptor-->1st ON-->2nd ON--> crosses and ascends--> 3rd ON --> thalamus to cortex.
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what are ganglia?
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a collection of neuronal cell bodies and glial cells outside the CNS. serve as relay stattions. sensory: recieve sensory infor and relays it to the CNS. Autonomic: relays impulses coming fro th CNS and sends it to internal organs.
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what is nerve injury?
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nerve cells do not divide so injury causes permanant loss. if the cell body is intact, there may be some limited repair. scar tissue is formed in these cells. when the fiber is injured the nucleus moves to the cells periphery and nissi bodies becomes greatly reduced in number. the nerve fiber distal to the injury degenerates along with its myelin sheath and the debris is collected by macrophages. gradually the muscle fibers show denervation atrophy. schwann cells form a compact cord. if the nerve fiber regeneration was sucessful the muscle fiber can also regenerate after recieving nerve stimuli.
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