Exam 1 Summer 2012 1 Homeostasis the maintenance of relatively constant conditions inside the body a Six levels of organization chemical cellular tissue organ b Body Fluids the volume and composition of the various fluids system and organismal level within our bodies are carefully regulated i Intracellular fluid fluid inside our cells ii Extracellular fluid all body fluids other than the ones inside our cells 1 Interstitial fluid between cells in tissues 2 Plasma the fluid component of blood 3 Lymph the fluid in our lymphatic vessels 4 Cerebrospinal the fluid within the CNS 5 Synovial fluid within most joints 2 Feedback systems a Negative feedback system act to stabilize the body when it is affected by external or internal changes Cause an OPPOSITE response to the initial change These are self limiting i Example sweating to cool your body lowers a rising ii Main components for Blood Pressure regulation negative temperature feedback system 1 Baroreceptors detect change in BP 2 Brain interprets info and send signals to heart and blood 3 Heart and blood vessels alter activity to solve problem b Positive feedback system used when you need a rapid or strong effect The response is the SAME as the initial change This stimulus works to reinforce the effect of initial stimulus To break a positive feedback system you need an outside event i Example Blood clotting vessels c Components of systems receptor detects change control center decides response and effector reacts to signals from control center and responds Simple Diffusion a passive process in which substances move 3 Diffusion freely through the lipid bilayer of the plasma membranes of cells without the help of membrane transport proteins Nonpolar hydrophobic molecules oxygen carbon dioxide and nitrogen gases fatty acids steroids and fat soluble vitamins A D E K water urea and small alcohols Facilitated Diffusion solutes that are too polar or highly charged for simple diffusion an integral membrane protein assists a specific substance across the membrane i Channel mediated facilitated diffusion a solute moves down its concentration gradient across the lipid bilayer through a membrane channel most are ion channels when a part of the channel protein acts a Gated as a plug or gate changing shape in one way to open the pore and in another way to close it ii Carrier mediated facilitated diffusion a carrier moves a solute down its concentration gradient across the plasma membrane passive no energy is required Glucose fructose galactose and some vitamins 4 Osmosis a type of diffusion in which there is net movement of a solvent through a selectively permeable membrane Water moves across the plasma membrane from an area of higher water concentration to an are of lower concentration i Moves between neighboring phospholipids molecules in the iii Osmolarity ii Moving through lipid bilayer via simple diffusion or aquaporins integral membrane proteins that function as water channels total concentration of solute particles in a solution solutions with iv Isotonic the same solute concentration as that of cytosol than that of cytosol cell loses water shrinks that of cytosol cell gains water ruptures v Hypertonic vi Hypotonic solutions having greater solute concentration solutions having lesser solute concentration than 5 Basic Cell Structures a Plasma membrane flexible out surface of cell used to communicate with other cells and with environment i Fluid mosaic model describes membrane structure A bilayer of phospholipids forms the structure Membrane proteins interact with the lipids All lipids and many proteins able to move freely b Cytoplasm has numerous organelles surrounded by cytosol c Nucleus large organelle that contains the cells chromosomes 6 Subclasses of Membrane proteins a Integral Proteins go through the b Peripheral Proteins only on one c Glycoproteins used for cell to entire phospholipids bilayer side of the lipid bilayer cell interaction Membrane Transports Primary Active Transport Energy derived from hydrolosis of ATP changes the shape of a carrier protein which pumps a substance across a plasma membrane against its concentration gradient i Pumps carrier proteins that mediate primary active ii Sodium Potassium Pump 3 Na out 2 K in transport Secondary Active Transport the energy stored in Na gradient is used to drive other substances across the membrane against their own concentration gradients HIGH Na CONCENTRATION PROVIDES ENERGY Na uses facilitated diffusion to get into cell and uses the Na K pump to get out Antiporter primary active transport Symporter secondary active transport Transport Vesicle a small spherical sac from the plasma membrane Endocytosis materials move into a cell in a vesicle formed i Receptor mediated highly selective type of endocytosis by which cell s take up specific ligands A vesicle forms after a receptor protein in the plasma membrane recognizes and binds to a particular particle in the extracellular fluid ii Phagocytosis the cell engulfs large solid particles such as worn out cells whole bacteria or viruses Only a few cells in the body called phagocytes are able to carry this out 1 Macrophages located in many body tissues sucking up liquid iii Pinocytosis tiny droplets of extracellular fluid are taken up d Exocytosis materials move out of a cell by the fusion with the plasma membrane of vesicles formed inside the cell i Both use ATP energy active transport ii Secretory cells that liberate digestive enzymes hormones mucus or other secretions 7 Resting membrane potential voltage across a membrane i Ranges from 5 to 100 V due to Na and K concentration gradients across the membrane ii Differential permeability of the plasma membrane to Na and K iii Na are inclined to enter the cell but they are not very permeable Steady state potential maintained by active transport ions 8 Protein Synthesis Organelles to know a i Attached ribosomes attached to the outer surface of the Ribosome are sites of protein synthesis nuclear membrane Synthesize proteins destined for specific organelles for insertion in the plasma membrane or for export from the cell ii Free ribosomes synthesize proteins used in the cytosol form of flattened sacs or tubules Extends from the nuclear envelope to which it is attached throughout the cytoplasm i Rough ER continuous with the nuclear membrane and b Endoplasmic Reticulum ER a network of membranes in the usually is folded into a series of flattened sacs outer surface is studded with ribosomes
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