NURS 8022 Exam 1 Review.

Exam #1 Study Guide Module 1 – Ch: 1-2 Cellular biology, membrane physiology, action potentials, skeletal and smooth muscle contraction, altered cellular tissue, and biology of aging Positive and negative feedback – what are they? Understand basics of what they do and how they affect Physiology • Negative feedback: promotes stability o Cancels out the original response – original stimulus or response is cancelled out at the end o Body must sense a change and attempt to return to normal - restores homeostasis o Ex: increased blood glucose – body increases insulin production – lowers blood glucose/homeostasis is restored • Positive feedback: promotes a change in one direction; instability; disease o Exaggeration or more of the original response o May be unstable or normal o Normal Ex: oxytocin release during childbirth stimulating labor contractions; platelets and blood clotting cascade Explain the structure of the membrane and the organization of its polar and non-polar components, including lipids and proteins • Membrane structure: phospholipid bilayer o Negative, hydrophobic tails inward; positive, hydrophilic heads outward o Semipermeable meaning permeable, but selective • Proteins o Provide selectivity to the membrane o Integral: channels, pores, carriers, enzymes, receptors, second messengers – spread through entire membrane o Peripheral: enzymes, intracellular signal mediators • Carbohydrates o Negative charge of carbo chains repels other negative charges o Involved in cell-cell attachments/interactions - often act as receptors o Play a role in immune reactions • Cholesterol – Fat/Lipids o Gases such as N2, O2, and CO2 (uncharged substances) can freely dissolve/Move across the lipid region of the cell membrane, these gases are nonpolar and hydrophobic, like the lipid region of the cell membrane, so they are able to freely pass across it NURS8022 Exam 1 Review. o Present in membranes in varying amounts o DECREASES membrane fluidity and permeability (except in plasma membrane) o INCREASES membrane flexibility and stability Cell energy and ATP production basics • Breakdown of carbs into glucose, proteins into amino acids, and fats into fatty acids • Glucose, amino acids, and fatty acids are processed into acetyl-coA • Acetyl-coA reacts with oxygen to produce ATP (aerobic process) o 38 ATP created per molecule of glucose degraded o Only 2 ATP created without oxygen (anaerobic) • ATP is chemical fuel for cellular processes • Adenosine + 3 phosphate groups = ATP o Bonds between 2nd and 3rd phosphates contain abundant energy o ATP converted to ADP produces energy o Mitochondrial enzymes reconvert ADP and liberated phosphate to ATP o 3 R’s: rupture, release, recycle • 3 uses of ATP o Membrane transport, synthesis of chemical compounds, and mechanical work Transport of molecules through the membrane; diffusion and what affects it; facilitated diffusion; active transport; osmosis and what it is • Molecules transported through membrane o Intracellular: K more abundant o Extracellular: Na more abundant • Membrane permeability and ion permeability o High permeability: easily move across membrane ▪ Water (even though water is polar, bc it is such a small molecule it can move freely across cell mem via protein or slipping btw the lipid tails itself), carbon dioxide, oxygen o Low permeability: more difficult to move across membrane ▪ Chloride, potassium, sodium • Ion permeability o Conductance: depends on probability that channel is open o Characteristics: ▪ Un-gated (passive movement): determined by size, shape, distribution of charge ▪ Gated: • voltage (ex: voltage dependent Na channels) • Chemically (ex: nicotinic ACh receptor channels) - substance binds to open gate • Diffusion: movement of ions/substances/molecules o Passive: down a concentration gradient from higher concentration to lower o Active: against concentration gradient from an area of lower concentration to higher o Will not occur if the membrane is non-permeable to the molecule ▪ Na and K will naturally want to diffuse in and out but cannot without channels because they are not permeable through the membrane o Lipid soluble (non-charged) substances move more readily o No energy required; no carrier required o Factors that affect net rate of diffusion: ▪ 1. concentration difference ▪ 2. electrical potential – charge difference on each side of membrane ▪ 3. pressure difference – higher pressure results in increased energy to cause net movement from high to low pressure • Facilitated diffusion (a type of passive diffusion): molecules move down its concentration gradient via a carrier or channel protein molecule that facilitates its passage o Diffusion depends on concentration of the carrier molecule – can reach Tmax depending on concentration of the carrier molecule o Does not move against electrochemical gradient o No energy required • Osmosis (a type of passive diffusion): movement of fluid across a membrane; passive transport from an area of lower solute concentration into an area of higher solute concentration o Water moves down it’s concentration gradient o Osmotic pressure: difference in solute concentration across the membrane creates osmotic pressure difference – this is driving force for movement of water o Hypotonic (low solute); hypertonic (high solute) o Osmosis stops when enough fluid has moved through the membrane to equalize the solute concentration on both sides of the membranes • Active transport-uses Carrier proteins o Primary active transport: molecules are pumped against a concentration gradient at the expense of energy (ATP) ▪ Direct use of energy o Secondary active transport: transport driven by the energy stored in the concentration gradient of another molecule or driver molecule (often Na+) ▪ Created originally by primary active transport – indirect use of energy • PRIMARY ACTIVE TRANSPORT EXAMPLES o Na+ K+ ATPase “Sodium Potassium Pump” ▪ PRIMARY ACTIVE TRANSPORT ▪ Carrier protein located on the plasma membrane of all cells ▪ Na/K ATPase = enzymes that converts ATP to ADP to release energy ▪ Regulates osmotic balance by maintaining Na+ and K+ balance – preventing cells from swelling and bursting