NUR 2063 Exam 1 Pathophysiology Notes(Pathophysiology Notes: Modules 1, 2, & 3), Exams of Nursing

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Pathophysiology Notes: Modules 1, 2, & 3 Module 1 Chapter 2: Homeostasis, Allostasis, and Adaptive Responses to Stressors Homeostasis & Allostasis Homeostasis: =~ Remaining stable while staying the same =~ Astate in which all systems are in balance = = Astate of equilibrium ¢ — Anideal “set point” despite alterations within the body Allostasis: ~~ Ability to successfully adapt to challenges ¢ Intricate regulatory processes orchestrated by the brain = = Adynamic process that maintains or re-establishes homeostasis in light of environmental and lifestyle changes Stress As A Concept Physical, chemical, or emotional factor resulting in tension of body or mind Actual physical and mental state that tension produces Real or perceived threat to homeostasis Direct consciously or indirect unconsciously sensed threat to the stability of the organism Physical, chemical, or emotional factor resulting in tension of body or mind Actual physical and mental state that tension produces Real or perceived threat to homeostasis + + + + + + + Direct consciously or indirect unconsciously sensed threat to the stability of the organism “ Three stages: Alarm, resistance/adaption, and exhaustion Fig. 2-2; > Alarm stage: fight-or-flight response as the result of stressful stimulus P.15 =~ -Hypothalamic-pituitary-adrenal (HPA) axis > Resistance/adaptation: activity of the nervous and endocrine systems in returning the body to homeostasis = Allostatic state: activity of various systems attempting to restore homeostasis > Exhaustion: point where body can no longer return to homeostasis P. 16 m = Allostatic overload: “cost” of body’s organs and tissues for an excessive or ineffectively regulated allostatic response; effect of “wear and tear” on the body Stressors > Agents or conditions that can produce stress; endanger homeostasis May be external or internal ¢ External examples: school, work, life event (wedding) ¢ Internal examples: cancer, child birth/pregnancy Physical, chemical, biological, social, cultural or psychological ¢ Physical: hand injury ¢ Social: standing in front of a class * Cultural: acceptance/ability to practice Vary in scope, intensity, and duration Reactions to stress vary depending upon genetic constitution, gender, past experiences, cultural influences, developmental stage, and age ¢ Past experience: a child afraid of a playground b/c he was previously abused there Can include both negatively and positively perceived events > Risk Factors: Not stressors, but conditions or situations that increase the likelihood of encountering a stressor; there is some control over our stressors Neurohormonal Mediators of Stress & Adaption > Catecholamines Play an integral role in allostasis Symphathico-adrenal system response mediates the fight or flight response Examples: Norepinephrine and epinephrine > Norepinephrine Constricts blood vessels and raises blood pressure Reduces gastric secretions > Epinephrine Enhances myocardial contractibility, increases heart rate, and increases cardiac output Causes bronchodilation Increase the release of glucose from the liver (glycogenolysis) and elevates blood glucose levels > Adrenocortical Steroids Critical to maintenance of homeostasis May synergize or antagonize effects of catecholamines ¢ Examples: Cortisol and aldosterone Cortisol ¢ Primary glucocorticoid ¢ Affects protein metabolism * Promotes appetite and food-seeking behaviors ¢ Had anti-inflammatory effects * Too much cortisol over time can lead to pro-inflammatory effects Aldosterone (secreted by the adrenal cortex) P. 17 P. 18 Module 1 Chapter 3: Cell Structure & Function Plasma Membrane ° Membrane Structure > Allcells enclosed by a barrier composed primarily of protein and lipid > Highly selective filter than shields internal cell context from external environment Plasma Membrane’s Functions Transport nutrients & waste products Generate membrane potentials Cell recognition & communication Growth regulation Sensor of signals that enable cell to respond & adapt to changes in environment Lipid Bilayer > Related to special properties of lipid molecules that cause them to arrange in bilayers > 3 types of membrane lipids: Cholesterol, phospholipids, glycolipids > All3 types are amphipathic (able to form bilayers in aqueous solutions) m Hydrophilic: water loving m@ Hydrophobic: water fearing Membrane Proteins > Approximately 50% of typical cell membranes mass: protein > Type of membrane protein in cell depends on cell’s primary functions > Type of protein varies with cell type and environmental conditions m Transmembrane proteins extend across bilayer & have contact with interal and external environments m@ Functions ¢ Transport charged & polar molecules in & out of cells ¢ Transduction of extracellular signals into intracellular messages > Some membrane proteins need tight junctions Act like a fence to confine some proteins m Connect neighboring cells vyYyYyyYyY Organization of Cellular Compartments Cytoskeleton > Organized protein network that prevents eukaryotic cell’s organelles from free floating > m Maintains cell’s shape @ Allows cell movement m Directs trafficking of substances within cell > Composed on 3 principal types of protein filaments (dynamic structures disassemble & reassemble with changing needs of a cell) = Actin filaments play pivotal role in cell movement = Microtubules organize cytoplasm & organelles & originate at centrosome = Intermediate filaments mechanically support cell Nucleus > Largest cytoplasmic organelle > Contains genetic information (DNA) of cell Endoplasmic Reticulum > Membrane network present in all eukaryotic cells Known as “gastrointestinal tract” of the cell Central role in synthesis of membrane components Rough & smooth types m@ Rough: coated with ribosomes, complexes of protein, and RNA = Smooth: lacks ribosomes; involved with lipid metabolism Golgi Apparatus > Stack of snooth membrane bound components (cisternae) > Organized in a series of 3 processing compartments ™ Cis-face: receives newly synthesized proteins & lipids = Medial: middle compartment m@ Trans-face: proteins & lipids leave for final destination Lysosomes & Peroxisomes > Lysosomes m Membrane-bound bags of digestive enzymes = Obtain materials they digest from 3 main pathways: endocytosis, autophagy, & phagocytic cells Final products of lysosomal digestion: amino acids, fatty acids, & sugars > Peroxisomes m Membrane-bound bags of enxymes that perform degradative functions = Important to kidney & liver cells; detoxify various substances @ Also called microbodies > Mitochondria m Powerhouses of the cell m Convert energy to forms that can be used to drive cellular reactions m Bound by 2 specialized membranes: inner membrane (matrix) & outer membrane containing large aqueous channels m@ Contain enzymes necessary for ATP production m Have arole in programmed cell death: apoptosis yyy Biochemical process whereby foodstuffs are used to provide cellular energy & biomolecules > Cell’s energy currency: ATP 2separate & opposite phases > Anabolism: energy-using metabolic process; results in synthesis of complex molecules > Catabolism: energy-releasing metabolic process; breakdown of nutrient sources Glycolysis > Anaerobic process Fig. 3-4; > Produces 2 ATP molecules P, 34 m= Interstitial digestion into small molecules- proteins become amino acids P. 18 — Monosaccharides: any of the class of sugars (e.g., glucose) that cannot be hydrolyzed to give a simpler sugar. [] Review ATP; 38 ATP molecules produced in % Citric Acid Cycle (Krebs Cycle) glycolysis (P. 35). Kahn > Oxidizes acetyl groups to form large quantities of hydride ions * * > *final step takes place in the mitochondria—results in complete oxygenation of glucose into the final product — Do not need to know the specifics, know the end products [] Oxidative Phosphorlyation > Produces ATP by reaction of ADP plus inorganic phosphate > Requires molecular oxygen (aerobic) > Needs ATP synthetase, a protein in the mitochondrial membrane Fig. 3; 1-7 & 1-8; P. 37 Functions of the Plasma Membrane Membrane Transport of Macromolecules > Endocytosis = Cellular ingestion of extracellular molecules m Two types: ¢ Pinocytosis: ingestion of fluids & small molecules ¢ Phagocytosis: ingestion of large molecules m Some macromolecules need receptor-mediated endocytosis > Exocytosis @ Cellular secretion = Opposite of endocytosis Membrane Transport of Small Molecules > Transport of lipid-soluble molecules @ Simple diffusion; electrochemical gradient: because of differences between intracellular & extracellular charges m@ Transport of water-soluble molecules ¢ Assisted by transport proteins (transmembrane proteins) * Most transporter proteins are highly specific for a particular molecule Module 1 Chapter 24: Fluid & Electrolyte Homeostasis & Imbalances Body fluid Body fluid flows in arteries, veins, & lymph vessels Body fluids are secreted into specialized compartments > Joints, cerebral ventricle, & intestinal lumen Fig. 24-1 & 24-4 Functions of body fluid > Surrounds & permeates the cells > Lubricant & solvent for metabolic chemical reactions > Transports oxygen, nutrients, chemical messengers, & waste products to their destinations > Important in regulating body temperature Abnormalities in body fluid Volume: too much (excess) or too little (deficit) Concentration: altered Electrolyte composition of body fluid: too much (hyper) or too little (hypo) Can cause clinical problems or death Occur as aresult of many different pathophysiologic conditions Body Fluid Homeostasis Body fluid: > Pertains to water within the body & the particles dissolved in it 2 major body fluid compartments > Extracellular fluid: outside of the cell m= 1/3 body fluid in adults Infants have more extracellular fluid as compared to intracellular > Intracellular fluid: inside the cell @ = 2/3 body fluid in adults Location of extracellular fluid > Interstitial compartment (between cells) > Vascular compartment (in blood vessels) > Dense connective tissue & bone > Transcellular fluid: synovial, cerebrospinal, Gl fluids Total Body Water Total of the water in all fluid compartments Percentage of body weight that is water varies > According to a person’s age > In proportion to body fat > Ininfants—75% > Inmen—60% > Inwomen—50% + Fluid Homeostasis Fig. 24-3 Dynamic process results from interplay of four subprocesses > Fluid intake > Fluid absorption > Fluid distribution > Fluid excretion Fluid Intake & Absorption Fluid intake is entry of fluid into the body by any route Thirst is triggered by: > Increased concentration of extracellular fluid (osmolality); decreased circulating volume > Inolder adults, thirst diminishes; may have insufficient fluid intake Other possible routes of intake > Intravenous intake > Intake tubes in Gl tract and other body cavities > Subcutaneous tissue or bone marrow infusion > Rectal intake (tap water enema) Fluid Distribution Capillary Forces > Move fluid from interstitial compartment into capillaries inward-pulling force of particles in vascular fluid > : outward push of interstitial fluid against outside of capillary walls Fluid distribution between interstitial & intracellular > Occurs by osmosis > Cell membranes are permeable to water but not to electrolytes > Water crosses the cell concentration inside & outside cells (osmosis) > Water goes to the higher osmolality Water movement out of cells > Occurs when particle concentration (osmolality) of the interstitial fluid becomes higher than the particle concentration inside cells Fig. 24-1 Water movement into cells > Occurs when the osmolality of the interstitial fluid becomes lower than the osmolality of the intracellular fluid P. 523 Fluid Excretion Urinary tract: Largest volume excreted Bowels: normal bowl function; increases w/ diarrhea Lungs: exhalation Skin: visible in sweat; insensible perspiration Amount of fluid excreted in the urine is controlled primarily by hormones (controlled by the adrenal cortex) > Antidiuretic hormone (ADH) > Aldosterone > Natriuretic peptides (ANP & BNP--heart) > Other minor hormones ADH > Synthesized by cells in the hypothalamus > Released from the posterior pituitary gland > Factors that increase release of ADH Increased osmolality (concentration) of the extracellular fluid Decreased circulating fluid volume Pain Nausea Physiologic & psychological stressors Causes reabsorption of water, which: * Decreases urine volume & fluid excretion * Concentrates the urine If ADH release is decreased, result is large dilute urine volume * Decreased osmolality of extracellular fluid ¢ Ethanol intake Aldosterone > Synthesized & secreted by cells in the adrenal cortex > Major stimulus for its release m= Angiotensin II ¢ From the renin-angiotensin system ¢ Activated by decreased circulating blood volume m Increased concentration of potassium ions in the plasma Causes renal tubules to reabsorb sodium & water (saline) Decreases fluid excretion, although by a different mechanism than ADH When more aldosterone is secreted, urine volume is smaller > Decreased secretion of aldosterone causes a larger urine volume ADH vs. Aldosterone > yyy @ Dilutes body fluids > m_ Expands extracellular fluid volume Natriuretic peptides > A-type natriuretic peptide (ANP) m Normally secreted from cells in the heart when the atria are stretched > B-type natriuretic peptide (BNP) m_ Released from ventricular cells when ventricular diastolic pressure increases abnormally, as in heart failure