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UWL BIO 312 - Homeostasis and body fluid part II

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Lecture 1,2 Current LectureI Anatomy and Physiologya. Cellsb. Tissuesc. OrgansII Homeostasisa. Control systemsIII Body Fluida. Distributionb. Diffusionc. osmosisAnatomy: study of the structure of the human body- Gross Anatomy: structures big enough to see macroscopically- Histology: cellular, microscopic, tissues- Cytology: structure of singular cells- Molecular Biology: protieins, ATP, other biochemicalPhysiology: study of the function of the bodyChemical Level: 100 naturally occurring elements in body- Only 24 are essential- C, H, O, N make up 96% of body weight- Minerals and other trace elements make up other 4%Cells: smallest units in body capable of carrying out life- About 50-100 trillion cells in body- About 200 types of cellso RBC is most plentiful, makes up about 1/3 of all cells- 2 general categories of cellular activities:o Basic functions: what every cel has to do to keep itself alive Obtain O2 and nutrients Biochemical reactions to produce ATP from nutrients Eliminate waste Synthesize complex moleculeso Specialized functions: specific function that contributes to the well-being of the whole Carry O2 (RBC) Line protect and absorb (epithelial) Differentiation: process by which unspecialized cells acquire specialized structure and functionTissues: group of cells and cell products working together to perform one or more specific functions- 4 main categories of tissues:o Nervous: internal communicationo Muscle: cause movemento Epithelial: line and divideo Connective: supportOrgans: 2 or more types of tissues working together Bio 312Internal Environment and Homeostasis of that Environment- Goal of the coordinated activities of our organ systems is to create an environment in which cells can live and function- Internal Environment: immediate surroundings of cellso Extracellular fluid (ECF)o Interstitial fluid (ISF) Cells obtain nutrients directly from the ISF Cells excrete waste directly into the ISFo Required parameters of ECF: closely regulated conditions pH concentration of electrolytes levels of O2 and CO2 nutrient levels (sugar, amino acid, fatty acid) waste levels (urea, creatinine) temperature volumeHomeostasis: maintenance of a relatively stable internal environment of the body necessary for the survival of the individual cells- changes will occur but the magnitude needs to be kept within narrow limits- body constantly exposed to stresses on homeostasis- activities of cells, tissues, organs constantly adjusted and coordinated to minimize disturbances- Homeostatic Control Systems: 2 main ones are nervous and endocrine systemso Imbalance in conditionso Imbalance detected by receptor (stimulus)o Input information sent along afferent pathway to control centero Output info sent along efferent pathway to the effectoro Response to output info causes changes to imbalance to attempt to return to homeostatic conditions - Negative feedback control: mechanism used to control internal conditionso Based off a negative disturbance, body makes changes to correct or minimize disturbance- Positive feedback control: the continuation of a process started on a small scale which becomes larger and more dramatic with more of detected processo RBCs begin to clot on wound, wound detected, more RBC clottingo Congestive heart failure: weakened hear leads to heart pumping less blood which leads to reduced O2 to muscles which weakens the heart even furthero Baby’s head begins to press against uterus, hormones tell uterus to expand, head pushes further against uterus, more hormones sent.Body Fluid Compartments:Water: most abundant substance in body- About 60% of body weight (inversely proportional to body weight)- Materials essential to function use water for transport as well as waste removal- Medium in which biochemical reactions occur- High heat capacity (ideal for thermoregulation)- All water in body: Total Body Water (TBW) distributed among 2 major locationso 2/3 located in cells (intracellular fluid)o 1/3 located outside of cells (extracellular fluid) Vast majority of this is interstitial fluid (80%) Other 20% is plasmao lymph and transcellular fluid make up negligible amounts of waterComposition of Body Fluids:- H2O is always solvent- 2 categories of solutes in body:o Nonelectrolytes: no net electrical charge Do not dissociate Usually organic molecules (glucose, lipids, urea)o Electrolytes: have net electrical charge Ions Vast majority (about 95%) of solutes in body are electrolytes- Almost all electrolytes have same concentration in plasma and ISF (except protein)o Ions so small that they can pass from plasma to ISF very easilyo Filtration: out of capillarieso Reabsorption: into capillaries- Sodium: major cation of ECF- Chlorine: major anion of ECF- Potassium: major cation of ICF- HPO4, SO4: major anions of ICFCell Membrane: differences in concentration between ICF and ECF are caused by properties of cell membrane- Composed of phospholipid bilayer with polar hydrophilic head and nonpolar hydrophobic tailo Because of the chemical composition, when these molecules are exposed to water, they will automaticallyassume the bilayer positiono Allowed to move laterally amongst each othero Prevents movement of particles acrosso Contain proteins classified by position as: Integral: goes through the entire membrane Peripheral: does not transverse entire membraneo Other types of membrane proteins: Anchoring proteins: attach cell membranes to one another or to internal/external structures Recognition protein: identify cell and prevent from immune system attack Enzymes: help speed up biochemical processes Receptor Proteins: allow for specific chemical signals to effect cell Carrier Proteins: move solutes across membrane (active or passive)- Leak Channels: size limited allow continuous passive movement (H2O, ions)- Gated Channels: size limited, close or open to regulate ion movement Cholesterol: help with flexibility Carbohydrates: various functions Aquaporin: water channelsMechanisms for Substances Crossing Membrane:Permeability of membrane determines what can pass through: freely permeable, selectively permeable, or impermeable- Diffusion: movement from high to low concentrationo Particles in state of random thermal motiono Random thermal motion causes net flux of particles to evenly distribute from higher to lower concentrationo


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UWL BIO 312 - Homeostasis and body fluid part II

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