Lesson 1.docx

Cell is the basic unit of the body -- each has a specialized function - Consume O2 and produce CO2 - All contain and are surrounded by fluid Microbiota outnumber the human cells and generally beneficial **Water most abundant constituent of the body -- 60% men, 50% women, 70% neonates** Inte...

Cell is the basic unit of the body -- each has a specialized function - Consume O2 and produce CO2 - All contain and are surrounded by fluid Microbiota outnumber the human cells and generally beneficial **Water most abundant constituent of the body -- 60% men, 50% women, 70% neonates** Internal environment - ECF - 30% of the body's water content - Plasma and interstitial fluid - Large amounts of Na, Cl, HCO3 - Oxygen, glucose, fatty acids, amino acids - ECF composition precisely regulated by kidneys - ICF - 70% of body's water content - K, Mg, PO4 - Cellular components are suspended in cytosol - Unequal distribution of ions creates a voltage difference across cell membranes. - total body concentrations of K= 45 and Na= 58 - Parameters with narrow limits compatible with life -- temperature, acid-base balance, potassium - Water balance - Daily intake = 2.5 L - Losses via urine, sweat, feces, diffusion through skin - Blood volume - 5 L - Plasma 3 L - RBCs 2 L - Intravascular volume maintained by RAAS and ADH - Examples of control mechanisms - O2 release by hemoglobin -- oxygenation hemoglobin dissociation curve - Excess Co2 concentrations stimulate respiratory centers - Increased BP -- baroreceptors are stretched and they inhibit vasomotor center to decrease SNS activity - Decreased BP -- relaxes stretch receptors, increased vasomotor center activity leading to vasoconstriction and increased heart pumping activities - Negative and positive feedback loops - Negative: reduce or change the output to bring the system back to baseline -- breathing - Positive: increase the change to amplify reactions - Osmosis -- diffusion of water low concentration of solute to a higher concentration of solute - Maintenance of cell volume - Controlled by movement of K-Na by energy dependent ATPase pump - Osmotic pressure - Pressure required to prevent continued movement of water - Determined by number of non-diffusible particles in solution - Osmolarity: concentrations of solutes - Osmolarity in plasma primarily determined by sodium concentrations - Plasma osmolarity = 2(Na+) + 0.055 (glucose) + 0.36(blood urea nitrogen) - Osmolarity: 290 mOsm/L contributed by Na, Cl, bicarb, protein (negligible), glucose, and urea - Na and Cl contribute 270 - Glucose and urea may contribute more during hyperglycemia and uremia - Plasma osmolarity = 2(Na+) + 0.055 (glucose) + 0.36(blood urea nitrogen) - Solutions = isotonic, hypertonic, hypotonic - Isotonic solutions stay in intravascular spaces (i.e. blood vessels) for 20-30 mins - Maintenance fluid calculations - 4/2/1 - works for adults and peds - 4 mL/kg/hour for 1^st^ 10 kg - 2 mL/kg/hour for 2nd 10 kg - 1 mL/kg/hour for remainder kg - Cell structure and function - Organelles have bilayers similar to cell membrane - **Proteins made in rough ER** - **Lipid made in smooth ER** - Nucleolus does not have a membrane -- collection of genetic material - Regions - Nucleus - Cytoplasm - Cell mostly comprised of water 70-85% and mostly proteins, lipids, and carbs with some ions - cell membrane -- composed of lipid bilayer that creates a semipermeable membrane - Comprised of phospholipids, sphingolipids (lipid with a sphingoid base primarily found in nervous system), cholesterol, and proteins - Phospholipids - Lecithins (phosphatidylcholines) - Sphingomyelins - Amino phospholipids (phosphatidylethanolamine) - Readily permeable to water, gas, fat soluble substances, O2 and CO2 - Nearly impermeable to water soluble substances - Hydrophilic portions face ECF and ICF - Lipophilic portions form the inner layer of the membrane - phospholipid bilayer - hydrophilic heads face ECF and ICF - lipophilic form inner layer of cell membrane - keeps out charged particles but let other things pass easily - Proteins - integral proteins: permanently embedded in membrane, span the entire bilayer - receptors -- second messengers - channels -- transport proteins through gradients - carrier proteins -- active transport - peripheral proteins: temporarily associated with lipid bilayer and do not fully span the membrane - tend to be attached to integral proteins - act as enzymes or controllers for transport of substances - Structural proteins -- microtubules - Enzymes - most proteins have glycocalyx -- give outside cells a negative charge to repel other negatively charged particles e.g. RBCs - Glycocalyx = membrane carbohydrates - Proteins with carb attached = glycoprotein OR lipid with carb attached = glycolipid - Glyco body is the one that protrudes outside of membrane - Act as receptors and modulate immune activity can attach to glycolax of other cells - Many are negatively charged and repel other negatively charged prticles - LOOK on Wikipedia for cytokines - Transfer of molecules - Diffusion - Simple Diffusion -- through phospholipid bilayer - Facilitated diffusion -- through channel protein or carrier protein - Charged water soluble molecules and ions do not pass - Osmosis -- through aquaporins or phospholipid bilayer - Endocytosis -- taking up of particle by cell - Phagocytosis = cell eating = ingestion of large particles, such as bacteria, whole cells, or portions of degenerating tissue. - Pinocytosis = cell drinking = taking up of molecules that form vesicles of ECF and particulate constituents inside the cell cytoplasm - Exocytosis -- release of a particle - Na-K ATPase pump - Need ATP - ATP attaches - K in Na out 3-2 - Sodium (Na)-potassium (K) adenosine triphosphatase (ATPase) is an enzyme present in all cells that catalyzes the conversion of adenosine triphosphate (ATP) to adenosine diphosphate (ADP). The resulting energy is used by the active transport carrier system (sodium pump) that is responsible for the outward movement of three sodium ions across the cell membrane for every two potassium ions that pass inward - Ion channels - Protein mediated transport -- includes ATP and glycoprotein - Transported against concentration gradient - Require energy from hydrolysis of ATP - Sodium ion co-transport (SGLT) = glucose can't move by itself - Transport of sodium ions and another substance - Cotransport = combine the movement of one molecule with its concentration gradient with the movement of another molecule with (symporter) or against (antiporter) its concentration gradient - the active transport of sodium ions in some tissues is coupled to the transport of other substances. For example, a carrier system present in the gastrointestinal tract and renal tubules will transport sodium ions only in combination with a glucose molecule. As such, glucose is returned to the circulation, thus preventing its excretion. Sodium ion cotransport of amino acids is an active transport mechanism that supplements facilitated diffusion of amino acids into cells. Epithelial cells lining the gastrointestinal tract and renal tubules are able to reabsorb amino acids into the circulation by this mechanism, thus preventing their excretion - Aquaporins: proteins permitting free flux of water across cell membranes - Cell nucleus - Genetic message determined by sequence of nucleotides - DNA transcribed to RNA, transferring generic message to ribosomes in the cytoplasm for protein synthesis - Mitochondria: site of energy production - 2 layered - Inner layer houses mitochondrial DNA. Space for the reservoir of protons created during electron transport - Energy from ATP used for transport, protein synthesis, and muscle contraction - ER = network of tubular structures called *cisternae* and flat vesicular structures that help process molecules made by the cell and transport them to their specific destinations in/out of cell - Rough ER ribosomes -- protein production - Ribosomes are site of protein production - Ribosome comprised of protein and RNA - Smooth ER no ribosomes -- lipid production - Sarcoplasmic reticulum -- stores Ca++ in muscle - Golgi apparatus - Storage depot for lipids and proteins - Site of glycosylation (carb+ molecule) and phosphorylation (phosphate+ molecule) - Lysosome production - Lysosomes -- garbage disposal -- intracellular digestive system - Filled with hydrolytic enzymes -- acidic with pH\