Cell Physiology Lecture Notes PDF

Lecture # 1 HOMEOSTASIS AND CELL PHYSIOLOGY Dr. Diakonova  Human Physiology Instructor Dr. Maria Diakonova Office: BO 3096 Phone: 419-530-7876 Email: [email protected] Office Hours: by appointment Course Description...

Lecture # 1 HOMEOSTASIS AND CELL PHYSIOLOGY Dr. Diakonova  Human Physiology Instructor Dr. Maria Diakonova Office: BO 3096 Phone: 419-530-7876 Email: [email protected] Office Hours: by appointment Course Description As a requirement for biology majors, this three credit hour lecture course covers topics relating to human physiology with a strong emphasis placed on homeostatic mechanisms and system-system interactions. The specific topics covered in this course include structural and functional analysis of the human endocrine, nervous, circulatory, respiratory, digestive and excretory systems. Students will be assessed with four exams given throughout the semester and an accumulative final exam at the end of the course. Recommended Material This course will be lecture-based. There is no required textbook and lecture notes (as PDF and PowerPoint Presentations) can be downloaded from the Blackboard website. These lecture notes will be updated regularly, but cannot substitute for class attendance. Textbooks recommended (but not required): Sherwood: Human Physiology from Cells to Systems; and/or Derrickson: "Human Physiology", (Wiley, 1st ed., ISBN is 9781119296744. It includes the WileyPlus Learning Space resources, online text, adaptive learning, videos and 3D animations, and online homework, along with the physical book). Textbooks are used as reference material, all lectures and notes will be made available to the students via Blackboard. Homeostasis is the effort to regulate the internal environment (keep it stable) External environment O2 CO2 Integumentary system Nutrients Digestive system Cells Respiratory Internal environment system Interstitial Blood plasma fluid O2 CO2 Nitrogenous Nutrients wastes Nutrients Nitrogenous wastes Cardiovascular system Urinary system Urine Solid wastes Copyright © 2016 by John Wiley & Sons, Inc. All rights reserved.  Homeostasis Defined as maintenance of a relatively stable internal environment – Dynamic steady state – Does not mean that composition, temperature, and other characteristics are absolutely unchanging Homeostasis is essential for survival and function of all cells Each cell contributes to maintenance of a relatively stable internal environment Chapter 1 Homeostasis: The Foundation of Physiology Human Physiology by Lauralee Sherwood ©2007 Brooks/Cole-Thomson Learning  Homeostasis Body cells are contained in watery internal environment through which life-sustaining exchanges are made Extracellular fluid (ECF)-internal environment – Fluid environment in which the cells live (fluid outside the cells) – Two components- Plasma, interstitial fluid Intracellular fluid (ICF) – Fluid contained within plasma membrane of all body cells Chapter 1 Homeostasis: The Foundation of Physiology Human Physiology by Lauralee Sherwood ©2007 Brooks/Cole-Thomson Learning Body cells Intracellular fluid Extracellular fluid: Interstitial fluid Plasma Blood capillary Copyright © 2016 by John Wiley & Sons, Inc. All rights reserved. All cells have some things in common: -DNA as genetic material (same code) -expression of genetic material as RNA and protein (catalysts) -cell membrane (selective barrier)  Cell Structure Typical Human Cell 10- 20 μm Trillions of cells ~200 cell types Most cells contain 3 major subdivisions: 1) Plasma membrane 2) Nucleus 3) Cytoplasm http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&uact=8&ved =0CAYQjB1qFQoTCLWzyu7huscCFQlsPgodOJYKaw&url=http%3A%2F%2Fclasses.midlandstech.edu %2Fcarterp%2FCourses%2Fbio210%2Fchap03%2Flecture1.htm&ei=eGjXVbWXBonY- QG4rKrYBg&psig=AFQjCNGe8_SdblRsxjxS7YXEkx5XVshVVA&ust=1440266732911260 Plasma Membrane is a fluid lipid bilayer embedded with proteins Phospholipids form a bilayer. The bilayer has a hydrophobic interior. This interior is sandwiched between hydrophilic inner and outer surfaces. Human Physiology : From Cells to Systems 7th ed. by Lauralee Sherwood ©2010 Brooks/Cole-Thomson Learning Movie 12 Plasma Membrane ECF (water) Polar heads (hydrophilic) Nonpolar tails Lipid bilayer (hydrophobic) Polar heads (hydrophilic) ICF (water) The lipid bilayer serves three important functions: It forms the basic structure of the membrane. Its hydrophobic interior is a barrier to water-soluble substances. This allows the intracellular compartment to be distinct: ICF vs ECF It allows the membrane to be fluid.  Cells bind together to form tissues - organs Cells are held together by three different means: 1) The extracellular matrix 2) Cell adhesion molecules in the plasma membrane 3) Specialized cell junctions  1. Extracellular matrix (ECM)- a meshwork of proteins in a watery like substance that serves as a biological “glue.” The ECM is secreted by local cells present in the matrix. Most abundant in connective tissue BASAL LAMINA (basal membrane; basement membrane) – thin mat of extracellular matrix that separates epithelial sheets, and many other types of cells such as muscle or fat cells, from connective tissue. Functions of the Basal Membrane: 1. barrier 2. mechanical support for epithelia 3. filtering (kidney cells) 4. influence of cell polarity  2. Cell adhesions molecules, i.e. cadherins Side-to side interaction between cadherins on the same cell Relatively low affinity But: Velcro principle Movie 13  3. Specialized cell junctions a) Desmosomes - act as “spot rivets” to anchor adjacent cells that are not touching. Found in tissues subject to stretching, ie, skin , heart, uterus. (cadherin family) b) Tight junctions- Firmly binds adjacent cells together Seal off the passageway between the two cells Found primarily in sheets of epithelial tissue Prevent undesirable leaks within epithelial sheets Note the distinct regions of the plasma membrane (exposed to different environments)  The role of tight junctions in allowing epithelia to serve as barriers to solute diffusion. Figure 19-24 Molecular Biology of the Cell (© Garland Science 2008) How a plasma membrane protein (and lipids) are restricted to a particular membrane domain c) Gap junctions- **(communicating junctions) Small connecting tunnels formed by connexons Especially abundant in cardiac and smooth muscle In nonmuscle tissues permit unrestricted passage of small nutrient molecules between cells Gap channel is 1.5nm Inorganic ions, sugars, AA, nucleotides, vitamins But not macromolecules (proteins, nucleic acids, polysaccharides)  Membrane Transport Cell membrane is selectively permeable (creates distinct environments ICF vs ECF) Two properties of particles influence whether they can permeate the cell membrane without assistance (permeable vs impermeable) – Relative solubility of particle in lipid Lipid soluble, uncharged nonpolar molecules – O2, CO2, & steroid hormones can pass easily – Size of the particle The relative permeability of a synthetic lipid bilayer to different Small polar molecules like water can cross – slow classes of molecules (aquaporins, water channels - fast) Passive carrier-mediated transport Human Physiology : From Cells to Systems 7th ed. by Lauralee Sherwood ©2010 Brooks/Cole-Thomson Learning animation  Active carrier-mediated transport Human Physiology : From Cells to Systems 7th ed. by Lauralee Sherwood ©2010 Brooks/Cole-Thomson Learning Three types of carrier-mediated active transport  Nucleus Typically largest single organized cell component Enclosed by a double-layered nuclear envelope Contains cell’s genetic material, DNA – DNA functions Directs protein synthesis Serves as genetic blueprint during cell replication Nucleolus - The nuclear site of rRNA transcription, processing, and ribosome assembly.  Cytoplasm Portion of cell interior not occupied by the nucleus Consists of – Cytosol Complex, gel-like mass in which the cytoskeleton is found – Organelles “little organs” Distinct, highly organized, membrane-enclosed structures organelles: nucleus with nucleolus, mitochondria, endoplasmic reticulum (smooth and rough), ribosomes, Golgi apparatus, lysosomes and peroxisomes, centrioles. cytoskeleton Cytoskeleton Movies 6 -8 Secretion of Proteins Synthesized by the ER Exocytosis and Endocytosis Movies 2 and 3  Mitochondria two membranes, outer and highly folded inner Cristae - folds of the inner membrane contain proteins used in cellular respiration Matrix - the region enclosed by the inner membrane Takes up oxygen and harness energy from the oxidation of food to produce ATP Own circular DNA Own ribosomes Own tRNA Mitochondria (and plastids) are thought to have originated when a bacterium was engulfed by a larger pre-eukaryotic cell  Mitochondria Selectively permeable permeable, porins Mitochondria convert O2 and nutrients into adenosine triphosphate (ATP). ATP is the chemical energy "currency" of the cell that powers the cell's metabolic activities. This process is called aerobic respiration and is the reason animals breathe oxygen. Without mitochondria animals would likely not exist because their cells would only be able to obtain energy from anaerobic respiration (in the absence of oxygen), a process much less efficient than aerobic respiration. Movie 10  Cellular Activities that Require ATP Synthesis of new chemical compounds Membrane transport Mechanical work ATP Production Sequence of steps involved in generation of ATP within the cell Glycolysis Citric acid cycle Electron transport chain  Cellular Respiration Intracellular reactions in which energy-rich molecules are broken down to form ATP Uses O2 and produces CO2 as waste Multiple Steps within the cytosol and mitochondria to produce a net of 32 ATPs Human Physiology : From Cells to Systems 7th ed. by Lauralee Sherwood ©2010 Brooks/Cole-Thomson Learning  Glycolysis Human Physiology : From Cells to Systems 7th ed. by Lauralee Sherwood ©2010 Brooks/Cole-Thomson Learning Figure: Summary of aerobic oxidation of glucose (and fatty acids) 1st part – pyruvate oxidation  Citric Acid Cycle Pyruvic acid from glycolysis is converted to acetyl CoA which enters citric acid cycle Citric acid cycle consists of eight separate biochemical reactions that are directed by enzymes of mitochondrial matrix The key purpose of the Citric Acid Cycle is to produce the hydrogens for entry into the electron transport system. These hydrogens contain electrons at high energy levels. These hydrogens are transferred to two different hydrogen carriers: NAD and FAD. Chapter 2 Cellular Physiology Human Physiology by Lauralee Sherwood ©2007 Brooks/Cole-  Citric Acid Cycle Human Physiology : From Cells to Systems 7th ed. by Lauralee Sherwood ©2010 Brooks/Cole-Thomson Learning  ATP generation in animal cells: four stages cytosol mitochondria glycolysis Citric acid cycle Electron transport ATP synthesis chain Oxidative phosphorylation is the process by which ATP is synthesized using the energy released by electrons as they transferred to O2. The general mechanism of oxidative phosphorylation As a high-energy electron is passed along the electron-transport chain, some of the energy released is used to drive the three respiratory enzyme complexes that pump H+ out of the matrix. The resulting electrochemical proton gradient across the inner membrane drives H+ back through the ATP synthase, a transmembrane protein complex that uses the energy of the H+ flow to synthesize ATP from ADP and Pi in the matrix. Oxidative Phosphorylation Movie 11 A summary of energy-generating metabolism in mitochondria Pyruvate and fatty acids enter the mitochondrion (bottom) and are broken down to acetyl CoA. The acetyl CoA is then metabolized by the citric acid cycle, which reduces NAD+ to NADH (and FAD to FADH2, not shown). In the process of oxidative phosphorylation, high-energy electrons from NADH (and FADH2) are then passed along the electron-transport chain in the inner membrane to oxygen (O2). This electron transport generates a proton gradient across the inner membrane, which is used to drive the production of ATP by ATP synthase. The NADH generated by glycolysis in the cytosol also passes electrons to the respiratory chain (not shown). Since NADH cannot pass across the inner mitochondrial membrane, the electron transfer from cytosolic NADH must be accomplished indirectly by means of one of several “shuttle” systems that transport another reduced compound into the mitochondrion; after being oxidized, this compound is returned to the cytosol, where it is reduced by NADH again. Energy Yield Anaerobic vs. Aerobic Conditions Food + O2 (necessary = CO2 (produced + H2O (produced + ATP (produced for oxidative by the citric acid by the electron by ATP phosphorylation) cycle) transport system) synthase