TOPIC 5 LECTURE SLIDES PDF

DIPLOMA OF HEALTH SCIENCES HUMAN STRUCTURE AND FUNCTION (HSF1000) Your pathway to Curtin. On campus. On track. www.curtincollege.edu.au  COMMONWEALTH OF AUSTRALIA Copyright Regulation 1969 WARNING This material has been copied and communicated to you...

DIPLOMA OF HEALTH SCIENCES HUMAN STRUCTURE AND FUNCTION (HSF1000) Your pathway to Curtin. On campus. On track. www.curtincollege.edu.au  COMMONWEALTH OF AUSTRALIA Copyright Regulation 1969 WARNING This material has been copied and communicated to you by or on behalf of Curtin University of Technology pursuant to Part VB of the Copyright Act 1968 (the Act) The material in this communication may be subject to copyright under the Act. Any further copying or communication of this material by you may be the subject of copyright protection under the Act. Do not remove this notice MODULE 5: HOW DO WE FUEL OUR BODY? Learning outcomes 1. List and explain the ways that ions and molecules can pass through the plasma membrane 2. Explain the process of osmosis and concentration gradients in controlling the movement of water across the plasma membrane 3. Describe ATP and ADP in terms of the release or input of energy in chemical reactions 4. Describe the main stages of glycolysis and name its products 5. Describe the main stages of the citric acid cycle (Krebs cycle) and name its products 6. Briefly explain oxidative phosphorylation (electron transport chain) and how ATP is produced in the process PREPARATION Read the following pages of your Textbook VanPutte, C. L., Regan, J. L. & Russo, A. F. (2017). Seeley’s Anatomy and Physiology (11th edition). New York, USA: McGraw-Hill. ISBN/ISSN: 9781743769072 ✓ Chapter 2: pages 35-37 ✓ Chapter 3: pages 61-67 and 69-77 ✓ Chapter 25: pages 934-943 VanPutte, C. L., Regan, J. L. & Russo, A. F. Seeley’s Anatomy and Physiology (10th ED) New York, USA: McGraw-Hill. ✓ Chapter 2: pages 34-36 ✓ Chapter 3: pages 59-64 and 67-76 ✓ Chapter 25: pages 921-930 VanPutte, C. L., Regan, J. L. & Russo, A. F. (2010), Seeley’s Anatomy and Physiology (9th ED). New York, USA: McGraw- Hill ✓ Chapter 2: pages 34-35 ✓ Chapter 3: pages 59-62 and 66-74 ✓ Chapter 25: pages 932-941  CELL MEMBRANE Boundary of cell –encloses and supports cell contents Separates intracellular vs. extracellular materials Attaches cells to other cells and to the surrounding matrix Cells communicate with their environment through their cell membrane Determines what can move into and out of the cell (selectively permeable) intra-and extracellular environment is different Difference in charge across membrane – membrane potential More positively charged ions on the outside and more positively charged ions on the inside Structure of the plasma membrane Primarily composed of lipids and proteins and some carbohydrates (only outer surface) Fluid mosaic model- appearance of the membrane, high flexible, not rigid or static Phospholipid bilayer – Phospholipids, Cholesterol Proteins: Many are involved in transporting molecules across the cell membrane, e.g. channel proteins, carrier proteins, ATP powered pumps Plasma Membrane: Composition Plasma membrane is selectively permeable: allows somethings to pass through, and not others Permeability of the plasma membrane depends of various factors Solubility in lipids Driving forces (up or down gradient) Molecular size Transport across the membrane can be ACTIVE or PASSIVE PLASMA MEMBRANE - FLUID MOSAIC MODEL Lipid bilayer - Highly impermeable barrier to most “charged”, “non lipid soluble” & “water” soluble substances - Integral proteins act as “pores, channels” or “carrier to allow impermeable substances to cross the membrane Structure of the plasma membrane- membrane proteins Inserted in the lipid bilayer Peripheral proteins Attached to either the inside or the outer surface of the lipid bilayer Integral proteins Penetrate deeply into the plasma membrane and may extend from the one surface to the other Many are involved in transporting molecules across the cell membrane, e.g. channel proteins, carrier proteins, ATP powered pumps (transport proteins)  TRANSPORT PROTEINS - CHANNEL PROTEINS Form a tiny channel through the plasma membrane Molecules of certain size, shape and charge can pass through Specific for particular molecules Non-gated ion channels always open Leak ion channels "Gated" ion channels Opened or closed by certain stimuli Ligand gated channels ✓ Open or close based on binding of a ligand Voltage gated channels ✓ Open or close based on change in membrane potential (voltage) **Ligand: is a term used for any molecule used by a cell to communicate with each other  TRANSPORT PROTEINS - CARRIER PROTEINS Also called transporters Integral proteins move ions or molecules from one side of membrane to the other Specific binding sites Protein changes shape to transport ions or molecules Resumes original shape after transport Uniporters – Moving one ion or molecule Symporters - “co transport” moving two different ion or molecules in same directions Antiporters – Move two different ions or molecules in different directions Transport across the membrane 3 types if passive transport Diffusion through the lipid bilayer (lipids soluble substances) Diffusion through ion channels ( water soluble substances) Felicitated diffusion using carrier ( water soluble substances) Active transport require cellular energy ( ATP) DIFFUSION & OSMOSIS - FIRST PRINCIPLE All molecules are in a state of random motion (kinetic energy) Solute Dissolved substance in a solution e.g. glucose, sucrose, ions (Na+, K+, Cl-) Solvent Liquid that holds solutes, generally water Solution Mixture formed when solute http://sciencewithme.com/sciencewithme/wp- content/uploads/2015/04/solutions_11.png dissolved in solvent DIFFUSION- THROUGH the lipid bilayer Lipid soluble substances e.g. gases, lipids, small alcohols and urea can diffuse across the bilayer A concertation gradient is usually the driving force for this type of transport Molecules move from an area of higher concentration → lower concentration Movement Continues until the molecules have evenly distributed themselves throughout the solution DIFFUSION- ACROSS the lipid bilayer Water soluble substances e.g. ions, sugars, amino acids and water need integral membrane proteins to move across the cell membrane Small ions (channels) Water (channels: aquaporins) Sugar & amino acids ( facilitated diffusion) A concertation gradient or electrical gradient is usually the driving force for this type of transport Molecules move from an area of higher concentration → lower concentration FACILITATED DIFFUSION Moves large, water soluble molecules or electrically charged molecules across the plasma membrane. A solute or molecule binds to a specific transporter on one side of the membrane and is released on the other side Amino acids and glucose in, manufactured proteins out PASSIVE ( no ATP required) http://schoolbag.info/biology/living /living.files/image149.jpg  ATP-POWERED TRANSPORT Requires energy in the form of ATP Breakdown of ATP→ ADP → Energy Transports substances AGAINST their concentration gradient (Low concentration → High concentration) so the cell can accumulate substances e.g. sodium potassium pump (maintains low concentration of Na+ & a high concentration of K+ in the cell cytosol) Membrane transport of complex molecules Exocytosis Movement of large molecules OUT of the cell Occurs in secretory cells Secretions in vesicles (membrane pockets)- vesicle fuse with cell membrane and release their content to the outside e.g. neurotransmitter secretions at the synapse Membrane transport of complex molecules Endocytosis Movement of large molecules INTO of the cell ✓ Pinocytosis – engulfing small particles & fluids ✓ Phagocytosis – engulfing large particles The plasma membrane forms vesicle around the substances to transported & the vesicles is taken into the cell Plasma Membrane: Composition Water molecules move across the membrane by diffusion through aquaporins (transmembrane proteins) that function as water channels The movement of water is called “osmosis” which is defined as the “movement of water from an area with Low SOLUTE concentration → high SOLUTE concentration across a semi permeable membrane”  OSMOSIS Osmosis is the diffusion of water across a selectively permeable membrane, e.g. the plasma membrane A selectively permeable membrane lets water to pass through but not any solutes dissolved in the water If the beaker contains distilled water (water with no solutes), water molecules will move back and forth across the membrane at the same rate The water level stays the same on both sides of the membrane http://isite.lps.org/sputnam/Biology/U3Cell/osmosis_1.png Osmosis – The driving forces When explaining the driving forces behind water movement are not referring to about the concertation of water instead we refer to the concertation of the solutes dissolved in it This is because water is the solvent for all solvent When solutes dissolves in water, the solutions displays an “osmotic pressure” or “drawing power” to encourage water towards it Thus, when there is a semi-permeable membrane, water always moves to the solutions with the highest osmotic pressure ( highest solute concentration) The solutions which water moves towards are said to have “high osmolarity”  EFFECT OF A SEMI-PERMEABLE MEMBRANE AND SOLUTE CONCENTRATION a. Solute added to one side of beaker. Solute molecules are too big to cross through the pores in the membrane Solute distributes itself evenly in one half of the beaker Water moves from area of low solute concentration to high solute concentration. Result: Water level on the RHS of the beaker drops and on the LHS of the beaker increases. Water is moving down its concentration gradient http://keepinapbiologyreal.wikispaces.com/file/view/osmo sis.gif/165682427/osmosis.gif EFFECT OF THE CONCENTRATION OF THE SOLUTION b. Double the amount of solute added The solute will evenly distribute itself in one side of the beaker. The solution in the left side of the beaker is twice as concentrated as the previous example. Again, water will move across from an area of low solute concentration to an area of higher solute concentration A greater volume of water moves across than in the previous example. The concentration of the solute determines how much water moves across the membrane The more concentrated a solution is, the more that solution will “pull” water towards it. A dilute or weak solution with a small number of solutes will only have a weak “pull” on water. A concentrated solution with a large number of solutes will have a strong “pull” on water. OSMOLARITY This “pull” on water created by solutes is termed the solution’s Osmotic pressure or Osmolarity Osmolarity is measured in Osmoles/L or mOsmoles/L. Generally in the body fluids we are working with solutions which are fairly dilute and so we use the unit mOsmoles/L. As we have seen, the osmolarity of a solution is directly related to the concentration of the solution. A weak solution will have a low osmolarity value A more concentrated solution will have a higher osmolarity value. A solution that has an osmolarity of 100mOsmol/L will have a smaller “pull” on water that a solution which has an osmolarity of 300mOsmol/L. So what use is this in the human body? OSMOLARITY AND BODY CELLS Body fluids have many dissolved solutes Body fluids can be divided into intracellular extracellular (intercellular & intravascular) The osmolarity of the intracellular fluid of a normal cell under normal conditions is approximately 290mOsmol/L TONICITY OF SOLUTIONS Tonicity is a measure of a solutions ability to change the volume of cells by altering their water content (amount /volume) If a cell is placed in a solution that has the same concentration of solute as the cell, that solution is said to be isotonic In isotonic solutions, there is no net movement of water, so cells maintain their normal shape When a cell in placed in a solution that has a higher concentration of solutes than the cell, that solution is said to be hypertonic In a hypertonic solution, cells will lose water which can case then to shrink and become dehydrated When a cell in placed in a solution that has a lower concentration of solutes than the cell, that solution is said to be hypotonic In a hypotonic solution, cells will gain water, which can cause them to swell and burst TONICITY OF SOLUTIONS Isotonic solution When a cell is placed in a solution that has the same osmolarity as the inside of the cell (290mOsmol/L), the solution is called isotonic Water will move between the intracellular and extracellular fluid at equal rates (no net movement of water) and the cell is happy. HYPERTONIC SOLUTION Let’s place a cell in a solution that has a higher osmolarity (>290mOsmol/L) than inside the cell (290mOsmol/L) The solution with the higher osmolarity contains a greater concentration of solutes. The solution is hypertonic. So it exerts a stronger “pull” on water. Water is literally pulled out of the cell. The cell loses water and shrinks (crenates) HYPOTONIC SOLUTION Let’s place a cell in a solution that has a lower Osmolarity (< 290mOsmol/L) than inside the cell (290mOsmol/L) A solution with a lower osmolarity contains a lower concentration of solutes The solution is hypotonic In this case the cell exerts a stronger “pull” on water Water is literally pulled into the cell The cell takes in water, it swells and can burst! OSMOSIS AND BODY CELLS Understanding these principles is important when examining conditions which move water from one body compartment to another. A patient needs to be infused with a solution via intravenous drip, to treat extreme dehydration. Need to rehydrate and encourage fluid movement back into cells. What solution would you use? Isotonic = will replace extracellular fluid, e.g. 290 mM solution Hypotonic = will help replace intracellular fluid e.g. 5% dextrose in water. Isotonic when you first give it, then the dextrose Is metabolised and there Is “free water” to move into cells. Give slowly and only to some patients Edema, where excess fluid is accumulating in cells and tissue. Giving a hypertonic solution will encourage fluid to move out of cells and tissue and into vascular system to be removed by the kidneys. Administer slowly and with caution Not to be given to patients with kidney or heart disease Danielle Dye BREAK TIME ☺ CELL TRANSPORT MECHANISMS Metabolism Total of all chemical processes that occur in body Metabolism includes Catabolism Chemical reactions where large molecules broken down to smaller molecules Anabolism Chemical process where small molecules joined to form larger molecules All molecules have energy stored in the bonds between their atoms http://academic.pgcc.edu/~kroberts/Lecture/ Chapter%205/05-01_Metabolism_L.jpg CHEMICAL ENERGY & ATP Our focus is chemical energy (& heat energy) There is a large amount of energy stored in the chemical bonds of nutrients When chemical bonds in nutrients (e.g. glucose) are broken down, energy is released This energy is used to combine adenosine diphosphate(ADP) with an inorganic phosphate molecule (Pi) to make adenosine triphosphate (ATP) ATP stores the energy released from breaking the chemical bonds ADP + Pi+ energy → ATP (capture energy in) Some energy released from breaking a chemical bond is not captured and stored as ATP but is lost as heat Heat is used to maintain body temperature  Adenosine Triphosphate (ATP) ATP is the cell’s preferred way to store energy The small amount of energy stored in each molecule of ATP is easier for the cell to access than the larger amount stored in nutrient molecules When the cell needs energy it breaks down ATP to ADP ATP ADP + Pi + energy This energy can be used by the cell to make new proteins, repair a damaged cell membrane, drive active transport across a membrane ATP is used for: muscle contractions, active transport, movement of structures within a cell  Stages of energy generation First stage Large molecules → smaller units Proteins → amino acids Fats → Glycerol & fatty acids Polysaccharides → monosaccharides Second stage Smaller units are broken down into few simple compounds that are essential in metabolism Third stage Citric acid (Krebs) cycle Oxidative Phosphorylation CELLULAR RESPIRATION Cellular respiration - The process that breaks down chemical bonds in food to produce energy that is then stored as ATP. Cellular respiration using glucose can be summarised as: 1glucose (C6H12O6) + 602 6H20 + 6C02 + 36-38ATP Three main stages 1.Glycolysis Cytoplasm 2.Citric acid cycle Mitochondrial matrix 3.Electron transport chain/oxidative phosphorylation Inner mitochondrial membrane GLYCOLYSIS 1 glucose 2 pyruvate + 2 ATP + 2 NADH Occurs in the cytoplasm Is anaerobic-does not require O2 Breaks down 1 glucose molecule (6 carbon sugar) into 2 pyruvate molecules (3 carbon mols.) Uses 2 ATPs in the early stages (phosphorylation- activates the glucose molecule ) Produces 4 ATP by the end net production of 2 ATP Produces 2 NADH molecules GLYCOLYSIS 1 glucose 2 pyruvate + 2 ATP + 2 NADH Stage 1: 2 ATP molecules are used to activate glucose (phosphorylation) ( glucose → fructose-1, 6 biphosphate) Uses 2 ATP molecules ATP GLYCOLYSIS 1 glucose 2 pyruvate + 2 ATP + 2 NADH Stage 2: Sugar cleavage 6C sugar molecule is split into two 3C sugars Each 3C sugar has a phosphate group  GLYCOLYSIS 1 glucose 2 pyruvate + 2 ATP + 2 NADH Stage 3: Oxidation and ATP formation The phosphate are split from the sugar and captured by the ADP to form 4 ATP molecules The remaining 3C sugar are converted to Pyruvic acid Final Products of Glycolysis 2 pyruvic acid molecules 2 NADH + H+ molecules A NET production of 2 ATP molecules If oxygen is available pyruvate moves into the 2nd stage –the citric acid cycle If oxygen is not available, pyruvate gets converted to lactic acid CITRIC ACID CYCLE- KREB CYCLE a) Acetyl CoA formation Matrix of the mitochondria Before the citric acid cycle begins - pyruvate(3C) is converted to acetyl CoA (2C), producing 1NADH and 1CO2 each glucose we started with produces 2 pyruvates for each glucose molecule, we have: 2 Acetyl CoA + 2 NADH + 2CO2 CITRIC ACID CYCLE B) Citric acid cycle Acetyl CoA enters the citric acid cycle, and is transferred to a 4C molecule to make a 6 carbon molecule (citrate) The citrate then goes through a series of chemical reactions and loses two C groups as 2 C02 to end up back as a 4C molecule ready to go through another cycle Every turn of the cycle produces 1ATP + 3 NADH + 1FADH2 + 2 C02 The cycle turns twice for every glucose that enters glycolysis 1 glucose 2 pyruvate → 2 Acetyl CoA 2ATP + 6 NADH + 2 FADH2+ 4 C02 plus the 2 NADH produced during acetyl CoA formation WHAT ARE NADH AND FADH2 ? Electron carrier molecules NAD+= nicotinamideadenine dinucleotide FAD+ = flavinadenine dinucleotide These molecules collect the electrons that are produced when chemical reactions occur during glycolysis and the citric acid cycle. e.g.NAD++ 2H+ +2 e- NADH + H+ They transport these electrons to the electron transport chain in the inner mitochondrial membrane, donate the electrons to the membrane carriers, and oxidative phosphorylation occurs to generate ATP  OXIDATIVE PHOSPHORYLATION (ELECTRON TRANSPORT CHAIN) Most of the energy produced by cellular respiration is by oxidative phosphorylation NADH and FADH2 produced by glycolysis and the citric acid cycle pass through the electron transport chain (ETC) in the inner membrane of the mitochondria The ETC is a series of electron donors and receptors. NADH and FADH2 donate their electrons to the first acceptor in the chain, releasing H+ in the process. Acceptor molecule 1 then passes the electrons on to the next molecules in the chain and so on. Oxygen is the final electron acceptor & water is produced The movement of electrons from molecule to molecule in the membrane releases energy, this energy is used to generate a proton (H+) gradient across the membrane. The protons then flow back across the membrane through a special channel. This flow of H+ is used by ATP synthase to produce ATP. Oxidative phosphorylation produces between 32 –34 ATP. OXIDATIVE PHOSPHORYLATION 2 ALTERNATE ENERGY SOURCES Fatty acids Undergo beta oxidation to form Acetyl CoA Acetyl CoA can enter citric acid cycle to generate ATP, NADH and FADH2 Amino acids Can be converted into intermediate compounds of CHO digestion e.g. Ketoacid, Pyruvate, Acetyl CoA  KEY TERMS By the end of this session, you should be able to recognise and define these terms Selectively permeable membrane, osmosis, tonicity, osmolarity, hypertonic, hypotonic, isotonic, concentration gradient, passive transport, active transport, diffusion, intracellular, solution, dialysis bag, glucose, pyruvate, phosphorylation, glucose 6-phosphate, glucose 3-phosphate, lactic acid, citric acid cycle, oxidative phosphorylation, ATP, ADP, NADH, FADH, electron, proton, mitochondrion.  QUESTIONS After completion of this session you should be able to answer the following questions 1. Why can some things pass through a plasma membrane whereas others can’t? 2. How do ions and molecules pass through the plasma membrane? 3. Why does water move from one place to another within the body? 4. What is ATP and why do we need it? 5. How is glucose used to produce energy within cells (describe the stages of cellular respiration)?