Lecture 2 - Plasma Membrane, Ion Movement, Homeostasis (Lecture Notes)

Plasma Membrane, Ion Movement, & Homeostasis Review: Chemistry & Elements Elements - Given chemical symbols such as O = oxygen N C = carbon H H = hydrogen N = nitrogen These elements make up majority of the...

Plasma Membrane, Ion Movement, & Homeostasis Review: Chemistry & Elements Elements - Given chemical symbols such as O = oxygen N C = carbon H H = hydrogen N = nitrogen These elements make up majority of the body C O  Overview: Ions Ion is an atom that has lost or gained an electron Calcium Potassium - ion ion Chloride ion Hydrogen Sodium ion ion Cation - Anion - Atom has lost an electron Atom has gained an electron Overall charge is positive (+) Overall charge is negative (-) Overview: What is a Protein? Protein - Proteins are complex molecules Play many critical roles in body Do most of the work in cells Some examples of proteins Antibodies Enzymes Messengers Storage Structural components Overview: Energy & ATP Adenosine Tri-Phosphate Adenosine Di-Phosphate (ATP) (ADP) Breaking a chemical bond releases energy that the body uses to do metabolic work Plasma Membrane Plasma Membrane: Overview Plasma Plasma Membrane - Membrane Flexible yet sturdy barrier Surrounds cells Contains cytoplasm of cell Cytoplasm Plasma Membrane: Proteins Membrane Proteins - Plasma membrane has proteins associated with it Some are permanently there (integral membrane proteins) Some can attach & detach at different times (peripheral membrane proteins) Plasma Membrane Plasma Membrane: Functions of Proteins Transport molecules Recognizing your own cells Molecule recognition & through membrane from not yours signaling Functions - Many different types of membrane proteins Help Joining adjacent cells Enzymatic activities Attachment to cytoskeleton determine together catalyzing chemical reactions & extracellular matrix functions of (structural stability of cell) cell membrane Plasma Membrane: Concentration Gradient Concentration Gradient Across Plasma Membrane - Difference in concentration of a chemical Between one side of plasma membrane & the other side Intracellular vs extracellular  Plasma Membrane: Electrical Gradient Electrical Gradient Across Plasma Membrane - Difference in concentration of ions - Between one side of plasma membrane & the other Ions are either positively or negatively charged Cation Anion Can exert pull or oppose movement Concentration gradient & charge Concentration gradient & charge (voltage) WORK IN SAME DIRECTION (voltage) OPPOSE EACH OTHER Plasma Membrane: Electrochemical Gradient Concentration Gradient Electrical Gradient Across Plasma Membrane Across Plasma Membrane Together, these gradients make up an electrochemical gradient & will impact movement of molecules across plasma membrane Transport Across Plasma Membrane Transport Across Plasma Membrane: Overview Transport Across Plasma Membrane - Processes that move molecules across plasma membrane Passive transport Simple diffusion Facilitated diffusion Osmosis Active transport Primary & secondary transport Passive Transport: Simple Diffusion Simple Diffusion - Diffusion is influenced by Extracellular Space Concentration gradient Temperature Surface area Diffusion distance Plasma Membrane Inside Cell Passive Transport: Facilitated Diffusion Facilitated Diffusion - Transmembrane proteins help solutes that are Extracellular Space or too highly charged move through lipid bilayer of plasma membrane Processes involve Channel proteins Carrier proteins Plasma Membrane Transmembrane Protein Inside Cell Passive Transport: Osmosis & Solution Concentration Concentration of Solutions - Osmosis occurs when there’s an imbalance of solutes outside a cell versus inside a cell Hypertonic solution, where a solute concentration ↑ than another solution’s Isotonic solution, where a solute concentration = to another solution’s Hypotonic solution, where a solute concentration ↓ than another solution’s Hypertonic Isotonic Hypotonic H 2 O Outside Cell Inside Cell Passive Transport: Osmosis (Water) Osmosis (Water) - Diffusion of water through a semipermeable membrane down its concentration gradient If a membrane is permeable to water, but not to a solute, water will equalize its own concentration by diffusing to the side of lower water concentration (side of higher solute concentration) Isotonic Solution Hypertonic Solution Isotonic, Hypertonic, & Hypotonic Solutions Dangers of None Isotonic Environments in Human Body - Critical aspect of homeostasis - internal environment where all cells are in isotonic solution When isotonic, concentration of water molecules is same outside & inside cells Cells maintain their normal shape & function Cells in hypertonic solution, they will shrivel as water leaves the cell via osmosis Cells in hypotonic solution will take on too much water & swell (risk of bursting) Shrivel Swell & Burst Clinical Note: Osmosis & Return to Homeostasis Administration of Solutions Intravenously - Isotonic IV solutions Put fluid into blood & stay there Build volume e.g., 0.9% NaCl Hypotonic IV solutions Shift fluid into cells (if already shrunk) e.g., diabetic ketoacidosis Hypertonic IV solutions Pull fluid out of cells (if already swollen) e.g., cerebral edema Active Transport: Primary Primary Active Transport - Extracellular Space Adenosine Tri-phosphate Concentration Gradient Energy derived from ATP changes shape of a transporter protein Transporter protein pumps a substance Plasma Membrane across a plasma membrane Against its concentration gradient Transporter Inside Cell Protein Active Transport: Secondary Secondary Active Transport - Uses energy from a concentration gradient, not ATP Energy from one substance’s concentration gradient drives other substances against its own concentration gradient Symporters - Antiporters - Both substances Substances travel travel in same in opposite direction directions Both into cell One into cell & Both out of cell one out Homeostasis & Feedback Loops Homeostasis: Overview Homeostasis - Condition of equilibrium (balance) in body’s internal environment Maintained by body’s regulatory processes As if certain systems have an ideal “set point” Range (periods spent higher & lower levels) Homeostasis Response to Environmental Challenge Homeostasis Homeostasis: Responding to Disruptions Homeostatic Imbalances - Occur because of disruptions from external or internal environments Outside of ranges, processes cannot continue Temperature Water balance Ion balance Homeostasis: Feedback Loop Basic Components of a Feedback Loop - 1. Signal (stimulus) Thing that is disrupting homeostasis 2. Controlled Condition What’s being monitored (e.g., blood pressure) 3. Receptor This is how system watches the controlled condition 4. Controller (processor) Interprets signal & determines best course of action 5. Effector Does the change to correct disturbance to normal Homeostasis: Neg. Feedback Loop Negative Feedback Loop - Responds in opposition to original stimulus Afferent signal sensing blood pressure goes too high Effector lowers pressure back to set range Loop stops Loop operates continuously until original stimulus is brought back into set range Effector(s) can include many organs *Just an example. Do not memorize figure Homeostasis: Pos. Feedback Loop Positive Feedback Loop - Opposite of negative feedback loop Positive feedback magnifies original signal Afferent signal senses stretch in cervix Effector muscles in walls of cervix contract Loop continues until birth is complete Birth decreases stretching of cervix Questions? Email me: [email protected]