Bio 141 | Lecture 4 | Passive & Active Diffusion & Regulation of Nervous System | 1/20/16
Bio 141 | Lecture 4 | Passive & Active Diffusion & Regulation of Nervous System | 1/20/16 Bio 141
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This 3 page Class Notes was uploaded by Gabriella Morales on Thursday January 21, 2016. The Class Notes belongs to Bio 141 at Pennsylvania State University taught by Dr. Jenelle Malcos in Winter 2016. Since its upload, it has received 26 views. For similar materials see Biology and Physiology in Biology at Pennsylvania State University.
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Date Created: 01/21/16
Passive vs. Active Diffusion Wednesday, January 20, 2016 9:09 AM Gated channels- only open at certain time sin response to certain conditions Carried-Mediated transport ( still passive, using a concentration gradient) Ex: Facilitated diffusion Large molecule that is trying to get through must bind to the membrane protein Once molecule bind the protein, the protein changes shape & helps move across, and then it gets transported into or out of the cell Types of Active Transport across a membrane Molecules go "up their gradient" (where they are already at a low concentration > high) o EX: A type of carrier mediated Membrane proteins involved with active transport are typically called "pumps" Protein pumps require ATP hydrolysis to function Protein pumps move solutes UP a concentration gradient o EX: Na/K pump Osmosis: Diffusion of water across a membrane Dependent on amount of dissolved "stuff" in solution Water diffuses from where its concentration is high (dilute solution ) to where its concentration is low ( concentrated solution ) Hypertonic- More solute compared to something else The solution is hypertonic to the cell ( in clicker example) Hypotonic- Below solute compared to something else The cell is hypotonic to the solution Isotonic- Same solution; Solutes are the same in both solutions Regulation - The Nervous System Wednesday, January 20, 2016 9:32 AM Regulation means maintaining a stable internal environment (homeostasis) Two Systems dedicated to this process o Endocrine > chemical messages ( slow hormones) o Nervous > electrical signals and chemical messages ( fast, neurotransmitters) Two major parts : CNS- Central Nervous System Consists of Brain & Spinal chord Serves as integration center PNS- Peripheral Nervous System Consists of nerves Serve to deliver/send info to CNS Characteristics of Neurons Specialized cells called neurons make up nervous tissue Three main characteristics 1 Excitability Cells can respond to stimuli from environment or other cells Results in an electrical signal (action poteintal ) Major evolution pressure to maintain this function as a form of communication 1 Conductivity Neurons can propagate an electrical signal over a distance from where it originated 1 Secretion Neurons can translate an electrical signal (stimulus) into a chemical signal Structure of Neurons: Cell body: Contains one nucleus (Soma) Dendrites: Short, thick extensions off the cell body o Site for receiving signals from other neurons Axon: Extension away from the cell body o Some can be myelinated to improve conductivity and help insulate Synapse: Site of communication between two neurons o Where secretion occurs o Space between two neurons Multipolar: Cell body is up more closer to the dendrites Bipolar neurons: Cell body is more centrally located Unipolar: Cell body is more shifted to once side Afferent (sensory) neurons ( called receptors) Specialized neurons to detect stimuli Start in PNS and travels to the CNS Functions to deliver info about environment or condition of the body to the CNS Interneurons Located in CNS Functions to receive and integrate info Efferent (motor) neurons Send signals from the CNS to effectors (targets) Muscles, organs, glands How do these pathways work? Communicate with electrical and chemical signals Electrical signal (action potential)