Bio II Notes 3/3
Popular in Laboratory
Popular in Department
This 5 page Study Guide was uploaded by Rocket on Wednesday March 16, 2016. The Study Guide belongs to BIO 1144 at Mississippi State University taught by Thomas Holder in Spring 2016. Since its upload, it has received 24 views.
Reviews for Bio II Notes 3/3
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 03/16/16
Nervous System Ch. 41, 42, 43 +Closely tied with Sensory system ❖ Central Nervous System (CNS) Increase of size of brain relative to body size (the more advanced the organism is) and nervous system functions CNS composed of Brain + Spinal Cord ex. Fish: 2:1 Reptiles: 25:1 Humans: 55:1 ➔ Peripheral Nervous System (PNS) All neurons and projections outside of CNS +Invertebrates simple system but difficult to distinguish between CNS and PNS ❏ Neurons Nerve cells which are the basic structural and functional units of Nervous systems Found in all phyla except porifera +Functions: Send and receive chemical and electrical signal +Structure: Soma (cell body): nucleus and regular organelles Dendrites: extensions of plasma membranes, incoming signals Axons: extensions of plasma membranes, sending signals ★ Glial Cells More abundant in nervous tissue than neurons x1000 fold Provide support + Myelin Sheath Allows for more efficient and insulation of impulses Oligodendrocytes (CNS) Schwann cell (PNS) Microglial cells: remove dead cells, cleaners Astrocytes: metabolic support, associated with nutrition of neurons Radial Glial Cell: layout pathway for neuron migration during embryonic development *Last 2 groups often called “Stem cells” able to produce more glial and neuronal cells 3 Types of Neuron + Sensory “Afferent” transmitting signals to CNS + Motor “Efferent” carry signals away from CNS to elicit response + Interneurons Interconnecting cells between other neurons Reflex Arc Involuntary Act: Stimulus → Receptor (striking knee) → sensory and interneurons neurons send to → CNS→ motor neurons and interneurons carry response back → (received at flexor muscles) Effector→ Response Electrical Properties +Membrane Potential Gatekeeper, only neurons and muscles cells generate electrical signals Difference in charge between inside and outside +Ion concentration and Electrical differences Provides concentration differences Cell considered “polarized” Ions will move through channels if open Different restrictions depending on chemical +Resting Membrane Potential When neurons are not sending signals +Selectively Permeable to chemicals leading to difference in charge Cation (+) Anions () Inside is more () Combined together Outside is more (+) makes it polarized +Anions inside drawn to cations on outside to edge 3 Factor Contributing to Resting Membrane Potential 1. SodiumPotassium Pump expenditure of ATP to pump molecules 3 Na + pumped out for every 2 K + in 2. Ion specific channels allows passive ion movement Works as long as channels are open Membrane is more permeable to K+ K+ channels more frequently open at resting potential 3. More () charged ions are inside cell (polarity) Electrochemical Gradient No net movement of molecules opposing forces of electro + chem can cause NEAR equilibrium (equal charges no K+ flow) Ion movement (+) or () Chemical movement of K+ Na+ Cl Imbalance normal created by inside and outside membrane Neuron Signaling Changes in membrane potential, changes in degree of polarization +Depolarization Membrane becomes less negative to surrounding solutions gated channels for Na + movement in so becomes more positive Membrane becomes less polarized +Hyperpolarization membrane becomes more negative K+ moves out becoming less positive membrane becomes more polarized *ALL cells exhibit membrane potential* *ONLY neurons and muscles cells are “excitable” capacity to generate electrical signals *Use of gated ion channels: Voltage gated: open/close in response to voltage charges Ligand (chemical) gated: open/close in response to chemicals ● Nerve Impulse Frequency: “language” higher frequency = greater excitation 1. Resting Potential Imbalance between K+ and Na+ Charge imbalance (gradient) between inside and outside axon +At rest → membrane selectively permeable to K+ 2. Action Potential “Electric potential” of impulse Rapid/brief change of nerve fiber “selfpropagating” After passing membrane it quickly returns to resting positions At a given point Na+ channels open Na+ diffuses in K+ diffuses out (due to electrical gradient changes) 3. Sodium/Potassium Pump Complex of proteins in membrane Pump out Na+ Both require Carry in K+ ATP expenditure 3Na+ : 2K+ Impulse Conduction Rate Conduction Rate: +Variable Sea anemones: 0.1m/second Mammals: 120m/second +Inverts Speed is directly related to axon diameter +Vertebrates Speed related directly between axon diameter and layers around myelin sheath Myelin sheaths is in sections: Nodes of Ranvier Saltatory conduction: “jumping”
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'