Nervous system

Nervous system - uNervous system 1 1.) Nerve Tissue...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
uNervous system 1 1.) Nerve Tissue function and organization a. Cell types: Neurons: carry electrical signals b. Glial cells and Schwann cells: support and electrical insulation, homeostasis (in order for electricity in ions to work, you need to keep concentrations correct) b.i. Schwann cells are important insulators on myelin sheath. c. Other structures: c.i. Schwann cells insulate axons: c.ii. Nodes of ranvier: help signals propagate faser c.iii. Axon hillock c.iv. Multiple sclerosis: autoimmune attack degrades the insulators. Slows down electrical signals. 2.) Ion Gradients a. Sodium concentration is higher on outside of cells a.i. 150 mM Na+ on extracellular side medium a.ii. 15mM Na+ on intracellular side a.ii.1. So sodium would want to rush inside the cell a.iii. Potassium: inside all of our cells and most cells in biology, a lot of potassium in cytoplasm ~150mM K+. (inside) and very little k+ outside (20-30 times less outside) a.iv. 70% of energy in brain is used as sodium potassium pump. ATP ADP used to pump 3 Na+ out of cell and pumps 2 K+ in. a.iv.1. This sets up the gradient a.iv.2. Membrane can be selectively permeable to only K+ or Na+ a.v. If a net positive ion moves out, inside becomes more negative. 3.) Resting Potential a. A million neurons per cm 3 b. Membrance is more permeable to K+, and less to Na+. if there are channels for K+ to diffuse, it will go out. potassium conduction is much larger than na+ at rest. b.i. So at rest, K+ is moving across border. Membrane becomes more and more negative until a point where potential stops increasing positive attracts negative. So when chemical gradient is = to electrical force. b.ii.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 01/10/2012 for the course BIOLOGY bild 2 taught by Professor Schroeder during the Fall '09 term at UCSD.

Page1 / 3

Nervous system - uNervous system 1 1.) Nerve Tissue...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online