Lecture2_membrane_potential_online - Lecture 2 Membrane...

Info icon This preview shows pages 1–10. Sign up to view the full content.

View Full Document Right Arrow Icon
Lecture 2 Membrane Potential and ion currents
Image of page 1

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

View Full Document Right Arrow Icon
The earliest animals with nervous systems lived hundreds of millions of years ago in primordial oceans… Their neurons generated action potentials by exploiting the chemistry of the surrounding seawater. Millions of years later, this created problems when animal’s tried to bring their nervous systems with them out of the ocean and onto land….
Image of page 2
Cerebrospinal Fluid (CSF) & Meninges You don’t live in seawater, but your nervous system does! When animals evolved from the sea onto land, they had to bring a bit of the ocean with them to keep their nervous systems working. Your brain (cerebrum) and spinal cord are wrapped in three layers of protective membrane called meninges : Dura Mater (thick outer layer) Arachnoid (spongy middle layer) Pia Mater (thin inner layer) Inside of these protective membranes, your nervous system is floating in a liquid called cerebrospinal fluid (CSF) which has a chemical composition very similar to seawater! dentalday.wikispaces.com
Image of page 3

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

View Full Document Right Arrow Icon
The ventricular system CSF is constantly manufactured by an organ called the choroid plexus, which resides in hollow tubes and cavities called ventricles that run throughout the brain and spinal cord
Image of page 4
Charged Ions Imagine we have two glasses of water.
Image of page 5

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

View Full Document Right Arrow Icon
Charged Ions Suppose we have two glasses of water. We dissolve sodium (Na+) into one glass, and chloride (Cl-) into the other glass.
Image of page 6
When the solutions are well mixed, the electrical charge is different in each glass. The sodium glass is positively charged (Na+), while the chloride glass is negatively charged (Cl-). WHY?????????? Na + Cl - Charged Ions Positively Charged Negatively Charged
Image of page 7

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

View Full Document Right Arrow Icon
Ions: atoms that carry a positive (+) or negative (-) charge CATIONS: positive charge ANIONS: negative charge 17p 11p Na + Cl - The nucleus of a chlorine atom contains 17 protons, but it usually has 18 electrons (because its outer shell prefers to be filled up). Since there is one more electron than proton, the sodium atom carries one extra negative charge. Such an atom is called a monovalent anion because there is a single (that is, “ monovalent ”) surplus charge that is negative (making it an “anion”). The nucleus of a sodium atom contains 11 protons, but it usually has only 10 electrons (because its outer shell prefers to remain empty). Since there is one more proton than electron, the sodium atom carries one extra positive charge. Such an atom is called a monovalent cation because there is a single (that is, “monovalent”) surplus charge that is positive (making it a “cation”).
Image of page 8
Ions: atoms that carry a positive (+) or negative (-) charge CATIONS: positive charge ANIONS: negative charge 17p 11p Na + Cl - 12p Mg 2+ divalent monovalent A magnesium atom is similar to a sodium atom, but it contains 12 protons rather than 11. Like sodium, it usually has only 10 electrons (because its outer shell prefers to remain empty).
Image of page 9

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

View Full Document Right Arrow Icon
Image of page 10
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern