Exam 3 (Chapter 3) Flashcards
What’s the job of the nervous system?
transmits signals (action potential) between the brain and the rest of the body, including internal organs.
Compare wire with neuron (leaky, not as conductive, moves ions rather than electrons)
Why can neurons (and muscle cells) send action potentials?
They have specific ion channels (voltage gated) while other cells don’t have these channels.
Know components of cytosol (water, a polar molecule, plus cations and anions)
- Water: the most important property of water is its uneven distribution of electrical charge. This electrical polarity makes water an effective solvent of other charged or polar molecules; that is, other polar molecules tend to dissolve in water.
- Ions: have a net electrical charge. Ions that are surrounded by water molecules are called spheres of hydration, and they effectively insulate the ions from one another.
- Cations: ions with a net positive charge.
Anions: ions with a net negative charge.
Know the important ions for the neuron (are they cations or anions? divalent or monovalent?)
- Monovalent cations: Na+ & K+
Divalent cation: Ca2+
Monovalent anion: Cl-
Structure and functions of the membrane -phospholipid bilayer, etc…
Polar head and nonpolar tail
What are the four components of all amino acids?
- hydrogen atom
- an amino group (NH3+)
- a carboxyl group (COO-)
- R group (residue)
How are proteins assembled?
proteins are synthesized by the ribosomes of the neuronal cell body. Amino acids are assembled into a chain connected by peptide chains. Proteins made of a single chain of amino acids are also called polypeptides.
What are the four levels of protein structure?
- Primary structure: the sequence of aa’s linked together by peptide bonds.
- Secondary structure: coiling of a polypeptide into an alpha helix or beta sheets
- Tertiary structure: proteins that can bend, fold, and assume a complex 3D shape.
- Quaternary structure: different polypeptides that can bond together to form a larger protein.
What is an ion channel?
a membrane-spanning protein that forms a pore that allows the passage of ions from one side of the membrane to the other.
How can ions move across the membrane?
- ion channels (move down their concentration gradient)
- Ion pumps (move against their concentration gradient). Needs ATP.
Be very familiar with the ion pump that he described
Na+/K+ pump:
Ohm’s Law- what does it tell us (what relationship)
The relationship between electrical current (I), voltage (V), and conductance (g)
What is an equilibrium potential-what does it tell us?
The electrical potential difference that exactly balances an ionic concentration gradient
How do concentration and electrical gradients arise?
Goldman equation-what does it tell us?
Takes into consideration the relative permeability of the membrane to different ions.
Know Eion for the main four ions
- K+: -80 mV
- Na+: 62 mV
- Ca2+: 123 mV
- Cl-: -65 mV
Know potassium channels-why is potassium so important to regulate?
How is potassium controlled in brain?
What are cations & anions?
- Cations: positive charged ions
- Anions: negatively charged ions
What are the temporal dynamics of the action potential?
when is myelination complete for humans?
25
what is the distribution of ions inside and outside of a standard neuron?
Na+/Ca2+ outside; K+ inside
What is driving force?
The likelihood of an ion diffusing
