1. Lectures 1, 2 (Review) Flashcards
What are the 4 specialized regions of nerve cells?
- Cell body (perikaryon)- portion of cell surrounding nucleus
Contains much of cells complements - Dendrites- arise from cell body and work with cell body to receive info
Contain neurotransmitter receptors - Axon- projection that arises from the cell body (point of origin is known as the axon hillock)
Action potential originates in axon - Presynaptic terminals- the multiple endings on the axon
Rapid conversion of the neuroma electrical signal into chemical signal
Slides 2-4 Lecture 1
What is the action potential?
Transient depolarization triggered by a depolarization beyond threshold
Use of Na channels in axon
Changes in ionic conductance with Na and K underlie the action potential
Slides 5-10 Lecture 1
How do different neuronal types respond to a continuous depolarization?
Neutrons can transform a simple input into a variety of output patterns
Slides 11-12 Lecture 1
What are the differences in the motor outputs between inhibitory neurons, small pyramidal cells, and large pyramidal cells?
Slide 12 Lecture 1
Slide 15 Lecture 1
What are the 4 types of channel gating?
- Ligand gated channels- open when Ligand binds to its receptor (energy from ligand binding drives channel open)
- Phosphorylation gated channels- protein phosphorylation and dephosphorylation regulate the opening and closing of these (energy for channel open comes from transfer of phosphate Pi)
- Voltage gated channels- changes in membrane voltage open and close some (changes in electric potential difference across membrane causes conformation change)
- Stretch or pressure gated- energy comes from mechanical forces that pass to channel through cytoskeleton
Slide 16 Lecture 1
What are the 3 mechanisms by which voltage gated channels become closed and nonactivatable?
- Refractory state (inactivated) after transition from resting (closed) state to a transient open state upon membrane depolarization
- Internal increase in Ca2+ due to activity of channel, may then inactivate the channel by binding to a specific recognition site
- Increase in internal Ca2+ concentration in voltage gated Ca2+ channels may produce inactivation through dephosphorylation of the channel
Slide 17 Lecture 1
Review phospholipids on slide 3 lecture 2
What is amphipathic
Which is hydrophilic and hydrophobic
Which is polar and non polar
Slide 3 Lecture 2
What happens at low concentration of phospholipids in water?
What about high concentrations?
They form a monolayer at low concentrations
At high concentrations they form micelles and eventually lipid bilayers
Slide 3 Lecture 2
What is Fick’s Law?
For uncharged solutes only
Jx=Px([X]o-[X]i)
Simplest description of diffusion
Slide 5 Lecture 2
Why do solutes cross a permeable membrane?
What contributes to this?
The driving force (that determines the passive transport of solutes across a membrane) is the electrochemical gradient or potential energy different acting on the solute between the 2 compartments
The concentration gradient, chemical potential energy different and (for charges solutes) the difference in voltage for the solutes all contribute to the electrochemical potential energy difference
Slide 6-7 Lecture 2
What is passive transport by facilitated diffusion?
Which of the 3 membrane proteins aid in passive transport?
Proteins enable ions to cross biological membranes by moving them downhill
Passive because it does not require energy
Membrane transport depends on presence of integral membrane proteins
Carriers: facilitate passive transport through membranes
What are the membrane protein pores?
What are porins, perforin, nuclear pore complex (NPC), and aquaporins (AQPs)?
Channels that are always open (leak)
Provide aqueous transmembrane conduit that is always open
Porins- in outer membranes of gram - bacteria and mitochondria
Perforin- cytotoxic T lymphocytes kill their target cell
NPC- regulates traffic into and out of nucleus
Aquaporins- channels just large enough to allow water molecules to pass through
Slide 10 Lecture 2
What are the membrane protein channels?
What is the gate, sensors, selectivity filter, open channel pore?
Gated pores
Formed by polypeptide subunits
Gate- determines whether channel is open or closed (conformational change)
Sensors- can respond signals (changes in membrane voltage; or second-messengers)
Selectivity filter- determines classes of ions (anions/cations) our particular ions (Na+/Ca2+) that have access to channel pore
Open channel pore- ions can flow through it passively by diffusion until the channel closes
Slide 11 Lecture 2
What are the membrane proteins carriers?
Carrier-mediated transport systems transfer a broad range of ions and organic solutes
Specific affinity for binding one or a small # of solutes
They never fully open gate through channel
No ATP required
Slides 12-13 Lecture 2
Diagram important on slide 13
How do transport rates across membrane differ for simple diffusion and carrier-mediated or facilitated diffusion?
For simple, the simple diffusion influx increases linearly with increases in [X]o
No max rate of transport
For carrier-mediated (facilitated) diffusion, in a cell membrane there is a fixed number of carrier and each carrier has limited speed. So when extracellukar X concentration is gradually increased the influx of X will eventually reach maximum once all carriers are full
Slide 14 Lecture 2
