Electrophysiology Flashcards
Nerve cell - Components
- Cell body
- Dendrites: Extensions for receiving inputs from other cells
- Synapses: Docking sites of other nerves or sensor cells
- Axon Hillock: spatial and temporal integration of all incoming signals
- Axon: propagation of the escitation to other nerve cells or actuators
Conduction Velocity and Dependence
Conduction velocity changes with the Diameter –> v = 6*Diameter
Efferent and Afferent
Efferent:
- from the brain to an organ –> carry out
Afferent:
- from the periphery towards the brain
Central Nervous System
1) Processing of the environmental information
- -> Five senses
2) Control of the skeletal musculature
Peripheral Nervous System
Interconnectors between sensors/actuators and the CNS
–> spinal cord & reflex arcs
Autonomous Nervous System
- -> Maintenance of the interiour milieu
1) Sympathetic NS: - regulation of body processes in the activation of power reserves
2) Parasympathetic NS:
- passivation of the body: relaxation
3) Regulation of the digestive tract
–> fight, relaxation, digestion
Homeostasis
Cell is an open system with an interior milieu
- describes the maintained equilibrium of the dynamic open system
- -> Separation of body from the surroundings is necessary
- -> Exchange of heat, O2, CO2, metabolic products requires open system
Interaction through diffusion & convection
Transport Processes (Types)
1) Passive Transport:
- Fick’s Law for diffusion
2) Active Transport:
- against concentration gradient
- energy is needed
- cell dies if active transport is not possible
3) Osmosis:
- based on osmotic pressure –> semipermeable membrane
Viscosity
internal friction
mean veloctiy of a particle is porportional to the Force
Chemical Potential
Fick’s Law of diffusion
- describes the effective force due to a concentration gradient resulting in a flow of a particle
Nernst Potential
difference between intracellular and extracellular ion concentrations
–> only consicer K+
1) Intracellular Medium: K+, A-
2) Extracellular Medium: Na+, Cl-
- Resting Potential
- -> diffusion force and electrical force are equal
The Na/K Pump
Failure of Pump
Active transport of:
1) Na+ out of the cell (against high gradient)
2) K+ into the cell (against small gradient)
failure of pump –> equalization of the intracellular and extracellular ion concentrations –> death (lack of oxygen or nourishment)
Saltatory Propagation (myelin sheath)
What happens if the inner resistance is decreased?
when the axon diameter is increased?
decrease of inner resistance –> increase of impulse velocity
increase in axon diameter –> increase in impulse velocity
increase radial membrane resistance rm –> increased insulation
Myelin sheath:
increase of Rm –> space constant increases
increase of Cm –> time constant increases
What is the membrane potential and what are the basic elements for the development of this potential?
potential difference between extra- and intracellular potential
- semipermeable membrane
- positive and negative ions
- concentration gradient
- ion channels
What does Fick’s law of diffusion put in relation?
Fick’s law relates the force developed due to a concentration gradient with the corresponding flux of particles
- the electric field forces work against the ion flow due to diffusion
