Nervous System Flashcards
Neuron
- Communication, information processing, control functions
- Work together with the endocrine system to maintain homeostasis
- Converts information to an electrical signal
Cell Body (soma)
Contains large nucleus and other organelles
Dendrites
- Key role: intercellular communication
- Site of vesicular/axonal transport
Synaptic Terminals
The end of an axon
Synapse
Site of communication between cells
Anatomical Divisions of the Nervous System: CNS
- Spinal cord and brain
- Integrates, processes and coordinates sensory data and motor commands
Anatomical Divisions of the Nervous System: PNS
- All neural tissue outside CNS (nerves, ganglia, sensory)
- Delivers sensory information to CNS and carries motor commands to peripheral tissues and systems
Functional Divisions of the Nervous System (PNS): Afferent
- Carries sensory information from PNS sensory receptors to CNS
> incoming division
Functional Divisions of the Nervous System (PNS): Efferent
- Carries motor commands from CNS to PNS muscles and glands
> outgoing division
> has somatic and autonomic components
Efferent: SNS (somatic nervous system)
- controls skeletal muscle contractions (voluntary response)
- reflexes (involuntary)
Efferent: ANS (autonomic nervous system)
- regulates smooth muscle, cardiac muscle, glandular secretion and adipose tissue
- sympathetic division: increased rate and force of contraction
- parasympathetic division: decreased rate and force of contraction
Neuroglia
- Preserve physical and biochemical structure of neural tissue
Neuroglia of the CNS: Ependymal Cells
- Line central canal of spinal cord and ventricles of brain
- Produce, secrete and monitor Cerebrospinal Fluid (CSF)
Neuroglia of the CNS: Astrocytes
- Maintain blood-barrier (isolates CNS)
- Create three-dimensional framework for CNS
- Repair damaged neural tissue
Neuroglia of the CNS: Oligodendrocytes
- Smaller cell bodies with fewer processes
- Processes contract other neuron cell bodies
- Wrap around axons to form myelin sheaths
Neuroglia of the CNS: Microglia
- Conduct phagocytosis to remove cellular debris, waste products and pathogens
Neuroglia of the PNS: Satellite cells
- Regulate environment around neurons like astrocytes in the CNS
Neuroglia of the PNS: Schwann Cells
- Form myelin sheaths around peripheral axons
Types of Neurons (Functional Classification): Sensory Neurons - form afferent division of PNS
Deliver information received from interoceptors, exteroceptors and proprioceptors to CNS
Types of Neurons (Functional Classification): Motor Neurons - form efferent division of PNS
Stimulate or modify the activity of a peripheral tissue, organ or organ system
Types of Neurons (Functional Classification): Interneurons - Located in CNS - situated between sensory and motor neurons
Distribute sensory inputs, coordinate motor inpute
Structural Classification of Neurons: Anaxonic
Have more than two processes but axons cannot be distinguished from dendrites
Structural Classification of Neurons: Bipolar
Two processes separated by the cell body
Structural Classification of Neurons: Unipolar neurons
Single elongate process, with the cell body situated off the side
Structural Classification of Neurons: Multipolar neurons
More than two processes, single axon and multiple dendrites
Resting Potential
- Transmembrane potential of a resting cell
- All neural activities begin with a change in the resting potential of a neuron
- A charge difference is maintained across the cell membrane > -70mV (sodium-potassium exchange pump stabilises)
What is the transmembrane potential?
Results from the unequal distribution of ions across the plasma membrane
Resting Potential: Extracellular
High concentrations of sodium ions and chloride ions
Resting Potential: Intracellular
High concentrations of potassium ions and negatively charged proteins
Electrochemical Gradients for Potassium and Sodium Ions: Potassium Ion Gradients
- At normal resting potential, an electrical gradient opposes the chemical gradient for potassium ions (K+). The net electrochemical gradient tends to force potassium ions out of the cell
- If the plasma membrane were freely permeable to potassium ions, the outflow of K+ would continue until the equilibrium potential (-90mV) was reached
Electrochemical Gradients for Potassium and Sodium Ions: Sodium Ion Gradients
- At the normal resting potential, chemical and electrical gradients combine to drive sodium ions (Na+) into the cell
- If the plasma membrane were freely permeable to sodium ions, the influx of Na+ would continue until the equilibrium potential (+66mV) was reached
Electrochemical Gradients for Potassium and Sodium Ions: Electrochemical gradient
Sum of all chemical and electrical forces acting across the plasma membrane