Chapter 28: Nervous System Flashcards
Nervous System
the organ system that forms a communication and coordination network among all parts of an animal’s body
What are the 3 functions of the nervous system?
1) Sensory Input
2) Integration
3) Motor Output
Sensory Input
The conduction of signals from sensory receptors to integration centers
What are considered sensory receptors and integration centers?
Sensory Receptors: skin, nose, ears, etc.
Integration Center: Brain, spinal cord
Integration
Interpretation of sensory receptors and the formulation of the response
Motor Output
Conduction of signals from the integration centers to the effectors
Stimulus
any factor that causes a nerve signal to be generated (change in environment)
- changes membrane’s potential by opening it
Effectors
a cell, tissue, or organ capable of carrying out some action in response to a command from the nervous system
What are the two divisions of the nervous system?
1) Central NS
2) Peripheral NS
Central Nervous System
the integration and command center of the nervous system; the brain, and in vertebrates, the spinal cord
Peripheral Nervous System
the network of nerves and ganglia carrying signals into and out of the central nervous system
Nerve
A ropelike bundle of fibers thats tightly wrapped in connective tissue
Neurons
Basic unit of nervous system (nerve cell)
1) Sensory Neurons
2) Interneurons
3) Motor Neurons
Ganglia
a cluster of nerve cell bodies of the cells whose axons and dendrites make up nerves
Sensory Neurons
a nerve cell that receives info from sensory receptors and conveys signals into the central nervous system
Interneurons
a nerve cell, entirely within the central nervous systems, that integrates sensory signals and may relay command signals to motor neurons
- carry impulses up/down the spinal cord and brain
Motor Neurons
a nerve cell that conveys signals from the central nervous system to effector cells, such as muscle cells or gland cells
Cell Body
the part of a cell, such as a neuron, that houses the nucleus
Dendrites
a neuron fiber that conveys signals from its tip inward, toward the rest of the neuron; in a motor neuron, one of several short, branched extensions that convey nerve signals toward the cell body
- Short, numerous, highly branched
- Signals from sensory cell or interneuron
Axon
a single long neuron fiber that conducts signals to another neuron or to an effector cell
Supporting Cells
in the nervous system, a cell that protects, insulates, and reinforces a neuron (ex. Schwann cell)
Myelin Sheath
a series of cells, each wound around, and thus insulating, the axon of a nerve cell in vertebrates. Each pair of cells in the sheath is separated by a space called a node of Ranvier
Nodes of Ranvier
an unmyelinated region on a myelinated axon of a nerve cell, where signal transmission occurs
- Signals will jump from node to node → faster 150 m/sec
Synaptic Knob
the relay point at the tip of transmitting neuron’s axon, where signals are sent to another neuron or to an effector
Resting Neuron
Contains potential energy in form of difference of electrical charge
- used to send info from one part to another
Resting Potential
Voltage across the plasma membrane of a resting neuron
- Caused by the membrane keeping negatively charged dissolved proteins/large organic molecules inside the cell and channels/pumps (made of protein) that regulate passage of inorganic ions
Threshold Potential
Minimum change in a membrane’s collage that must occur to generate an action potential
- all or none effect
Sodium-Potassium (Na+ - K+) Pumps
a membrane protein that transports sodium ions out of, and potassium ions into, a cell against their concentration gradients. The process is powered by ATP.
- Na+ low inside the cell and K+ high inside cell
Action Potential
a self-propagating change in the voltage across the plasma membrane of a neuron; a nerve signal
What are the events of transmission of nerve signals?
Polarized –> stimulus –> depolarized/action potential –> repolarized
Synapse
Junction between two neurons or a neuron and its effector
- Electrical and chemical
Electrical (Synapse)
Direct connection b/w each axon and dendrite
- found where speed is crucial