Nervous System Flashcards
Nerve cells that transmit information within the body
NEURONS
2 types of signals to communicate
Electrical signals
Chemical signals
signals to communicate in Long distances
Electrical signals
signals to communicate in Short distances
Chemical signals
Nourishes or insulates most of the neurons
Glia (glial cell)
Transmission of information is from a ___________ to a _________________
presynaptic cell (neuron) to a postsynaptic cell
(neuron/muscle/gland cell) Glia (glial cell)
INFORMATION PROCESSING
3 stages
Sensory input
Integration
Motor output
INFORMATION PROCESSING:
Sensors detect external stimuli and internal conditions
Transmits information along sensory neurons
SENSORY INPUT
INFORMATION PROCESSING:
Sensory information is sent to the brain or ganglia Interneurons integrate the information
INTEGRATION
INFORMATION PROCESSING:
Leaves the brain or ganglia via the motor neurons. Triggers muscle or gland activity
MOTOR OUTPUT
Voltage of every cell across the plasma membrane
MEMBRANE POTENTIAL
Membrane potential of a neuron that do not send signals
Changes in membrane potential act as signals, transmitting and processing information
RESTING POTENTIAL
In a mammalian neuron at resting potential
Concentration of K is highest inside the cell Concentration of Nat is highest outside the cell
Sodium-potassium pump
Use the energy of ATP to maintain these K and Nat gradients across the plasma membrane
K diffuses out of the cell
A neuron at resting potential has many open K channels and fewer open Na+ channels
Major source of membrane potential
The build up of negative charge with the neuron
Massive change in the membrane voltage when the membrane potential passes a certain level
ACTION POTENTIAL
ACTION POTENTIAL characteristics
With constant magnitude
Are all-or-none
Transmits signals over long distances
Occurs when neurons that contain gated ion channels open or close in response to stimuli
ACTION POTENTIAL
Triggered by the opening of ion channels
Reduction in magnitude of the membrane potential
Depolarization
Occurs after an action potential
A second action potential that cannot be initiated
A result of temporary inactivation of Na channels
REFRACTORY PERIOD
Speed of action potential increases with the axon’s diameter
EVOLUTIONARY ADAPTATIONS OF AXON STRUCTURE
Insulates the axons in vertebrates
Causes an action potential’s speed to increase up of glial cells
Myelin sheath
glial cells types
Oligodendrocytes in CNS
Schwann cells in PNS
Gaps in the myelin sheath where voltage-gated Na channels are found
Area where action potentials are formed
Nodes of Ranvier
Process where action potentials in the myelinated axons jump between the nodes of Ranvier
Saltatory Conduction
______ communicate with other cells at synapses
Neurons
Synthesizes and packages the neurotransmitter in synaptic vesicles located in the synaptic terminal
Presynaptic neuron
The _________ causes the release of the neurotransmitter
action potential
___________ diffuses across the synaptic cleft and is received by the postsynaptic cell
Neurotransmitter
may bind specifically to more than a dozen different receptors
single neurotransmitter
ends when neurotransmitters are removed from the synaptic cleft
Receptor activation and postsynaptic response
Common neurotransmitter in vertebrates and invertebrates
Involved in muscle stimulation, memory formation, and learning
ACETYLCHOLINE
Simplest animals with nervous system
Neurons are arranged in nerve nets
Cnidarians
Series of interconnected nerve cells
Nerve nets
For more complex animals
Axons of multiple neurons are bundled together
nerves
Nerves channel and organize information flow through the
___________
nervous system
Exhibited by bilateral animals
Clustering of sensory organs at the front end of the body Flatworms are the simplest cephalized animals
CEPHALIZATION
NERVOUS SYSTEM two types
Central Nervous System (CNS)
Peripheral Nervous System (PNS)
Consists of the brain and longitudinal nerve cords
Central Nervous System (CNS)
Consists of neurons carrying information in and out of the CNS
Peripheral Nervous System (PNS)
Nervous system organization usually correlates with the _______
animals’ lifestyle
clams, chitons have simpler system
Sessile molluscs
squids, octopi have more sophisticated system
Complex molluscs
Functions to nourish, support, and regulate neurons Astrocytes
Induce cells lining capillaries in the CNS to form tight junctions, resulting in a blood-brain barrier and restricting the entry of most substances into the brain
Glial Cells
develops from a hollow nerve cord
CENTRAL NERVOUS SYSTEM
The cavity of the nerve cord gives rise
to the narrow central canal of the spinal cord and the ventricles of the brain
The canal and ventricles fill with ____,
supplies the CNS with nutrients and hormones and carries away wastes
cerebrospinal fluid
Consists of neuron cell bodies, dendrites, and unmyelinated
axons
Grey matter
Consists of bundles of myelinated axons, has fats
White matter
Conveys information to and from the brain and generates basic patterns of locomotion
Also produces reflexes independently of the brain
SPINAL CORD
Body’s automatic response to a stimulus
Reflex
Transmits information to and from the CNS and regulates movement and the internal environment
PERIPHERAL NERVOUS SYSTEM
transmit information to the CNS
Afferent neurons
transmit information away from the CNS
Efferent neurons
2 efferent components
Motor system
Autonomic nervous system
Carries signals to skeletal muscles Voluntary
Motor system
Regulates smooth and cardiac muscles Generally involuntary
Autonomic nervous system
AUTONOMIC NERVOUS SYSTEM
2 parts
Sympathetic division
Parasympathetic division
Regulates arousal and energy generation “fight-or-flight”
Sympathetic division
Has antagonistic effects on target organs and promotes calming “rest and digest”
Parasympathetic division
The vertebrate brain is ______ specialized
regionally
3 main regions of the brain
Forebrain
Midbrain
Midbrain
Has activities including processing of olfactory input, regulation of sleep, learning, and any complex processing
Forebrain
Coordinates routing of sensory input
Midbrain
Controls involuntary activities and coordinates motor activities
Hindbrain
Comparison of vertebrates shows
that relative sizes of particular brain regions vary
These size differences reflect
relative importance of the particular brain function
_____ has resulted in a close match between structure and function
Evolution
