Sensory (Afferent)
Transmits information from the periphery to the CNS; contains receptors
Motor (Efferent)
Transmits information from the CNS to the rest of the body; sends motor information to effectors
Somatic Sensory
Recieves info from skin, fascia, joints, skeletal muscle, special senses
Visceral Sensory
Recieves sensory information from viscera
Somatic Motor
voulntary" nervous system; innervates skeletal muscle
Autonomic Nervous System
involuntary" nervous system; innervates cardiac and smooth muscle tissue
Typical Neuron
The dendrites and cell body receive signals from other neurons (via synapses). In response to these signals, the neuron can generate a nerve impulse (action potential) at the axon hillock. The action potential will travel down the axon to the axon termina
Anaxonal
neuron has no axon or an extremely short one; neurons are typically found in sensory systems, such as the visual, olfactory, and auditory systems.
Unipolar
One process extends from the cell bodyand forms central and peripheral processes, which together comprise an axon.
Most ______ neurons are sensory neurons that conduct impulses along afferent pathways to the CNS for interpretation.
Bipolar
Two processes extend from the cell body:
One is a fused dendrite.
The other is an axon.
Rare found only in ear and eye.
Multipolar
Many processes extend from the cell body:
One is an axon (which may split)
All others are dendrites. neurons are most commonly motor neurons or interneurons that conduct impulses within the CNS.
Neuroglia
Cells that provide metabolic support and immune protection for neuronsOutnumber neurons in the CNS 10:150% of brain massInclude:
astrocytes (CNS)
microglia (CNS)
ependymal cells (CNS)
oligodendrocytes (CNS)
Schwann cells (PNS)
satellite cells (PNS)
Astrocytes
Most abundant glial cellsGive nervous tissue structural support. Processes cover capillaries (part of the blood brain barrier). Connect between neurons and capillariesTake up glucose from blood and deliver it as lactic acid to neurons. Control the chemica
Oligodendrocytes
Myelination in the central nervous system
Schwann Cells
Myelination in the peripheral nervous system
Ependymal Cells
line the cerebrospinal fluid-containing cavities of the brain and spinal cordtypically ciliated -beating of cilia circulates CSF
Microglia
Play a protective role similar to macrophages of the immune system; Monitor the health of neuronsRemove damaged cells; Fight invading microorganisms
Membrane Potential
differences are always measured inside with respect to outside; When the recording electrode enters the cell, you see that the inside is more negative than the outside.
Polarized
Because there are positive charges along the outside and negative charges along the inside, the resting cell membrane is electrically ____.
Depolarized
If the membrane potential becomes less negative, then the cell membrane is said to be _______. If the membrane in the area of the axon hillock is ______ above a certain threshold, then the nerve will generate a nerve impulse (an action potential) that wil
Hyperpolarized
If the membrane potential becomes more negative, then the cell membrane is said to be ________.
Voltage Gated Channels
Voltage Gated Channels
Mylenation
Axons with larger diameters conduct nerve impulses faster. But _____ allows the same rate of impulse conduction (10-100 m/s) with much smaller axon diameters.
Saltatory Conduction
In myelinated axons, the action potential propagates by ____ ; proceeding by leaps rather than by smooth gradual transitions; The Na+current spreads passively from node to node, so the membrane potential decreases with distance. Because the nodes of Ranvi
Electrical Synapses
Presynaptic cell and postsynaptic cell are connected by channel proteins (gap junctions)Gap junctions provide a low resistance pathway for the nerve impulse to pass from one cell to the next; quicker than chemical synapses, take up larger surface area
Chemical Synapse
(1)An action potential arrives at the presynaptic terminal bulb, resulting in a transient depolarization.
(2)Depolarization opens voltage-gated calcium channels, allowing calcium ions to rush into the terminal.
(3)This increase in the calcium concentratio
Receptor types found at chemical synapses.
Excitatory post-synaptic potential (EPSP)
a depolarizing stimulus
Brings the membrane potential closer to threshold (i.e. makes the neuron more likely to fire)
Inhibitory post-synaptic potential (IPSP)
�a hyperpolarizing stimulus
�Takes the membrane potential further from threshold (i.e. makes the neuron less likely to fire)
Post Synaptic Potential
graded potentials -a local change in the membrane potential that decreases with distance.
To be Considered a Neurotransmitter
The molecule must be synthesized in the neuron. The molecule must be present in the presynaptic terminal. The molecule must be released upon presynaptic stimulation. When added to the extracellular fluid, it should mimic the effects of presynaptic stimula
Neurotransmitters
Three major categories + Acetylcholine 1. monoamines 2. amino acids 3.neuropeptides The major "workhorse" neurotransmitters of the brain are glutamic acid (=glutamate) and GABA. In the brain, the monoamines and acetylcholine perform specialized modulating
Major Neurotransmitters
Secreory Vesicles
made in the cell body and must be transported to the axon terminal; transported by molecular motors along microtubules inside the cell that run the length of the axon;
Neuromuscular Synapse
a relay synapse;
Relay Synapse
an action potential in the presynaptic cell always causes an action potential in the post-synaptic cell.