Chapter 11 Flashcards
peripheral nervous system (PNS)
it includes sensory receptors, nerves, ganglia, and plexuses. The sensory division of the PNS detects stimuli and transmits information in the form of action potentials to the CNS.
central nervous system (CNS)
consists of the brain and spinal cord.
Sensory receptors
endings of neurons, or separate, specialized cells that detect temperature, pain, touch, pressure, light, sound, odor, and other stimuli.
nerve
bundle of axons and their sheaths; it connects the CNS to sensory receptors, muscles, and glands.
cranial nerves/ spinal nerves
12 pairs originate the brain, and 31 pairs of spinal nerves originate from the spinal cord
ganglion
a collection of neuron cell bodies located outside the CNS.
plexus
an extensive network of axons and, in some cases, neuron cell bodies, located outside the CNS.
The PNS has two functional subdivisions: The sensory division (afferent (toward) division) and the motor division (efferent (away) division)
- sensory - transmits electrical signals, called action potentials, from the sensory receptors to the CNS. The cell bodies of sensory neurons are located in dorsal root ganglia near the spinal cord or in ganglia near the origin of certain cranial nerves.
- motor division - transmits action potentials from the CNS to effector organs, such as muscles and glands.
The motor division is divided into the somatic nervous system (SNS) and the autonomic nervous system (ANS).
-somatic nervous system controls conscious activities -ANS controls subconscious activities.
synapse
junction of a neuron with another cell; axons extend through nerves to form connections with skeletal muscle cells.
The ANS is subdivided into the sympathetic division and the parasympathetic division.
In general, the sympathetic division is most active during physical activity, whereas the parasympathetic division regulates resting functions, such as digesting food or emptying the urinary bladder.
enteric nervous system (ENS)
consists of plexuses within the wall of the digestive tract; enteric neurons monitor and control the digestive tract independently of the CNS through local reflexes.
The two types of cells that make up the nervous system are neurons and nonneural cells.
Neurons receive stimuli, conduct action potentials, and transmit signals to other neurons or effector organs. Nonneural cells are called neuroglia cells, and they support and protect neurons and perform other functions.
neuron cell body
cell body
Nissl bodies
The neurofilaments separate abundant ER which are located primarily in the cell body and dendrites; primary site of protein synthesis in neurons.
dendritic spines
Many dendrite surfaces have small extensions called dendritic spines, where axons of other neurons form syn- apses with the dendrites.
axon hillock
In most neurons, a single axon arises from this cone-shaped area of the neuron cell body
initial segment
beginning of the axon
trigger zone
Action potentials are generated at the trigger zone, which consists of the axon hillock and the part of the axon nearest the cell body.
axoplasm/axolemma
The cytoplasm of an axon is sometimes called the axoplasm, and its plasma membrane is called the axolemma.
presynaptic terminals
Axons terminate by branching to form small extensions with enlarged ends
neurotransmitters
Within the presynaptic terminals are these numerous small vesicles that contain chemicals
Sensory neurons (or afferent neurons)
conduct action potentials toward the CNS
motor neurons (or efferent neurons)
conduct action potentials away from the CNS toward muscles or glands.