The Nervous System

Questions and Answers

What are the primary components of the central nervous system (CNS)?

The primary components of the CNS are the brain and spinal cord.

Differentiate between the afferent and efferent divisions of the peripheral nervous system.

The afferent division brings sensory information to the CNS from receptors, while the efferent division carries motor commands from the CNS to effectors.

Describe the role of neuroglia in the nervous system.

Neuroglia cells support and protect neurons, preserving the physical and biochemical structure of neural tissue.

What is the function of dendrites in a neuron?

Dendrites bring information from the environment to the neuron cell body. Signup and view all the answers

Explain the difference between sensory neurons and motor neurons.

Sensory neurons (afferent) carry information from sensory receptors to the CNS, while motor neurons (efferent) carry commands from the CNS to muscles or glands. Signup and view all the answers

What classification of neuron is characterized by having one continuous process?

Unipolar neurons are characterized by having one continuous process extending from the cell body. Signup and view all the answers

Identify the two types of neuroglia found in the peripheral nervous system (PNS) and their functions.

The two types are satellite cells, which regulate the environment around neurons, and Schwann cells, which myelinate PNS neurons. Signup and view all the answers

What is Wallerian degeneration and its significance in nerve injury?

Wallerian degeneration is the process where the axon distal to an injury site degenerates, and macrophages clean the area. Signup and view all the answers

What are the five membrane processes involved in neural activity?

The five processes are resting potential, graded potential, action potential, synaptic activity, and information processing. Signup and view all the answers

What is the significance of the synaptic cleft in neuron communication?

The synaptic cleft is the narrow space between the pre-synaptic cell that sends the message and the post-synaptic cell that receives it. Signup and view all the answers

Study Notes

Nervous System

Consists of Central Nervous System (CNS) and Peripheral Nervous System (PNS)
CNS includes brain and spinal cord, responsible for information processing and higher functions (intelligence, emotion, memory)
PNS includes all neural tissue outside of CNS, responsible for transmission of electrical signals and sensory and motor information

Peripheral Nervous System (PNS)

Afferent division: brings sensory information to CNS, receives input from receptors
Efferent division: carries motor commands from CNS to effectors (targets), exits CNS

Neurons

Receive and send signals
Anatomy:
- Dendrites: bring information from environment to cell
- Cell body (soma): contains nucleus
- Axon: carries impulse away from soma
- Axolemma: plasma membrane of neuron
- Axoplasm: cytoplasm in axon
- Telodendria: extensions at end of axon
- Synaptic terminals: contain neurotransmitters

Synapse

Specialized site of communication between neuron and another cell
Pre-synaptic cell: sends message, contains neurotransmitters
Post-synaptic cell: receives message, contains receptors for neurotransmitters
Synaptic cleft: narrow space between cells

Classification of Neurons

Anaxonic: brain and sense organs, all cell processes look alike
Bipolar: special sensory organs (ear, eye, nose), 2 distinct processes
Unipolar: axon and dendrites continuous, cell body off to one side, found in sensory neurons of PNS
Multipolar: 2 or more dendrites and 1 axon, most common in CNS, all motor neurons controlling skeletal muscles

Sensory Receptors

Relay stimuli to sensory neurons
Interoceptors: monitor sensations from systems inside body (intero = inside)
Exteroceptors: monitor sensations from external environment (extero = outside)
Proprioceptors: monitor body position and movement of joints and muscles (proprio = one's own)

Functional Classification of Neurons

Sensory neurons: afferent neurons of PNS, receive information from receptors and transmit to CNS
Motor neurons: efferent neurons of PNS, carry motor commands from CNS to effectors
Interneuron: association neurons, integrate sensory and motor information, involved in higher-order states (memory, planning, learning, cognition)

Neuroglia

4 types in CNS:
- Oligodendrocytes: myelinate CNS neurons
- Microglia: phagocytes that remove cell debris, wastes, and pathogens
- Ependymal cells: form epithelium to line ventricles and central canal, produce and circulate CSF
- Astrocytes: form 3D framework, regulate environment around neurons, and form blood-brain barrier
2 types in PNS:
- Satellite cells: regulate environment around cells
- Schwann cells: myelinate PNS neurons

Wallerian Degeneration and Repair

Axon distal to injury site degenerates, macrophages clean up area
Schwann cells proliferate and form solid cellular cord following path of axon, allowing for repair of damaged PNS nerves
Limited repair in CNS due to scar tissue and chemicals blocking axon growth