cns and pns Flashcards
What does ‘afferent’ mean?
Coming towards CNS
What does ‘efferent’ mean?
Coming out of/away from CNS
Define ‘nerve’.
Cable-like bundle of nerve fibers (axons) in the periphery, grouped in fascicles
What are ‘ganglia’?
Collection of neural cells (neurons + satellite cells) in the periphery
Define ‘plexus’.
A network of nerves that branch out and intersect
What is a ‘system’ in the context of biological organization?
Collection of organs (e.g., nervous system)
What is an ‘organ’?
A collection of different tissues that work together to perform a function
What is ‘tissue’?
A collection of cells that work together to perform a particular task
What are ‘cells’?
The basic building blocks of tissues
What is the main function of neurons?
Detect inputs, integrate info, send signals to other cells
What do glial cells do?
Provide functional and structural support to neurons
List the components of a neuron.
- Soma (cell body)
- Axon
- Dendrites
What is the function of the axon?
Transmits electrical impulses from cell body of a neuron to other neurons
What are dendrites?
Branching extensions of neuron that receive messages from other nerve cells
What is the hillock in a neuron?
The last site in the soma where synaptic inputs are summated/integrated
What is the AIS in a neuron?
Earliest site of action potential initiation, non-myelinated axon
What type of neuron transmits sensory information such as touch, sound, and light to the CNS?
Sensory neurons
Sensory neurons are responsible for conveying external stimuli to the central nervous system.
What is the function of motor neurons?
Carries signals from the CNS to muscles and glands to initiate a response
Motor neurons play a critical role in executing bodily responses.
What type of neuron transmits signals between sensory and motor neurons within the CNS?
Interneuron
Interneurons are essential for processing information within the central nervous system.
What is the role of astrocytes in the CNS?
Buffer ions and neurotransmitters, secrete chemicals for synaptogenesis, part of blood-brain barrier, provide nutrients, repair damage
Astrocytes support neuronal function and help maintain a stable environment.
What cells are responsible for myelinating axons in the CNS?
Oligodendrocytes
Myelination is crucial for efficient signal transmission in the nervous system.
What is the function of microglia?
Macrophage activity, phagocytic, debris removal, immune defense
Microglia act as the immune cells of the CNS, protecting against pathogens and clearing waste.
What do ependymal cells line and what is their function?
Line the ventricles and central canal; create CSF
Ependymal cells are involved in the production and circulation of cerebrospinal fluid.
What is the role of Schwann cells in the PNS?
Myelinate axons, protect unmyelinated axons, provide trophic support
Schwann cells facilitate nerve regeneration and support neuronal health.
What do satellite cells do in the PNS?
Surround somata of neurons; assist in regulating the external chemical environment
Satellite cells help maintain homeostasis for neurons in ganglia.
What does CNS stand for?
Central Nervous System
What is the role of the CNS?
Central processing center that receives, integrates, interprets info from periphery and sends info back to periphery
What is Gray Matter composed of?
Neuronal and glial cell bodies and unmyelinated axons
What does White Matter represent?
Networking between processing centers through myelinated axons
What is the primary function of the Spinal Cord?
Communicates signals to and from the body via spinal nerves
How is the Spinal Cord divided?
Into segments, each connecting to a pair of sensory and motor nerves
What type of information do axons and cell bodies in the dorsal spinal cord convey?
Mostly sensory info
What is the primary function of axons and cell bodies in the ventral spinal cord?
Transmit signals controlling movement
What are the two divisions of the PNS?
Somatic and autonomic
What does the Somatic Nervous System control?
Skeletal muscle through voluntary and involuntary movements
What are afferents in the context of the Somatic Nervous System?
Sensory info to the CNS
What are efferents in the context of the Somatic Nervous System?
Motor info from the CNS
What are cranial and spinal nerves responsible for?
Afferent and efferent pathways to and from the CNS
What is a neural circuit?
Arrangement of neurons interconnected by synapses that perform a particular function
What does the Autonomic Nervous System control?
Internal organs and functions such as breathing, heartbeat, and digestion
Where does the Sympathetic division originate?
Thoracic and lumbar levels
Where does the Parasympathetic division originate?
Brainstem (cranial) and sacral levels
What is the primary function of the Enteric division?
Embedded in the wall of the gastrointestinal tract
Are sympathetic preganglionic axons short or long?
Short
Are parasympathetic preganglionic axons short or long?
Long
What neurotransmitter is used by sympathetic postganglionic neurons?
NE (norepinephrine)
What neurotransmitter is used by parasympathetic postganglionic neurons?
Ach (acetylcholine)
