Module 2: The Nervous System Flashcards
The Nervous System
Coordinates both voluntary and involuntary activities of various systems of the body.
Broadly divided into 2 major systems = Central nervous system and Peripheral nervous system
Central nervous system (CNS)
Includes the brain and spinal cord
Peripheral nervous system (PNS)
Consists of nerves and structures (with some exceptions) that connect the CNS to all parts of the body
What is another way that the nervous systems can be classified by?
Classification based on the nervous system’s innovations and regulations of somatic and visceral structures→ Somatic nervous system (SNS) and Autonomic nervous system (ANS)
Somatic → “soma”
Refers to body
Visceral
Refers to organs
Somatic nervous system (SNS)
Mostly regulates muscular function
Autonomic nervous system
Regulates visceral (organ) and some special functions
Further divided into Sympathetic and Parasympathetic nervous systems
How are the functions of the nervous system brought about, or mediated?
Mediated by different types of cells within the brain and spinal cord and other structures such as ganglia
Types of cells within the nervous system
2 broad types = neurons and glial cells
Neuron(s)
- A basic functional unit of the nervous system
- Mostly communicate with other cells via synapses
- Contains a cell body with a nucleus → “perikaryon”
- Two types of “processes” (finger-like projections from the cell body that can conduct and transmit signals)→Dendrite and Axon
Dendrite
- Transmits impulses aka signals towards the cell body
- There are generally multiple dendrites
Axon
- Transmits impulses aka signals away from the all body
- Always starts as a singular process from the cell body → may divide into multiple processes after traveling a distance from its origin
Types of neurons
3 types → based on the structure of the neuron’s processes
1. Unipolar (aka Pseudounipolar) 2. Bipolar 3. Multipolar
Unipolar aka Pseudounipolar neuron
Dendrite and axon combine into a single process toward the cell body
Bipolar neuron
Dendrites join together as a common trunk before reaching the cell body at a different site than the origin site of the axon
Multipolar neuron
A number of dendrites join the cell body at different points. Most neurons are multipolar
How does a neuron communicate with another neuron, aka communication between neurons?
Neurons communicate with each other via the formation of synapses and they transmit info in the form of action potentials a
Synapses= communicationi between one neuronal membrane to another
Communication is via transmission of signals that can be chemical or electrical signals.
Types of connections (synapses)
Axosomatic vs. Axodendritic vs. Axoaxonic
Axosomatic synapse
Connection between an axon of one neuron and a cell body of another neuron
Axodendritic synapse
Connection between an axon of one neuron and a dendrite of another neuron
Axoaxonic synapse
Connection between an axon of one neuron and an axon of another neuron
Neuronal aggregations
Aggregations of cell bodies
Nuclei
Aggregations of cell bodies in the brain
Ganglia
Aggregations of cell bodies in the peripheral nerves
Glia aka glial cells
Cells that support neurons by providing nutrition to neurons and help with “neurotransmission” → they do not directly participate in neurotransmission
These cells produce “myelin”