BIOL 273 - Unit 2.1 Flashcards
Three functions of the nervous system
- Receives information (using sensory neurons to receive from external environment)
- Integrates information (organizes info and brings it together with already stored info)
- Transduces information (sends apprpriate signals to the appropriate target)
Two main parts of the nervous system
- Central Nervous system
- Peripheral nervous system
Central nervous system made up of
brain and spinal cord
Peripheral Nervous system
Part of the nervous system outside of the brain and spinal cord
- consists of sensory (afferent) and motor (efferent) neurons
Neurons
- generate and trasmit electrical impulses over long distances
4 main parts of the neuron
- Soma (cell body)
- Dendrites
- Axon
- Axon terminals
Soma
cell body
- nucleus and biosynthetic machinery
- center of the chemical processes
- keeps cell alive
Clusters of cells bodies in the CNS
nuclei
Dendrites
slender processes that receive information
- transmits electrical signals towards soma
Clusters of nerve cell bodies in the PNS
ganglion
Axon
cytoplasmic extension that sends out information
- transmits electrical signal away from soma
Bundles of axons in the CNS forming a pathway are known as
Tracts
Bundles of axons in the PNS forming a pathway are known as
Nerve (which extends from th CNS to the targets of the component neurons)
Axon Terminals
- end of axon
- connection between neuron and other cells
- participates in synapse (called presynaptic)
Three ways neurons structures can be classified
- Pseudounipolar
- Bipolar
- Multipolar
Pseudounipolar
somatic sensory neurons
- axon and dendrites fuse during development into a single process
Bipolar
smell/vision sensory neurons
- they contain a single axon and dendrite
Multipolar
CNS and effertent
- have a single axon process
- have two or more dendrites
Three ways a neuron can be classified according to function
- Afferent (sensory) neurons
- Interneurons
- Efferent (motor) neurons
Afferent (sensory) neurons
- receive information from the receptor cells
- transmit sensory information to the CNS
- cell bodies are located outside the CNS
- Long cytoplasmic extensions transmit information to cells (interneurons) within the CNS
Interneurons
- These neurons are located inside the CNS
- Makes up 96% of all neurons
- Transmit information signals within CNS
- Integrate infor from afferent neurons and previous info and transmit signals to efferent neurons
Efferent (motor) neurons
- receive information from the interneurons
- efferent neuron cell bodies are located within CNS
- Cytoplasmic extensions transmit info to Effectors such a muscles, glands etc
Glial cells
- associated with neurons
- DO NOT CARRY electrical signals over long distances
- communicate with each other and with nearby neurons using electrical and chemical signals
Two ways Glial cells contribute to the function of neurons in two main ways
- Aid in nerve impulse conduction
- Maintain the microenvironment around neurons
2 types of glial cells of the Peripheral Nervous System
- Schwann cells
- Satellite cells
Schwann cells
- glial cell of pns
- wraps around axons
- forms myelin (which acts as an electrical insulator)
Satellite cells
- non-myelinating schwann cells
- support nerve cell bodies
4 types of glial cells of the Central nervous system
- Oligodendria
- Astroglia (astrocytes)
- Microglia
- Ependymal cells
Oligodendria
they are the CNS version of the Schwann cell
- wrap around axons
Astroglia
small star shaped cells
- contacts blood vessels and neurons
- maintain neuron microenvironment (helps maintain homeostasis in extracellular fluid around neurons)
Microglia
very small specialized immune cell (macrophage-like)
- function is to remove damaged cells and foreign invaders
Ependymal cells
- epithelial cells that produce cerebral spinal fluid (CSF)
- Create selectively permeable barrier between compartments of the brain
