Neurons and Spinal Cord Flashcards
What are the three general functions of the nervous system?
Sensory, integrative, and motor
What are the two major divisions of the nervous system?
The central nervous system (CNS) and the peripheral nervous system (PNS)
How is the peripheral nervous system divided up?
It is divided into the somatic and autonomous nervous system
What is the function of neuroglia?
They fill spaces, provide structural frameworks, produce the components of myelin, and carry out phagocytosis
What are the types of neuroglia in the central nervous system?
- microglial cells
- oligodendrocytes
- astrocytes
- ependymal cells
What are microglial cells?
A type of neuroglia in the CNS that support neurons and phagocytise bacterial cells, and form scars in areas of damage.
What are oligodendrocytes?
A type of neuroglia in the CNS that align along nerve fibers. They provide a myelin sheath around axons within the brain and spinal cord.
What are astrocytes?
A type of neuroglia in the CNS that provide structural support, join parts by their abundant cellular processes, and help regulate the concentration of nutrients and ions within the tissue. Form scar tissue that fills spaces following CNS injury.
What are ependymal cells?
A type of neuroglia in the CNS that form an epithelial-like membrane that covers specialised brain parts and form inner linings that enclose spaces in the brain and spinal cord.
What structure in the brain do astrocytes help form?
The blood-brain barrier
What are the neuroglia in the peripheral nervous system?
Schwann cells
What is chromatophilic substance? (also know as Nissl bodies)
A large granular body found in neurons. These granules are rough endoplasmic reticulum (RER) with rosettes of free ribosomes, and are the site of protein synthesis
What is neurilemma?
The outermost layer of Schwann cells that surrounds the axon of the neuron. It forms the outermost layer of the nerve fiber in the peripheral nervous system.
When peripheral nerves are damaged, their _____ can regenerate. The ___________ plays an important role in this process. In contrast, the ___ axons are myelinated by oligodendrocytes which do not provide a __________. Consequently, damaged CNS neurons usually do not regenerate.
When peripheral nerves are damaged, their **axons **can regenerate. The **neurilemma **plays an important role in this process. In contrast, the **CNS **axons are myelinated by oligodendrocytes which do not provide a neurilemma. Consequently, damaged CNS neurons usually do not regenerate.
What are the three groups that neurons are classified into?
- Multipolar neurons
- Bipolar neurons
- Unipolar neurons
What are the main features of multipolar neurons?
- many processes arising from cell bodies
- only one process of each neuron is an axon, the rest are dendrites
What are the main features of bipolar neurons?
- have two processes, one arising from each end of the cell body
- one process of an axon, the other is a dendrite
What are the main features of **unipolar **neurons?
- have a single process extending from cell body
- the process divides into two branches which function as a single axon
- there is a peripheral process and a central process
The cell bodies of some _________ neurons aggregate in specialised masses of nervous tissue called _____ which are located outside the _____ and ______ _____.
The cell bodies of some **unipolar **neurons aggregate in specialised masses of nervous tissue called **ganglia **which are located outside the **brain **and spinal cord.
What are the types of neuron based on their function?
- sensory neurons
- interneurons
- motor neurons
What do sensory (afferent) neurons do?
**Transmit **nerve impulses from peripheral body parts to the brain or spinal cord. They either have special receptor ends or are closely associated with receptor cells in the skin or in sensory organs.
What do interneurons do?
They transmit impulses from one part of the brain or spinal cord to another
What is an aggregation of the bodies of interneurons called?
A nucleus (plural nuclei). They are similar to ganglia, but in the CNS.
What do motor (efferent) neurons do?
Transmit impulses out of the brain or spinal cord to effectors.
What is a synapse?
A junction between any two communicating neurons
Neurons are seperated by a gap called a _______ _____.
Synaptic celft
What are the chemicals that transmit impulses?
neurotransmitters