1.4 - Nervous System
Explain the difference in Schwann cell (PNS) vs. Oligodendrocyte cell (CNS) myelination
1 Schwann cell myelinates 1 axon in the PNS whereas 1 oligodendrocyte can myelinate as many as 60 axons in the CNS
Name the 4 structures of the neuron?
1. Cell body (soma) 2. Processes (contains dendrites and axon) 3. Axon hillock 4. Axon terminals
How many neurons vs. neuroglia are there in the human brain?
100 billion neurons to (10x100) billion neuroglia
Neurons respond to stimuli by generating electrical signals. These signals create what two potentials?
Action and graded
The axon hillock is where an ............ ............ starts
Action potential
What the names of the two divisions within the PNS?
Afferent and Efferent
Neurons can be classified by structure. What are these three classifications?
Bipolar, unipolar and multipolar
This neuron structure contains organelles and a nucleus. It is the ........ ........
Cell body (Soma)
The peripheral nervous system (PNS) consists of which body parts?
Cranial and spinal nerves, ganglia
Neuron processes receive and send information. What are they and which process does which task?
Dendrites - Receives information Axons - Sends information as electrical signals (action potentials)
Neurons are excitable cells that transmit what kind of signal?
Electrical
True or false. The Afferent division is responsible for sending out motor commands from the CNS?
False. That is the responsibility of the Efferent division. Afferent brings sensory information in. * Can be remembered using the acronym S>A>M>E Sensory Afferent Motor Efferent
What is the term for clusters of neuronal cell bodies in the PNS?
Ganglia
What affect does myelination have on electrical conductivity?
Increases the speed of electrical conductivity
What is the function of the neuroglia?
Insulate, support, and protect neurons
What is the function of the nervous system?
It gathers sensory information, interprets it and generates motor activity in response
What is the function of interneurons and where are they located?
Links the sensory and motor neurons. Located in the CNS (Spinal cord)
What is the name of the sheath that protects and electrically insulates the axon?
Myelin
What is the term for a bundle of axons in the PNS?
Nerves
The nervous system is composed of which two components?
Neurons and neuroglia. Neurons are the fundamental unit of the nervous system
Neurons communicate with each other by releasing chemical signals called .........
Neurotransmitters
What is the term for clusters of neuronal cell bodies in the CNS?
Nuclei
What are the four cell types of neuroglia in the CNS?
Oligodendrocytes Astrocytes Ependymal cells Microglia
What does an axon terminal do?
Release neurotransmitters to communicate with other cells
What are the two cell types of neuroglia in the PNS?
Satellite and Schwann
Name the each neuroglia cell type responsible for axon myelination in both the PNS and CNS
Schwann cells (PNS) Oligodendrocytes (CNS)
What is the function of efferent neurons?
Sending motor information from the CNS to the PNS
What is the function of afferent neurons?
Sending sensory information from the PNS into the CNS
What muscle type is used by the somatic nervous system?
Skeletal
What muscle types are used by the autonomic nervous system? What makes them different to the somatic?
Smooth and cardiac muscle, glands. Muscles in the autonomic system aren't controlled
What is the name of the two systems within the PNS?
Somatic and autonomic nervous systems
The central nervous system (CNS) consists of which body parts?
The brain, cranial nerves and spinal cord
The nervous system can be divided into which two systems?
The central and peripheral nervous system
How many processes do unipolar neurons contain?
They contain a single fused process (dendrites and mostly axon). Cell body is to the side. Most sensory neurons have this structure
How many processes do multipolar neurons contain?
They contain multiple processes (two or more dendrites and one axon) Motor neurons have this neuron structure
How many processes do bipolar neurons contain and where are they located within the body?
They contain two processes (one axon and one dendrite). Are used in the special senses e.g. retina and olfactory system
What is the term for a bundle of axons in the CNS?
Tracts
What is the function of the neuron?
Transmit information through electrical impulses