Nervous Tissue Flashcards
What does nervous tissue include?
2
Nerve cells
Glia
What does the nervous system include?
It includes all the nervous tissue of the body
What are the functional units of the nervous system?
Nerve cells
What are nerve cells also called?
Neurons
What are neurons protected and supported by?
Neuroglia or glia
How many different structures of neurons are there?
Four
Classify neurons by structure.
Anaxonic neuron
Bipolar neuron
Unipolar neuron
Multipolar neuron
Classify neurons by function.
3
Sensory neurons
Interneurons
Motor neurons
What do sensory neurons do?
They bring nerve signals to the brain and spinal cord
What do interneurons do?
They bring nerve signals from one nerve cell to another within the brain and spinal cord
What do motor neurons do?
They bring nerve signals away from the brain and spinal cord
What are the three main parts of a neuron?
Dendrites
Axons
Synapses
What do dendrites do?
They receive inputs
What do axons do?
Electrical signals travel out along the axon
What do synapses do?
A chemical is released at the synapse
What are sensory receptors?
They are structures that respond to stimuli
From where do nerve cells receive signals?
From sensory receptors or other neurons in a circuit
What part of the neuron receives a signal?
The dendrite
Where is the dendrite of a neuron located?
Around the cell body
What is the cell body also called?
Soma
What do neurons do when they receive signals?
3
They respond to incoming signals
The cell body decided on response
Response is carried on an axon (AP)
What do axons communicate with?
2
Other neurons
Effectors - usually muscle to make a response
What do axons do?
They create and pass electrical signals (AP) along their length
How long is the longest axon?
1m in length
What is the end of the axon called?
The synaptic terminal
What are released from the synaptic terminal?
Chemicals
Where do nerves communicate?
At a synapse
What is a synaptic cleft also called?
Junction gap
What is a junction gap?
Synaptic cleft
Classify reflexes
4
By processing site
By complexity of circuit
By response
By development
What are the two different reflexes that are differentiated by processing site?
Spinal reflexes
Cranial reflexes
What are spinal reflexes?
Processing in the spinal cord
What are cranial reflexes?
Processing in the brain
What are the two different reflexes that are differentiated by complexity of circuit?
Monosynaptic
Polysynaptic
What is a monosynaptic reflex?
One synapse
What is a polysynaptic reflex?
Multiple synapses (two to several hundred)
What are two different reflexes that are differentiated by development?
Innate reflexes
Acquired reflexes
What are innate reflexes?
They are genetically determined
What are acquired reflexes?
They are learned reflexes
What are two different reflexes that are differentiated by response?
Somatic reflexes
Visceral (autonomic) reflexes
What are somatic reflexes?
2
Control skeletal muscle contractions
Include superficial and stretch reflexes
What are visceral (autonomic) reflexes?
Control actions of smooth and cardiac muscles, gland
What is a nerve reflex?
A fast, predictable, protective, automatic (subconscious) response to a stimulus
What is the circus involved in a nerve reflex?
A reflex arc
What are the five parts of a reflex arc?
Sensory receptor structure
Sensory nerve cell
Interneuron(s) (in most cases)
Motor nerve cell
Effector
What does the CNS include?
Brain and spinal cord
What does a reflex pathway involve?
The central nervous system
The peripheral nerves
What do the peripheral nerves include?
3
Cranial nerves
Spinal nerves
Sensory receptors
Where is sensory information processed?
In the central nervous system
What is grey matter?
2
Grey matter of the brain and spinal cord is where nerve cell bodies are concentrated
This is also the site of incoming signals (and therefore synapses)
Why is grey matter grey?
Because of cell body structures
What is the function of grey matter?
Decisions are made in the grey parts of the brain and spinal cord
Where is grey matter mostly present in the brain?
Grey matter is mostly on the outside of brain tissue
Where is grey matter mostly present in the spinal cord?
The centre of the spinal cord
What is white matter?
White matter of the brain and spinal cord is where bundles of axons are found
What is the function of white matter?
This is because white matter consists of the connections between one part of the brain and another
Why is white matter white?
White because of fatty tissue (myelin) in the glial cells that surround the axon
List the events in the flow of information.
6
Sensory receptor
Sensory neuron
Integration
Interneuron
Motor neuron
Effector cells
What is grey matter?
This is where information from one neuron is passed onto another neuron -> this involves processing
What is white matter?
Where information is brought from one part of the CNS to another ->this involves pathways
What is neuroglia?
Nervous tissue that support neurons
What are schwann cells?
Surround axons in Peripheral nervous system
What do schwann cells do?
2
They are responsible for myelination of peripheral axons
Participate in repair process after injury
Explain the central nervous system (CNS).
3
Brain and spinal cord
Divided into grey and white matter
Supported by glia, CT and blood vessels
Explain the Peripheral nervous system (PNS).
3
Cranial and spinal nerves
Nerves can have both sensory and motor axons
Nerves are supported by glia, CT and blood
