Nerve Tissue Flashcards
What are the functions of the nerve tissue?
Rapid and specific communication
Keeping up with changing environment
What is the composition of the nerve tissue
Neurons which are specialized nerve cells and electrically excitable
Support cells which help neurons, they are called neuralgia. They are non conducting so not electrically excitable
What are the categories of neurons ?
Sensory-gather information from receptors
Interneurons-form a communicating network
Motor-convey impulses to effector cells
What is the cell structure of a neuron?
Perikaryon-cell body Large rounded euchromatic nucleus Well developed RER concentrated in granules called Nissl bodies Golgi complex Many mitochondria Lysosomes No centrioles Cytoskeleton made with neurofilaments and microtubules Cell processes Synapses that transmit information
What are the cell processes?
Axon-from the perikaryon to the next neuron or effector
Dendrites-From periphery to the perikaryon
What is the purpose of the synapse?
The synapses transmit information.
They can be excitatory or inhibitory
What is the structure of an axon?
Axolemma (plasma membrane)
Axoplasm- axonal cytoplasm which does not have Nissl bodies or ribosomes but have a developed SER and mitochondria
Cytoskeleton with abundant microtubules and neurofilaments
What are the characteristics of axon?
One per cell Received signal from perikaryon Variable length Axon hillock with no Nissl bodies Myelin sheath might be present and provide insulation for the axon Might have collateral branches
What are the types of axonal transport?
Anterograde flow
Fast retrograde flow
What are the characteristics of anterograde flow?
From the perikaryon Involves organelles like mitochondria Neurotransmitters vesiccles Actin filaments, proteins Motor is kinesin 2 types: Slow-tubular, actin, neurofilaments Fast-SER vesicles, NT vesicles, mitochondria
What are the characteristics of Fast retrograde flow?
To the perikaryon
Material taken by endocytosis
Transport used by viruses and toxins
Motor is dynein
What are the characteristics of dendrite?
Delivers signal to the perikaryon
Short, thick, tapered
Highly branched forming dendritic trees and synaptic contacts
Have dendritic spines which increase the areas of synapses
Non myelinated
Possess Nissl bodies and many free ribosomes
No Golgi complex
What are the major types of neurons?
Pseudounipolar
Bipolar
Multipolar
What are the characteristics of pseudounipolar neurons?
Sensory
One process with 2 branches-a peripheral process from the periphery and a central process to the CNS
Where do you find pseudounipolar neurons?
Spinal ganglia in the dorsal nerve root
Cranial nerve ganglia
What are the characteristics of bipolar neurons?
Sensory
Small with 2 short processes (dendrite and axon)
Non myelinated
Where do you find bipolar neurons?
Retina
Cochlea
Olfactory mucosa
What are the characteristics of multipolar neurons?
Motor Interneurons Multiple processes with single axon and many dendrites 2 types in the CNS: Golgi type I with long axon Golgi type II with short axon
What are the types of synapse?
Electrical-have gap junctions or ion passage
Chemical-most common
What are the characteristics of chemical synapse?
No protoplasmic continuity Have a presynaptic cell with presynaptic terminal Synaptic cleft Postsynaptic cell (receptors) Can be inhibitory or excitatory