Podcast
Questions and Answers
Which type of neuron has only one process that divides into two branches?
Which type of neuron has only one process that divides into two branches?
What structure is the main part of a neuron responsible for synthesizing neurotransmitters?
What structure is the main part of a neuron responsible for synthesizing neurotransmitters?
Which type of nerve fiber has the largest diameter and is heavily myelinated?
Which type of nerve fiber has the largest diameter and is heavily myelinated?
What is the role of neuroglia in the nervous system?
What is the role of neuroglia in the nervous system?
Signup and view all the answers
How are neurons classified according to the length of their axons?
How are neurons classified according to the length of their axons?
Signup and view all the answers
Which part of the neuron is primarily responsible for receiving signals from other neurons?
Which part of the neuron is primarily responsible for receiving signals from other neurons?
Signup and view all the answers
What is the primary function of Schwann cells?
What is the primary function of Schwann cells?
Signup and view all the answers
Which part of the neuron is characterized by a prominent nucleolus and basophilic cytoplasm?
Which part of the neuron is characterized by a prominent nucleolus and basophilic cytoplasm?
Signup and view all the answers
Which type of ganglion consists of unipolar sensory neurons?
Which type of ganglion consists of unipolar sensory neurons?
Signup and view all the answers
What characteristic does a multipolar neuron display?
What characteristic does a multipolar neuron display?
Signup and view all the answers
What is the primary role of myelin in the nervous system?
What is the primary role of myelin in the nervous system?
Signup and view all the answers
Which type of cell is responsible for myelination in the peripheral nervous system (PNS)?
Which type of cell is responsible for myelination in the peripheral nervous system (PNS)?
Signup and view all the answers
What characterizes the nodes of Ranvier?
What characterizes the nodes of Ranvier?
Signup and view all the answers
What type of neuroglial cell is characterized by long, thin processes with less branching?
What type of neuroglial cell is characterized by long, thin processes with less branching?
Signup and view all the answers
Which component is NOT part of the structure of peripheral nerves?
Which component is NOT part of the structure of peripheral nerves?
Signup and view all the answers
What type of synapse primarily uses neurotransmitters for communication?
What type of synapse primarily uses neurotransmitters for communication?
Signup and view all the answers
What is one of the key functions of neuroglial cells?
What is one of the key functions of neuroglial cells?
Signup and view all the answers
What characteristic distinguishes microglial cells?
What characteristic distinguishes microglial cells?
Signup and view all the answers
Which pair correctly identifies the type of neuron found in the sympathetic chain ganglia?
Which pair correctly identifies the type of neuron found in the sympathetic chain ganglia?
Signup and view all the answers
Which layer of connective tissue surrounds each individual nerve fiber in a peripheral nerve?
Which layer of connective tissue surrounds each individual nerve fiber in a peripheral nerve?
Signup and view all the answers
Signup and view all the answers
Study Notes
Nervous Tissue Overview
- Nervous tissue is one of the four basic tissues in the body
- It comprises two cell types: neurons and neuroglia
- It forms the basis of the nervous system
Nervous System Division
- Divided into two main parts:
- Central nervous system (CNS): Brain and spinal cord
- Peripheral nervous system (PNS): Cranial nerves, spinal nerves, and ganglia
- Functionally divided into:
- Sensory (afferent)
- Motor (efferent)
- Interneurons
Neuron Structure
- The structural and functional unit of the nervous system
- Composed of:
- Cell body (perikaryon, soma, cyton)
- Processes: Axon and dendrites
Neuron Cell Body (LM & EM)
- LM: Large, rounded, central nucleus; basophilic cytoplasm (Nissl granules)
- EM: Ribosomes, mitochondria, RER, Golgi apparatus, prominent nucleolus; vesicular, numerous polyribosomes (Nissl granules)-related to protein synthesis, especially neurotransmitters synthesis.
Neuron Processes
-
Axon:
- Single, arising from the axon hillock (no Nissl granules)
- Long and thin, constant diameter, smooth contour
- Contains neurofibrils, SER, mitochondria; no Nissl granules
- Terminal arborization
- Axolemma (membrane) and axoplasm (cytoplasm)
-
Dendrites:
- Multiple, short, branching
- Irregular contour (thick origin, thin apex)
- Contains Nissl granules, mitochondria, SER, neurofibrils
- Arise from the cell body
Neuronal Classification
- Based on polarity (number of processes):
- Unipolar (rare in humans)
- Pseudounipolar (sensory neurons)
- Bipolar (retina)
- Multipolar (most common; e.g., polygonal, stellate, pyramidal)
- Based on axon length:
- Golgi type I (long axon)
- Golgi type II (short axon)
- Based on axonal diameter and myelin sheath thickness:
- Type A fibers (large diameter, heavily myelinated)
- Type B fibers (medium diameter, moderately myelinated)
- Type C fibers (small diameter, unmyelinated)
Myelin Sheath
- Formed by lipids (from cell membrane)
- Wraps around axon, interrupted at nodes of Ranvier
- Protective insulation, crucial for rapid signal transmission
- Not stained by H&E; stained by osmic acid (black circles)
Myelin Formation (Myelination)
- Schwann cells (PNS) wrap axons repeatedly, squeezing cytoplasm between layers; major role in myelination in the PNS
- Oligodendrocytes (CNS) form myelin in the CNS
Peripheral Nerve Trunk
- Varying number of nerve fibers grouped into bundles
- Nerve fibers are acidophilic (stained by H&E)
- CT investment of peripheral nerves:
- Endoneurium (thin layer of loose CT around each fiber)
- Perineurium (dense CT around each bundle)
- Epineurium (thicker dense CT covering the whole trunk)
- Function of CT: nourish, support, protect
Neuroglial Cells (CT of the NS)
-
Astrocytes (types A & B):
- Protoplasmic: Large, branching cells, (perivascular feet)
- Fibrous: Longer, thinner processes, important in supporting framework, maintaining blood brain barrier
- Both contain intermediate filaments (GFAP)
- Oligodendrocytes: Small, oval nucleus, few processes; myelin production in CNS
- Microglial cells: Small, oval nucleus, thin cytoplasmic processes with spines;Mononuclear phagocytic cells (brain macrophage)
Synapses
-
Junctions between neurons, where nerve impulses are transmitted
-
Comprises: presynaptic, postsynaptic membranes & synaptic cleft
-
Morphology:
- Axo-dendritic
- Axo-somatic
- Axo-axonic
- Dendro-dendritic
-
Type of transmission:
- Chemical (neurotransmitters)
- Electrical (ions flow through gap junctions)
Ganglia
- Nodular structures of neuronal cell bodies in PNS, covered by CT capsule
- Types include sympathetic ganglia (mostly small, multipolar neurons with eccentric nuclei, numerous scattered neurons) and spinal ganglia (large, primarily pseudounipolar neurons with centrally located nuclei, fewer neurons, arranged in bundles)
Spinal & Sympathetic Ganglia
- Spinal ganglia generally associated with the spinal nerves; contain a higher proportion of pseudounipolar neurons than other types
- Sympathetic ganglia are usually part of the sympathetic chain, with smaller, multipolar neurons and a more scattered organization
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Explore the essential components of nervous tissue and understand the structure and function of neurons. This quiz covers the divisions of the nervous system and the cellular anatomy of neurons. Test your knowledge about the basis of our nervous system!
