Neuroanatomy 1 Flashcards
Meninges - definition and names (3)
Three membranes of connective tissue that cover the brain and spinal cord
What two structures form the central nervous system?
Brain (encephalon) and spinal cord (Medulla spinalis)
What structures form the peripheral nervous system?
Cranial, spinal, and named nerves
Dura mater
Pachymenix: thickest and most external layer of the meninges
What are the main functions of the nervous system?
- General considerations:
- Informs animal about its environment
- internal and external environment
- Initiates responses to that environment
- Regulates and coordinates other systems
- e.g. locomotion, cardiovascular, digestion, respiration, circulation
- Informs animal about its environment
- Allows animal to interact, adapt and react to its environment
- Acts with and is also controled by the endocrine, immune, and sensory organs
What does ‘afferent’ mean in the context of the nervous system?
impulse towards the CNS
What does ‘efferent’ mean in the context of the nervous system?
impulse away from the CNS
What is the canal that the spinal cord runs through down the spine, and what parts of the vertebrae comprise this canal?
Vertebral canal
Vertebral foramina
How many cranial nerves (nerves that exit the brain) are there?
12 pairs
Spinal nerves are named according to which five regions?
- cervical
- thoracic
- lumbar
- sacral
- caudal
Through which gaps do paired spinal nerves leave the vertebral column?
Intervertebral foramina
How many pairs of cervical nerves are there?
8 pairs
What is a nerve plexus?
A branching network of intersecting nerves
The afferent system is composed of s___ (afferent) ___ (PNS) and the a_____ _____ (CNS)
The afferent system is composed of sensory (afferent) neurons (PNS) and the ascending pathway (CNS)
The efferent system is comprised of b_____ ____ (PNS) that may be:
- s_____ (lower motor neurons; usually under conscious control; locomotor system), or
- a________ (visceral, usually not under conscious control; organs, blood vessels, glands; sympathetic/parasympathetic).
The d______ ______ (CNS) is comprised of upper motor neurons.
The efferent system is comprised of motor neurons (PNS) that may be:
- somatic (lower motor neurons; usually under conscious control; locomotor system), or
- autonomic (visceral, usually not under conscious control; organs, blood vessels, glands; sympathetic/parasympathetic).
The descending pathway (CNS) is comprised of upper motor neurons.
What are the two basic cell types of the nervous system?
- Neurons
- Neuroglia (glial cells)
What are the four types of neuroglia and which broad part of the NS are they found in?
- Schwann cells (PNS)
- Oligodendrocytes (CNS)
- Astrocytes (CNS)
- Microglia (CNS)
What is the other term for the neuron cell body?
Perikaryon
What is the most prominent structure in the nucleus of a neuron and what is its primary function?
The nucleolus is a region found within the cell nucleus that is concerned with producing and assembling the cell’s ribosomes
Neurons have large amounts of ______ endoplasmic reticulum. These regions (rich in ribosomes, which make the cytoplasm of neurons stain quite darkly) are called ______ bodies/substance.
Neurons have large amounts of rough endoplasmic reticulum. These regions (rich in ribosomes, which make the cytoplasm of neurons stain quite darkly) are called Nissl bodies/substance.
Processes on neurons such as dendrites and axons are called _____.
Processes on neurons such as dendrites and axons are called neurites.
__________ are neurites that come off of the cell body, have a tapered shape, contain similar contents to the cell body, and are often quite short. they make up the ______ field, the signalling receptive zone of the neuron.
Dendrites are neurites that come off of the cell body, have a tapered shape, contain similar contents to the cell body, and are often quite short. they make up the dendritic field, the signalling receptive zone of the neuron.
The _______ is a neurite (process) coming out of the cell body that is narrow, often long, does not taper, can have collateral branches, has little ER (is pale staining), and is the signalling response zone.
The axon is a neurite (process) coming out of the cell body that is narrow, often long, does not taper, can have collateral branches, has little ER (is pale staining), and is the signalling response zone.
The a_______ _______ is the site of neuronal signal generation.
The axon hillock is the site of neuronal signal generation.
What are telodendria (sing. = telodendron)?
Distal branches of a neuronal axon that can further branch into axon terminals, each ending in a synaptic bulb.
What is a ganglion (pl. ganglia)?
Cluster of cell bodies in a connective tissue sheath in the peripheral and autonomic NS
Can have sensory or motor function
What is a dorsal root ganglion?
Cluster of cell bodies of sensory nerves located in the posterior region of various vertebrae along the spinal column
In the CNS, a cluster of cell bodies is called a _____ (pl. _____), and a group of these is called a _______.
In the CNS, a cluster of cell bodies is called a nucleus (pl. nuclei), and a group of these is called a centre.
________ neurons carry impulses towards the CNS, ________ neurons carry impulses away from the CNS, and ______ have cell bodies and processes within the CNS.
sensory/afferent neurons carry impulses towards the CNS, notor/efferent neurons carry impulses away from the CNS, and interneurons have cell bodies and processes within the CNS.
What are the functional segments of a motor neuron?
- cell body segment = nucleus & cytoplasm, metabolic segment, location not critical to function, usually found in well-protected areas
- receptive segment = cell body & dendrites, receives signals
- Trigger zone = axon hillock, site of nerve impulse generation
- Conductile segment = axon (& myelin sheath if present), site of impulse conduction
- Transmissive segment = terminal end, telodendria, transmits signal to post-synaptic region
What properties form the basis for the morphological classification of neurons?
- Shape of cell body
- Number of processes
- Shape of processes
- Ramifications of processes
What are the four types of neurons classified by polarity?
- Unipolar
- Pseudounipolar
- Bipolar
- Multipolar
What characterises a unipolar neuron? Give an example
One cell body and one process (axon)
- Stimulated by environment (sensory)
- Send the resulting impulse through a cell process directly to a muscle or gland cell
- e.g. Olfactory cells
- »fish not mammals
What characterises a bipolar neuron? Give an example
One cell body and two processes (axons)
- Retina of the eye
- Ganglia of cranial nerve VIII
- »Vestibulocochlear nerve
- Olfactory nerves of Mammals
What characterises a pseudounipolar neuron? Give an example
A pseudounipolar neuron has one axon that projects from the cell body for relatively a very short distance, before splitting into two branches — one that extends to the central nervous system, and the other that extends to the peripheral nervous system. Pseudounipolar neurons are sensory neurons that have no dendrites, the branched axon serving both functions
- Cell body appears to grow out to one side
- One process (axon) which branches
- Central and Peripheral branch
- Found within sensory ganglia of most cranial nerves
What characterises multipolar neurons? Give an example
Single cell body with many processes - one axon (axon hillock on cell labelled 4) and multiple dendrites
E.g. motor neurons
What is the term for sensory receptors at the terminal ends of sensory neurons that detect pain, heat, and cold?
Free Nerve Endings
What is the term for sensory receptors at the terminal ends of sensory neurons that detect cold specifically?
end bulbs
What is the term for sensory receptors at the terminal ends of sensory neurons that detect heat specifically?
Raffini’s corpuscles
What is the term for sensory receptors at the terminal ends of sensory neurons that detect stretch?
stretch receptors
What is the term for sensory receptors at the terminal ends of sensory neurons that detect pressure and rapid vibrations?
Pacinian corpusles
What are the terminal endings of motor neurons called and what characterises them?
motor end plate
Neuromuscular junction - sits within skeletal muscke
Unmuelinated (bare axon at end)
What is the other term for Schwann Cells?
neurolemmocytes
Each Schwann cell membrane (with fatty substance) wraps around _____
Each Schwann cell membrane (M; with fatty substance) wraps around one axon
Schwann cell membranes are also called….
nurilemma or sheath of Schwann
have layers of lipid and protein in rings
What is the term for the unmyelinated gaps at the junctions between two successive Schwann cells in the PNS that allow for saltatory conduction?
Nodes of Ranvier
What is the name of the cell type that myelinates fibres in the CNS?
Oligodendrocytes
Unmyelinated fibres in the PNS are still surrounded by ______ for protection.
schwann cells
(just not sheathed)
What comprises a:
neuron
nerve fibre
nerve
- Neuron: nerve cell (cell body and processes)
- Nerve fibre: axon together with endoneurium
- Nerve: Collection of nerve fibres (PNS) enclosed in connective tissue
What is the term for the connective tissue sheath around a single nerve fibre?
endoneurium
What is the term for the connective tissue sheath around a bundle of nerve fibres (fasciculus)?
perineurium
What is the term for the connective tissue sheath around a nerve (bundle of fasciculi)?
epineurium
