OVERVIEW OF THE NERVOUS SYSTEM Flashcards
Neurons (Nerve Cells)
Basic functional unit (signalling unit), with a cell body, short processes (dendrites, receiving inputs to neurons), long processes (axons, carrying outputs to the next neuron)
Motor Neuron
Impulses from the CNS to the periphery, initiating action
- Short dendrites
- Long axons
Sensory Neuron
Impulses from the periphery to the CNS
- Long dendrites
- Short axons
Glial cells
Non-neuronal cells that do not produce electrical impulses.
- Supporting cells
- Maintains homeostasis, forms myelin and provides supports and protection for neurons
Glial cells in the PNS
Satellite (Supports cell bodies, regulates Co2 and O2 around neurons) and Schwann Cells (Neurotrophic factors, forms myelin sheath)
Glial cells in the CNS
Oligodendrocytes (forms myelin sheaths), microglia (acts as scavengers to remove cell debris), astrocytes (helps maintain the blood brain barrier, forms scar tissue) and ependymal cells (contributing to the formation of CSF)
Glial cells and neurological disease
Most brain tumors are gliomas (occupies the brain and spinal cord)
- Glial cells can undergo mitosis
- Antibodies can attack oligodendrocytes (insulation of neurons are compromised)
Peripheral nervous system
Includes all of the nerves that branch out from the brain and spinal cord and extend to other parts of the body including muscles and organs.
- Connects the CNS to the organs, limbs and skin
- The autonomic nervous system is divided into three parts: the sympathetic nervous system, the parasympathetic nervous system and the enteric nervous system.
Central nervous system
Includes the brain and spinal cord
White matter
White matter is made up of myelinated material, mainly axons, functions to distribute action potentials, coordinating communicaation
-White matter on the outside in the spinal cord and white matter in the centre in the brain (connects all parts of the cortex for communication)
Grey matter
Grey matter is composed of non-myelinated components (cell bodies, synapses)
- A collection of cell bodies creates a mass of grey matter
- This is a nucleus in the CNS
- In the PNS, it is a dorsal root ganglion (transmit sensory information)
- Grey matter is on the centre on the spinal cord and outside in the brain (the cortex on the outside is the processing unit)
Primary Motor cortex
Provides signals for the production of skilled movements
Primary somatosensory cortex
Provides somatic sensations (detecting touch, proprioception, nociception and temperature)
Wernicke’s area
Located on the temporal lobe, left side of the brain
- Language development
- Speech comprehension
Broca’s area
Located on the frontal lobe, left side of the brain
-Linked to speech production
Auditory cortex
Located on the temporal lobe
-Perceiving sound
Meninges
Three layers protecting the brain and spinal cord
- Dura mater: Just below the bone, tough outermost layer
- Arachnoid mater: Contains CSF. cushioning brain
- Pia mater: Innermost layer, aids in CSF production
Ventricles
4 cavities located within the brain that contains CSF
Corpus callosum
Large C-shaped nerve fiber bundle found beneath the cerebral cortex, stretching across the midline of the brain, connecting the left and right hemisphere
- White matter structure
- Ensures communication between the two hemispheres
Internal capsule
White matter structure in the inferomedial part of each hemisphere
- Carries information past basal ganglia (primary motor control)
- Connects brainstem (spinal cord) to the cortex (information processing center)
Thalamus
Paired gray matter structure of the diencephalon located near the center of the brain. It is above the midbrain or mesencephalon, allowing for nerve fiber connections to the cerebral cortex in all directions — each thalamus connects to the other via the interthalamic adhesion.
-Relays sensory and motor signals, regulation of consciousness and alertness
Basal ganglia
Located around the thalamus
- Involved in motor coordination
- A group of subcortical nuclei responsible primarily for motor control, as well as other roles such as motor learning, executive functions and behaviors, and emotions.
- Pathology involves movement disorders such as Parkinson’s disease
Limbic system
A group of structures found deep within the brain, including the hippocampus, amygdala
-Involved in emotion and memory formation
Brainstem
Connects the cerebral hemispheres to the cerebellum and spinal cord
- Where cranial nerves emerge from
- All spinal tracts run through the brainstem
- Maintains and regulates breathing, circulation of blood and level of consciousness
Spinal cord
A column of nerve tissue that runs from the base of the skull down the center of the back.
- The spinal cord and membranes are surrounded by the vertebrae (back bones).
- Relays messages from sensory receptors to the brain
- Pass along messages from sensory receptors to the brain
- Coordinate reflexes
- Most sensory neurons do not pass directly to the brain ut synapses in the spinal cord, allowing faster reflex actions
