Nervous system Flashcards
What is the nervous system divided into and what are the cell types
Divided into:
Central nervous system (brain + spinal cord)
Peripheral nervous system (cranial + spinal nerves)
Composed of only 2 types of cells:
Neurons – produce & transmit nerve impulse – present in nerves
Supporting cells – aid function of neurons – 5-10X more abundant than neurons (especially in brain)
Label the nerve fibre composition diagram
Label the diagram
Classify the neurons
- Multipolar neurons – motor neurons
- Pseudounipolar neurons – sensory neurons
- Bipolar neurons – found in retina, inner ear & olfaction area of brain
Explain myelination in CNS
Oligodendrocytes responsible for myelinating axons
Each oligodendrocyte can myelinate multiple axons simultaneously
Myelination in CNS occurs in regions such as brain & spinal cord
Explain myelination in PNS
Schwann cells responsible for myelinating axons in PNS
Each Schwann cell myelinates single segment of axon
Gaps between adjacent Schwann cells are called Nodes of Ranvier
What are the supporting cells of PNS
Schwann cells
Form myelin sheath
Satellite cells
Support functions of neurons within sensory & autonomic ganglia
What are the supporting cells of CNS
Oligodendrocytes
Form myelin sheath
Astrocytes
Help form junction between capillaries & neurons
Microglia
Phagocytose pathogens & cellular debris from immune system of brain & spinal cord
Ependymal cells
Line cavities of CNS & produce cerebrospinal fluid
What are the parts of the brain
- Cerebrum
- Cerebellum
- Brainstem
What are the spinal nerve groups
Cervical
Thoracic
Lumbar
Sacral
Caudal
What are the 3 neuronal junctions
Synapses
Neuron-to-neuron
Can be excitatory or inhibitory
Only in grey matter
Neuromuscular junctions
Neuron-to-muscle
Always excitatory
Neuroglandular junctions
Neurone-to-glandular cells
Mostly secretory glands
What is the difference between afferent & efferent neurons
Afferent (sensory) - convey information towards CNS
Efferent (motor) - convey information away from CNS
What are interneurons
Association neurons
Connect 1 point in CNS with another
Used to transfer information between neurons
Extra synapses mean more points for information suppression or enhancement
What are the functional components of peripheral nerves
Motor:
General skeletal muscles
Somatic efferent (GSE)
Mostly under conscious control
General visceral muscles
Autonomic (GVE) - smooth muscle, cardiac muscle, glandular tissue
No conscious control
Sensory
Somatic pain, temperature, touch (GSA)
Kinaesthesia, proprioception (GSA)
Visceral sensation including baroreceptors (GVA)
What are the components of the spinal cord
White matter:
Dorsal columns: ascending (sensory) tracts
Ventral columns: descending (motor) tracts
Grey matter:
Neurones
Synapses
Dorsal horn – sensory neurones
Lateral horn – autonomic neurones
Ventral horn – motor neurones
Central canal
Continuous with ventricles in brain
Fill in the diagram of the spinal cord
Label the diagram of the spinal cord
Dorsal root is afferent
Ventral root is efferent
Join to make spinal nerve
What is the cauda equina
Spinal cord ends before end of vertebral canal due to differential growth rates in fetus
Cauda equina is collection of spinal nerves that descend from bottom of spinal cord within vertebral canal
Starts when spinal nerves end
Components of autonomic nervous system
Sympathetic:
General increase in alert state
Fear, flee, fright, fun & frolic
Widespread effects
Parasympathetic:
Local control of action
Urination, salivary glands, GIT, heart rate
Opposite effects
Label the blood vessels of the brain
What are the arteries supplying the brain
Rostral cerebral arteries – supply medial aspect of cerebral hemispheres
Middle cerebral arteries – supply lateral & ventrolateral aspects of cerebral hemispheres
Caudal cerebral arteries – supply occipital lobes
Rostral cerebellar arteries – supply rostral aspects of cerebellum
Caudal cerebellar arteries – supply caudal & lateral aspects of cerebellum
Label the pink & orange arteries
What is the rete mirabile
Network of vessels located within cavernous sinus
What is the blood brain barrier
Selective barrier between circulating blood & parenchyma of nervous system
Selective block to large molecules
Mainly active transport
