T1L17: Principles of the Nervous System 1 Flashcards
Axon hillock
Origin of axon
Very excitable
Axon/nerve fibre
Transmit action potential
Usually only one
Axon terminals
Synapse on other neurons, effector organs or forms specialised ending
Afferent
Information TO CNS
Primary sensory neuron
Efferent
Information AWAY from CNS
Motor neurons
Chemical synapses [4]
Majority
Use neurotransmitters
Depolarisation of presynaptic membrane opens Ca2+ channels
Vesicles fuse +release neurotransmitter
Astrocytes [6]
Provide structural support
Supply nutrients
Maintain ionic environment (remove K+)
Neurotransmitter uptake
Repair nervous system
Form barrier around vessels
Oligodendrocytes [2]
Production and maintenance of myelin sheath
One oligodendrocyte myelinates multiple axons
Microglia [4]
• Immune cells
• Phagocytic (like macrophage)
• Cytotoxic (release H2O2)
Promote repair
Neuroglia of PNS [4]
• Schwann cells = neuroglia of PNS Myelinate axons (spiral wrapping) Important for regeneration - substrate to grow alongside One schwann myelinate one axon cell
Forebrain
• Cerebral hemisphere = highly divided
• Outer grey matter = cerebral cortex
○ 10-20 billion neurons / 2.5 mm thick
○ Highly folded to fit into skull
• Process motor and sensory information
80% of cortex function in cognition
Frontal lobe
Primary motor cortex
Parietal lobe
Primary somatosensory cortex
Temporal lobe
Primary auditory cortex & olfaction
Occipital lobe
Primary visual cortex
Forebrain - thalamus
Relay centre of brain
Paired structure
Centrally located
All sensory NOT smell
Forebrain - hypothalamus
Controls ANS and endocrine system
Hindbrain
Cerebellum coordinate complex muscular movement
Spinal cord
Extend from atlas to 1st lumbar vertebrae
Sit within vertebral canal
PNS to brain (sensory) and back (motor)
Involved in reflexes and segmentally organised
Spinal cord anatomy
Inner core of gray matter: neuronal cell bodies
Outer, white matter: myelinated axons and convey info to/from bones
Peripheral nervous system
• Connects CNS with periphery
• Nerve supply to muscles, glands, skin, vessels, viscera
• Peripheral nerves convey motor, sensory and autonomic axons
Two components:
1. Somatic (voluntary) component
(skeletal muscles, touch, pain)
2. Autonomic (involuntary) component
(organs, vessels)
But many peripheral nerves contain axons from both components
- Therefore, not always anatomically separate
Somatic component - motor
Somatic motor neurons
spinal cord/brainstem cells -> efferent fibres from CNS -> muscle
Somatic component - somatosensory neurons
Axons of primary sensory n external environment (exteroceptive) and within body (proprioceptive)
