Topic 2 - The Peripheral Nervous System Flashcards
What is homeostasis?
Maintenance of a constant, balances environment within the body
What are ganglia?
The plural of ganglion, in the PNS they are groups or knots of cell bodies
What are the two main sections of the nervous system?
The Central Nervous System (CNS), The Peripheral Nervous System (PNS)
What is the CNS made up of?
The brain and spinal chord
What is the PNS made up of?
All the neurones carrying information to and from the CNS
What are affecter neurones?
They carry information to the CNS
What are effector neurones?
They carry information away from the CNS
What are the two divisions of the PNS?
The autonomic nervous system and the somatic nervous system
What are the two divisions of the autonomic nervous system?
The sympathetic and parasympathetic
What is a neurone?
The basic structural and functional unit of the nervous system
What are the 3 parts of the neurone?
The axon, the cell body and the dendrites
How is information relayed along a neurone?
Information is relayed electrically along axons and dendrites through the movement of ions
What does the axon do?
The axon carries information away from the cell body, axons of one neurone connect with the dendrites of other neurones, or with other cells at synapses
What do dendrites do?
Dendrites carry information to the cell body (Detect)
What does the spinal cord consist of?
The spinal cord consists of ascending and descending neurones that carry information to and from the brain
What protects the spinal cord?
The spinal cord is protected by the vertebrae, it runs through a canal created by tunnels in each vertebrae (the vertebral canal)
What is the difference between a child and adult spine?
In children the end of the spinal cord is level with the L3 vertebrae, the vertebral column grows faster than the spinal cord into adulthood where the spinal cord ends level with L1
What is the tunnel called running through the vertebrae?
The vertebral foreman
What happens when the vertebrae are stacked?
When the vertebrae are stacked on top of each other to form the spine, the foreman form the vertebral canal that runs the whole length of the vertebral column
What is the outer section of the spinal cord formed of?
The outer section of the spinal cord is formed of white matter
What does white matter consist of?
The white matter consists of axons of neurones that form ascending or descending pathways
What is the inner section of the spinal cord formed of?
The inner section of the spinal cord is formed from grey matter
What does grey matter consist of?
Grey matter is where cell bodies of neurones are located and is where synapses occur between these cell bodies, their dendrites and axons of other neurones
Where do nerves from the body enter the spinal cord?
The nerves from the body enter through the dorsal roots (dorsal horn)
Where do nerves from the spinal cord exit?
The nerves exit the spinal cord through the ventral root (ventral horn)
What runs through the lateral column?
Descending motor tracts from the cerebral cortex mostly run in the lateral corticospinal tract
What runs through the dorsal column?
Sensory neurones carrying fine touch and proprioception from the limbs run in the dorsal columns
What runs through the ventral horn?
Sensory neurones carrying pain and temperature fibres run separately in the anterolateral fasciculus (aka spinothalamic tract)
LEARN DIAGRAM OF ASCENDING AND DESCENDING TRACTS
NOTES
Where do autonomic nerves run?
Autonomic nerves don’t run within the spinal cord but alongside it in a collection of ganglia
What does the PNS do?
The peripheral nervous system exists to carry information to and from the CNS
What are nerves called that travel to the CNS?
Afferent nerves travel to the CNS
What are nerves called that travel away from the CNS?
Efferent nerves travel away from the CNS
What is the autonomic nervous system and what does it do?
The autonomic nervous system is the ‘subconscious’ control of our bodies, generally innervating smooth muscle of tissues or glands, it is involved with actions such as temperature control (via sweating and vasomotor), continence (control bowel and bladder movements), secretions and gastric motility
Where do autonomic neurones arise from?
Autonomic neurones arise from the spinal cord and directly from the brain