9- structure and function of the mammalian nervous system Flashcards
function of central nervous system
Acts as the coordinator of the nervous system.
components of central nervous system
• Spinal cord.
• Brain.
• Relay neurons (brain interneurons).
components of peripheral nervous system
• Neurons not in the CNS that spread throughout the body.
• Sensory neurons.
• Motor neurons.
• Receptors.
structure of the spinal cord
• Cylinder of nervous tissue in the neural canal of vertebrae.
• Has a thick membranous wall and a small central canal.
• Cerebrospinal fluid provides nutrients to cells lining the canal.
grey matter
• Central area is made up of motor neuron cell bodies, synapses, and relay neurons.
• Grey due to lack of myelin.
white matter
• Longitudinal axons that surround grey matter.
• A myelin sheath gives a lighter appearance to axons.
• Connect different parts of the body.
spinal nerves
• Extend at intervals along the spinal cord.
• They split into dorsal and ventral roots near the spinal cord.
Dorsal roots (uppermost dorsal)
• Carries sensory neurons.
• The cell bodies occur within the dorsal root, forming the dorsal root ganglion.
Ventral root (lower ventral)
Carries motor neurones.
medulla oblongata
• Location → Base of the brainstem.
• Function → Controls breathing and heart rate (i.e. reflex centres).
cerebellum
• Location → Behind the top part of the brainstem, under the occipital lobes.
• Function → Controls balance and coordination of movement, balance and posture.
cerebrum
• Location → Largest part of the brain, encompassing most of the forebrain.
• Function → Initiates voluntary movement, behaviour (personality etc).
hypothalamus
• Location → Below the thalamus, just above the brainstem.
• Function → Thermoregulation, osmoregulation, hormone secretions, basic drives.
autonomic nervous system
• Involuntary.
• Receives input from internal receptors, produces output to smooth muscles and glands.
sympathetic motor system
• Coordinates the fight or flight response.
• Tends to stimulate / increase a process.
• The neurotransmitter is noradrenaline.
• Known as the “adrenergic system”.
parasympathetic motor system
• Coordinates the rest or digest response.
• Tends to inhibit / decrease a process.
• The neurotransmitter is acetylcholine.
• Known as the “cholinergic system”.
• The sympathetic and
parasympathetic systems work antagonistically so that body processes can always be increased or decreased to be optimum.
somatic nervous system
• Voluntary.
• Receives input from sense organs, produces output to skeletal muscles.
