Nervous System. Some Interesting Facts 85 billion (85,000,000,000) neurons in the human brain. 3,000...
-
Upload
shanna-hunter -
Category
Documents
-
view
212 -
download
0
Transcript of Nervous System. Some Interesting Facts 85 billion (85,000,000,000) neurons in the human brain. 3,000...
Nervous System
Some Interesting Facts
• 85 billion (85,000,000,000) neurons in the human brain.
• 3,000 years one cell/second • 1 neuron cell body = 10 microns wide
85,000,000,000 neurons = 850 km
• If you use a basketball (diameter = ~24 cm) as the cell body, then your axon would have to be 240,000 cm (2.4 kilometers)
in length!
► A baby's brain is a mystery.
► The mystery begins in the womb -- only four weeks into gestation the first brain cells, the neurons, are already forming at an astonishing rate: 250,000 every minute.
► Billions of neurons will form links with billions of other neurons and eventually there will be trillions and trillions of connections between cells.
► Every cell is precisely in its place, every link between neurons carefully organized. Nothing is random, nothing by chance.
CNS Development
Functions of the Nervous System1. Sensory input
· changes = stimuli
2. Integration· processing
3. Motor output· response to stimuli
(The response activates muscles or glands)
Neuron
Slide 7.10
· Extensions outside the cell body· Dendrites –
toward the cell body
· Axons –away from the cell body
Figure 7.4a
Neurons
Figure 12.2b
Glial Cells
Anatomy of the Nervous System
Slide 7.2
· Central nervous system (CNS)· Brain
· Spinal cord
· Peripheral nervous system (PNS)· Nerve outside the brain and spinal cord
Central nervous system (CNS)– Brain– Spinal cord
CNS is protected by• Bone • Meninges• CSF
Bone
Meninges
CSF
Spinal cord
CSF ?
LP?
Structure of spinal cord
• Roots dorsal, ventral
• Hornsanterior, posterior, lateral
• Columnsanterior, posterior, lateral
Dorsal
Ventral
WhiteMatter
GrayMatter
CentralCanal
Spinal Cord
Gray Matter
Dorsal
Lateral
Ventral
Horns
vv
• Root dorsal, ventral
• Nerve
• Ramus/Brunchanterior, posterior
Dorsal
Ventral
WhiteMatter
Spinal Cord White Matter
Ascending (Sensory)
Figure 16.1
touch & conscious proprioception
pain & temperature
unconscious proprioception
Descending (motor)
Muscle movement
Muscle balance
Brain