Transcript Slide 1
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 System 1. Sensory input changes = stimuli 2. Integration processing 3. Motor output response to stimuli (The response activates muscles or glands) Neuron Extensions outside the cell body Dendrites – toward the cell body Axons – away from the cell body Figure 7.4a Slide 7.10 Neurons Glial Cells Figure 12.2b Anatomy of the Nervous System Central nervous system (CNS) Brain Spinal cord Peripheral nervous system (PNS) Nerve outside the brain and spinal cord Slide 7.2 Central nervous system (CNS) – Brain – Spinal cord CNS is protected by • Bone • Meninges • CSF Bone Meninges CSF Spinal cord LP? CSF ? Structure of spinal cord • Roots dorsal, ventral • Horns anterior, posterior, lateral • Columns anterior, posterior, lateral Spinal Cord Gray Matter Dorsal White Matter Central Canal Ventral Gray Matter Horns Dorsal Lateral Ventral v v • Root dorsal, ventral • Nerve • Ramus/Brunch anterior, posterior Spinal Cord White Matter Dorsal Ventral White Matter Ascending (Sensory) touch & conscious proprioception unconscious proprioception Figure 16.1 pain & temperature Descending (motor) Muscle balance Muscle movement Brain