Transcript
This is amazing. Try to read the paragraph below, then consider what it actually says. The brain is a
wonderful thing isn’t it?
Aoccdrnig to rscheearch at Cmabrigde Uinervtisy, it deosn’t mttaer in waht oredr the ltteers in a wrod are, the olny iprmoatnt tihng is taht the frist and lsat ltteer be at the rghit pclae. The rset can be a total mses and you can sitll raed it wouthit porbelm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe and the biran fguiers it out
aynawy…WOW!
Interesting Brain facts
• The adult human brain weighs about 3 pounds
• Einstein’s was 2.7 pounds
• The human brain has about 100 billion neurons
• The human spinal cord has about 13,500,000 neurons
• The world record for time without sleep is 264 hours or 11 days by Randy Gardner in 1965!
• Unconsciousness will occur 8-10 seconds after loss of blood supply to the brain.
• Neurons multiply at a rate of 250,000 neurons per minute during early pregnancy
General Functions of the Nervous System
• Words to KNOW– Neurons
– Neuroglial cells
– Dendrites
– Axon
– Nerves
– Synapses
– Neurotransmitters
– Central Nervous System
– Peripheral Nervous System
• sensory receptors
• effectors– Somatic
– Autonomic
Cell Types of Neural Tissue• neurons• neuroglial cells
Divisions of the Nervous System
• Central Nervous System• brain• spinal cord
• Peripheral Nervous System• peripheral nerves
• cranial nerves (12)• spinal nerves (31)
Divisions Nervous System
MIGRAINES• Read Clinical Application 10.1• 70% are women; perhaps hormonal influences• Actually a response to changes in the
diameters of blood vessels in the face, head and neck; constricting and dilating
• Classic 4-6 hours• Common 3-4 days• Familial Hemiplegicfew hours to days; also
paralyzes one side of the body
Neuron Structure
Myelination of Axons
White Matter• contains myelinated axons•faster impulses
Gray Matter• contains unmyelinated structures• cell bodies, dendrites
Dendrite
Axon terminal
Schwann cell nucleus
Node of Ranvier
AxonMyelin
Nucleus
Cell Body
Quiz Friday over neurons!!!
Multiple SclerosisClinical Application 10.2
Symptoms• blurred vision• numb legs or arms• can lead to paralysis
Causes• myelin destroyed in various parts of CNS• hard scars (scleroses) form• nerve impulses blocked• muscles do not receive innervation• may be related to a virus
Classification of Neurons
Bipolar• two processes• eyes, ears, nose
Unipolar• one process• ganglia
Multipolar• many processes• most neurons of CNS
Classification of Neurons
Sensory Neurons• carry impulse to CNS• most are unipolar• some are bipolar
Interneurons• link neurons• multipolar• in CNS
Motor Neurons• multipolar• carry impulses away from CNS• carry impulses to effectors
Regeneration of A Nerve Axon
The Synapse
Nerve impulses pass from neuron to neuron at synapses
Synaptic Transmission
-Impulse travels away on axon- Synaptic knob becomes permeable to Calcium ions, they flood in- Allows synaptic vesicles to fuse with the membrane
Synaptic Transmission
-Neurotransmitters are released via exocytosis into the synaptic cleft-Neurotransmitters float over to receptors on the postsynaptic neuron (dendrite)-Impulse continues-Reuptake occurs with leftover neurotrans- mitters or they are broken down
Neurotransmitters
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