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