nervous_system

Nervous System : 

Nervous System Central Nervous System (CNS): brain and spinal cord. Peripheral Nervous System (PNS): nerves of the body                      -- Includes 31 pairs of spinal nerves                    -- And  12 pairs of cranial nerves

Basic Divisions of the Nervous System : 

Basic Divisions of the Nervous System Figure 12.2

THREE BASIC FUNCTIONS OF THE NERVOUS SYSTEM : 

THREE BASIC FUNCTIONS OF THE NERVOUS SYSTEM Sensory -  gathers info Integrative - information is brought together Motor - responds to signals, homeostasis

Peripheral Nervous System : 

Peripheral Nervous System SOMATIC NERVOUS SYSTEM  -  skeletal muscles, under voluntary control AUTONOMIC NERVOUS SYSTEM - smooth muscles, glands, involuntary

Neurons : 

Neurons

Neuroglial Cells  (p 208) : 

Neuroglial Cells  (p 208) - support cells for the neurons   1.  Microglial : scattered throughout, digest debris or bacteria 2.  Oligodendrocytes:  provide insulation around the axons 3. Astrocytes:  connect blood vessels to neurons 4.  Ependymal Cells:  form a membrane that covers brain-like parts

Slide 7: 

5.  Schwann cells:  form the insulating sheath around the neurons within the PERIPHERAL nervous system *Myelin Sheaths - necessary for insulation of neurons

Supporting Cells in the CNS : 

Supporting Cells in the CNS Microglial cells respond to immunological alarms

Supporting Cells in the CNS : 

Supporting Cells in the CNS Creates the myelin sheath that insulates axons

Supporting Cells in the CNS : 

Supporting Cells in the CNS Astrocytes connect neurons to blood vessels

Supporting Cells in the CNS : 

Supporting Cells in the CNS Figure 12.12a

Supporting Cells in the CNS : 

Supporting Cells in the CNS

Supporting Cells in the CNS : 

Supporting Cells in the CNS

Supporting Cells : 

Supporting Cells

Neuron Structure : 

Neuron Structure Neurofibril -  fibers Chromatophilic substance (rough ER) - transport system Myelin -insulation surrounding axons Nodes of Ranvier - gaps in the insulation

White vs Grey Matter : 

White vs Grey Matter Myelinated (white matter) – myelinated axons Unmyelinated (grey matter) - unmyelinated

Label : 

Label

NEURON (main cell of the nervous system) : 

NEURON (main cell of the nervous system) All neurons do three things: Receive a signal. Can be any type of stimulus (change in environment, signal from another neuron, etc). Transmit a signal to another location. E.g. finger touching something • signal to spinal cord or brain. Stimulate another cell Another neuron • transmit signal Muscle • contraction Gland • secretion

The Neuron : 

The Neuron Other special characteristics Longevity – can live and function for a lifetime Do not divide – fetal neurons lose their ability to undergo mitosis; neural stem cells are an exception High metabolic rate – require abundant oxygen and glucose

Types of Neurons : 

Types of Neurons Functional: Sensory, Motor, Interneurons Structural: (A) Bipolar(B) Unipolar(C) Multipolar

Nerve Impulses : 

Nerve Impulses

Nerve Impulses : 

Nerve Impulses At rest, the inside of a neuron's membrane has a negative charge. As the figure shows, a Na+ / K+ pump in the cell membrane pumps sodium out of the cell and potassium into it. However, because the cell membrane is a bit leakier to potassium than it is to sodium, more potassium ions leak out of the cell. As a result, the inside of the membrane builds up a net negative charge relative to the outside.

Slide 25: 

Animations of Nerve Impulses http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter14/animation__the_nerve_impulse.html http://outreach.mcb.harvard.edu/animations/actionpotential.swf

The Synapse : 

The Synapse Synapse - junction between two communicating neurons Nerve pathway - nerve impulse travels from neuron to neuron Synaptic Transmission Dendrite ' cell body ' along axon ' synapse (gap) To complete the signal, a NEUROTRANSMITTER is released at the gap to signal the next neuron

Structure of a Synapses : 

Structure of a Synapses Figure 12.8a, b

Neurotransmitters : 

Neurotransmitters Excitatory - increase membrane permeability, increases chance for threshold to be achieved Inhibitory - decrease membrane permeability, decrease chance for threshold to be achieved

Types of Neurotransmitters : 

Types of Neurotransmitters Acetylcholine - stimulates muscle contraction Monoamines - Norepinephrine & Dopamine (sense of feeling good, low levels = depression) Serotonin (sleepiness) Endorphins (reduce pain, inhibit receptors)

Drugs that Affect Synapses and Neurotransmitters : 

Drugs that Affect Synapses and Neurotransmitters Curare Strychnine Cocaine, morphine, alcohol, ether and chloroform Mescaline and LSD Ecstasy

Antidepressants : 

Antidepressants Zoloft is part of a class of drugs called selective serotonin reuptake inhibitors, or  SSRIs for short. SSRIs act on a specific chemical within the brain known as serotonin. This is one of several chemicals used to send messages from one nerve cell to another.

Impulse Processing : 

Impulse Processing Neuronal pool - groups of neurons that make hundreds of synaptic connections and work together to perform a common function

Types of Nerves : 

Types of Nerves Sensory Nerves - conduct impulses into the brain or spinal cord Motor Nerves - carry impulses to muscles of glands Mixed Nerves - contain both sensory and motor nerves

Neurons Classified by Function: Sensory vs. Motor Neurons : 

Neurons Classified by Function: Sensory vs. Motor Neurons Figure 12.11

Nerve Pathways : 

Nerve Pathways Reflex arc - only includes a few neurons Reflex Behavior - automatic, subconscious responses Knee-jerk reflex - maintains uprightedness Withdrawal reflex - avoidance of painful stimuli