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Nervous System. Chapter 10 & 11. Do Now . T hink of at least 2 ways in which the Integumentary system is directly related to the Nervous system, and describe them in your notebook Watch this video and tell me if you know what the problem is. What are his symptoms?
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Nervous System Chapter 10 & 11
Do Now • Think of at least 2 ways in which the Integumentary system is directly related to the Nervous system, and describe them in your notebook • Watch this video and tell me if you know what the problem is. What are his symptoms? • http://www.youtube.com/watch?v=InSn2BLDwfQ
The Nervous System : communication A. Neurons = masses of nerve cells that transmit information 1. Cell Body - contains the nucleus and two extensions 2. Dendrites – shorter, more numerous, receive information 3. Axons – single, long “fiber” which conducts impulse away from the cell body, sends information
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 Figure 12.2
Sensory - gathers info • Integrative - information is brought together • Motor - responds to signals, homeostasis THREE BASIC FUNCTIONS OF THE NERVOUS SYSTEM
Motor Functions Somatic Nervous System - skeletal (voluntary) Autonomic Nervous System - smooth muscles, glands (involuntary)
Neuroglial Cells (p 208) - support cells for the neurons 1. Microglial Cells: scattered throughout, digest debris or bacteria Microglial cells respond to immunological alarms
Neuroglial Cells (p 208) 2. Oligodendrocytes: provide insulation around the axons
Neuroglial Cells (p 208) 3. Astrocytes: connect blood vessels to neurons I connect to blood vessels
Neuroglial Cells (p 208) 4. Ependymal Cells: form a membrane that covers brain-like parts
5. Schwann cells: form the insulating myelin sheath around the neurons Practice with neuroglia coloring!
Axon - long section, transmits impulses Dendrite - small extensions from the cell body; receive information Neurofibrils - fibers within the axon
Chromatophilic substance (rough ER) - transport system • Myelin -insulation surrounding axons • Nodes of Ranvier - gaps in the insulation
Myelinated (white matter) – myelinated axons Unmyelinated (grey matter) - unmyelinated White vs Grey Matter
Interesting Facts about the Neuron The nerve fibers of newborns are unmyelinated - this causes their responses to stimuli to be course and sometimes involve the whole body. Try surprising a baby! 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
Functional: Sensory, Motor, Interneurons Structural: (A) Bipolar(B) Unipolar(C) Multipolar Types of Neurons
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, 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. Nerve Impulses 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
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 The Synapse
Excitatory - increase membrane permeability, increases chance for threshold to be achieved Inhibitory - decrease membrane permeability, decrease chance for threshold to be achieved Neurotransmitters
Acetylcholine - stimulates muscle contraction • Monoamines - Norepinephrine & Dopamine (sense of feeling good, low levels = depression) • Serotonin (sleepiness) • Endorphins (reduce pain, inhibit receptors) Types of Neurotransmitters
Curare • Strychnine • Cocaine, morphine, alcohol, ether and chloroform • Mescaline and LSD • Ecstasy Drugs that Affect Synapses and Neurotransmitters
Dangers of Ecstasy (MDMA) The neurotransmitter serotonin is vital in regulating many of our basic functions. Serotonin is, among other things, the feel good neurotransmitter and helps to regulate body temp. Our brain cells are constantly trying to bring some amount of serotonin back into the cells and out of the synapse using serotonin reuptake transporters. Ecstasy essentially takes these upkeep transporters and reverses their roles. This causes a massive flood of serotonin from the brain cells into the synapse. The most common cause of Ecstasy-related death is overheating (hyperthermia). MDMA interferes with the body's ability to regulate its own body temperature and to see other warning signs allowing the body to overheat without discomfort especially when dancing for hours in hot clubs.
LSD; lysergic acid diethylamide Actions/Effects: LSD alters the action of the neurotransmitters serotonin, norepinephrine, and dopamine, triggering extreme changes in brain function. Physical effects include increased body temperature, heart rate, and blood pressure. Psychological effects include perceptual and thought distortions, hallucinations, delusions, and rapid mood swings. Cocaine blocks reuptake of dopamine
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. Antidepressants
Neuronal pool - groups of neurons that make hundreds of synaptic connections and work together to perform a common function These "pools" help us remember sequential tasks, like tying a shoe or riding a bike. 9.8 Impulse Processing
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 9.9 Types of Nerves
Neurons Classified by Function: Sensory vs. Motor Neurons Figure 12.11
Reflex arc - only includes a few neurons • Reflex Behavior - automatic, subconscious responses • Knee-jerk reflex - maintains uprightedness • Withdrawal reflex - avoidance of painful stimuli 9.10 Nerve Pathways
9.11 The Meninges Dura mater - outermost layer Arachnoid mater - no blood vessels, in between layer (resembles a spider web) Pia mater -inner membrane, contains nerves and blood vessels to nourish cells
The Meninges CSF - cerebrospinal fluid See video of a Spinal Tap Figure 13.25a
passes down the vertebral canal, has 31 segments (each with a pair of spinal nerves) Spinal Cord Cervical enlargement = supplies nerves to upper limbs (neck)Lumbar enlargement = supplies nerves to the lower limbs (lower back) FUNCTION: conducting nerve impulses, serves as a center for spinal reflexes
ASCENDING - impulses travel to the brain (sensory)DESCENDING - impulses travel to the muscles (motor)
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