Nervous system
Download
1 / 69

Nervous system - PowerPoint PPT Presentation


  • 59 Views
  • Uploaded on

Nervous system. Nervous system. 2 main parts 1) Central Nervous System (CNS) Brain: central processing center Spinal cord: extends down back below brain. Nervous system. 2 main parts 2) Peripheral Nervous System (PNS) Connects CNS to muscles, sensory cells, etc.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Nervous system' - nhung


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

Nervous system1
Nervous system

  • 2 main parts

    • 1) Central Nervous System (CNS)

    • Brain: central processing center

    • Spinal cord: extends down back below brain


Nervous system2
Nervous system

  • 2 main parts

    • 2) Peripheral Nervous System (PNS)

    • Connects CNS to muscles, sensory cells, etc.

    • 12 pairs of cranial nerves (attached to brain)

    • _________ pairs of spinal nerves (attached to spinal cord)


Nervous system3
Nervous system

  • Functions:

    • 1) Monitors changes in external and internal environment

    • Receptors: gather information


Nervous system4
Nervous system

  • Functions:

    • 1) Monitors changes in external and internal environment

    • Receptors: gather information

    • 2) Sends messages in response to information gathered

    • Effectors: cells that respond to message (glands, muscles)


Nervous system5
Nervous system

  • 3 types of nerve cells (neurons)

    • Sensory neurons (act as receptors)

      • Found in skin, organs. Cell body of neuron outside of CNS. Long dendrites, ____________ axons


Nervous system6
Nervous system

  • 3 types of nerve cells (neurons)

    • Motor neurons (carry message to effectors)

      • Cell bodies contained within CNS. Short dendrites, long axons


Nervous system7
Nervous system

  • 3 types of nerve cells (neurons)

    • Association neurons (often link sensory and motor neurons)

      • Cell bodies in CNS. Connect motor and sensory neurons. Connect sensory neurons to ____________


The neuron
The neuron

  • Functional unit of nervous system

  • Neuron: dendrite (incoming messages), cell body, axon (outgoing message)


Neuroglia
Neuroglia

  • Neuroglia (supporting cells)

  • Schwann cells (PNS) and oligodendrocytes (CNS)

  • Form myelin sheath, Nodes of Ranvier


Neuroglia1
Neuroglia

  • Myelinated axons are whitish: called white matter in nerves/spinal cord/brain

  • Unmyelinated axons/dendrites and cell bodies are grayish: called gray matter


Neuroglia2
Neuroglia

  • Secrete myelin (80% ___________)

  • Cells wrap axon in a whitish “jelly roll”: myelin sheath


Neuroglia3
Neuroglia

  • Functions:

    • 1) support and protect nerve cell from injury

    • 2) nourish nerve cell (lies between blood vessels and neurons)

    • 3) electrical insulator: increases rate of impulse, insulates against firing of other neurons

    • 4) aids in regeneration of sensory nerves after ______________


Neuroglia4
Neuroglia

  • Example of importance: Multiple Sclerosis (MS)

  • 2 million people worldwide

  • Body’s immune system attacks myelin sheaths

  • Result: poor nerve impulse conduction. Lose ability to _____________ muscles

  • Cause? Uncertain: genetics, viral infection


How a nerve works
How a nerve works

  • Nerve impulse:

    • electrochemical signal

    • great speed: up to _________ miles per hour

    • resting nerve has charge difference across membrane: membrane “polarized”

    • impulse: wave of depolarization caused by sudden influx of Na+ into axon

    • followed by repolarization: return to original polarized state


How a nerve works1
How a nerve works

  • Resting neuron

    • Lots Na+ outside membrane and K+ on inside

    • Charge is + outside and - inside due to Cl- and proteins on inside of membrane

    • Maintained by Na-K pumps


How a nerve works2
How a nerve works

  • Resting neuron

    • Neuron said to be polarized

    • Charge difference across membrane called _________ potential. About -70 millivolts (mV)


How a nerve works3
How a nerve works

  • Resting neuron movie


How a nerve works4
How a nerve works

  • Firing neuron

    • stimulus arrives

    • if stimulus is enough, causes neuron to fire

    • firing is production of an action potential across membrane: change in _____________ distribution

    • goes from -70 mV (resting potential) to +30 mV (at peak of action potential)


How a nerve works5
How a nerve works

  • Firing neuron

    • 1) membrane channels open to allow Na+ to rush in

    • 2) extra K+ channels open and lots of K+ flows out

    • This repolarizes membrane

    • 3) Refractory period: time during which original state is regenerated by Na-K pumps. During this time, neuron __________ fire again.


How a nerve works6
How a nerve works

  • The firing neuron movie


How a nerve works7
How a nerve works

  • Nerve firing:

    • All or none response. A nerve either fires or it doesn’t

    • Very brief. Lasts about ________ millisecond

    • Transmitted along sections of axon like “the wave” in a stadium


How a nerve works8
How a nerve works

  • Myelin sheaths speed impulse movement

    • allow action potential to jump between nodes

    • action potential only produced at nodes, not in between


How a nerve works9
How a nerve works

  • Myelin sheaths speed impulse movement

    • like stadium with sections of empty seats. “Wave” jumps to next filled section

    • called saltatory conduction


How a nerve works10
How a nerve works

  • Note speed of myelinated axons

  • Note also that axon diameter influences speed of impulse. Larger axon, ___________ speed.


Neuron to neuron transmission
Neuron to neuron transmission

  • 2 neurons usually don’t touch

  • Share synapse: tiny intercellular space (synaptic cleft)


Neuron to neuron transmission1
Neuron to neuron transmission

  • Chemical transmission of impulse:

    • 1)Action potential in firing axon stimulates release of synaptic vesicles into synapse


Neuron to neuron transmission2
Neuron to neuron transmission

  • Chemical transmission of impulse:

    • 2) Vesicles contain neurotransmitters

    • 3) Neurotransmitters diffuse across cleft to _________ proteins in postsynaptic membrane (dendrite of other neuron or muscle cell as shown here)


Neuron to neuron transmission3
Neuron to neuron transmission

  • Chemical transmission of impulse:

    • 4) Receptor proteins cause start of action potential in postsynaptic membrane

    • 5) Enzymes ______________ neurotransmitters when transmission is completed. Prepares synapse for the next impulse.


Neurotransmitters
Neurotransmitters

  • Vital substances in transfer of messages between neurons


Neurotransmitters1
Neurotransmitters

  • 2 main types

    • 1) excitatory transmitters: cause depolarization of postsynaptic membrane

    • 2) inhibitory transmitters: stabilize membrane against depolarization


Neurotransmitters2
Neurotransmitters

  • Acetylcholine: Neurotransmitter between motor nerve axon and skeletal muscle cell

  • Example of excitatory neurotransmitter

  • Causes depolarization of muscle cell membrane and stimulation of ________________


Neurotransmitters3
Neurotransmitters

  • How stop stimulus? Acetylcholinesterase: enzyme breaks down acetylcholine

  • What happens if acetylcholinesterase inhibited? Muscle contraction uncontrolled.

  • This is _________......

  • Some chemicals designed to kill by inhibiting acetylcholinesterase


Neurotransmitters4
Neurotransmitters

  • Nerve gas: works by inhibiting acetylcholinesterase

  • Example, VX gas featured in “The Rock”

VX gas spheres in “The Rock”


Neurotransmitters5
Neurotransmitters

  • Nerve gas: works by inhibiting acetylcholinesterase

  • Example, sarin gas

  • Used in Tokyo subway attack by religious cult in 1995 (12 dead)


Neurotransmitters6
Neurotransmitters

  • Nerve gas: works by inhibiting acetylcholinesterase

  • Example, sarin gas

  • Used by Saddam Hussein and his pal “Chemical Ali” in 1988 against Kurds at Halabjah (5,000 killed)


Neurotransmitters7
Neurotransmitters

  • Nerve gas: works by inhibiting acetylcholinesterase

  • Example, sarin gas

  • US Army used incinerator at Anniston AL to destroy some sarin gas (Sept. 2003)


Neurotransmitters8
Neurotransmitters

  • GABA: an inhibitory neurotransmitter

  • Allows ________ into neuron membrane, making it even more negative inside.

  • Thus harder to develop action potential


Neurotransmitters9
Neurotransmitters

  • Some sedatives take advantage of GABA mechanism

  • Ex, Valium: enhances binding of GABA to its receptors. Harder for neurons to fire.


Neurotransmitters10
Neurotransmitters

  • Serotonin: Involved in sleep regulation and emotional states

  • Insufficient serotonin production involved in depression, Parkinson’s disease


Neurotransmitters11
Neurotransmitters

  • Prozac: blocks reabsorption of serotonin to make up for _________ of production


Neurotransmitters12
Neurotransmitters

  • Serotonin

  • LSD: blocks serotonin receptors in portion of brain to produce hallucinations or “trip”


Neurotransmitters13
Neurotransmitters

  • Cocaine: Affects neurons in brain’s “pleasure pathways” (limbic system)


Neurotransmitters14
Neurotransmitters

  • Slows reabsorption of transmitters, so pleasure messages intensified


Neurotransmitters15
Neurotransmitters

  • Addiction: body adjusts to drug. Example, cocaine

  • Decrease number of neurotransmitter receptors

  • When drug removed, synapse _________ sensitive


Neurotransmitters16
Neurotransmitters

  • Addiction example, nicotine


Neurotransmitters17
Neurotransmitters

  • Nicotine binds to brain receptors that normally bind acetylcholine

  • Influences a number of other neurotransmitters and their receptors

  • Result is stimulating


Neurotransmitters18
Neurotransmitters

  • Problem: brain cells adjust numbers and sensitivities of many brain receptors

  • If nicotine removed (stop smoking), system unbalanced. Effects unpleasant


Neurotransmitters19
Neurotransmitters

  • Example, nicotine

  • Takes time to recover


Synaptic integration
Synaptic Integration

  • Recall that there are two types of neurotransmitters: excitatory and inhibitory

  • So, synapses can be either excitatory or inhibitory, depending on the neurotransmitter produced

  • CNS neurons often receive input from many other neurons


Synaptic integration1
Synaptic Integration

  • Example, 1 spinal cord motor neuron might have 50,000 synapses!

  • Action of that neuron depends on the total effect of both excitatory (red) and inhibitory (blue) inputs


Parts of the nervous system
Parts of the Nervous System

  • Central nervous system: brain and spinal cord


Parts of the nervous system1
Parts of the Nervous System

  • Brain: Hindbrain

    • 1) Medulla oblongata: continuation of spinal cord. Pathway to higher brain centers (traffic controller)

    • Contains reflex centers that control: breathing, heart rate, blood pressure, swallowing

    • Damage to this area is __________!


Parts of the nervous system2
Parts of the Nervous System

  • Brain: Hindbrain

    • 2) Pons: carries impulses from one side of ______________ to other. Regulates chewing, salivation, facial expressions, eye movements


Parts of the nervous system3
Parts of the Nervous System

  • Brain: Hindbrain

    • 3) Cerebellum: receives information from sense organs, muscles, cerebrum

    • Involved in equilibrium, coordination of muscles


Parts of the nervous system4
Parts of the Nervous System

  • Brain: Midbrain

    • 4) Small area in humans: midbrain connects hindbrain to forebrain


5) Brain: Forebrain

  • Cerebrum: Main processing center. Regulates vision, speech, hearing, olfaction, memory, logic, consciousness, etc.


5) Brain: Forebrain

  • Thalamus: analyzes sensory information and relays it to cerebrum

  • Hypothalamus: regulates sleep, metabolism, body temperature, water balance, appetite, thirst, pleasure

  • Note connection of hypothalamus to _____________ gland


Brain comparisons
Brain comparisons

  • Humans with highly developed cerebrum: largest portion of brain


Parts of the nervous system5
Parts of the Nervous System

  • Spinal cord: cable of neurons running down back. Information highway!

  • Inner zone: gray matter. Interneurons and cell bodies of motor neurons

  • Outer zone: white matter. Axons and dendrites of neurons.


Parts of the nervous system6
Parts of the Nervous System

  • Spinal cord: also contains reflex arcs

  • Very fast responses because information doesn’t travel to _______________ for processing


Parts of the nervous system7
Parts of the Nervous System

  • 2 neuron arc: has only sensory and motor neuron involved. Example, knee jerk reflex


Parts of the nervous system8
Parts of the Nervous System

  • 3 neuron arc: has sensory and motor neuron, but ________________ present also. Example, cutaneous spinal reflex


Parts of the nervous system9
Parts of the Nervous System

  • Brain to spinal cord mass ratio

  • Gives rough measure of intelligence

  • Fish/amphibians 1:1

  • Cat 4:1

  • Tailed monkey 15:1

  • Human 55:1

  • ____________ 61:1

  • Who’s more intelligent??


Parts of the nervous system10
Parts of the Nervous System

  • Peripheral Nervous System

    • Afferent system: carry impulse from sensory neuron to CNS. Sensory pathways.

    • Efferent system: carry impulses from CNS to muscles (effectors). Motor pathways.


Parts of the nervous system11
Parts of the Nervous System

  • Peripheral Nervous System

    • Efferent system: carry impulses from CNS to muscles (effectors). Motor pathways.

      • Somatic: CNS to skeletal muscles (_________________)

      • Autonomic: CNS to smooth muscles (involuntary)


Parts of the nervous system12
Parts of the Nervous System

  • Peripheral Nervous System

    • Autonomic: CNS to smooth muscles (involuntary)

    • Made of two antagonistic subdivisions (have __________ effects)

      • 1) Sympathetic

      • 2) Parasympathetic


Parts of the nervous system13
Parts of the Nervous System

  • Autonomic

    • 1) Sympathetic (on edge). Speed up body functions and activities to prepare for defense

    • Increase heart rate, glucose release, decrease blood to digestive system, more blood to muscles


Parts of the nervous system14
Parts of the Nervous System

  • Autonomic

    • 2) Parasympathetic (laid back)

    • _________________ of sympathetic system


ad