nervous system ch 9. pre. and suf. quiz thursday ax- axlegangli- swelling dendr- treelemm- peel/rind...
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Nervous System
Ch 9
Pre. And Suf. Quiz Thursday
• Ax- axle gangli- swelling
• Dendr- tree lemm- peel/rind
• Funi-small cord or fiber moto- moving
• Mening- membrane peri-around
• Plex- interweave sens- feeling
• Syn- together ventr- belly/stomach
What is the nervous system?
• A system of nerves and supporting tissues that create the
• Senses (Sight, Hearing, etc..)
• Thought
• Muscle Movement
• Feelings
What is the job of the nervous system?
• Sensory function: Detect changes in and out of the body.
• Motor function: Effect Muscles & glands.
• Integrative function: To connect the Sensory and Motor function. Produces thought.
What are the two major parts of the nervous system and what are
they composed of?• Central nervous system: Brain
and Spinal chord
• Peripheral nervous system: All other nerves
Vs.
Parts of the Peripheral Nervous System (PNS)
• Somatic Nervous System– Called Voluntary Nervous System
• Autonomic Nervous System– Involuntary Nervous System– 2 Major Branches
• Sympathetic– Fight or flight– Liver: glycogen to glucose, Bronchi dilate,
Adrenaline increases, Heart rate and breathing increase
• Parasympathetic– Calms body down. Decreases Heart and
breathing, increases digestion.
Parasympathetic vs. Sympathetic Nervous System
The NSIn Action
Autonomic Nervous System
in Action
What is nervous tissue?
• Neurons: or nerve cells. Conduct the impulses.
• Neuroglial/ Glial cells: nurse cells to neurons. Protect, feed, speed up the signal. May be the cause of Alzheimer's and Parkinson's.– Schwann Cells: form myelin sheath
What are the parts of a nerve?
• Axon
• Dendrite
• Cell Body
• Nucleus
• Myelin
• Node of Ranvier
What are the types of nerve cells?
• Unipolar: used in ganglia. Nucleus is off to the side.
• Bipolar: used in eyes, nose, and ears. Nucleus is in the middle.
• Multipolar: used in brain and spinal cord. Nucleus is within the dendrites.
Nerve Cell
• Cell body: cytoplasm, organelles: mitochondria, lysosomes, golgi apparatus, and Nucleus.
• Dendrites: pick up the nerve signal.
• Axon: Long, may be branched carry nerve signals Away.
Review of
A Neuron
Do nerve cells reproduce once mature?
• No. That is the problem. They can grow axon ends, but once the nucleus is damaged that nerve will not grow back.
What are Neuroglial Cells?
• Schwann cells: wrap around axon and speeds up nerve signals. Mainly fat called Myelin. Can’t carry nerve signal so the charge jumps over them at the nodes of Ranvier. = Grey Matter
• Astrocytes: Structural support & feed• Microglial Cells: Phagocytize
invaders & broken cell parts
What difference does it make if a nerve has Schwann cells or not?
• Nerves that have a large diameter and are myelinated are super-fast: 120m/s
• Nerves with a small diameter that are unmyelinated are slow: 0.5m/s
How do nerves communicate?
• Through Neurotransmitters: chemical signals sent from the Axon terminals of the nerve.
• Nerves communicate through electrical signals.
• These electrical signals are created through action and resting potentials.
How is an action potential reached?
• Change in nerve membrane permeability. Na+ rushes in the nerve is depolarized (loses its charge).
• K+ then rushes out which repolarizes the nerve cell.
• 1/1000 of a second. Both steps together are the action potential.
• Active transport soon reestablishes the resting potential.
Action Potential
Action Potential Explained
So… How does a nerve signal reach resting potential?
• Nerve has a slightly negative charge inside and a slightly positive charge outside at rest. = Polarized See fig 7.9
• K+ ions are inside, Na+ ions outside. Negative charge can’t diffuse through the membrane.
• Active transport is used to push Na+ out and K+ in. More + leave than enter= neg. charge inside.
What do muscles and nerves have in common?
• All or none response. The nerve impulse is either conducted or not. The intensity of the signal does not change.
How is an action potential sent?
• Write one paragraph explaining it without looking in your notes.
• Someone or someone's will be chosen to read their explanations to the class.
How are Neurotransmitters released?
• Action potential causes Ca+ ions to enter the terminal end of the axon.
• Synaptic vesicles then fuse with the membrane.
• Contents are released into the synaptic cleft.
• Neurotransmitters are decomposed and the vesicles retreat to be refilled.
How do Neurotransmitters Communicate?
Neurotransmitter Actions NIH Worksheet
Group Work: Summarize how you think the neuron works.
NIHNeurotransmitters
What is a Synapse?
• The junction between two communicating nerves.
• Presynaptic neuron to the synaptic cleft to the Postsynaptic neuron
Synaptic Cleft
Impulse
Presynaptic neuron
Vesicle
Transmitters
Synaptic cleft
Receptors
Postsynapticneuron
Postsynaptic activity
If a drug like procaine decreased the membrane permeability to Na+
ions, what would be the effect?
• Impulses from one nerve can not pass to the next region. The action potential can’t be reached. Used by doctors as a local anesthetic.
What kind of neurotransmitters cross the synaptic cleft?
• Acetylcholine: Muscles
• Epinephrine/ Adrenaline: Fight or Flight
• Norepinephrine: almost the same as epinephrine but has no effect on the heart.
• Dopamine: brain functions: not working= schizophrenia and Parkinson's
• Seratonin: suppresses pain impulses
Need a review? Hit the button.Go through each of them EXCEPT the second one.
How does a reflex work?
• Reflex Arc
• Stimulus Receptor end of a Sensory neuron Interneuron (reflex center, often the spinal cord) Motor neuron Effector (Muscle being moved)Response
Reflex Arc
Can you control a reflex?
• No. Reflexes are automatic & unconscious.
• Anesthesiologists will often use this information to test if the medicine is working.
Reflex
Lab
Some neurons are Sensory Receptors
• Naked Nerve Endings=Pain
• Meissner’s Corpuscles= Touch
• Pacinian Corpuscles= Deep Touch
• Many Others: Figure 7.7
Factoid: Your funny bone is really yourUlnar nerve (close to the surface of your body.)
What do other neurons do?
• Mirror Neurons in the Brain
PBS Special: 2005 14 minutes
On Mirror Neurons