Transcript The Nervous System
The Nervous System
Central Nervous System (CNS) Peripheral Nervous System (PNS)
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Get Your Clicker! Contract a K-W-L chart on loose-leaf List everything you already
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Functions
Monitors internal and external environments Integrates sensory information Coordinates voluntary and involuntary responses of other organ systems 2 subdivisions: CNS – brain and spinal cord Intelligence, memory, emotion PNS – all other neural tissue sensory, motor
Receptors and Effectors
Receptors
– receive sensory info
Afferent division
– carries info from sensory receptors to the CNS
Efferent division
– carries info from CNS to PNS effectors (muscles, glands, adipose)
Somatic Nervous System
(SNS) Controls skeletal muscles (voluntary)
Autonomic Nervous System
(ANS) Controls involuntary actions Sympathetic Division (increase heart rate) Parasympathetic Division (decreases heart rate)
Classwork:
Construct a flow chart detailing the direction in which information flows in the nervous system
The sensory part of the PNS is...
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Somatic division Sympathetic division Parasympathetic Afferent division Efferent division Control center
17% 17% 17% 17% 17% 17% 1 2 3 4 5 6
The fight or flight response is the...
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Somatic division
17%
Sympathetic division Parasympathetic division Afferent division Efferent division Control Center
17% 17% 17% 17% 17% 1 2 3 4 5 6
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A change in ambient temperature would be detected by Somatic division Sympathetic division Afferent division Efferent division Control Center
33% 33% 22% 11% 1 0% 2 3 4 5
Label Neuron
Read the functions to determine the structure of a typical neuron
Neurons Communicate w/other neurons
Soma
-Cell body
Dendrites
- receive info
Axon
- sends signal to synaptic terminals (terminal buds)
Synapse
– site of neural communication (gap)
Myelin
– fatty insulation
Node of Ranvier
– exposed axon between myelin 3 structural types:
Multipolar
– multiple dendrites & single axon (motor neurons)
Unipolar
– continues dendrites & axon, cell body lies to side (sensory neurons)
Bipolar
– one dendrite and one axon w/cell body between them (special senses)
Types of Neurons
3 functional types
Sensory
– afferent division info about surrounding environment position/movement skeletal muscles digestive, resp, cardiovasc, urinary, reprod, taste, and pain
Motor
– efferent division (response) skeletal muscles cardiac and smooth muscle, glands, adipose tissue
Interneurons
Brain and spinal cord - memory, planning, and learning
Neuroglia
Regulate environment around neurons; can be phagocytes; actively divide
Functions in CNS: maintains the blood-brain barrier create myelin (lipid) to coat axon
Nodes
– gaps between myelinated sections I
nternodes
– areas covered in myelin Phagocytic cells Secrete cerebrospinal fluid (CSF)
The most common type of neuron is 1.
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multipolar bipolar unipolar
94% 1 0% 2 6% 3
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The part of the neuron that has receptor proteins on its surface is Dendrites soma axon Myelin sheath
33% 33% 17% 17% 1 2 3 4
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The part of the neuron that increases the speed of transmission is the Dendrites soma axon Myelin sheath
38% 44% 6% 13% 1 2 3 4
Complete Action Potential POGIL
Remember: •Discuss each question and answer with your group •Use the information from the models to support your responses •You may use any resources to assist you
Membrane Potential Cells are polarized (measured in volts) Resting potential of neuron -70mV Remains stable due to Na+/K+ Pumps Na+ Cl K+ Proteins Net - charge Leak channels – always open (K+ diffuses out) Gated channels circumstance – open/closed under specific
Changes in Membrane Potential
Depolarization
Stimulus opens Na+ gated channels increase +charge of cell towards 0mV
Action Potentials
Affects entire surface of cell membrane (+) feedback as nerve impulse continues
Hyperpolarization
Stimulus opens K+ gated channels Increases –charge (from -70mV to -80mV) Restores resting potential
Action Potential: All or Nothing Principal Only skeletal muscle fibers and neuron axons have excitable membranes Graded potential increases pressure until sufficient enough to reach action potential Resting potential (-70mV) Reaches Threshold (-60mV) Refractory Period – cell cannot respond to stimulation Depolarization Repolarization Continuous Propagation chain rxn until reaches cell memb Unmyleinated – 1m/s (2mph) Salatory Propagation Myelinated (blocks flow of ions except at nodes) Action potential jumps from node to node 18-40m/s (30-300mph)
Neural Communication
Nerve impulse
in the form of action potentials along axons – info moving At end of axon the action potential transfers to another neuron or effector cell by release of
neurotransmitters
from synaptic terminal (only occur in 1 direction) Activity of neuron depends on balance between:
Excitatory neurotransmitters
depolorization ACh & Norepinephrine
Inhibitory neurotransmitters -
hyperpolarization Dopamine, Seratonin, GABA
An excitatory neurotransmitter
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Increases electrical impulse Causes the release of more neurotransmitters Is released in a synaptic cleft All of the above
0% 1 0% 2 0% 3 0% 4
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The resting membrane potential inside a neuron is 0mV 30mV -60mV -70mV
0% 1 0% 2 0% 3 0% 4
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After stimulus, the rush of sodium ions into the cell is called depolarization repolarization hyperpolarization
0% 1 0% 2 0% 3
The action potential is propagated by 1.
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More Na+ rushing into the cell K+ leaving the cell Neurotransmitters binding to dendrite Vesicles release neurotransmitters
0% 1 0% 2 0% 3 0% 4
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The cell’s charge at the peak depolarization is 0mV 30mV -60mV -70mV
0% 1 0% 2 0% 3 0% 4
During repolarization
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The resting potential is restored K+ diffuse out of cell The cell membrane becomes negatively charged again All of the above
0% 1 0% 2 0% 3 0% 4
Once the action potential reaches the axon terminal, the signal will be carried to the next neuron by 1.
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Na+ ions Neurotransmitters K+ ions All of the above
0% 1 0% 2 0% 3 0% 4
If an excitatory neurotransmitter binds to neuron number one, how will that affect the number of neurotransmitter released? 1.
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more less No effect at all
0% 1 0% 2 0% 3
If previous neuron releases GABA, an inhibitory neurotransmitter, how will that affect neuron #2 1.
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Increase electrical stimulus Decrease electrical stimulus Increase neurotransmitters released decreased neurotransmitters released 1&3 2&4
0 of 30 0% 1 0% 2 0% 3 0% 4 0% 5 0% 6
Reflexes
Reflex
– involuntary response to stimulus w/o requiring the brain
Reflex arc-
sensory neuron Interneuron motor neuron (opposes initial stimulus) Ex. Knee jerk reflex Babinski reflex (infants only) Stroke sole of foot out toes fan Plantar reflex (adults only) Stroke sole of foot toes curl Signals sent to brain by interneurons allow for control Ex. Toilet training, gag, blink