Central Nervous System (CNS) Peripheral Nervous System (PNS) The Nervous System Central Nervous System (CNS) Peripheral Nervous System (PNS)

Do Now: Get Your Clicker! Contract a K-W-L chart on loose-leaf List everything you already Know about the Nervous System in the K-column List everything you Want to know in W-column

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... Somatic division Sympathetic division Parasympathetic Afferent division Efferent division Control center

The fight or flight response is the... Somatic division Sympathetic division Parasympathetic division Afferent division Efferent division Control Center

A change in ambient temperature would be detected by Somatic division Sympathetic division Afferent division Efferent division Control Center

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 Internodes – areas covered in myelin Phagocytic cells Secrete cerebrospinal fluid (CSF)

The most common type of neuron is multipolar bipolar unipolar

The part of the neuron that has receptor proteins on its surface is Dendrites soma axon Myelin sheath

The part of the neuron that increases the speed of transmission is the Dendrites soma axon Myelin sheath

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 Leak channels – always open (K+ diffuses out) K+ Proteins- Net - charge Na+ Cl- Gated channels – open/closed under specific circumstance

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 – info moving in the form of action potentials along axons 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 Increases electrical impulse Causes the release of more neurotransmitters Is released in a synaptic cleft All of the above

The resting membrane potential inside a neuron is 0mV 30mV -60mV -70mV

After stimulus, the rush of sodium ions into the cell is called depolarization repolarization hyperpolarization

The action potential is propagated by More Na+ rushing into the cell K+ leaving the cell Neurotransmitters binding to dendrite Vesicles release neurotransmitters

The cell’s charge at the peak depolarization is 0mV 30mV -60mV -70mV

During repolarization The resting potential is restored K+ diffuse out of cell The cell membrane becomes negatively charged again All of the above

Once the action potential reaches the axon terminal, the signal will be carried to the next neuron by Na+ ions Neurotransmitters K+ ions All of the above

If an excitatory neurotransmitter binds to neuron number one, how will that affect the number of neurotransmitter released? more less No effect at all

If previous neuron releases GABA, an inhibitory neurotransmitter, how will that affect neuron #2 Increase electrical stimulus Decrease electrical stimulus Increase neurotransmitters released decreased neurotransmitters released 1&3 2&4 0 of 30

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  toes fan out Plantar reflex (adults only) Stroke sole of foot toes curl Signals sent to brain by interneurons allow for control Ex. Toilet training, gag, blink

Testing reflexes activity