The Nervous System 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...

1 2 3 4 5 6

17% 17% 17%17%17%17%1. Somatic division

2. Sympathetic division

3. Parasympathetic

4. Afferent division

5. Efferent division

6. Control center

The fight or flight response is the...

1 2 3 4 5 6

17% 17% 17%17%17%17%1. Somatic division

2. Sympathetic division

3. Parasympathetic division

4. Afferent division

5. Efferent division

6. Control Center

A change in ambient temperature would be detected by

1 2 3 4 5

11%

0%

22%

33%33%1. Somatic division

2. Sympathetic division

3. Afferent division

4. Efferent division

5. 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

1 2 3

94%

6%0%

1. multipolar

2. bipolar

3. unipolar

The part of the neuron that has receptor proteins on its surface is

1 2 3 4

33%

17%17%

33%1. Dendrites

2. soma

3. axon

4. Myelin sheath

The part of the neuron that increases the speed of transmission is the

1 2 3 4

6%

44%

38%

13%

1. Dendrites

2. soma

3. axon

4. 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

K+Proteins-

Net - charge

Leak channels – always open (K+ diffuses out)

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

1 2 3 4

0% 0%0%0%

1. Increases electrical impulse

2. Causes the release of more neurotransmitters

3. Is released in a synaptic cleft

4. All of the above

The resting membrane potential inside a neuron is

1 2 3 4

0% 0%0%0%

1. 0mV

2. 30mV

3. -60mV

4. -70mV

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

1 2 3

0% 0%0%

1. depolarization

2. repolarization

3. hyperpolarization

The action potential is propagated by

1 2 3 4

0% 0%0%0%

1. More Na+ rushing into the cell

2. K+ leaving the cell

3. Neurotransmitters binding to dendrite

4. Vesicles release neurotransmitters

The cell’s charge at the peak depolarization is

1 2 3 4

0% 0%0%0%

1. 0mV

2. 30mV

3. -60mV

4. -70mV

During repolarization

1 2 3 4

0% 0%0%0%

1. The resting potential is restored

2. K+ diffuse out of cell

3. The cell membrane becomes negatively charged again

4. All of the above

Once the action potential reaches the axon terminal, the signal will be carried to the next neuron by

1 2 3 4

0% 0%0%0%

1. Na+ ions

2. Neurotransmitters

3. K+ ions

4. All of the above

If an excitatory neurotransmitter binds to neuron number one, how will that affect the number of neurotransmitter released?

1 2 3

0% 0%0%

1. more

2. less

3. No effect at all

If previous neuron releases GABA, an inhibitory neurotransmitter, how will that affect neuron #2

1 2 3 4 5 6

0% 0% 0%0%0%0%

1. Increase electrical stimulus

2. Decrease electrical stimulus

3. Increase neurotransmitters released

4. decreased neurotransmitters released

5. 1&3

6. 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