Nervous system lecture

central nervous system

brain and spinal cord

peripheral nervous system

neural tissue outside of central nervous system

spinal nerves

carry impulses to and from the spinal cord

cranial nerves

carry impulses to and from the brain

interoceptors

internal senses (taste, internal pressure)

exteroceptors

external senses (touch, temp, sight, smell, sound)

proprioceptors

monitor position and movement (skeletal muscles and joints)

afferent division of peripheral nervous system

nerves bring sensory info to CNS

efferent division of peripheral nervous system

nerves carry motor commands to effectors (glands, organs and smooth muscle)

somatic nervous system

division of efferent division

Controls voluntary movements of skeletal muscles

autonomic nervous system

division of efferent division

controls involuntary organs, glands, cardiac and smooth muscle

impulses go from hypothalamus to effectors

sympathetic nervous system (fight or flight)

the division of the autonomic nervous system that

increases heart rate, blood flow, energy, breathing, sweating, mental activity

decreases digestion and urination

parasympathetic nervous system (rest and digest)

division of the autonamic nervous system that

decreases heart rate and breathing

increases urination and digestion

neurons

cells that send and receive electrical impulses

amiotic (don't divide)

last entire life

neuroglia

cells that support and protect neurons

perikaryon

neuron cytoplasm

nissl bodies

Rough endoplasmic reticulum in neurons that produce neurotransmitters

dendrites

Branchlike parts of a neuron that are specialized to receive information.

axons

Carry impulses away from the cell body onto the next

multipolar neuron

A neuron with a single axon and multiple dendrites

unipolar neuron

A neuron with one axon attached to its soma

anaxonic neuron

many dendrites but no axon

bipolar neuron

one axon and one dendrite

telodendria (collaterals)

branches at ends of axons

synaptic terminals

tips of telodendria

contain vesicles with neurotransmitters

sensory neurons (afferent)

carry information to the CNS

motor neurons (efferent)

neurons that carry outgoing information from the central nervous system to the effectors

interneurons (association)

links between sensory and motor neurons. found in the brain or spinal cord

responsible for higher functions such as memory, learning and emotion

ependymal cells (CNS)

line ventricles of brain and central canal of spinal cord

secretes and circulates cerebrospinal fluis

astrocytes (CNS)

maintain blood-brain barrier and stabilizes neurons

microglia (CNS)

Migrate through neural tissue

Clean up cellular debris, waste products, and pathogens

Oligodendrocytes (CNS)

produce myelin which insulates axons and increases the speed of action potentials

nodes of Ranvier (CNS)

gaps between myelin (bare axon)

Satellite cells (PNS)

protect/nourish neuron cell bodies in PNS

Function similar to astrocytes of CNS

Schwann cells (PNS)

Form myelin sheath around peripheral axons

fluid inside cell

potassium (K) and anions (A)

fluid outside cell

sodium (Na)

resting potential

-70mV

Depolarization

inside of the cell becomes more positive

greater than -70mV

hyperpolarization

inside of cell becomes more negative

more negative than -70mV

electrical impulses

when cells become more positive

chemically gated channels

Open in the presence of specific chemicals

voltage-gated channels

respond to electrical charges produced by the movement of ions

mechanically gated channels

Respond to membrane distortion (pressure)

sodium potassium pump

a carrier protein that uses ATP to actively transport sodium ions out of a cell and potassium ions into the cell

graded potential

a shift in the electrical charge in a tiny area of a neuron can lead to an action potential if strong enough

graded potential depolarization

sodium enters cell through channel and cell becomes more positive which produces an elecrtical impulse

graded potential repolarization

When the stimulus is removed, sodium pumps out and membrane potential returns to normal

action potential

if graded potential reaches -55mV or more, impulse travels down entire axon

all or none principle

Refers to the fact that the action potential in the axon occurs either full-blown or not at all at -55mV

action potential depolarization

reaches -55mV and voltage gated sodium channels allow more sodium in

action potential repolarization

potential becomes more positive until reaching +30mV and sodium channels close and potassium leaves through channels but remain open until -70mV

action potential refractory period

potassium channels close and potassium goes into cell while sodium leaves

Propagation

The spread of the action potential down an axon

continuous propagation

Action potentials along an unmyelinated axon; slow

saltatory propagation

Action potential along myelinated axon

Faster and uses less energy than continuous propagation

depolarization occurs at nodes of ranvier and jumps over myelin

propagation speed factors

bigger diameter of axon and more myelin=faster

Type A fibers

myelinated, largest diameter

Type B fibers

myelinated, medium diameter

Type C fibers

unmyelinated, smallest diameter

synapse

connection between a neuron and another structure

electrical synapse

presynaptic and postsynaptic locked together at gap junctions and action potential spreads directly to postsynaptic cell

chemical synapse

Neurotransmitters released by the presynaptic cell lead to graded potential in post synaptic cell

steps of a synapse

1. action potential reaches synaptic knob and depolarizes

2. calcium releases and releases neurotransmitters across synaptic cleft

excitatory neurotransmitters

open sodium channels and depolarize postsynaptic membranes, promoting action potentials

inhibitory neurotransmitters

open potassium channels and hyperpolarize postsynaptic membranes, suppressing action potentials

Which type of receptor in your body would detect the sound of a voice of someone talking to you?

exteroceptor

A nerve impulse traveling from the CNS to a sweat gland would travel along the:

autonomic part of the efferent division

Nissl bodies are found in which part of a neuron?

cell body

During a Graded Potential, channels open allowing ________ to move into the neuron causing the cell to depolarize.

sodium

In regards to an action potential, what type of channel opens during repolarization?

voltage gated potassium channels

Sodium Inactivtion occurs during which step of an action potential?

repolarization

Which type of propagation would occur along an unmyelinated axon?

continuous