Nervous System Flashcards by Gabriel Mervil

Components: brain and spinal cord
Functions: receives, processes, and transfers
information

Central nervous system (CNS):

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Components: nerves outside CNS
Sensory neurons: carry information toward
the CNS
Motor neurons: carry information away from
CNS

Peripheral nervous system (PNS):

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information about changes in the environment carried TO

the CNS. Monitors changes (stimuli) inside and outside body

Sensory input

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sorts, process and interpret sensory input and make appropriate
response

Integration

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Motor output

signals carried AWAY from the CNS; activates effectors

(muscles or glands) to cause a response (motor output) to sensory input

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(SNS) motor neurons – voluntary control over

skeletal muscles

Somatic nervous system

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(ANS) motor neurons – regulates smooth

and cardiac muscles and glands

Autonomic nervous system

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Resting and Digesting”

normal activity

Parasympathetic nervous system

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astrocytes

form brain blood barrier (BBB =
restrict movement of material between blood
and CSF)

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oligodendrocytes

myelin sheath (white 
matter = lipids; surrounds many axons)

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microglia

phagocytosis of microbes and

cellular debris

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produce and circulate CSF

cerebrospinal fluid

ependymal

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Function: support, nourish and protect

6 types!

astrocytes, oligodendrocytes, microglia, ependymal, Schwann Cells, Satellite Cells

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Parts / Structures of a Neuron

Dendrites = process on cell body that conducts an impulse
toward the cell body

Cell body aka Soma = the nucleus and nucleolus
surrounded by cytoplasm and typical organelles

Axon = nerve fiber arising from the cell body, capable of
conducting an action potential / impulse.

Initial segment / axon hillock = cone shaped elevated area;
site of action potential generation

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area of axon where an action potential

occurs (are where there is no myelin sheath)

Node of Ranvier

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dilated terminal end of a neuron ; stores

synaptic vesicles.

Axon terminal

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store neurotransmitters

Synaptic vesicles

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chemical signal released from a

neuron that will bind to a receptor of another cell

Neurotransmitter

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chemical signal released from a

neuron that will bind to a receptor of another cell

Neurotransmitter

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Cluster of

cell bodies

PNS= ganglion,
CNS= nuclei

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Cluster of

cell bodies

PNS= ganglion,
CNS= nuclei

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Bundle of

axons

PNS= nerve
CNS=  tract

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Structural Diversity

Multipolar = motor neuron (Lisa Simpson Model:
single axon, multiple dendrites)

Bipolar = sensory neuron from eyes, ear, nose (see
saw: one main axon, one main dendrite: sensory neuron from
special senses)

Unipolar = somatic sensory neurons: touch and stretch
(hanger shape : one end dendrite, one end axon terminal)

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motor neuron (Lisa Simpson Model: 
single axon, multiple dendrites)

Multipolar

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sensory neuron from eyes, ear, nose (see | saw: one main axon, one main dendrite: sensory neuron from special senses)

Bipolar

somatic sensory neurons: touch and stretch | hanger shape : one end dendrite, one end axon terminal

Unipolar

somatic sensory neurons: touch and stretch | hanger shape : one end dendrite, one end axon terminal

Unipolar

What involves ions channels and membrane potentials (resting, graded and action potentials)?

Electrical Signals in Neurons

What involves ions channels and membrane potentials (resting, graded and action potentials)?

Electrical Signals in Neurons

What are the 4 ion channels in the Electrical Signals in Neurons?

1. leakage = randomly open and close ( leak ions across) 2. voltage = open upon a change in membrane potential; Example = Na+ and K+ movement 3. ligand = open due to attachment of a hormone or neurotransmitter 4. mechanical = open due to vibration, pressure or stretching

randomly open and close ( leak ions | across)

Leakage

randomly open and close ( leak ions | across)

Leakage

open upon a change in membrane | potential; Example = Na+ and K+ movement

voltage

open upon a change in membrane | potential; Example = Na+ and K+ movement

voltage

open due to attachment of a hormone or | neurotransmitter

ligand

open due to vibration, pressure or | stretching

. mechanical

open due to vibration, pressure or | stretching

. mechanical

What are the major intracellular positive | ions (cations)?

Potassium (K+) ions

What are the major extracellular positive | ions (cations).

Sodium (Na+) ions

There are 3 types of potentials:

1. Resting Membrane Potential 2. Action Potential 3. Graded Potential

There are 3 types of potentials:

1. Resting Membrane Potential 2. Action Potential 3. Graded Potential

Define: Resting Membrane Potential (RMP)

70 mV difference from inside to outside of cell • Inside of cell is negative relative to the outside of the cell • RMP = -70 mV • Na+/K+ pump restores

Define: Resting Membrane Potential (RMP)

70 mV difference from inside to outside of cell • Inside of cell is negative relative to the outside of the cell • RMP = -70 mV • Na+/K+ pump restores

Resting Potential can be around___? and what is the average.

-40 - -90 mV Average= -70

Resting Potential can be around___? and what is the average.

-40 - -90 mV Average= -70

The_____? difference between inside and outside a living cell is the resting membrane potential and is said to _____? the cell membrane.

voltage, “polarize”

The_____? difference between inside and outside a living cell is the resting membrane potential and is said to _____? the cell membrane.

voltage, “polarize”

______: due to the existing ion concentration | gradients across plasma membrane

“Potential energy”,

Extracellular fluid

high Na+ concentration

Intracellular fluid

high K+ concentration

1. occurs at the dendrites 2. vary in size and strength 3. travel short distances to axon hillock

Graded Membrane Potentia

1. occurs at the axon hillock 2. one size and strength 3. travel long distance to axon terminals 4. all or none principle: threshold is met

Action Potential

depolarization (positive deflection | toward zero) *AWAY*

EPSP

hyperpolarization (negative | deflection, more negative)

IPSP

• Decrease in membrane potential • Make inside of cell less negative or closer to zero than RMP (-70mV) • Normal means for impulse transmission – stimulation

Depolarization

* Increasing membrane potential * Potential more negative than –70mV * Impulse will not be transmitted - inhibited

Hyperpolarization

THE 2 TYPE PRESYNAPTIC NEURON IMPULSE | GENERATION

Depolarization, Hyperlariztion

Graded potentials increase permeability by opening Na+ | chemical gates - Na+ enters cell

Depolarization

When depolarization reaches critical level (called threshold), Na+ voltage gates open and Na+ rushes in generating action potential (AP) at the axon hillock

Depolarization

AP becomes self-generated (positive feedback)- as Na+ enters neuron through voltage gates, causes other Na+ voltage gates to open

Depolarization

K+ voltage gates open and K+ leaves cell | • Potential moves back toward a negative value

Repolarization

Occurs because K+ gates closes slower than Na++ gates

Hyperpolarization

Na+-K+ pump restores original ionic distribution (Na+ out, K+ in) across membrane of the resting state

Restoration of RMP

THE 4 TYPES GENERATION OF ACTION | POTENTIAL

Repolarization, Hyperpolarization, Restoration of RMP

Define: Propagation of Impulses

Conduction of the nerve impulse or action potential (continuous & saltatory)

unmyelinated axons | very slow

continuous

myelinated axons node of R. to node of R. | very fast

saltatory

• ______ – larger transmits faster •_____ of myelin sheath – increases nerve conduction velocity or transmission; impulse jumps from node to node (Saltatory conduction). No myelin – slower because entire axon (dendrite or cell body) must be depolarized (Continuous conduction)

Axon diameter, Degree | CONDUCTION VELOCITY

Chemical Synapses are;

Axon, Receptors, Synaptic

Chemical Synapses are;

Axon, Receptors, Synaptic

_____ terminals on presynaptic neuron contains synaptic | vesicles which contain neurotransmitters

Axon

_____ terminals on presynaptic neuron contains synaptic | vesicles which contain neurotransmitters

Axon

______for neurotransmitters present on postsynaptic | neuron

Receptors

______for neurotransmitters present on postsynaptic | neuron

Receptors

________–fluid-filled space between neurons

Synaptic cleft

CONDUCTION ACROSS CHEMICAL | SYNAPSES #1?

1. Action potential causes Ca2+ voltage gates to open in axon terminal of presynaptic neuron

CONDUCTION ACROSS CHEMICAL | SYNAPSES #2?

2. Ca2+ entry into pre-synaptic neuron triggers exocytosis - synaptic vesicles fuse with membrane of axon terminal to release neurotransmitters

CONDUCTION ACROSS CHEMICAL | SYNAPSES #3?

3. Neurotransmitters bind to receptors on postsynaptic membrane

CONDUCTION ACROSS CHEMICAL | SYNAPSES

4. Chemical gated ion channels open in postsynaptic membrane – type of ion channel opened determines if post-synaptic cell is an IPSP or EPSP

FATE OF NEUROTRANSMITTERFATE OF NEUROTRANSMITTER

1. Diffusion of NT away from synapse • Ex. Dopamine 2. Enzyme degradation of neurotransmitter • Ex. Acetylcholine (acetylcholinesterase) 3. Reuptake of NT into presynaptic terminal or Astrocytes • Ex. Norepinephrine, Serotonin