chapter 37: neurons and nervous system Flashcards by Ryan Wallace

In humans, the central nervous system consists of the _____, which is housed in the _____ and the ______, which is housed in the _____.

a.
spinal cord; vertebral column; sensory neurons; limbs

b.
brain; vertebral column; spinal cord; skull

c.
brain; skull; spinal cord; vertebral column

d.
peripheral nervous system; limbs; brain; skull

c.
brain; skull; spinal cord; vertebral column

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What unique structural adaptations are found in the mammalian brain that allowed mammals to become adept at higher mental activities?

a.
A higher degree of crevasses and folds in the neocortex that increases the surface area of the brain

b.
An increased number of blood vessels that increases the vascularization of the brain

c.
A more direct connection to the spinal cord for faster conduction of neural impulses

d.
A cranium that will protect the brain from damage

a.
A higher degree of crevasses and folds in the neocortex that increases the surface area of the brain

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Which of the following statements about an action potential is not true?

a.
Repolarization occurs when potassium leaves the axon.

b.
There is a rapid change in polarity from about -70 mV to about +35 mV during depolarization.

c.
Depolarization occurs when sodium gates open and allow sodium ions to enter the axon.

d.
Potassium gates open after the sodium gates and allow potassium ions to leave the cell.

e.
An action potential takes 2 to 5 seconds.

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Neurotransmitters are molecules that cross the synaptic cleft and

a.
Always excite the postsynaptic neuron

b.
Integrate the pre-synaptic action potential

c.
Always inhibit the postsynaptic neuron

d.
Either excite or inhibit the postsynaptic neuron

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What portion of the brain provides reasoning to keep us from acting out strong feelings?

a.
Reticular activating system

b.
Pineal gland

c.
Brain stem

d.
Limbic system

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What are characteristics of invertebrate nervous system?

lack neurons and individual cells respond

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3 things that Information gathering from the environment by a vertebrate is aided by:

Paired eyes, ears, and olfactory structures
Cephalization: concentration of nervous tissue in the anterior head region
Bilateral symmetry with a vast increase in the number of neurons

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How are vertebrate nervous systems organized?

-Many more neurons than invertebrates
-Brain controls nervous system
1. Hindbrain
2. Midbrain
3. Forebrain

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what are the two divisions of the nervous system

central nervous system and peripheral nervous system

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What allows mammals to become adept at higher mental activities?

A higher degree of crevasses and folds in the neocortex that increases the surface area of the brain

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two kinds of nervous tissue

neurons and neuroglia

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three parts of a neuron

cell body
dendrites
axons

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what are the different types of neurons

sensory, motor, and interneuron

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what is a sensory neuron

take sensory information from the environment and sends the signal to the brain

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what is a motor neuron?

communicate information from the brain to tissue and organs throughout the body, allowing for movement

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what is an interneuron?

make up the majority of neurons in the body
essentially the “middle man”, transmitting information between sensory and motor neurons
play a key role in learning, memory, and planning

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how does the transmission of nerve impulses work

Movement of unequally distributed ions
Voltage: electrical potential difference between two points

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what is resting potential

-Membrane potential -70 mV (millivolts)
-Ion distribution
-Axon cytoplasm also contains large, negatively charged particles!
-Sodium-potassium pump

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what is action potential

-Rapid change in polarity
-Transport Na+ & K+
-An action potential is generated only after a stimulus larger than the threshold!!
-2 milliseconds

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what is depolarization (action potential)

Inside of a neuron becomes positive because of the sudden entrance of sodium ions
-70 mV to 35 mV

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what is repolarization (action potential)

Inside of a neuron becomes negative due to potassium ions leaving

what are nodes of Ranvier

gaps in myelin sheath around nerve fiber

what is saltatory conduction?

movement of nerve impulses from one node to another via “jump”

action potential moved on previous section undergoes what?

refectory period: Na+ gates unable to open

what is a synapse

connection space between the dendrite of one cell and the axon of another cell -Membrane of first neuron called presynaptic; membrane of next neuron postsynaptic

what is the synaptic cleft

small gap between membranes of the presynaptic and postsynaptic cells

what are neurotransmitters

chemical stored at the ends of axons that is responsible for transmission across synapse -Channels for Ca+ open -Vessels to bind with presynaptic membrane -Neurotransmitters released -Bind with specific receptor proteins at postsynaptic membrane -Either excite or inhibit the postsynaptic neuron

3 major functions of the CNS

1. receives sensory input 2. performs integration 3. generates motor output

what is the CNS protected by?

-Protected by bone -Wrapped in three protective membranes called meninges -Spaces between meninges filled with cerebrospinal fluid

2 major functions of spinal cord

Center for relax actions: automatic responses to external stimuli Communication between brain & spinal nerves

what kind of matter does the spinal cord contain

Central gray matter & peripheral white matter

what is gray matter?

-Nonmyelinated axons and cell bodies in the central nervous system -nerve signals travel slower, no insulation

what is white matter?

-Myelinated axons in the central nervous system -Run together in tracts - insulation - faster signals

Characteristics of the brain

-Brain allows us to perceive our environment, reason, & remember -Nerve pulses same in all neurons -CNS integrates all incoming data

characteristics of the cerebrum

-Largest outermost portion -Communicates & coordinates activities of all other parts of the brain

characteristics of cerebral hemisphere

-Either of the two lobes of the cerebrum in vertebrates -Each control opposite sides of the body

characteristics of the cerebral cortex

-Thin, highly convoluted outer layer of gray matter that covers hemispheres -Tens of billions of neurons

characteristics of the cerebellum

-Portion of the brain that coordinates skeletal muscles to produce smooth, graceful motions -Integrates sensory input from the eyes, ears, muscles, and joins with motor information from the cerebral cortex

characteristics of basal nuclei (or ganglia)

-Bulk of cerebrum composed of white matter; gray matter located deep within white matter -primarily in midbrain -works with cerebellum in integrating motor commands -ensures proper muscle groups are activated at the correct time

what is the reticular activating system

-Complex network of nuclei & nerve fibers -Receives sensory signals -> sends up to higher control centers -Receives motor signals -> sends to spinal cord -relay center, translates motor and sensory signals to cerebrum -filters out unnecessary information

what does the limbic system do?

-Provides reasoning to keep us from acting out strong feelings -emotion regulation -hippocampus and amygdala

what does the hippocampus do

aware of past experiences stored in sensory association areas

what does the amygdala do

cause these experiences to have emotional overtones

characteristics of the peripheral nervous system

-Outside CNS -Contains nerves & ganglia -Paired cranial & spinal nerves part of PNS -Sensory & motor functions

what are the two divisions of the PNS

somatic and autonomic nervous system

functions of the somatic nervous system

-Take sensory information from external receptors in skin & joints to CNS -Carry motor commands away from CNS to the skeletal muscles -works with skeletal muscles: voluntary movement

what is one of the only ways that the somatic nervous system can signal involuntary movement?

the reflex arc

functions of the autonomic nervous system

-Regulates active of smooth & cardiac muscles & glands -Automatic function -Innervate all internal organs -Use two neurons & one ganglion for each impulse

two divisions of the autonomic nervous system

sympathetic and parasympathetic

functions of the sympathetic division

-Fight-or-flight responses -Accelerates heartbeat & dilates bronchi -Active muscles require a ready supply of glucose & oxygen -Inhibits digestive tract -essential in animal survival

functions of the parasympathetic division

-“Housekeeper” -Promotes all internal responses associated with a relaxed state -Promotes digestion, slows heartbeat, dilate pupils