Unit III: The Nervous System (2)

Question 1

What is the refractory period, and when does it occur?

Answer 1

The plasma membrane does not respond normally to additional depolarization stimuli from when an action potential begins until the resting membrane potential has been reestablished.
*It begins when the voltage-gated- sodium ion channels open at the threshold.

Question 2

What is meant by the propagation of action potential?

Answer 2

The action potential spreads along the surface of an axon and does not diminish as it moves from its source.

Question 3

The rate of the propagation of action potential is determined by what?

Answer 3

Axon diameter and presence of myelin sheaths.

Question 4

Continuous Propagation

Answer 4

*No myelin sheaths.
*Action potentials are much slower
*Action potential spread by depolarizing the adjacent region of the axon membrane.

Question 5

Saltatory Propagation

Answer 5

Term for impulse conduction over myelinated axons.
Action potentials jump from one node to the next.
Action potentials are faster.
Myelin limits the movement of ions across the axon membrane.

Question 6

Synapse

Answer 6

The junction between the processes of two neurons or between a neuron and effector organ, where neural impulses are transmitted by chemical means.

Question 7

What happens when an action potential reaches the axon terminal of the postsynaptic neuron?

Answer 7

Calcium flows in, and vesicles with neurotransmitters move and are released from the last nerve into the synaptic cleft to transmit the signal to the next neuron
Goes from a electrical to chemical

Question 7

Gray matter

Answer 7

Nuclei
Neural Cortex (outer layer of the cerebral cortex)

Question 8

White Matter

Answer 8

Axons with myelin.
(white matter tracts) link with nuclei in other regions of the brain.
With neurons of the neural cortex and spinal cord.

Question 9

Cerebrum

Answer 9

Can be separated into right and left.
Conscious thoughts, sensations, intellect, memory, and complex movements all originate from here.
Largest part of the brain.

Question 10

3 parts of the brain stem

Answer 10

Midbrain, pons and medulla oblongata

Question 11

What protects the brain?

Answer 11

The skull, meninges, cerebrospinal fluid, and blood-brain barrier.

Question 12

What are the three layers of meninges?

Answer 12

Dura mater, arachnoid mater, and pia mater.

Question 13

Dura Mater

Answer 13

Tough sheath, the most outer layer of the three. Has two- periosteal and meningeal.

Question 14

Pia mater

Answer 14

Thin clings to the first layer of brain tissue.

Question 14

Arachnoid Mater

Answer 14

Middle layer, made of collagen and elastin.

Question 15

Cerebrospinal Fluid

Answer 15

Works as a liquid shock absorption, watery cushion, and chemical balance environment for the brain. It is continuously circulating.

Question 16

Blood-Brain Barrier

Answer 16

A stable chemical enviornment contains astrocytes.

Question 16

Where is CSF formed? Where is it located?

Answer 16

Choroid Plexus

It circulates through cavities in the ventricles of the brain and central canal.

Question 17

What substances can and cannot pass through the blood-brain barrier?

Answer 17

Can: Small lipid-soluble molecules, such as alcohol, respiration gases, nicotine, and certain anesthetics.
Cannot: Water-soluble molecules, such as proteins

Question 18

What are the effects of stress on the blood-brain barrier?

Answer 18

It makes the BBB leaky and sensitive to substances.

Question 19

What is the cerebral cortex?

Answer 19

The surface of the cerebral hemisphere that is highly folded and covered by a collection of neurons that form a thin superficial layer of gray matter.

Question 19

What are the functions of the cerebrum?

Answer 19

Interprets all sensory information.
Conscious thought process.
Intellectual functions.
Memory storage and subconscious regulation of skeletal contractions.

Question 20

Where is the cerebral cortex located?

Answer 20

The outermost layer of the brain.

Question 21

What is the functions of the cerebral cortex?

Answer 21

Higher brain functions such as thought, memory, language, reasoning, decision-making, emotion, perception, and voluntary movement.

Question 22

Gyri

Answer 22

Rounded elevated areas- increases the surface area! The more gyri the more neurons that are contained.

Question 23

Sulci

Answer 23

Shallow grooves or depressions.

Question 24

Fissures

Answer 24

Deep grooves- divide large brain regions.

Question 25

Longitudinal Fissure

Answer 25

Divides the brain into halves- right and left.

Question 26

Central Sulcus

Answer 26

Deep grooves divide the anterior frontal lobe from the posterior parietal lobes.

Question 27

What are tracts?

Answer 27

Bundles of nerve fibers, also known as axons, connect different brain and spinal cord areas.

Question 28

Association Fibers

Answer 28

Neurons whose axons communicate on one side of the brain.

Question 29

Commissural Fibers

Answer 29

Carry information from right to left and left to right. Allows for communication on both sides.

Question 30

Projection Fibers

Answer 30

Travel downwardsignals to the spinal cord, sending signals from the lower part of the brain to the spinal cord.

Question 31

What do the projection fibers link?

Answer 31

*Links the cerebral cortex to the diencephalon, brainstem, cerebellum, and spinal cord.

Question 32

What are the three types of functional areas?

Answer 32

Motor, sensory and association.

Question 33

Motor Areas of the Brain

Answer 33

Away from the brain.
Motor output- such as skeletal muscles.
Located on the frontal lobe.

Question 34

Sensory Areas of the Brain

Answer 34

Receiving information.
Located in the parietal, temporal, and occipital lobe.

Question 35

Association Areas of the Brain

Answer 35

Makes sense of the signals
Coordinates incoming and outgoing sensory-motor areas of the cortex.
Located on the parietal, temporal and occipital lobes.

Question 36

Corpus Callosum

Answer 36

Thick band of nerve fibers located deep within the brain that connects the left and right hemispheres.