Download Microscopic Nervous System and Reflexes with answers

Microscopic Nervous System and Reflexes Test Review
1. What are the two major divisions of the nervous systems? Central Nervous System, Peripheral Nervous
System
2. Which body structures comprise the central nervous system (CNS)? Brain and spinal cord What is the
CNS function? receive signals and bring them together, creating sensations, adding to memory, or helping to
produce thoughts that translate sensations into perceptions
3. Describe the structure and function of the peripheral nervous system (PNS). PNS is made up of nerves
and sense receptors that lie outside the brain and spinal cord; it is divided into sensory
(afferent)function and motor (efferent) function
4. What is the difference between afferent nerves and efferent nerves? Afferent nerves are sensory
nerves that transmit impulses to the brain and spinal cord; efferent nerves are motor nerves that are
sent out from the CNS to muscles and glands
5. What are the 2 subdivisions of the efferent nerves and the function of each? Somatic NS which is
voluntary and controls the skeletal muscles and the autonomic NS which is involuntary and controls
the heart, smooth muscles and glands
6. Name the 2 types of nervous tissue found in the nervous system. Neurons which transmit impulse and
neuroglial cells which support and protect the neurons
7. Name and tell the function of the 4 nueroglial cells.
Microglial Cells – scattered throughout; support neurons and phagocytize bacterial cells and cellular
debris; Astrocytes – found between neurons and blood vessels; provide structural support, join parts by
numerous cellular processes, help regulate the concentrations of nutrients within tissue; form scar tissue that
fills spaces following injury to the CNS; Ependymal Cells – form an epithelial like membrane that covers
specialized brain parts and forms the linings that enclose spaces within the brain and spinal cord;
Oligodendrocytes: provide support and insulation to axons in the CNS; equivalent to the function performed by
Schwann cells in the PNS
8. What is the difference between white matter and gray matter? White matter is made up of myelinated
neurons and gray matter is made up of unmyelinated neurons; in the brain gray matter is on the
outside and white on the inside, but in the spinal cord white matter is on the outside and gray on the
inside
9. What are neurotransmitters? A chemical molecule that is released at the end of the synaptic knob,
crosses the synaptic cleft, and triggers a nerve impulse on the next neuron, muscle or gland
10. Neurons are classified according to function. How many types are there, and what are their functions?
Sensory Neurons (afferent neurons) – carry impulses from peripheral body parts into the brain or
spinal cord; most are unipolar, but some are bipolar; Interneurons (internuncial or association neurons) –
lie within the brain and spinal cord; multipolar and link other neurons; transmit impulses from one part of the
brain or spinal cord to another; direct incoming sensory impulses to appropriate parts for processing and
interpreting; Motor Neurons (efferent neurons) – multipolar and carry impulses out of the brain or spinal cord
to effectors; stimulate muscles to contract or glands to secrete
11. There are three different neuron structures. Name and describe the structure and function of each.
Cell body (soma) - consists of granular cytoplasm, cell membrane, organelles, and a network of fine threads
called neurofibrils, which extend into nerve fibers; Dendrites – one neuron may have many dendrites; short and
highly branched; together with the membrane, dendrites are the neuron’s main receptive surfaces with which
fibers from other neurons communicate; Axons – one neuron has only one axon; arises from slight elevations of
the cell body; begins as a single fiber but may give off side branches; near its end it may have fine extensions
that contact the receptive surfaces of other cells, transmitting fibers of the neuron
12. What does it mean when a cell membrane is polarized? There is an unequal ion distribution on each
side of the cells membrane causing the inside of the neuron to be negative and the outside to be
positive.
13. What has to happen before an action potential can take place? The cell must receive a stimulus,
sodium channels must open and allow enough sodium to enter the cell body to cause the voltage to go
from -70mV to -55mV which means it has reached threshold
14. What does an action potential do to the membrane of the neuron? Causes sodium channels to open
and sodium to enter which will depolarize the membrane
15. What ions depolarize the membrane? Sodium What ions repolarize the membrane? potassium
16. What factors influence how fast nerve impulses travel? Presence of myelin, diameter of axon, and
body temperature
17. What kinds of effects can neurotransmitters have on receiving cells? Excitatory or inhibitory
18. What ion is necessary for the release of the neurotransmitters? calcium
19. What happens to the neurotransmitters after the action potential ceases? Either decomposed or taken
back up into the synaptic knob
20. Explain what a somatic reflex is and the role the brain plays in it. involuntary stimuli transmitted to skeletal
muscles from neural arcs in the spinal cord
21. What are autonomic reflexes? involuntary stimuli transmitted to cardiac and smooth muscle
What activities do autonomic reflexes influence? carry out autonomic actions of swallowing, sneezing,
coughing, and vomiting
22. Classification of neurons by structure: Bipolar Neurons – cell body has two nerve fibers one arising from
each end; one is an axon and the other is a dendrite; located within specialized parts of the eye, nose and ears;
Unipolar Neurons – single nerve fiber that extends from the cell body then divides into two branches; one
connecting to a peripheral body part and functioning as a dendrite, and the other entering the brain or spinal
cord and functioning as an axon; some cell bodies gather in specialized masses of nervous tissue called
ganglia(located outside the brain or spinal cord); Multipolar Neurons – have many nerve fibers arising from
their cell bodies; only one fiber is an axon and the rest are dendrites; neurons which lie within the brain or spinal
cord
23. What is the sequence of a reflex arc? Stimulus-receptors-afferent neuron-interneuron-efferent neuroneffector-response
24. Be able to label diagrams 6.1 on page 197/6.2 on page 199/ and 6.3 on page 200.
25. Explain neurotransmission from reception of the stimulus to the release of the neurotransmitters. In your
discussion include necessary ions and their actions, changes in polarity, and parts of neuron affected.