T14. FUNCTIONS OF THE NERVOUS SYSTEM

Question 1

What is the main role of the nervous system in homeostasis?

Answer 1

It contributes to internal coordination by sending messages between cells using electrical and chemical signals.

Question 2

How does the endocrine system communicate?

Answer 2

By means of chemical messengers (hormones) secreted into the blood.

Question 3

What are the anatomical divisions of the nervous system?

Answer 3

Central nervous system (CNS) and peripheral nervous system (PNS).

Question 4

What structures are part of the CNS?

Answer 4

Brain and spinal cord enclosed in bony coverings.

Question 5

What structures are part of the PNS?

Answer 5

All nerves and ganglia outside the brain and spinal cord.

Question 6

What are the basic functions of the nervous system?

Answer 6

Motor (skeletal muscle control), sensory (senses control), and automatic (reflexes).

Question 7

What are the higher functions of the nervous system?

Answer 7

Cognition (thinking), emotions (feelings), and consciousness.

Question 8

What are the 3 basic steps of body control by the nervous system?

Answer 8

1. Sensory input, 2. CNS processing, 3. Effector output.

Question 9

What is the first step in nervous system control of the body?

Answer 9

Sensory receptors detect information, which is carried by afferent neurons via action potentials.

Question 10

What are EPSPs and IPSPs?

Answer 10

Excitatory and inhibitory postsynaptic potentials generated at synapses between neurons.

Question 11

What is the second step in nervous system control of the body?

Answer 11

The brain and spinal cord process input and determine the response based on past experiences.

Question 12

What is the third step in nervous system control of the body?

Answer 12

CNS sends commands to effectors (muscles and glands) via efferent neurons of the PNS.

Question 13

What are the types of conduction in neurons?

Answer 13

Saltatory (myelinated fibers) and continuous (non-myelinated fibers).

Question 14

What happens to most sensory information entering the brain?

Answer 14

Over 99% is discarded as irrelevant.

Question 15

What happens to important sensory information in the brain?

Answer 15

It produces excitatory reactions and is sent to integrative and motor brain regions to initiate a response.

Question 16

What is the storage of information in the brain called?

Answer 16

Memory, which occurs mainly in the cerebral cortex and is a function of synapses.

Question 17

What happens to the majority of sensory input?

Answer 17

It is stored for future control of motor activities and for thinking processes.

Question 18

Where does most memory storage occur?

Answer 18

In the cerebral cortex.

Question 19

What are the three major functional levels of the CNS?

Answer 19

Spinal cord level, lower brain (subcortical) level, and higher brain (cortical) level.

Question 20

What is the spinal cord level responsible for?

Answer 20

Walking, withdrawal reflexes, blood vessel control, GI movements, and urinary excretion.

Question 21

What is the lower brain or subcortical level responsible for?

Answer 21

Subconscious functions like blood pressure, respiration, equilibrium, and feeding reflexes.

Question 22

Which brain areas are involved in lower brain functions?

Answer 22

Medulla, pons, cerebellum, mesencephalon, amygdala, hypothalamus.

Question 23

What responses can still occur after cerebral cortex destruction?

Answer 23

Anger, excitement, sexual response, pain, and pleasure reactions.

Question 24

What is the role of the higher brain or cortical level?

Answer 24

Thought processes and memory; it works with lower centers and cannot function alone.

Question 25

What initiates cortical wakefulness?

Answer 25

Lower brain centers initiate wakefulness in the cerebral cortex.

Question 26

What are neural pools?

Answer 26

Groups of neurons functioning together for specific body functions (e.g. breathing rhythm, walking).

Question 27

What is a discharge zone?

Answer 27

Area where one input neuron can cause postsynaptic cells to fire.

Question 28

What is a facilitated zone?

Answer 28

Area where neurons need assistance from other inputs to fire.

Question 29

What are neural circuits?

Answer 29

Interconnected neurons that process, integrate, and transmit information.

Question 30

What do neural circuits control?

Answer 30

Functions such as breathing rhythm and rhythmic limb movement while walking.

Question 31

What is a diverging neural circuit?

Answer 31

One neuron branches to synapse with several postsynaptic cells.

Question 32

What is a converging neural circuit?

Answer 32

Multiple inputs funnel to one neuron or neural pool.

Question 33

What is a reverberating circuit?

Answer 33

Neurons stimulate each other in sequence, with one reactivating the first to repeat the process.

Question 34

What is a parallel after-discharge circuit?

Answer 34

Input neuron stimulates chains of neurons with different synapses that reconverge and continue firing after stimulus stops.

Question 35

What signals do interneurons in the spinal cord receive?

Answer 35

From peripheral nerves, corticospinal fibers, and descending brain pathways.

Question 36

What happens after interneurons receive converging signals?

Answer 36

They send signals to motor neurons to control muscle function.

Question 37

What happens in the discharge zone of a circuit?

Answer 37

One neuron alone can trigger a postsynaptic response.

Question 38

What happens in the facilitated zone of a circuit?

Answer 38

A neuron needs assistance from other inputs to trigger firing.