Nervous system

Question 1

Which systems play the most important roles in maintaining homeostasis?

Answer 1

The nervous and endocrine systems

Question 2

What is neurology?

Answer 2

The branch of medical science that deals with the normal functioning and disorders of the nervous system.

Question 3

What are the 3 basic functions of the nervous system?

Answer 3

1. detecting stimuli (sensory function);
2. analyzing, integrating, and storing sensory information (integrative function);
3. responding to integrative decisions (motor function).

Question 4

What does the central nervous system include?

Answer 4

The brain and spinal cord.

Question 5

What does the peripheral nervous system include?

Answer 5

Cranial and spinal nerves.

Question 6

Which two divisions of the PNS are there?

Answer 6

• Afferent (brings sensory information to CNS)

- Efferent (carries motor commands from CNS to muscles/glands/etc

Question 7

Which two subdivisions of the motor (efferent) PNS are there?

Answer 7

Somatic (voluntary control over skeletal muscles)

Autonomic (involuntary control over cardiac + smooth muscles, glands)

Question 8

What two types of cells does nervous tissue consist of?

Answer 8

Neurons and neuroglia

Question 9

What are neurons?

Answer 9

Cells specialized for nerve impulse conduction and provide most of the unique functions of the nervous system, such as sensing, thinking, remembering, controlling muscle activity.

Question 10

What are neuroglia?

Answer 10

They support, nourish, and protect the neurons and maintain homeostasis in the interstitial fluid that bathes neurons.

Question 11

What three parts do most neurons consist of?

Answer 11

Dendrites (main input region)
Cell body (integration occurs)
Axon (main output, usually one per neuron)

Question 12

Which three classifications of neurons are there?

Answer 12

Multipolar, bipolar and unipolar.

Question 13

What are the functional classifications of neurons?

Answer 13

• Sensory (~10^6): carry sensory information to CNS
• Motor (~500k): carry information from CNS to effectors
• Interneurons(~2*10^10) Located within CNS between sensory and motor neurons

Question 14

What is the function of neuroglia?

Answer 14

They support, nurture, and protect neurons and maintain the interstitial fluid that bathes them. (~50% of CNS volume)

Question 15

What do neuroglia include in the two nervous systems?

Answer 15

In CNS: strocytes, oligodendrocytes, microglia and ependymal cells.
In PNS: Schwann cells and satellite cells.

Question 16

Which two types of neuroglia produce myelin sheaths?

Answer 16

Oligodendrocytes and Schwann cells.

Question 17

What is the function of astrocytes?

Answer 17

• Control the chemical environment of the brain
• Brace neurons and form barrier against capillaries
• Abundant, star-shaped cells

Question 18

What is the function of microglia?

Answer 18

• Spiderlike phagocytes

- Dispose of debris

Question 19

What is the function of ependymal cells?

Answer 19

• Line cavities of the brain and spinal cord

- Cilia assist with circulation of cerebrospinal fluid

Question 20

What is the function of oligodendrocytes?

Answer 20

• Wrap around nerve fibers in the central nervous system

- Produce myelin sheaths

Question 21

What is the function of satellite cells?

Answer 21

Protect neuron cell bodies

Question 22

What is the function of Schwann cells?

Answer 22

Form myelin sheath in the PNS

Question 23

How do neurons communicate?

Answer 23

By means of nerve action potentials, or nerve impulses.

Question 24

How are action potentials generated?

Answer 24

The existence of a membrane potential and the presence of coltage-gated channels for NA+ and K+.

Question 25

What is the resting membrane potential (RMP)?

Answer 25

-70mV

Question 26

How does the RMP arise?

Answer 26

An unequal distribution of ions on either side of the plasma membrane and a higher membrane permeability to K+ than to Na+. The level of K+ is higher inside and the level of Na+ is higher outside, a situation that is maintained by sodium–potassium pumps.

Question 27

What is depolarisation?

Answer 27

The loss and then reversal of membrane polarization (from –70 mV to +30 mV) due to the opening of voltage-gated Na+ channels.

Question 28

What is repolerisation?

Answer 28

Recovery of the membrane potential to the resting level due to the opening of voltage-gated K+ channels.

Question 29

What is the all-or-none principle?

Answer 29

If a stimulus is strong enough to generate an action potential, the impulse generated is of a constant size.

Question 30

What is the difference between continuous conduction and saltatory conduction?

Answer 30

In saltatory conduction a nerve impuls leaps from Ranvier nodes along a myelinated axon.

Question 31

What two types of synapses are there?

Answer 31

• Electrical synapses: impulses conducted between adjacent neurons via gap junctions (smooth/cardiac muscle, the brain)
• Chemical synapses: presynaptic neurons release neurotransmitters which will bind to receptors on the plasma membrane of the postsynaptic neuron. Only one-way.

Question 32

What does an excitatory neurotransmitter do?

Answer 32

Depolarizes the postsynaptic neuron’s membrane, brings the membrane potential closer to threshold, and increases the chance that one or more action potentials will arise.

Question 33

What does an inhibitory neurotransmitter do?

Answer 33

hyperpolarizes the membrane of the postsynaptic neuron, thereby inhibiting action potential generation.