Nervous System

Question 1

What are the two main divisions of the nervous system?

Answer 1

Central Nervous System (CNS: brain & spinal cord) and Peripheral Nervous System (PNS: nerves connecting to CNS).

Question 2

What are the three main functions of the nervous system?

Answer 2

Sensory (detect changes), Integrative (process and decide), Motor (respond via effectors).

Question 3

What are the three main parts of a neuron?

Answer 3

Dendrites, cell body, axon.

Question 4

What is the role of dendrites?

Answer 4

Receive signals; provide receptive surfaces; a neuron can have many.

Question 5

What is the role of the axon?

Answer 5

Conducts impulses away from the cell body; only one axon per neuron.

Question 6

What is the function of Schwann cells?

Answer 6

Form the myelin sheath around PNS axons → insulate and speed conduction.

Question 7

What are Nodes of Ranvier?

Answer 7

Gaps between Schwann cells in the myelin sheath where impulses occur.

Question 8

What are the three structural types of neurons?

Answer 8

Unipolar (ganglia), Bipolar (eyes, nose, ears), Multipolar (brain & spinal cord).

Question 9

What are the three functional types of neurons?

Answer 9

Sensory (afferent, unipolar), Interneurons (CNS, multipolar), Motor (efferent, multipolar).

Question 10

Name the 5 major types of neuroglial cells and functions.

Answer 10

Microglial → phagocytize bacteria/debris

Oligodendrocytes → form CNS myelin

Astrocytes → structural support, nutrient regulation, connect neurons to blood vessels

Ependymal cells → form epithelial-like membranes in CNS (ventricles, meninges)

Schwann cells → form PNS myelin, aid axon repair

Question 11

What is the resting membrane potential and how is it maintained?

Answer 11

–70 mV, maintained by sodium-potassium pump (3 Na⁺ out, 2 K⁺ in).

Question 12

What happens when a neuron reaches threshold potential (–55 mV)?

Answer 12

Sodium channels open → Na⁺ rushes in → depolarization. Then K⁺ channels open → K⁺ exits → repolarization.

Question 13

What is an action potential?

Answer 13

A rapid change in membrane potential that travels along an axon.

Question 14

How does myelin affect conduction?

Answer 14

Causes saltatory conduction (impulse “jumps” node to node), which is faster than unmyelinated conduction.

Question 15

What is the “all-or-none” response?

Answer 15

Once threshold is reached, an action potential always fires at full strength.

Question 16

What is a synapse?

Answer 16

The junction between two neurons, separated by a synaptic cleft.

Question 17

What are synaptic knobs?

Answer 17

Axon terminals that release neurotransmitters.

Question 18

What are excitatory vs inhibitory neurotransmitters?

Answer 18

Excitatory → trigger impulses; Inhibitory → prevent impulses.

Question 19

What is convergent conduction?

Answer 19

Many inputs converge on one neuron → additive effect.

Question 20

What is divergent conduction?

Answer 20

One neuron sends impulses to many outputs → spreads the signal.

Question 21

What is the function of a synapse?

Answer 21

It connects a neuron to a second cell, transmitting action potentials.

Question 22

Who discovered that nerves release chemicals instead of only electrical signals?

Answer 22

Otto Loewi – discovered acetylcholine (“Vagusstoff”).

Question 23

What are electrical synapses connected by?

Answer 23

Gap junctions.

Question 24

Most synapses are what type?

Answer 24

Chemical synapses.

Question 25

What triggers neurotransmitter release from vesicles?

Answer 25

Ca²⁺ entering via voltage-gated channels.

Question 26

What is an EPSP?

Answer 26

Excitatory postsynaptic potential (moves membrane toward +).

Question 27

What is an IPSP?

Answer 27

Inhibitory postsynaptic potential (moves membrane toward –).

Question 28

What neurotransmitter did Loewi identify in the vagus nerve?

Answer 28

Acetylcholine (ACh).

Question 29

Where is ACh excitatory?

Answer 29

Neuromuscular junction (NMJ).

Question 30

What is the effect of curare?

Answer 30

Blocks nicotinic ACh receptors → flaccid paralysis.

Question 31

Loss of cholinergic neurons in the hippocampus is linked to what disease?

Answer 31

Alzheimer’s disease.

Question 32

Nicotinic receptors are stimulated by what?

Answer 32

Nicotine (agonist).

Question 33

Muscarinic receptors are found where?

Answer 33

Smooth muscle, cardiac muscle, glands, and brain.

Question 34

What enzyme breaks down ACh?

Answer 34

Acetylcholinesterase (AChE).

Question 35

Botulinum toxin causes what type of paralysis?

Answer 35

Flaccid paralysis.

Question 36

Tetanus toxin causes what type of paralysis?

Answer 36

Spastic paralysis.

Question 37

Dopamine, norepinephrine, and epinephrine are derived from what?

Answer 37

Tyrosine (catecholamines).

Question 38

What neurotransmitter is derived from tryptophan?

Answer 38

Serotonin (5-HT).

Question 39

Parkinson’s disease is caused by degeneration of what neurons?

Answer 39

Dopaminergic neurons in the substantia nigra.

Question 40

Overactivity of the mesolimbic dopamine system is linked to what disorder?

Answer 40

Schizophrenia.

Question 41

What is the main inhibitory neurotransmitter in the spinal cord?

Answer 41

Glycine.

Question 42

What is the most common inhibitory neurotransmitter in the brain?

Answer 42

GABA.

Question 43

Deficiency of GABA neurons is linked to what disease?

Answer 43

Huntington’s disease.

Question 44

What neurotransmitters are excitatory amino acids?

Answer 44

Glutamate and aspartate.

Question 45

Endorphins belong to what class of neurotransmitters?

Answer 45

Endogenous opioids (polypeptides).

Question 46

What neuropeptide strongly stimulates appetite?

Answer 46

Neuropeptide Y.

Question 47

What natural compounds mimic THC in the brain?

Answer 47

Endocannabinoids.

Question 48

What gaseous neurotransmitter is linked to vasodilation and erection?

Answer 48

Nitric oxide (NO).

Question 49

What enzyme converts ATP to cAMP during catecholamine signaling?

Answer 49

Adenylate cyclase.

Question 50

What happens during synaptic plasticity?

Answer 50

Repeated use strengthens (LTP) or weakens (LTD) synapses.