Chapter 4

Question 1

Axon

Answer 1

Transmits an electrical signal (action potential) from soma to synaptic knob

Question 2

Axon Hillock

Answer 2

Integrates excitatory and inhibitory signals from dendrites and fires an action potential if excitatory signal are strong enough to reach the threshold
* Where action potential is initiated

Question 3

Dendrites

Answer 3

Receive incoming signals and carry them to the soma

Question 4

Myelin Sheath

Answer 4

• Acts as insulation around axons
• Speeds up conduction
• Nods of Ranvier form gaps along axon
• Saltatory conduction of action potentials

Question 5

Soma

Answer 5

Cell body and contains nucleus, endoplasmic reticulum, and ribosomes

Question 6

Synaptic Bouton

Answer 6

Lies at end of axon and releases neurotransmitters

Question 7

Nucleus

Answer 7

Collection of cell bodies in central nerous system

Question 8

Ganglion

Answer 8

Collection of cell bodies in peripheral nervous system

Question 9

Astrocyte

Answer 9

Nourish neurons and form blood-brain barrier

Question 10

Ependymal Cells

Answer 10

Produce cerebrospinal fluid

Question 11

Microglia

Answer 11

Ingest and break down waste products and pathogens

Question 12

Olgiodendrocytes

Answer 12

Produce myelin in central nervous system

Question 13

Schwann Cells

Answer 13

Produce myelin in peripheral nervous sytem

Question 14

Na+/K+ ATPase

Answer 14

• Maintains resting membrane potential
• At approximately -70 mV

Question 15

Temporal Summation

Answer 15

Integration of multiple signals close to each other in time

Question 16

Spatial Summation

Answer 16

Integration of multiple signals close to each other in space

Question 17

Sodium Channel

Answer 17

• Opens first at threshold (~ -50 mV)
• Regulated by inactivation (~ 35 mV)
• Only reversed by repolarizing cell
• Opening of sodium channel causes depolarization

Question 18

Potassium Channel

Answer 18

• Opens second (~ 35 mV)
• Regulated by closing at low potentials (little below ~ -70 mV)
• Opening of potassium channel causes repolarization, eventually hyperpolarization

Question 19

Absolute Refractory Period

Answer 19

Cell unable to fire an action potential regardless of intensity of stimulus

Question 20

Relative Refractory Period

Answer 20

Cell can fire an action potential only with stimulus stronger than normal

Question 21

Calcium

Answer 21

Responsible for fusion of neurotransmitter vesicles with nerve terminal membrane

Question 22

Stopping Neurotransmitter’s Action

Answer 22

1. Enzymatic Degradation
2. Reuptake
3. Diffusion

Question 23

Central Nervous System

Answer 23

Made up of brain and spinal chord

Question 24

Peripheral Nervous System

Answer 24

Made up of cranial and spinal nerves and sensors

Question 25

Afferent (Sensory) Neurons

Answer 25

Bring signals from sensor to central nervous system * Enters spinal cord on the dorsal side * Recieves stimulus bringing it to threshold * Receptor becomes depolarized allowing it to transduce stimulus to action potential * Sensory neuron to CNS where neurotransmitters released

Question 26

Efferent (Motor) Neurons

Answer 26

Bring signals from central nervous system to effector

Question 27

Somatic Nervous System

Answer 27

Responsible for voluntary actions * Most notably moving muscles

Question 28

Autonomic Nervous System

Answer 28

Responsible for involuntary actions Ex: heart rate, bronchial dilation, dilation of pupils, exocrine gland function, peristalsis

Question 29

Sympathetic Nervous System

Answer 29

* Promotes fight-or-flight response * Ex: increased HR, bronchial dilation, redistribution of blood to locomotor muscles, dilation of pupils, slowing of digestive and urinary function

Question 30

Parasympathetic Nervous System

Answer 30

* Promotes rest-and-digest functions * Ex: slowing HR, constricting bronchi, redistributing blood to gut, promoting exocrine secretions, constricting pupils, promoting peristalsis and urinary function

Question 31

Monosynaptic Reflex

Answer 31

Sensory (afferent, presynaptic) neuron fires directly onto a motor (efferent, postsynaptic) neuron

Question 32

Polysynaptic Reflex

Answer 32

* Sensory neuron may fire directly onto motor neuron but interneurons are used too * Interneurons fire onto other motor neurons

Question 33

Resting Membrane Potential

Answer 33

Depends on differential distribution of ions across axon membrane and active transport of ions across membrane

Question 34

Nerves

Answer 34

* Individual axons that are bundled * Single nerve can carry multiple types of information (sensory, motor, or both)

Question 35

Tracts

Answer 35

* Individual axons bundled * Contains only one type of information

Question 36

Hyperpolarized

Answer 36

Potential across axon membrane is more negative than normal resting potential * Occurs right after an action potential and caused by excess potassium exiting neutron

Question 37

Depolarized

Answer 37

Potential across axon membrane is less negative than normal resting potential

Question 38

Repolarized

Answer 38

Restoring of membrane pontential following depolarisation

Question 39

Polarized

Question 40

Somatic Division Peripheral Nervous System

Answer 40

* Innervates skeletal muscles * Responsible for voluntary movement * Reflex arcs (reflexive responses to certain stimuli that involve only sensory and motor neuron) * Pathway can involve various amounts of neurons

Question 41

Preganglionic Neuron

Answer 41

Releases Acetylchole as neurotransmitter in sympathetic and parasympathetic nervous system

Question 42

Postganglionic Neuron

Answer 42

Sympathetic Nervous System: Releases norepinephrine Parasympathetic Nervous System: Releasess acetylcholine

Question 43

Voltage-Gated Calcium Channels

Answer 43

* Nerve terminal depolarizes * Channels open allowing influx of Calcium * Calcium triggers fusion of synaptic vesicles containing neurotransmitters with membrane of neuron at nerve terminal * Exocytosis of neurotransmitters into synapse