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Human Biology, 13th Edition - Sylvia S. Mader > Ch 13 - Nervous System > Flashcards

Ch 13 - Nervous System Flashcards

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1
Q

What are the two major divisions of the nervous system?

A
  1. The central nervous system (CNS)

2. The peripheral nervous system (PNS)

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2
Q

What body parts belong to the CNS?

A

The brain and spinal chord

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3
Q

What body parts belong to the PNS?

A

Cranial nerves and spinal nerves.

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4
Q

What are the 3 functions of the nervous system?

A
  1. Receives sensory input
  2. Performs information processing and integration, summing up the input it receives from all over the body
  3. Generates motor output. Nerve signals from the CNS go by way of the PNS to muscles, glands and organs
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5
Q

What 2 types of cells does nervous tissue contain, and what is their role?

A
  1. Neurons = transmit nerve signals between parts of nervous system
  2. Neuroglia = support and nourish neurons
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6
Q

What are the different types of neuroglia in the CNS? What about in the PNS?

A

In the CNS…

  1. Microglia
  2. Astrocytes
  3. Oligodendrocytes

In the PNS…
1. Schwann cells

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7
Q

What are astrocytes?

A

Provide metabolic and structural support directly to the neurons

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8
Q

What is microglia?

A

They’re phagocytic cells that help remove bacteria and debris

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9
Q

What are oligodendrocytes?

A

They’re neuroglial cells in the CNS that form the myelin sheath

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10
Q

What are Schwann cells?

A

They’re neuroglial cells in the PNS that compose the myelin sheath. In the CNS, these cells are called oligodendrocytes.

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11
Q

What is a sensory receptor?

A

A special structure that detects changes in the environment

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12
Q

What are interneurons?

A

Neurons that receive input from sensory neurons and also from other neurons in the CNS. Thereafter, they sum up all the information received from other neurons before they communicate with motor neurons. They lie entirely within the CNS.

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13
Q

What are motor neurons?

A

Takes nerve impulses away from the CNS to an effector (muscle fiber, organ or gland)

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14
Q

What are effectors?

A

They carry out responses to environmental changes, whether these are external or internal

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15
Q

What 3 physical structures do all neurons contain? What are their roles?

A
  1. Dendrites = receive signals from sensory receptors or other neurons
  2. Cell body = contains the nucleus and organelles
  3. Axon = conducts nerve impulses
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16
Q

What are nerve fibers composed of? A nerve?

A

Individual axons. Collectively, multiple axons form a nerve.

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17
Q

What is the longest axon in the human body?

A

The longest axons in the human body, for example, are those of the sciatic nerve (a combination of multiple axons), which run from the base of the spine to the big toe of each foot. These single-cell fibers may extend a meter or even longer.

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18
Q

What are nodes of Ranvier?

A

The gaps where there is no myelin sheath

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19
Q

Why is the myelin sheath so important?

A

It plays a very important role in the rate at which signals move through the neuron. For example, when myelin breaks down (as in MS, or multiple sclerosis), it becomes more difficult for neurons to transmit information. In effect, MS “short circuits” the nervous system and causes the nerve signal to fail.

The myelin sheath also plays an important role in nerve regeneration within the PNS. If an axon is accidentally severed, the myelin sheath will remain and serve as a passageway for new fiber growth.

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20
Q

What is MS?

A

Multiple sclerosis. When the myelin sheath breaks down, and neurons can’t transmit information well.

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21
Q

What is resting potential? How does it exist?

A

Like a battery that holds the potential to turn on a flashlight, neurons also has potential, or energy, much like a fully charged battery. This energy is called its resting potential.

It exists because the cell membrane is polarized. In other words, positively charged ions are stashed outside the cell, and negatively charged ions are stashed inside the cell. Inside of the cell, there are large negatively charged proteins that are too big to diffuse across the membrane. Outside of the cell there are positively charged Na+ ions. Positively charged potassium ions (K+) also contribute to the positive charge outside of the cell.

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22
Q

How many volts (or millivolts) of stored energy does a neuron have at resting potential?

A

-0.070 volts, or -70 millivolts (-70mV)

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23
Q

How do neurons maintain resting potential in order to be able to work?

A

Neurons use a protein carrier in the membrane called the sodium-potassium pump, which pumps sodium ions (Na+) out of the neuron and potassium ions (K+) into the neuron. This action “recharges” the cells after the neuron’s resting energy has been used up.

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24
Q

What is an action potential?

A

When a stimulus activates the neuron, and it conducts nerve signals. The stimulus must be strong enough to cause the cell to reach threshold, which is the amount of voltage that will result in an action potential. If the threshold voltage is never reached, an action potential will never occur. Threshold voltage is -55 mV. If that voltage is reached, the action potential happens automatically.

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25
Q

What are the steps the ensue after a stimulus causes the cell to reach threshold?

A
  1. Starting w/ resting potential:
    Inside cell: –
    Outside cell: +
  2. Stimulus causes cell to reach threshold (-55 mV). Depolarization begins…
  3. Depolarization: Sodium-potassium pump opens, and Na+ rushes into cell. Cell charge changes from negative to positive
    Inside: +
    Outside: –
  4. Repolarization: After depolarization occurs, potassium protein channels open and K+ leaves the cell. Cell becomes negative again.
    Inside: –
    Outside: +
  5. Sodium-potassium pump returns K+ ions to the inside of the cell and Na+ ions to the outside of the cell. Negative charge of the axon is maintained as the ions swap places.
    Inside: –
    Outside: +
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26
Q

What is depolarization? Repolarization? How long do these processes take to complete?

A

Depolarization = when the charge (or polarity) inside of the axon changes from negative to positive. The voltage increases from -70 mV to -55 mV to +35 mV.

Repolarization = when the charge (or polarity) inside of the axon changes from positive to negative again. The voltage decreases from +35 to -55 to -70 mV.

The entire process takes 3-4 milliseconds to complete

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27
Q

How are action potentials propagated along an axon? What is saltatory conduction?

A

If an axon is unmyelinated, an action potential at one locale stimulates an adjacent part of the axon membrane to produce an action potential. Conduction along the entire axon in this fashion can be slow (about 1m/second) in thin axons because each section of the axon must be stimulated.

If a fiber is myelinated, an action potential at one node of Ranvier causes an action potential at the next node, jumping over the entire myelin-coated portion of the axon. In thick, myelinated fibers the rate of transmission is more than 100 meters per second (m/s).

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28
Q

What is a refractory period?

A

A way to ensure the one-way direction of a signal from the cell body down the length of the axon to the axon terminal. As soon as the action potential has passed by each successive portion of an axon, that portion undergoes a short refractory period during which it is unable to conduct an action potential.

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29
Q

What separates the sending neuron from the receiving neuron?

A

Synaptic cleft

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30
Q

How are signals transmitted at the synapses?

A
  1. Nerve signals travel through an axon
  2. An action potential arrives at an axon terminal where synaptic vesicles enclose neurotransmitters, waiting to be released
  3. Calcium ions (Ca2+) enter the axon terminal, which stimulates the synaptic vesicles to migrate to and fuse with the plasma membrane
  4. Synaptic vesicles release neurotransmitters into the synaptic cleft
  5. Neurotransmitters bind to receptors on the membrane of the receiving neuron
    6a. When an EXCITATORY neurotransmitter binds to a receptor, Na+ diffuses into the receiving neuron, and another action potential begins.
    6b. When an INHIBITORY neurotransmitter binds to a receptor, K+ exits the receiving neuron, which prevents an action potential from kicking off.
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31
Q

Is acetylcholine an inhibitory or excitatory neuron?

A

In the PNS…

In skeletal muscles it’s excitatory (to cause muscles to contract). In cardiac muscle it’s inhibitory, causing heart rate to slow down.

It has either an excitatory or inhibitory effect on smooth muscle or glands, depending on their location.

Active in the CNS and PNS.

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32
Q

What characterizes an excitatory vs. an inhibitory neurotransmitter (NT)?

A

Excitatory if NTs cause Na+ to diffuse into the receiving neuron.

Inhibitory if NTs cause K+ to exit the receiving neuron.

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33
Q

What are two different ways a neurotransmitter is removed from the synaptic cleft?

A
  1. It’s reabsorbed by the sending membrane, possibly for repackaging in the synaptic vesicles or for molecular breakdown
  2. It’s inactivated by enzymes
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34
Q

What is the enzyme called that inactivates acetylcholine?

A

AChE = Acetylcholinesterase

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35
Q

What would happen if the neurotransmitter were to linger inside of the synaptic cleft?

A

The receiving cell would be unable to respond to a new signal from a sending cell

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36
Q

Is norepinephrine an inhibitory or excitatory neuron? Why’s it important?

A

Generally it excites smooth muscle. In the CNS, norepinephrine is important to dreaming, waking, and mood.

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37
Q

What is serotonin?

A

It’s involved in the thermoregulation, sleeping, emotions and perception

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38
Q

What is synaptic integration?

A

The summing up of all excitatory and inhibitory signals to see which type of signal is happening the most. If a neuron receives more inhibitory than excitatory signals, summing these signals may prohibit the axon from reaching threshold and then depolarizing. (Because an inhibitory neurotransmitter drives the neuron farther from an action potential, and an excitatory neurotransmitter drives the neuron closer to an action potential)

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39
Q

What are meninges? What are the three layers of the meninges, and where is CSF contained?

A

A protective membrane that surrounds/wraps the spinal cord and the brain. From the outermost to innermost layer:

  1. Dura mater (just under the skull)
  2. Arachnoid (mater)

–2a. Subarachnoid space (where cerebrospinal fluid is contained)

  1. Pia mater (covers the brain)
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40
Q

What is meningitis?

A

An infection of the meninges that is caused by either bacterial or viral pathogens.

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41
Q

What are the spaces between the meninges filled with, and what does that cushion and protect?

A

Cerebrospinal fluid, which cushions and protects the CNS

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42
Q

What is cerebrospinal fluid (CSF), and what roles does it play?

A

It’s the fluid between the 2nd and 3rd layer of the meninges, located between the arachnoid and pia mater. It plays several roles:

  1. Helps protect the CNS by acting like a cushion against sudden impact or injury to brain or spinal cord
  2. Removes waste products
  3. Allows brain and spinal cord to become buoyant (brain weighs 50g vs 1,500g)
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43
Q

How does CSF compare to plasma?

A

Compared to plasma, CSF has a higher concentration of Na+, Cl+ and magnesium. But it has a lower concentration of K+ and Ca+. Has only trace amounts of cells, proteins and immunoglobulins

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44
Q

What are the ventricles?

A

The brain has four ventricles, which are interconnecting chambers that produce and serve as a reservoir for cerebrospinal fluid.

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45
Q

What is hydrocephalus? Speak to babies vs. adults.

A

“Water on the brain”

In an infant, the brain can enlarge due to CSF accumulation. In adults, the brain can’t enlarge, but rather is pushed against the skull and can cause severe brain damage

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46
Q

What is gray matter vs. white matter?

A

Both are types of tissue. The grey matter contains the cell bodies, dendrites and the axon terminals, where all synapses are. The white matter is made up of axons, which connect different parts of grey matter to each other. It is the white matter that allows communication to and from grey matter areas and controls the functions the body is unaware of, such as temperature, blood pressure and heart rate

Gray matter = contains cell bodies and short, nonmyelinated fibers

White matter = contains myelinated axons that run together in bundles called tracts

From wiki: “Grey matter is distinguished from white matter in that it contains numerous cell bodies and relatively few myelinated axons, while white matter contains relatively few cell bodies and is composed chiefly of long-range myelinated axons. The colour difference arises mainly from the whiteness of myelin.”

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47
Q

Where is the spinal cord located?

A

It extends from the base of the brain through a large opening in the skull called the foramen magnum then extends through the vertebral canal

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48
Q

What happens at the intervertebral foramina?

A

Spinal nerves project from the entire spinal cord through small openings called intervertebral foramina

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49
Q

What other part of the CNS contains cerebrospinal fluid besides the meninges?

A

The central canal of the spinal cord

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50
Q

What are the dorsal and ventral roots?

A

Dorsal/sensory roots of a spinal nerve contain sensory fibers entering the gray matter.
—- dorsal = sensory

Ventral/motor root of a spinal nerve contain motor fibers exiting the gray matter
—- ventral = motor

Both roots join before the spinal nerve leaves the vertebral canal, forming a mixed nerve.

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51
Q

Which part of the nervous system do spinal nerves belong to? What about dorsal and ventral roots?

A

Mixed spinal nerves = PNS

Dorsal/ventral roots = CNS

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52
Q

What does white matter contain?

A

Ascending tracts taking information TO the brain (located on back of spine–posterior), and descending tracts take information FROM the brain (located in front of spine (anterior).

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53
Q

Why does the left side of the brain control the right side of the body and vice versa?

A

Because many tracts cross just after they ender and exit the brain

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54
Q

What are tracts?

A

Myelinated axons that run together throughout the nervous system in bundles called tracts. These tracts oftentimes carry the same type of information.

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55
Q

Which type of matter creates the butterfly image in the spine?

A

Grey matter (in the center of the spinal cord). White matter surrounds the grey butterfly

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56
Q

What is the dorsal root ganglion?

A

The cell body of the sensory/dorsal neuron

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57
Q

What does the gate control theory of pain propose?

A

That the tracts in the spinal cord have “gates” and that these gates control the flow of pain messages from the peripheral nerves to the brain. The pain messages can be allowed to pass directly to the brain or can be prevented from reaching the brain. Endorphins can temporarily block pain messages.

58
Q

If the spinal cord is cut in the thoracic region, what happens?

A

The lower body and legs are paralyzed. This is called paraplegia

59
Q

If the spinal cord is cut/injured in the neck area, what happens?

A

Quadriplegia, or complete paralysis

60
Q

What is the role of reflex actions?

A

The spinal cord is the center for thousands of reflex arcs. A stimulus first generates signals that travel in sensory axons to the spinal cord. Interneurons integrate the incoming data and relay signals to motor neurons, which respond to the stimulus and cause muscles to contract. This can be done for skeletal muscles OR internal organs. For example, when blood pressure falls, internal receptors in the arteries and aorta general nerve signals that pass through sensory fibers to the spinal cord thn up the ascending tract to the brain. Nerve signals pass down a descending tract to the spinal cord, where motor signals cause blood vessels to constrict so that blood pressure rises

61
Q

What has the human brain been called?

A

The last great frontier, or the extreme limit of understanding, of biology

62
Q

Which part of the brain is associated with the two lateral ventricles, the third ventricle and the fourth ventricle?

A

1-2: The cerebrum

3: The diencephalon
4: The cerebellum

63
Q

What’s another word for the cerebrum? What role does it play?

A

Also called the telencephalon.

The largest portion of the brain (contains the cortex). It’s the last center to receive sensory input and carry out integration before commanding voluntary motor responses. It communicates with and coordinates the activities of the other parts of the brain

64
Q

What divides the left and right cerebral hemispheres? How do these hemispheres communicate?

A

The longitudinal fissure divides the right and left hemispheres. They communicate via the corpus callosum.

65
Q

What is the corpus callosum?

A

An extensive bridge of nerve tracts between the two hemispheres of the brain, creating a bridge for communication between the two sides of the brain. It’s located in the center of the brain, underneath the cortex. It’s a small, fetus-looking section of the brain

66
Q

What are gyri and sulci?

A

Gyri are the thick folds of the cortex that protrude outward. They’re separated by shallow grooves called sulci that dip inward, which divide each hemisphere into lobes

67
Q

What are the different lobes of the brain?

A

The frontal lobe (forehead)
The parietal lobe (posterior to the frontal lobe)
The occipital lobe (posterior to the parietal lobe)
The temporal lobe (inferior to the frontal and parietal lobes, sitting behind the temple/ears)

68
Q

What is the cerebral cortex in short?

A

An outer layer of gray matter that covers the cerebral hemispheres. It contains over 1 billion cell bodies and unmyelinated axons. It’s the region of the brain that accounts for sensation, voluntary movements and all the thought processes we associate with consciousness

69
Q

What are the two long portions of the cortex called surrounding the central sulcus in the brain?

A

The primary motor area on the left, and the primary somatosensory area on the right

70
Q

What is the primary motor area?

A

It’s in the frontal lobe just before (anterior to) the central sulcus. Voluntary commands to skeletal muscles begin in the primary motor area. The muscles that involve very fine, precise movements take up a large portion of the primary motor area (like swallowing, salivating, expression). Hand movements also require tremendous accuracy. These two structures command 2/3rds of the primary motor area

71
Q

What is the primary somatosensory area?

A

It’s just posterior to the central sulcus in the parietal lobe. Sensory information from the skin and muscles arrive here. The face and hands, again, require the largest proportion of the sensory cortex.

Reception areas for other primary sensations, such as taste, vision, hearing and smell, are located in other areas of the cortex. See pg. 294

72
Q

What are association areas?

A

Places where integration occurs and where memories are stored.

73
Q

What is the main association area of the primary motor area?

A

PREMOTOR AREA (also called motor association cortex – organizes motor functions) –> Primary motor area sends signals to the Cerebellum (integrates them)

74
Q

What is the main association area of the primary somatosensory area?

A

The somatosensory association area (parietal lobe), which processes and analyzes sensory information from the skin and muscles.

75
Q

What is the main association area of the primary visual area?

A

The visual association area (occipital lobe), which associates new visual info with stored visual memories. It might decide if we’ve seen a face, scene or symbol before

76
Q

What is the main association area of the primary auditory area?

A

The auditory association area (temporal lobe), which associates new auditory info with stored auditory memories. It might decide if we’ve heard something before, like the word “mom”

77
Q

What are processing centers?

A

Receive information from the other association areas and perform higher-level analytical functions.

78
Q

What is the prefrontal area?

A

A processing center that receives info from other association areas and uses this information to reason and plan our actions. Integration in this area accounts for our ability to reason, think critically, and formulate appropriate behaviors.

79
Q

What is Wernicke’s area vs. Broca’s area?

A

Processing centers, both found in the left cerebral cortex.

Wernicke’s area = helps us understand both the written and spoken word. Then it sends that information to…

Broca’s area = for grammatical refinement and help stimulating the muscles needed for speaking and writing in the primary motor area.

80
Q

What happens to the brain as more neurons become myelinated?

A

The brain grows in size and complexity, allowing people to be more capable of things like speech and motor skills.

81
Q

What are basal nuclei?

A

Masses of gray matter deep within the white matter that integrate motor commands to ensure that the proper muscle groups are stimulated or inhibited

82
Q

What is Parkinson disease?

A

Believed to be caused by degeneration of specific neurons in the basal nuclei.

83
Q

What structures are located in the diencephalon?

A

Encircles the 3rd ventricle. The hypothalamus and thalamus are located here.

84
Q

What role does the hypothalamus play?

A

It’s an integration center that helps maintain homeostasis. It regulates hunger, sleep, thirst, body temperature, and water balance. It also controls the pituitary gland, which links the nervous system to the endocrine system.

85
Q

What role does the thalamus play?

A

The thalamus receives visual, auditory and somatosensory (touch) input (NOT smell) via cranial nerves and tracts from the spinal cord. The thalamus integrates this information and sends it on to the appropriate portions of the cerebrum. It also participates in higher mental functions such as memory and emotions.

86
Q

What role does the pineal gland play?

A

Secretes melatonin and is located in the diencephalon.

87
Q

What is the cerebellum? What does it look like, and how is it separated from the brain stem?

A

It looks like a sideways tree, where white matter branches out amongst gray matter. It’s separated from the brain stem by the fourth ventricle.

It receives input from the eyes, ears, joints and muscles about the present position of the body parts. Also maintains posture and balance by sending motor signals by way of the brain stem to skeletal muscles. Voluntary movements. Assists the learning of new motor skills, such as playing piano.

88
Q

What structures are located in the brain stem?

A

The midbrain
The pons
The medulla oblongata

89
Q

What role does the midbrain play?

A

Acts as a relay station for tracts passing between the cerebrum and the spinal cord or cerebellum. Also has REFLEX centers for visual, auditory and tactile responses

90
Q

What role does the pons play?

A

Pons = bridge. Contains bundles of axons traveling between the cerebellum and the rest of the CNS. Also functions w/ the medulla oblongata to regulate breathing rate. REFLEX centers coordinate head movements in response to visual and auditory stimuli.

91
Q

What role does the medulla oblongata play?

A

Contains REFLEX centers for regulating heartbeat, breathing and vasoconstriction (blood pressure). Also contains REFLEX centers for vomiting, coughing, sneezing, hiccuping and swallowing.

92
Q

What are ascending vs. descending tracts?

A 
Ascending = groups of axons that travel together to convey sensory information
Descending = groups of axons that travel together to transmit motor information
93
Q

What is reticular formation

A

A complex network of nuclei (which are masses of gray matter) and fibers that extend the length of the brain stem. It’s a component of RAS, or reticular activating system.

94
Q

What is RAS?

A

Reticular activating system (RAS), composed of a network of nuclei, or masses of gray matter. Receives sensory signals and sends them to higher centers. Motor signals sent by way of the RAS are sent to the spinal cord. The RAS arouses the cerebrum via the thalamus and causes a person to be alert. You can awaken the RAS by surprising someone with sudden stimuli, like an alarm clock or hiding behind a door to scare someone.

95
Q

What is the limbic system? What are the main structures within this system?

A

Main structures: Amygdala and the hippocampus
An evolutionary/ancient group of linked structures deep within the cerebrum. It blends primitive emotions and higher mental functions into a united whole. This is why eating and sexual behavior (primitive emotions) seem pleasurable (higher mental functions). Unpleasant emotions, such as hatred, are translated by the limbic system into a stress response.

96
Q

What role does the amygdala play?

A

Sensation of fear. In charge of fight or flight response. Luckily, the frontal cortex can override the limbic system and cause you to rethink the situation and prevent you from acting out strong reactions. Some memories of ours are emotionally charged because the amygdala seems to be responsible for fear conditioning and associating danger with sensory stimuli received from various parts of the brain.

97
Q

What role does the hippocampus play?

A

Believed to play a crucial role in learning and memory. Acts as an information gateway during the learning process. It determines what info about the world is to be sent to memory and how it will be encoded and stored by other regions in the brain. Serves as a bridge between the sensory association areas (where memories are stored) and the prefrontal area (where memories are used to make decisions, solve problems, and plan)

98
Q

What role does the (pre)frontal cortex play?

A

Executive functions. Planning, decision-making, problem-solving and self-control

99
Q

What is Alzheimer disease?

A

A brain disorder characterized by gradual loss of memory.

100
Q

What are the higher mental functions?

A

Memory = ability to hold a thought in mind or recall events from the past

Learning = retain and use memories

Language

Speech

101
Q

What are the different types of memory?

A

Short-term memory = active in our prefrontal area

Long-term memory = a mixture of semantic memory (numbers, words, etc.) and episodic memory (persons, events, etc.). For example, you can’t recall a phone number without thinking about the person associated with that number. Or you can’t think about a word without associating it with a particular event

Semantic memory = numbers, words, etc.

Episodic memory = persons, events, etc.

Skill memory = involved in performing motor activities such as riding a bike or doing gymnastics. You have to think about a skill when you first learn it, but later it becomes automatic

102
Q

Where are long-term memories stored and retrieved?

A

They’re stored in bits and pieces throughout the sensory association areas of the cerebral cortex.
Visions are stored in the vision association area
Sounds in the sound association area, etc.

103
Q

What is long-term potentiation (LTP)?

A

After synapses have been used intensively for a short time, they release more neurotransmitters than before. This creates stronger synaptic connections between neurons, and could play a role in memory. “Neurons that fire together wire together.” This phenomenon called LTP may be involved in memory storage.

104
Q

What type of memory does language depend on?

A

Semantic

105
Q

What would damage to wernicke’s area or broca’s area do?

A

damage to wernicke’s area = inability to comprehend speech
damage to broca’s area = inability to speak and write

For example, if the corpus callosum is severed, the patient is termed “split brain” because there’s no connection between the right and left hemispheres anymore. Thus, if they view and object with only the right eye, the image will be sent to the right hemisphere. The person could choose the correct object for a particular use – scissors to cut paper, for example – but will be unable to name that object.

106
Q

How do the left and right hemispheres differ?

A 
Left = 
Verbal
Logical, analytical
Rational
More global
Right =
Nonverbal, visuospatial
Intuitive
Creative
More specific
107
Q

What is the peripheral nervous system, and what structures does it include?

A

PNS STRUCTURE = includes cranial nerves and spinal nerves.

PNS SYSTEMS: the somatic and autonomic nervous system.

The SOMATIC nervous system is composed of:

  • Voluntary motor output
  • Involuntary reflexes (reflex arc)

The AUTONOMIC nervous system is further divided into two groups:

  • Sympathetic
  • Parasympathetic
108
Q

What are ganglia?

A

Collections of nerve cell bodies outside the CNS.

109
Q

What are nerves?

A

The axons, or long part, of neurons

110
Q

How many pairs of cranial nerves do humans have? What about spinal nerve pairs?

A

12 pairs that are attached to the brain. Some are only sensory nerves, some are only motor fibers, and others are mixed nerves. See pg. 300

We have 31 pairs of spinal nerves. All spinal nerves are mixed nerves.

111
Q

Which cranial nerve represents the vagus nerve?

A

Cranial nerve X (10)

112
Q

What’s the anatomy of spinal nerves?

A

Dorsal = sensory input (direct sensory information toward the spinal cord)

Ventral = sensory output (conduct signals away from the spinal cord)

113
Q

What is the somatic system?

A

Nerves in the somatic system serve the skin, skeletal muscles and tendons. Somatic sensory nerves take sensory information from external sensory receptors to the CNS. Motor commands leaving the CNS travel to skeletal muscles. This creates voluntary movement/motor output.

The somatic system is also controls involuntary reflexes, which are automatic responses to a stimulus in the somatic system.

114
Q

What is a reflex arc, and which part of the PNS is involved in this?

A

This reflex path only involves the spinal cord. If your hand touches boiling water, sensory receptors in the skin generate nerve signals that move along sensory fibers (dorsal) to the spinal cord. Then interneurons synapse with motor neurons, which output to an effector muscle. The effector muscle responds to the stimulus by contracting to pull away your hand as quickly as possible to avoid being burned.

Meanwhile, other interneurons could also synapse with nerves that lead to the brain. That would allow your brain to perceive “pain” and add on other reactions in addition to the reflex that occurred. You might yell out in pain, or wince your face

115
Q

What are some features that both the sympathetic and parasympathetic nervous systems share?

A
  1. They function automatically and usually in an involuntary manner
  2. They innervate all internal organs
  3. They use two neurons and one ganglion for each impulse. The first neuron has a cell body within the CNS and a preganglionic fiber that enters the ganglion. The 2nd neuron has a cell body within a ganglion and a postganglionic fiber that leaves the ganglion.

See pg. 302

116
Q

Where do the preganglionic fibers of the sympathetic arise? What part of the spinal cord?

A

The middle, or thoracolumbar portion. Preganglionic fiber is short, and postganglionic fibers are long. Fight or flight response: Accelerates heart beat and dilates bronchi to get more oxygen, inhibit digestion, etc. The neurotransmitter normally released by postganglionic axons is norepinephrine (NE), which is like epinephrine, or adrenaline.

117
Q

Where do the preganglionic fibers of the parasympathetic arise? What part of the spinal cord?

A

Includes a few cranial nerves (incl. the vagus nerve), as well as fibers that arise from the bottom (sacral) portion of the spinal cord. Referred to as the craniosacral portion of the autonomic system. Preganglionic fiber is long, and postganglionic fibers are short.

Acetylcholine is the nuerotransmitter in the parasympathetic nervous system. Promotes all internal responses of a ‘relaxed’ state. (rest and digest)

118
Q

Comparison of somatic motor and autonomic motor pathways

A

see pg. 303

119
Q

What neurotransmitter is essential in the CNS for memory circuits in the limbic system?

A

Acetylcholine

120
Q

What neurotransmitter is important for dreaming, waking and mood?

A

Norepinephrine

121
Q

What neurotransmitter plays a central role in the brain’s regulation of mood?

A

Dopamine

122
Q

What neurotransmitter is used in the basal nuclei to help organize coordinated movements?

A

Dopamine

123
Q

What neurotransmitter is involved in thermoregulation, sleeping, emotions and perceptions?

A

Serotonin

124
Q

What other neurotransmitter is abundant in the CNS?

A

GABA

125
Q

What are neuromodulators? Provide examples.

A

Naturally occurring molecules that block the release of a neurotransmitter or modify a neuron’s response to a neurotransmitter. Substance P and endorphins are neuromodulators

126
Q

What is substance P?

A

A neuropeptide that is released by sensory neurons when pain is present.

127
Q

What are endorphins?

A

Endorphins block the release of substance P and serve as natural painkillers. They’re produced during a time of physical and emotional stress. Associated with the “runner’s high” of joggers

128
Q

What are the basic modes of action of pharmaceuticals and illegal drugs? What are examples of each, and what do these drugs do on a high level?

A
  1. Promote the action of a neurotransmitter, usually by INCREASing the amount of neurotransmitter at a synapse. a. Xanax and Valium increase GABA to prevent panic attacks and anxiety
    b. Prozac, Paxil and Cymbalta allow norepinephrine or serotonin to accumulate at the synapse. These are anti-depressants.
    c. Drugs used for Alzheimer disease allow acetylcholine to accumulate at the synapses in the limbic system
  2. They interfere with or DECREASE the action of a neurotransmitter
    a. Caffeine keeps us awake by interfering w/ the effects of inhibitory neurotransmitters in the brain.
    b. Antipsychotic drugs for schizophrenia decrease the activity of dopamine
  3. They REPLACE or mimic a neurotransmitter or neuromodulator.
    a. Opiates (codeine, heroin and morphine) bind to endorphin receptors, and thus they reduce pain and produce a feeling of well-being.
129
Q

Define “drug abuse”

A

When a person takes a drug at a dose level and under circumstances that increase the potential for harmful effects. Psychological and/or physical dependence on the drug.

130
Q

What is addiction?

A

Physical dependence on a drug, where a person has become tolerant to the drug. Withdrawal symptoms occur when he/she stops taking the drug.

131
Q

What type of affect do the following drugs have on our CNS and route?

  1. Alcohol
  2. Nicotine
  3. Cocaine
  4. Methamphetamine/ecstasy
  5. Heroin
  6. Marijuana/K2
A
  1. Alcohol - Depressant
  2. Nicotine - Stimulant
  3. Cocaine - Stimulant
  4. Methamphetamine/ecstacy - Stimulant
  5. Heroin - Depressant
  6. Marijuana/K2 - Psychoactive
132
Q

Why is alcohol a depressant?

A

It increases the action of GABA, an inhibitory neurotransmitter. It can lead to feelings of relaxation, lowered inhibitions, impaired concentration and coordination, slurred speech, and vomiting.

133
Q

Why is nicotine a stimulant?

A

Nicotine causes a release of epinephrine from the adrenal glands, increasing blood sugar and causing the initial feeling of stimulation. As blood sugar falls, depression and fatigue set in.

In the CNS, nicotine stimulates neurons to release dopamine, a neurotransmitter that promotes a temporary sense of pleasure, and reinforces dependence on the drug.

134
Q

How is cocaine a stimulant?

A

It’s an alkaloid derived from the shrub Erythroxylon coca. Cocaine interferes with the reuptake of dopamine at synapses, increasing overall brain activity. The result is a rush of well-being that lasts from 5-30 minutes. Crack is the street name for cocaine that is smoked.

135
Q

What happens to a person whose addicted to cocaine?

A

They’re hyperactive with little desire for food or sleep but an increased sex drive. This is followed by a crash period (fatigue, depression, irritability, and lack of interest in sex). Men who use cocaine often become impotent. The brain makes less dopamine to compensate for a seemingly endless supply.

136
Q

What happens when you take meth? How is it made?

A

A rush of euphoria, energy, alertness and elevated mood is the most immediate effect of meth. It’s made in a lab using toxic chemicals, such as common ingredients used in many cold and asthma medications.

137
Q

What is amphetamine psychosis?

A

Chronic use of meth results in this. Characterized by paranoia, hallucinations, irritability and aggressive, erratic behavior

138
Q

What are the side effects of taking ecstasy?

A

Similar side effects as other stimulants, but also interferes with temperature regulation, leading to hyperthermia, high blood pressure and seizures.

139
Q

What is heroin derived from? What does it do? What are its effects?

A

The resin or sap of the opium poppy plant. It binds to endorphin receptors. Long-term users commonly acquire hepatitis, HIV/AIDS and various bacterial infections, due to the use of shared needles.

140
Q

What are opiates?

A

Drugs derived from the opium poppy plant.

141
Q

What does THC do?

A

It binds to a receptor for anandamide, a naturally occurring neurotransmitter that is important for short-term memory processing and perhaps for feelings of contentment.

142
Q

What is K2?

A

A synthetic compound that’s 10x as potent as THC

Human Biology, 13th Edition - Sylvia S. Mader (16 decks)

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