Kaplan Prep - Nervous System Flashcards
1
Q
The function of the nervous system is to integrate and control the other body systems. Explain how the nervous system does this.
A
The nervous system receives and processes information and sends out signals to the muscles and glands to elicit an appropriate response. In this way, the nervous system integrates and controls the other systems of the body.
2
Q
What are the 2 parts of the central nervous system?
A
the brain & the spinal cord
3
Q
What are the two ways that the two parts of the central nervous system are protected?
A
The skull protects the brain & the vertebrae protect the spinal cord
4
Q
How do the central nervous system and the peripheral nervous system interact?
A
The central nervous system can SEND signals or impulses TO and RECEIVE impulses FROM the peripheral nervous system
5
Q
What is included in the peripheral nervous system?
A
The peripheral nervous system includes all nerves not in the brain or spinal cord which are the cranial nerves that connect directly to the brain and the spinal nerves which project from either side of the spinal cord.
6
Q
What are the 2 divisions of the peripheral nervous system?
A
The peripheral nervous system can be divided into a sensory or afferent division and a motor or efferent division.
7
Q
Describe the movement of nerve impulses in the peripheral nervous system.
A
The peripheral nervous system receives impulses from the sensory organs via the afferent division and then relays signals or impulses from the central nervous system to muscles and glands via the motor or efferent division.
8
Q
What are the 2 divisions of the efferent division of the peripheral nervous system?
A
The efferent division can be further divided into the somatic system and the autonomic system.
9
Q
What three things are controlled by the somatic nervous system?
A
The somatic system nerves control:skeletal, muscles, skin, joints
10
Q
What two things are controlled by the autonomic nervous system?
A
The autonomic system nerves control:the glands smooth muscles of the internal organs (they are not generally under conscious control)
11
Q
What are the 2 divisions of the autonomic nervous system?
A
The 2 divisions of the autonomic nervous system are the sympathetic and parasympathetic nervous systems.
12
Q
What is the function of the sympathetic nervous system?
A
The sympathetic nervous system: activates and prepares the body for vigorous muscular activity, stress, and emergencies.
13
Q
What is the function of the parasympathetic nervous system?
A
The parasympathetic system: lowers activity operates during normal situations, permits digestion, conserves energy
14
Q
Identify the parts of the neuron shown in the diagram.
A
a = dendrite b = cell body c = nucleus d = axon e = myelin sheath f = Schwann cell g = Node of Ranvier h = axon terminal
15
Q
What are three unusual characteristics of neurons?
A
- Neurons do not undergo mitosis (cell division) 2. Neurons require enormous amounts of fuel being able to survive just minutes without oxygen 3.Neurons can last an entire human lifetime.
16
Q
What are the three parts of a neuron?
A
1.the dendrites 2.the cell body 3.the axon
17
Q
What is the function of the neuron cell body?
A
The neuron cell body synthesizes all nerve cell products.
18
Q
What are three aspects of the structure of the neuron cell body?
A
1.Consists of a large nucleus 2.the nucleus is surrounded by cytoplasm 3.it contains the normal organelles
19
Q
Describe the structure and function of the dendrite.
A
The dendrites are numerous short extensions that emanate from the cell body which receive information from other neurons conducting those nerve impulses toward the cell body.
20
Q
Describe the axon, including the number in each neuron, function, structure and organelles.
A
The single axon conducts nerve impulses away from the cell body to its axon terminals where it is emitted across a synapse to the dendrite of another neuron. Axons can vary in length being as long as three feet. Axons are composed of cells like the cell body but lack rough endoplasmic reticulum.
21
Q
Describe the composition and function of Schwann cells.
A
The axon is coated in short sections called Schwann cells mainly composed of a white fatty layer called the myelin sheath rolled around the axon which insulates the nerve fiber from others and increases the speed of nerve impulses.
22
Q
Describe the location and function of the Nodes of Ranvier.
A
The Schwann cell insulating sections are not continuous, having gaps between them called Nodes of Ranvier. At these exposed nodes, the nerve impulse is forced to jump to the next node in a manner called salutatory conduction, greatly increasing the nerve impulse transmission along the axon.
23
Q
What important organelle is absent from the neuron cell body and what does the absence of this organelle indicate about activity of the cell body?
A
The cell body lacks centrioles making it incapable of mitosis.
24
Q
Describe the function and site of synthesis and storage of neurotransmitters.
A
One of the main functions of the cell body is to manufacture neurotransmitters, which are chemicals stored in secretory vesicles at the end of axon terminals. When neurotransmitters are released by the axon terminal vesicles, they participate in the transmission of the nerve impulse from one neuron to another.
25
List the four types of support neuroglial cells and a function of each.
ependymal cells which circulate cerebrospinal fluid and allow fluid exchange between brain, spinal cord and CSF) oligodendrocytes which insulate the central nervous system axons (similar to Schwann cells in the PNS). astrocytes which (control chemical environment of neurons). microglial cells (protect CNS by scavenging dead cells and infectious microoganisms).
26
List the 3 STRUCTURAL classes of neurons, and describe the structure and an example of each.
Multipolar neurons have three or more extensions, one axon and many dendrites and are found as motor neurons or interneurons within the CNS. Bipolar neurons have two extensions, one axon and one dendrite and are found as receptors cells in the visual and olfactory systems. Unipolar neurons have one extension which branches into two, one central process running to the CNS and another peripheral process running to the sensory receptor and are found as sensory neurons in the peripheral nervous system.
27
Are sensory neurons are unipolar, bipolar or multipolar?
unipolar
28
What are the most common type of neurons in the body?
multipolar nuerons
29
List the 3 FUNCTIONAL classes of neurons, and describe the structure and an example of each.
Sensory neurons are unipolar and carry impulses from receptors in the skin or internal organs toward the CNS. Motor neurons are multipolar and carry impulses from the central nervous system to muscle fibers or glands. Interneurons are usually multipolar and found within the central nervous system only and they transmit impulses between sensory and motors neurons conveying messages between various parts of the central nervous system, such as from one side of the brain or spinal cord to the other, or from the brain to the spinal cord, and vice versa.
30
What is the technical term used to describe a nerve impulse and what causes the impulse?
A nerve impulse is called an action potential and is caused by the movement of unequally distributed ions on either side of an axon's plasma membrane.
31
An axon's membrane is polarized with a resting potential of -70 mV. Explain what this means and what maintains this resting potential.
The axon plasma membrane is polarized, meaning that one side has a different charge than the other side. This difference called a resting potential means that the charge on the inside of the axon's cell membrane is 70 millivolts less than the outside of the membrane. A sodium- potassium pump using active transport carries ions across the plasma membrane and because three Na+ ions are pumped out as two K+ ions are pumped in a relative positive charge develops and is maintained on the outside of the membrane.
32
Label each numbered section (1-4) of the diagram which describes an action potential.
1 = resting state 2 = depolarization 3 = repolarization 4 = afterpolarization.
33
Describe what happens to the charges on the axon cell membrane during depolarization and what causes this to happen.
During the resting phase both sodium and potassium gates that control the relative charges on sides of the membrane are closed. During depolarization the sodium gates open and sodium rushes into the axon and the inside becomes more positive than the outside causing the membrane potential to become more positive.
34
Describe what happens to the charges on the axon cell membrane during repolarization and what causes this to happen?
During repolarization the sodium gates close and potassium gates open allowing potassium to rush out of the axon. This returns a negative charge to the inside of the axon re-establishing the negative potential.
35
What happens during afterpolarization?
The potassium gates that open during repolarization are slow to close and there is generally an afterpolarization undershoot of the potential.
36
What causes the difference in intensity of a sensation?
The difference in intensity of a sensation is due to the number of neurons stimulated and the frequency with which they are activated.
37
How is an impulse passed from one nerve cell to another?
There is a minute fluid-filled space, called a synapse, between the axon terminal of the sending neuron and the dendrite of the receiving neuron. When a nerve impulse reaches the end of an axon, neurotransmitters are released into the synapse. These bind with a receptor on the next neuron, opening Na+ gates in the receiving dendrite which causes depolarization and the impulse is carried.
38
What prevents continuous stimulation of a nerve synapse and how is this accomplished?
The short existence of neurotransmitters in the synapse prevents continuous stimulation. Some synapses contain enzymes that rapidly inactivate neurotransmitters and other synapses rapidly absorb the neurotransmitter.
39
What is the mnemonic to remember which cranial nerves are sensory or motor or both
Some say marry money but my brother says big brains matter more
40
What is the mnemonic to remember the cranial nerves?
On old Olympus' towering top a Finn and German viewed some hops
41
For each cranial nerve, state the number, the name, whether sensory or motor, and what it controls
1st - Olfactory - Sensory - Sense of smell. 2nd - Optic - Sensory - Sense of sight. 3rd - Oculomotor - Motor - Eye movement. 4th -Trochlear - Motor - Eye movement. 5th - Trigeminal - Motor and Sensory - Chewing and sensation of face, nose, and mouth. 6th - Abducens - Motor - Eye movement. 7th - Facial - Motor and sensory - Facial expressions and sensation of tongue. 8th - Vestibulocochlear - Sensory - Hearing and balance. 9th - Glossopharyngeal - Motor and sensory - Swallowing and taste. 10th - Vagus - Motor and sensory - Digestion, regulation of heart rate, sensation of digestive tract. 11th - Accessory - Motor - Rotation of the head and shrugging of the shoulders. 12th - Hypoglossal - Motor - Tongue movements.
42
List the 5 types of human spinal nerves and how many of each there are.
Humans have eight pairs of cervical (cranial) nerves, twelve pairs of thoracic nerves, five pairs of lumbar nerves, five pairs of sacral nerves, and one pair of coccygeal nerves.
43
Describe in detail the structure of spinal nerves within the vertebral column.
Each spinal nerve emerges from the spinal cord by two short roots, the dorsal root which contains the axons of afferent sensory neurons, which conduct impulses to the cord and the ventral root which contains the axons of efferent motor neurons, which conduct impulses away from the cord. These two roots join just before a spinal nerve leaves the vertebral column.
44
Describe in detail the structure of spinal nerves AFTER LEAVING the vertebral column.
Almost immediately after immerging from the vertebral column, a spinal nerve divides into branches called the dorsal ramus and ventral ramus. The smaller dorsal ramus contains nerves that serve the dorsal portions of the trunk including the skin and muscles of the back. The larger ventral ramus contains nerves that serve the remaining ventral parts of the trunk and the upper and lower limbs.
45
Describe a nerve plexus and list the four major body nerve plexuses.
A nerve plexus is a network of interconnecting spinal nerves carried together to some target location. Major plexuses include: cervical plexus, brachial plexus, lumbar plexus, sacral plexus
46
What is the most important nerve of the cervical plexus and what structure does it supply?
The phrenic nerve is the most important nerve of the cervical plexus and supplies both motor and sensory fibers to the diaphragm.
47
List the five nerves that form the Brachial plexus.
The five nerves that form the Brachial plexus are the: Ulnar nerve, Axillary nerve, Radial nerve, Median nerve, Musculocutaneous nerve
48
What 3 muscles are served by the axillary nerve?
The axillary nerve supplies: the deltoid muscle, the teres minor muscles and the triceps brachii muscle.
49
What muscles are served by the radial nerve?
The radial nerve supplies the triceps brachii muscle as well as 12 muscles in the forearm.
50
What muscle is served by the median nerve?
The median nerve supplies flexor muscles of the forearm.
51
What causes carpal tunnel syndrome?
Compression of the median nerve causes carpal tunnel syndrome.
52
What muscles are served by the musculocutaneous nerve?
the flexor muscles of the arm.
53
What muscles are served by the ulnar nerve?
The ulnar nerve supplies the flexor muscles of the forearm, wrist, and hand.
54
What is the major nerve of the Lumbar plexus?
The femoral nerve is the major nerve of the Lumbar plexus.
55
What is the major nerve of the sacral plexus and what is unusual about this nerve?
The sciatic nerve is the major nerve that comes from the sacral plexus and is the largest nerve in the human body.
56
What muscles are served by the femoral nerve?
The femoral nerve supplies the hip flexors and knee extensors.
57
What areas are served by the sciatic nerve?
The sciatic nerve supplies the inferior trunk and posterior surface of the thigh.
58
What structures are served by the somatic nervous system?
The somatic nervous system serves the musculoskeletal system and the exterior sense organs, including the skin.
59
What is a receptor and what structures serve as receptors within the somatic nervous system?
Receptors receive environmental stimuli and then initiate nerve impulses. Exterior sense organs (and skin) are receptors in the somatic nervous system.
60
What is an effector and what structures serve as effectors within the somatic nervous system?
Effectors bring about a reaction to a stimulus. Muscle fibers are effectors in the somatic nervous system.
61
Define the term reflex and give a subconscious example and an obvious example.
Reflexes are nearly instantaneous, automatic, involuntary motor responses to stimuli occurring inside or outside of the body. Reflexes may be subconscious as the regulation of blood sugar by the hormones or may be obvious as touching a very hot object and immediately withdrawing your hand.
62
Explain why a reflex arc occurs so quickly and why this speed is necessary.
To help an organism avoid injury, a reflex arc provides an immediate withdrawal from dangerous stimuli. The advantage of the reflex arc is production of a response by way of the spinal cord without the need to wait for processing by the brain.
63
List the 5 components of a reflex arc.
The five components of a reflex arc are: the receptor, the afferent neuron, the integration center, the efferent neuron, the effector
64
Why do spinal reflexes occur much faster than ones involving the brain?
Spinal reflexes occur much faster, not only because they involve fewer neurons, but also because the electrical signal does not have to travel to the brain and back.
65
Give 2 examples of spinal reflexes.
Examples of spinal reflexes are:the flexor reflex (withdrawal of your hand from a very hot object) and the stretch reflex on an opposing muscle to prevent over-stretching of its antagonist.
66
What are the two divisions of the autonomic nervous system?
The two divisions of the autonomic system are: the sympathetic system and the parasympathetic system
67
How do the two divisions of the autonomic nervous system function relative to each other?
The two divisions of the autonomic system cause essentially opposite effects on the same visceral organ; if one stimulates, the other inhibits.
68
What five functions does the sympathetic nervous system perform during an emergency situation?
During an emergency situation, the sympathetic system: accelerates the heartbeat, dilates the bronchi, increases the breathing rate supplying needed oxygen, causes the liver to deliver more glucose, inhibits the digestive tract
69
What type of internal responses are promoted by the parasympathetic nervous system?
The parasympathetic system promotes all the internal responses we associate with a relaxed state.
70
Describe the four effects caused by the parasympathetic nervous systems on heart blood vessels, the lungs and the digestive tract.
The parasympathetic nervous system: has no effect on heart blood vessels, constricts bronchioles of the lungs, increases peristalsis, relaxes the sphincters of the digestive tract
71
What four effects are caused by the sympathetic nervous systems on heart blood vessels, the lungs and the digestive tract?
The sympathetic nervous system: dilates heart blood vessels, dilates bronchioles of the lungs, decreases the activity of the digestive tract, constricts the sphincters of the digestive tract
72
What are the four parts of the human brain?
The human brain is made up of:the cerebral hemispheres, diencephalon, brain stem, cerebellum
73
List the three parts of the diencephalon.
The diencephalon is made up of the:thalamus, hypothalamus, epithalamus
74
List the three major parts of the brain stem.
The brain stem is made up of the: mid-brain, pons, medulla oblongata.
75
Describe the number, location and function of the brain ventricles.
There are four ventricles in the interior of the brain, chambers filled with cerebrospinal fluid which is produced there.
76
How is the medulla oblongata involved with the heart and lungs?
The medulla oblongata regulates heartbeat and breathing.
77
How is the pons involved with the eyes and ears?
The pons regulates head movements in response to visual and auditory stimuli. The pons acts as a relay station between the cerebrum and the spinal cord or cerebellum.
78
The pons functions to relay impulses between what centers?
The pons acts as a relay station between the cerebrum and the spinal cord or cerebellum.
79
How is the hypothalamus involved with the entire internal environment of the body and the endocrine system in particular?
The hypothalamus maintains homeostasis, the constancy of the internal environment and controls the pituitary gland and serving as a link between the nervous and endocrine systems.
80
All except what sensory impulses are channeled through the thalamus?
All sensory impulses (except those associated with the sense of smell) are channeled through the thalamus.
81
What is the function of the pineal body?
The pineal body secretes melatonin to control the wake-sleep cycle.
82
What is the function of the choroid plexus?
The choroid plexus produces cerebrospinal fluid.
83
Describe the location and structure of the cerebellum?
The cerebellum, below and at the back of the brain, is convoluted and divided into two hemispheres with deep fissures subdividing it into three lobes. It is composed of a thin outer cortex of gray matter and internal white matter.
84
Describe, in detail, surface appearance of the cerebral cortex.
The cerebral cortex is highly convoluted with raised ridges of tissue called gyri, separated by shallow grooves called sulci. The deeper grooves, called fissures, separate large regions of the brain. The median longitudinal fissure separates the cerebral hemispheres from one another and the transverse fissure separates the cerebral hemispheres from the cerebellum.
85
List the four lobes of the cerebrum.
The four lobes of the brain are the frontal, parietal, temporal and occipital.
86
List and describe the 3 functional areas of the cerebrum.
The cerebral cortex contains three kinds of functional areas: motor areas that control voluntary motor functions; sensory areas that provide for conscious awareness of sensation; and association areas that act mainly to integrate information.
87
What does the frontal lobe control?
The frontal lobe controls motor functions.
88
What is the function of the parietal lobe?
The parietal lobe receives information from receptors located in the skin, such as those for touch, pressure, and pain.
89
What is the function of the occipital lobe?
The occipital lobe interprets visual input.
90
What is the function of the temporal lobe?
The temporal lobe has sensory areas for hearing and smelling.
91
What areas of the brain does the limbic system connect?
The limbic system connects the frontal lobes, the temporal lobes, the thalamus, and the hypothalamus. The limbic system is our feeling brain since stimulation of different areas of the limbic system causes rage, pain, pleasure, or sorrow.
92
List three illnesses caused by the limbic system's involvement in stress production.
Extensive connections between the limbic system and lower and higher brain regions cause acute emotional stress to produce visceral illnesses, such as stomach ulcers, high blood pressure, and irritable bowel syndrome.
93
What determines learning and forgetting?
Learning is accompanied by an increase in the number of synapses, while forgetting involves a decrease in the number of synapses.
94
List the 4 protections for the brain.
The brain is protected by the skull of the skeletal system, membranes, a cushion of cerebrospinal fluid and the "blood-brain barrier".
95
Describe the 3 brain meninges.
The leathery dura mater is the double-layered outer meninx. The middle arachnoid meninx is a loose layer separated from the dura mater by the subdural space. The inner pia mater meninx is composed of connective tissue and is tightly attached to the brain.
96
Describe cerebrospinal fluid including its composition, formation and function.
Cerebrospinal fluid is similar in composition to blood plasma, from which it arises by permeating through the choroid plexus capillaries. Once formed the CSF circulates through the ventricles and into the subarachnoid space bathing and floating the brain.
97
What causes the blood-brain barrier and what is its function?
The blood-brain barrier is due to the relatively impermeable brain capillaries, these provide a stable chemical environment for the brain protecting it from variations which would cause uncontrollable firing of neurons.
98
Describe the spinal cord and its extension.
The spinal cord is protected by the surrounding vertebral column and extends from the brain stem to the first lumbar vertebra where it officially terminates as the conus medullaris. The extension of the cord beyond L1 is a collection of nerve roots called the cauda equina which runs to its end at the coccyx.
99
What is the function of the spinal cord and how does it accomplish this?
The spinal cord and its extension is the means by which all impulses travel between the brain and the rest of the body by way of the set of 31 pair of spinal nerves.
100
List the 3 protections for the spinal cord.
Like the brain, the spinal cord is protected by the bony vertebral column, meninges and cerebrospinal fluid.
101
Describe the 3 spinal cord meninges and their associated tissues and fluids.
The outer meninx, a single layer called the spinal dural (mater) sheath is separated from the vertebral column by a cushioning fat-filled epidural space. The space between the middle arachnoid and inner pia mater meninges is filled with cerebrospinal fluid.
102
Why is a spinal tap performed in the subarachnoid space inferior to L1.
Because the cord ends at L1, the cerebrospinal filled subarachnoid space inferior to this point is the location chosen to perform a spinal tap removal of fluid for diagnostic testing.
103
Identify the parts of the spinal cord in the diagram.
1 anterior horn 2 posterior horn 3 gray commissure 4 anterior feniculous 5 lateral feniculous 6 posterior feniculous 7 anterior commissure 8 anterior median fissure 9 posterior median sulcus 10 central canal 11 anterior root 12 posterior roots 13 dorsal root ganglian
104
Describe the composition of the gray matter of the spinal cord.
The gray matter of the cord is composed of multipolar neurons and supporting cells.
105
Describe the composition of the white matter of the spinal cord.
The white matter of the cord is composed of myelinated and un-myelinated nerve fibers.
106
Describe the function of the white matter of the spinal cord.
The white matter fibers of the spinal cord are composed of ascending tracts that proceed up to the brain carrying sensory inputs and descending tracts that proceed down to (or within) the cord carrying motor outputs.
107
List and describe 4 types of brain damage
Brain damage can occur at the site of an impact. A slight injury of this type is called a concussion since the symptoms are mild and transient including dizziness or brief loss of consciousness. A more serious impact injury, a brain contusion, results in significant tissue damage which usually causes unconsciousness (coma), ranging in duration from hours to a lifetime. Hemorrhage can cause blood to accumulate increasing intracranial pressure and compressing brain tissue. Traumatic head injuries can also result in swelling of the brain due to water uptake by brain tissue.
108
Describe stroke
Strokes occur when blood circulation to a brain area is blocked resulting in tissue death due to lack of oxygen and nutrients being supplied to brain cells. This is most often caused by a clot or fat deposit blocking a cerebral artery but can also be due to compression of brain tissue by hemorrhage or edema. Stroke victims often die but those who survive usually suffer paralysis, cognitive deficits, speech problems, emotional difficulties and pain. Some patients recover at least a portion of their lost faculties, because undamaged neurons sprout new branches that spread into the area of injury and take over some lost functions.
109
Describe Alzheimer's Disease
Alzheimer's Disease is a progressive degenerative disease of the brain, usually seen in elderly people, that ultimately results in mental decline. Its victims exhibit early difficulty remembering newly learned information and then increasingly severe symptoms, including disorientation, mood and behavior changes; deepening confusion about events, time and place; unfounded suspicions about family, friends and caregivers; more serious memory loss and behavior changes; and difficulty speaking, swallowing and walking. Alzheimer's disease is associated with structural changes in the brain, particularly in the cerebral cortex.
