5. Nervous System Flashcards
(375 cards)
1
Q
What are the two main divisions of the nervous system?
A
Central nervous system (CNS) and peripheral nervous system (PNS).
2
Q
What does the CNS consist of?
A
Brain and spinal cord.
3
Q
What does the PNS consist of?
A
All neural tissue outside the CNS, including cranial and spinal nerves.
Great question! Let’s break it down clearly:
The Peripheral Nervous System (PNS) consists of all the nerves and ganglia outside the brain and spinal cord (which make up the Central Nervous System, or CNS).
Here’s what that includes:
- Cranial Nerves
• These are 12 pairs of nerves that come directly out of the brain (especially the brainstem) and mostly control functions in the head and neck.
• Example: The optic nerve for vision, or the vagus nerve that helps regulate heart rate and digestion. - Spinal Nerves
• These are 31 pairs of nerves that emerge from the spinal cord.
• They branch out to serve the rest of the body—your arms, legs, skin, and organs.
• Each spinal nerve connects to a specific part of your body, sending signals back and forth between that area and the CNS. - Ganglia
• These are clusters of neuron cell bodies found outside the CNS.
• Think of them like mini relay stations that help process and transmit nerve signals.
So in simple terms:
The PNS is the communication highway between your brain/spinal cord and the rest of your body. It sends sensory information to the CNS and carries out motor commands from the CNS.
Would you like a visual analogy or diagram to go with this?
4
Q
What are the two main cell types in nervous tissue?
A
Neurons and glial cells.
5
Q
What is the function of neurons?
A
To generate and propagate electrical signals.
6
Q
What do glial cells do?
A
Support and maintain neural tissue.
7
Q
What is the soma of a neuron?
A
The cell body that contains the nucleus.
8
Q
What are dendrites?
A
Extensions of the neuron that receive signals.
9
Q
What is an axon?
A
A fiber that transmits signals away from the neuron.
10
Q
What is a nucleus in the CNS?
A
A collection of neuron cell bodies.
11
Q
What is a ganglion?
A
A collection of neuron cell bodies in the PNS.
12
Q
What is a tract?
A
A bundle of axons in the CNS.
13
Q
What is a nerve?
A
A bundle of axons in the PNS.
14
Q
What are the three basic functions of the nervous system?
A
Sensation, integration, and response.
15
Q
What is sensation?
A
Receiving information about the environment.
16
Q
What is integration?
A
Combining sensory input with cognition and memory to determine response.
17
Q
What is response?
A
A motor output to muscles or glands.
18
Q
What is the somatic nervous system responsible for?
A
Conscious perception and voluntary motor responses.
19
Q
What is the autonomic nervous system responsible for?
A
Involuntary control, such as heart rate and digestion.
20
Q
What is the enteric nervous system?
A
Controls digestive system functions independently of the CNS.
21
Q
What are examples of somatic sensory receptors?
A
Receptors in skin, limbs, and special sense organs.
22
Q
What are examples of autonomic sensory receptors?
A
Receptors in visceral organs like the lungs.
23
Q
What are the two branches of the autonomic motor division?
A
Sympathetic and parasympathetic.
24
Q
What are enteric sensory receptors?
A
Chemoreceptors and stretch receptors in the GI tract.
25
What are the effector organs of the somatic nervous system?
Skeletal muscles.
26
What are the effector organs of the autonomic nervous system?
Smooth muscle, cardiac muscle, and glands.
27
What are the effector organs of the enteric nervous system?
Smooth muscle and glands of the GI tract.
28
What are the three functional types of neurons?
Sensory neurons, interneurons, and motor neurons.
29
What are the three structural types of neurons?
Unipolar, bipolar, and multipolar.
30
What is the function of sensory neurons?
Transmit stimuli from the body to the CNS.
31
What is the function of interneurons?
Process and store information in the CNS.
32
What is the function of motor neurons?
Transmit stimuli from the CNS to the body.
33
What are the major parts of a neuron?
Soma, dendrites, axon, axon hillock, myelin sheath, terminal arborizations.
34
What is the axon hillock?
The tapering region where the axon originates from the cell body.
35
What is the axoplasm?
The cytoplasm within the axon.
36
Where are action potentials generated?
In the trigger zone, which includes the axon hillock and initial segment.
37
What are nodes of Ranvier?
Gaps in the myelin sheath of axons.
38
What is a synaptic end bulb?
An enlargement at the axon terminal that forms a synapse with a target cell.
39
How many cranial nerves are there?
12 cranial nerves.
40
Which cranial nerves are purely sensory?
Olfactory (I), Optic (II), Vestibulocochlear (VIII).
41
Which cranial nerves are purely motor?
Oculomotor (III), Trochlear (IV), Abducens (VI), Spinal Accessory (XI), Hypoglossal (XII).
42
Which cranial nerves are mixed?
Trigeminal (V), Facial (VII), Glossopharyngeal (IX), Vagus (X).
43
What is the function of the vagus nerve (X)?
Controls thoracic and abdominal organs; contributes to autonomic control.
44
What mnemonic helps remember the names of the cranial nerves?
'On Old Olympus’ Towering Tops, A Finn Vet Gary Viewed Ancient Hops.'
45
What mnemonic helps remember cranial nerve function?
'Some Say Marry Money, But My Brother Says Big Brains Matter More.'
1. Some – Sensory (CN I – Olfactory)
2. Say – Sensory (CN II – Optic)
3. Marry – Motor (CN III – Oculomotor)
4. Money – Motor (CN IV – Trochlear)
5. But – Both (CN V – Trigeminal)
6. My – Motor (CN VI – Abducens)
7. Brother – Both (CN VII – Facial)
8. Says – Sensory (CN VIII – Vestibulocochlear)
9. Big – Both (CN IX – Glossopharyngeal)
10. Brains – Both (CN X – Vagus)
11. Matter – Motor (CN XI – Accessory)
12. More – Motor (CN XII – Hypoglossal)
46
What are the four types of CNS glial cells?
Astrocytes, oligodendrocytes, microglia, and ependymal cells.
47
What are the two types of PNS glial cells?
Satellite cells and Schwann cells.
48
What is the function of astrocytes?
Support neurons, maintain the blood-brain barrier.
49
What is the function of oligodendrocytes?
Insulate CNS axons with myelin.
50
What is the function of microglia?
Act as CNS immune cells, performing phagocytosis.
51
What is the function of ependymal cells?
Produce and circulate cerebrospinal fluid (CSF).
52
What is the function of satellite cells?
Support neuron cell bodies in the PNS.
53
What is the function of Schwann cells?
Form myelin sheath around PNS axons.
54
What is the blood-brain barrier?
A selective barrier that limits the substances entering the CNS.
55
What structure produces cerebrospinal fluid?
The choroid plexus, using ependymal cells.
56
How does myelination differ between Schwann cells and oligodendrocytes?
Schwann cells myelinate one axon segment; oligodendrocytes myelinate multiple axons.
57
What are the four major regions of the adult brain?
Cerebrum, diencephalon, brain stem, and cerebellum.
58
What is gray matter composed of?
Neuron cell bodies and dendrites.
59
What is white matter composed of?
Myelinated axons.
60
Why is white matter white?
Because myelin is a lipid-rich insulating substance.
61
Where is gray matter located in the brain?
In the outer cortex and in some deep brain structures.
62
What is the cerebrum?
The largest part of the brain, divided into left and right hemispheres.
63
What is the cerebral cortex?
The outer layer of gray matter responsible for sensory analysis, memory, learning, and cognition.
64
What increases the surface area of the cerebral cortex?
Folds called gyri and sulci.
Your cerebral cortex is the outermost layer of your brain. Its surface has many folds, giving it a wrinkled appearance. The folds consist of many deep grooves called sulci and raised areas called gyri.
65
What separates the two cerebral hemispheres?
The longitudinal fissure.
66
What structure connects the two hemispheres?
The corpus callosum.
67
What are the basal nuclei responsible for?
Cognitive processing and planning movements.
68
What does the limbic cortex regulate?
Emotion, memory, and behavior.
69
What is the main function of the cerebral cortex?
Higher mental functions, sensory interpretation, and coordination of movement.
70
What does the precentral gyrus control?
Primary motor functions.
The precentral gyrus, also known as the primary motor cortex or motor strip, is a fold in the frontal lobe that
controls voluntary movement.
It's located on the lateral surface of each frontal lobe, running parallel to the central sulcus
71
What does the postcentral gyrus process?
Primary somatosensory information.
The postcentral gyrus is a prominent area in the brain, specifically located in the parietal lobe, and is primarily known for its role in processing somatosensory information
72
What are the four main lobes of the cerebral cortex?
Frontal, parietal, temporal, and occipital.
73
What is the function of the frontal lobe?
Motor functions, planned movement, speech production, and personality.
74
What is Broca’s area responsible for?
Speech production.
75
What is the function of the parietal lobe?
Somatosensation (touch, pressure, pain, proprioception).
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What is the function of the temporal lobe?
Auditory perception, speech comprehension, memory.
77
What is Wernicke’s area responsible for?
Speech comprehension.
78
What is the function of the occipital lobe?
Visual processing.
79
What is the homunculus?
A map of the body on the cerebral cortex representing sensory and motor areas.
80
Why are some body parts larger in the homunculus?
More cortex is devoted to more sensitive areas.
81
Which parts have disproportionately large sensory areas?
Toes, fingers, and lower face.
82
What is the primary sensory cortex?
The area where sensory processing begins.
83
What is the visual cortex topography?
Visual information is inverted and reversed as it enters the cortex.
84
What is the function of the ventral visual stream?
Identifies visual stimuli and their significance.
85
What is the function of the dorsal visual stream?
Locates objects and guides body movement.
86
What are the main parts of the diencephalon?
Thalamus and hypothalamus.
The diencephalon’s four key components are:
1. Thalamus – the principal sensory‐relay station to the cerebral cortex.
2. Hypothalamus – homeostatic control center, regulating autonomic, endocrine, temperature, hunger/thirst, and circadian functions.
3. Epithalamus (includes the pineal gland) – secretes melatonin, helps govern sleep–wake cycles.
4. Subthalamus – motor‑related region just below the thalamus (often grouped with basal nuclei circuits).
87
What is the function of the thalamus?
Relay station for all sensory information except smell.
88
What role does the thalamus play in motor commands?
It relays output from the basal nuclei to the cerebral cortex.
89
What is the function of the hypothalamus?
Regulates homeostasis, the autonomic nervous system, and the endocrine system.
90
Which gland does the hypothalamus regulate?
The anterior pituitary gland.
91
What connects the hypothalamus to the pituitary gland?
The infundibulum.
92
What type of tissue makes up the anterior pituitary?
Epithelial tissue.
93
What type of tissue makes up the posterior pituitary?
Neural tissue.
94
What is the function of the pineal gland?
Releases melatonin to regulate sleep-wake cycles.
95
What triggers melatonin release?
Darkness detected by the retina via the hypothalamus.
96
What are the three parts of the brain stem?
Midbrain, pons, and medulla oblongata.
97
What is the function of the midbrain?
Processes visual, auditory, and somatosensory information.
98
What are the superior colliculi responsible for?
Integrating visual, auditory, and touch stimuli.
99
What are the inferior colliculi responsible for?
Processing auditory signals.
100
What is the pons responsible for?
Connecting the cerebellum to the brain stem and aiding motor control.
101
What is the medulla responsible for?
Regulating cardiovascular and respiratory functions.
102
What is the reticular formation involved in?
Sleep, wakefulness, and attention.
103
What midbrain structure is affected in Parkinson’s disease?
The substantia nigra.
104
What is the main function of the cerebellum?
Compares motor commands with sensory feedback for coordination.
105
What structure provides sensory feedback to the cerebellum?
The inferior olive.
106
Where does cerebellar output go?
To the midbrain, which sends signals to the spinal cord.
107
What does the cerebellum help regulate?
Balance, coordination, and motor learning.
108
What arteries supply the brain?
Internal carotid and vertebral arteries.
109
What do the vertebral arteries form?
The basilar artery.
110
What is the Circle of Willis?
A circular system of arteries that ensures constant brain perfusion.
111
What do dural sinuses do?
Drain blood from the brain into the jugular veins.
112
What is the function of the superior sagittal sinus?
Absorbs CSF and drains into venous circulation.
113
What are the main components of the limbic system?
Hippocampus and amygdala.
114
What is the function of the hippocampus?
Formation of new memories.
115
What is the function of the amygdala?
Processing emotions like fear and aggression.
116
What lobe contains structures of the limbic system?
The limbic lobe.
117
How does the limbic system influence the hypothalamus?
It sends emotional signals that trigger autonomic and endocrine responses.
118
What are the three layers of the meninges?
Dura mater, arachnoid mater, and pia mater.
119
What is the function of the meninges?
They protect the brain and spinal cord.
120
What is the dura mater?
The tough, outermost layer of the meninges.
121
What is the arachnoid mater?
The middle layer of the meninges, with spider-web-like trabeculae.
122
What is the pia mater?
The innermost layer that closely follows brain contours.
123
What is the subarachnoid space filled with?
Circulating cerebrospinal fluid (CSF).
124
What are arachnoid granulations?
Structures where CSF is reabsorbed into the bloodstream.
125
Why is a lumbar puncture done in the lower lumbar region?
To avoid damaging the spinal cord.
126
What is the blood-brain barrier (BBB)?
A selective barrier between the blood and CNS.
127
What substances can diffuse across the BBB?
Oxygen, carbon dioxide, alcohol, and anesthetics.
128
What substances require active transport to cross the BBB?
Glucose and amino acids.
129
What substances cannot cross the BBB?
Proteins, antibiotics, and white blood cells.
130
Why is the BBB important?
It protects the CNS from toxins and pathogens.
131
Why does the BBB create problems for drug delivery?
Many medications cannot cross the BBB.
132
What is the function of CSF?
Protects the brain, cushions it, and removes waste.
133
Where is CSF produced?
In the choroid plexuses of the brain’s ventricles.
134
What are the four brain ventricles?
Two lateral ventricles, third ventricle, and fourth ventricle.
135
What connects the lateral ventricles to the third ventricle?
The interventricular foramina.
136
What connects the third to the fourth ventricle?
The cerebral aqueduct.
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Where does CSF exit the ventricular system?
Through the median and lateral apertures into the subarachnoid space.
138
What cells produce CSF?
Ependymal cells in the choroid plexus.
139
What condition results from blocked CSF flow?
Hydrocephaly.
140
Where is the spinal cord continuous with the brain?
At the medulla oblongata.
141
What are the main surface features of the spinal cord?
Anterior median fissure and posterior median sulcus.
142
What enters through the dorsal root?
Sensory axons.
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What exits through the ventral root?
Motor axons.
144
What is the cauda equina?
A bundle of spinal nerves resembling a horse's tail.
145
How many spinal nerves are there?
31 pairs: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal.
146
What is the conus medullaris?
The tapered end of the spinal cord.
147
What is the filum terminale?
An extension of the pia mater at the end of the spinal cord.
148
What does the posterior horn do?
Processes sensory information.
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What does the anterior horn do?
Sends motor signals to skeletal muscles.
150
Where is the lateral horn found?
Thoracic, upper lumbar, and sacral regions.
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What type of neurons are found in the lateral horn?
Autonomic motor neurons.
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What type of neuron controls the big toe?
Multipolar motor neuron in the sacral spinal cord.
153
What are spinal cord tracts?
Bundles of myelinated axons in white matter.
154
What do ascending tracts do?
Carry sensory info to the brain.
155
What do descending tracts do?
Carry motor commands from the brain.
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What are the dorsal column tracts?
Fasciculus gracilis (lower body) and fasciculus cuneatus (upper body).
157
What sensations does the dorsal column system carry?
Fine touch and proprioception.
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Where does the dorsal column system decussate?
In the medulla.
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What is the spinothalamic tract responsible for?
Pain, pressure, and temperature.
160
Where does the spinothalamic tract decussate?
In the spinal cord.
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What is the corticospinal tract responsible for?
Voluntary motor control.
162
What is the pyramidal decussation?
Where corticospinal tract fibers cross over in the medulla.
163
What does the lateral corticospinal tract control?
Appendicular (limb) muscles.
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What does the anterior corticospinal tract control?
Axial (trunk) muscles.
165
What is the extrapyramidal system?
Indirect motor pathways including tectospinal, reticulospinal, and vestibulospinal tracts.
166
What is the rubrospinal tract involved in?
Fine motor correction from cerebellar feedback.
167
What are the two roots of spinal nerves?
Dorsal (sensory) and ventral (motor).
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What is the dorsal root ganglion?
A cluster of sensory neuron cell bodies.
169
Where do spinal nerves exit the vertebral column?
Through intervertebral foramina.
170
What does the dorsal ramus innervate?
Back muscles and skin.
171
What does the ventral ramus form?
Nerve plexuses (cervical, brachial, lumbar, sacral, coccygeal).
172
Which plexus supplies the diaphragm?
Cervical plexus.
173
Which plexus supplies the upper limbs?
Brachial plexus.
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Which plexus supplies the lower limbs?
Lumbar and sacral plexuses.
175
What spinal nerves form the cervical plexus?
Ventral branches of C1–C4.
176
What does the cervical plexus innervate?
Superficial neck muscles and skin over neck and back of head.
177
Which nerve innervates the diaphragm?
Phrenic nerve.
178
What is the origin of the phrenic nerve?
C3, C4, C5.
179
What is the motor function of the phrenic nerve?
Innervates the diaphragm.
180
What is the sensory function of the phrenic nerve?
Innervates diaphragmatic pleura and pericardium.
181
Which cervical nerve innervates skin of the shoulder and anterior chest wall?
Supraclavicular nerve (C3, C4).
182
Which nerve innervates the anterior and lateral neck?
Transverse cervical nerve (C2, C3).
183
What spinal nerves form the brachial plexus?
C5–T1.
184
What does the brachial plexus innervate?
Motor and sensory innervation of the upper limbs.
185
What are the five main nerves of the brachial plexus?
Axillary, radial, musculocutaneous, ulnar, median.
186
Which nerve innervates the deltoid and teres minor?
Axillary nerve (C5, C6).
187
Which nerve innervates the extensors of the elbow, wrist, and hand?
Radial nerve (C5–T1).
188
Which nerve innervates the biceps and brachialis?
Musculocutaneous nerve (C5–C7).
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Which nerve innervates the flexor digitorum profundus and hand muscles?
Ulnar nerve (C7–T1).
190
Which nerve travels through the carpal tunnel?
Median nerve (C5–T1).
191
What spinal nerves form the lumbar plexus?
L1–L4.
192
Which nerve innervates the anterior thigh muscles?
Femoral nerve (L2–L4).
193
Which nerve innervates thigh adductors?
Obturator nerve (L2–L4).
194
What are the cutaneous branches of the lumbar plexus?
Iliohypogastric, ilioinguinal, and lateral femoral cutaneous nerves.
195
Which nerve supplies skin of the lateral thigh?
Lateral femoral cutaneous nerve (L2–L3).
196
Which nerve innervates the skin above the pubis?
Iliohypogastric nerve.
197
Which nerve passes through the inguinal canal?
Ilioinguinal nerve (L1).
198
What spinal nerves form the sacral plexus?
L4–S4.
199
Which two nerves form the sciatic nerve?
Common fibular and tibial nerves.
200
Which nerve innervates biceps femoris and tibialis anterior?
Common fibular nerve (L4–S2).
201
Which nerve innervates hamstrings and posterior leg muscles?
Tibial nerve (L4–S3).
202
What nerve innervates gluteus medius and minimus?
Superior gluteal nerve (L4–S1).
203
What nerve innervates gluteus maximus?
Inferior gluteal nerve (L5–S2).
204
Which nerve supplies skin of the posterior thigh?
Posterior femoral cutaneous nerve (S1–S3).
205
Which nerve innervates perineal muscles and skin?
Pudendal nerve (S2–S4).
206
What forms the coccygeal plexus?
Ventral branches of S4–S5 and Co1.
207
Which nerve innervates the skin of the coccyx?
Coccygeal nerve.
208
What are the two main divisions of the nervous system?
Central nervous system (CNS) and peripheral nervous system (PNS).
209
What does the CNS consist of?
Brain and spinal cord.
210
What does the PNS consist of?
All neural tissue outside the CNS, including cranial and spinal nerves.
211
What are the two main cell types in nervous tissue?
Neurons and glial cells.
212
What is the function of neurons?
To generate and propagate electrical signals.
213
What do glial cells do?
Support and maintain neural tissue.
214
What is the soma of a neuron?
The cell body that contains the nucleus.
215
What are dendrites?
Extensions of the neuron that receive signals.
216
What is an axon?
A fiber that transmits signals away from the neuron.
217
What is a nucleus in the CNS?
A collection of neuron cell bodies.
218
What is a ganglion?
A collection of neuron cell bodies in the PNS.
219
What is a tract?
A bundle of axons in the CNS.
220
What is a nerve?
A bundle of axons in the PNS.
221
What are the three basic functions of the nervous system?
Sensation, integration, and response.
222
What is sensation?
Receiving information about the environment.
223
What is integration?
Combining sensory input with cognition and memory to determine response.
224
What is response?
A motor output to muscles or glands.
225
What is the somatic nervous system responsible for?
Conscious perception and voluntary motor responses.
226
What is the autonomic nervous system responsible for?
Involuntary control, such as heart rate and digestion.
227
What is the enteric nervous system?
Controls digestive system functions independently of the CNS.
228
What are examples of somatic sensory receptors?
Receptors in skin, limbs, and special sense organs.
229
What are examples of autonomic sensory receptors?
Receptors in visceral organs like the lungs.
230
What are the two branches of the autonomic motor division?
Sympathetic and parasympathetic.
231
What are enteric sensory receptors?
Chemoreceptors and stretch receptors in the GI tract.
232
What are the effector organs of the somatic nervous system?
Skeletal muscles.
233
What are the effector organs of the autonomic nervous system?
Smooth muscle, cardiac muscle, and glands.
234
What are the effector organs of the enteric nervous system?
Smooth muscle and glands of the GI tract.
235
What are the two types of synapses?
Electrical and chemical synapses.
236
Where are electrical synapses mainly found?
In the CNS and cardiac muscle.
237
What is the key feature of an electrical synapse?
Direct ion flow through gap junctions between cells.
238
What is the key feature of a chemical synapse?
Use of neurotransmitters to relay signals across the synaptic cleft.
239
What are the structures of a chemical synapse?
Presynaptic terminal, synaptic cleft, postsynaptic membrane, neurotransmitter vesicles, and receptors.
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What is an example of a chemical synapse?
The neuromuscular junction (NMJ).
241
What happens first when an action potential reaches a synapse?
Opening of voltage-gated calcium channels in the presynaptic membrane.
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What does calcium influx trigger?
Fusion of synaptic vesicles and neurotransmitter release.
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What happens after neurotransmitter release?
It diffuses across the synaptic cleft and binds to receptors on the postsynaptic membrane.
244
What is a postsynaptic potential?
A local voltage change caused by ion flow through ligand-gated channels.
245
What determines if a postsynaptic potential is excitatory or inhibitory?
The type of ion channel opened (e.g., Na+ for depolarization, Cl- for hyperpolarization).
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What neurotransmitter system uses acetylcholine?
The cholinergic system.
247
What are the two types of acetylcholine receptors?
Nicotinic (ionotropic) and muscarinic (metabotropic).
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What are examples of amino acid neurotransmitters?
Glutamate, GABA, and glycine.
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What are examples of biogenic amines?
Dopamine, serotonin, norepinephrine, and epinephrine.
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How are neurotransmitters removed from the synaptic cleft?
Enzymatic degradation or reuptake into neurons or glia.
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What are ionotropic receptors?
Ligand-gated ion channels like the nicotinic receptor.
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What are metabotropic receptors?
G protein-coupled receptors that activate intracellular signaling cascades.
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What is the role of second messengers in neurons?
They mediate intracellular responses like enzyme activation or gene expression.
254
What is the function of sensory receptors?
Convert stimuli into nerve impulses for brain interpretation.
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What are the three structural types of sensory receptors?
Free nerve endings, encapsulated endings, specialized cells.
256
What are the three receptor classifications based on location?
Exteroceptors, interoceptors, proprioceptors.
257
What is a generator potential?
Graded potential from nerve endings that can trigger an action potential.
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What is a receptor potential?
Graded potential in specialized cells that triggers neurotransmitter release.
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What is sensory adaptation?
A decrease in action potential frequency with a persistent stimulus.
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What are rapidly adapting receptors?
Receptors that respond quickly and stop firing with continuous stimulus.
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What are slowly adapting receptors?
Receptors that continue firing as long as the stimulus persists.
262
What is a reflex?
A rapid, involuntary response to a stimulus.
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What is a reflex arc?
The neural pathway by which a reflex is mediated.
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What are the components of a reflex arc?
Sensory neuron, interneuron, motor neuron.
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What is an ipsilateral reflex?
A reflex where the response occurs on the same side as the stimulus.
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What is a contralateral reflex?
A reflex where the response occurs on the opposite side of the stimulus.
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What are the four categories of reflexes?
Spinal, cranial, somatic, and autonomic.
268
What is a spinal reflex?
A reflex mediated by the spinal cord, like the knee-jerk reflex.
269
What is a cranial reflex?
A reflex mediated by the brainstem, like tracking eye movement.
270
What is a somatic reflex?
A reflex involving skeletal muscle contraction.
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What is an autonomic reflex?
A reflex involving smooth/cardiac muscle or glands, like heartbeat or peristalsis.
272
What initiates a stretch reflex?
Stretching of a skeletal muscle's muscle spindles.
273
What is the response in a stretch reflex?
Reflexive contraction of the stretched muscle.
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What is reciprocal innervation in a stretch reflex?
Relaxation of antagonistic muscles during contraction of the stretched muscle.
275
What initiates a tendon reflex?
A substantial amount of tension in a tendon.
276
What is the response in a tendon reflex?
Relaxation of the skeletal muscle attached to the tendon.
277
What is the role of the Golgi tendon organ?
To sense increased tension in tendons.
278
What is the function of the inhibitory interneuron in the tendon reflex?
To inhibit motor neurons and reduce muscle contraction.
279
What is reciprocal innervation in a tendon reflex?
Contraction of antagonistic muscles and relaxation of the target muscle.
280
What initiates an extensor reflex?
A painful stimulus affecting one limb.
281
What is the response of the extensor reflex?
Contraction of extensor muscles in the opposite limb to maintain balance.
282
How is the extensor reflex related to the flexor reflex?
It occurs simultaneously but in the opposite limb.
283
Is the extensor reflex ipsilateral or contralateral?
Contralateral.
284
What is the purpose of a flexor reflex?
To withdraw a limb from a painful stimulus by contracting flexor muscles.
285
What initiates the flexor reflex?
Activation of pain-sensitive neurons in response to a painful stimulus.
286
Which pathway does the sensory neuron follow in the flexor reflex?
It fires an action potential that travels via the dorsal root of a spinal nerve into the spinal cord.
287
What happens after the sensory neuron enters the spinal cord?
It synapses with ascending and descending interneurons.
288
What role do interneurons play in the flexor reflex?
They synapse ipsilaterally with motor neurons that trigger contraction in flexor muscles.
289
What is the final result of the flexor reflex?
Muscular contraction that causes the limb to withdraw from the painful stimulus.
290
What is an example of a situation that can trigger the flexor reflex?
Stepping on a nail or touching hot water.
291
In the brain pathway example, where does the sensory signal end?
At the cerebral cortex after being relayed through the thalamus.
292
What does the upper motor neuron do in response to a stimulus?
Sends an action potential to the spinal cord to activate lower motor neurons.
293
What is the correct answer to the knowledge check about what occurs in a flexor reflex response?
Interneuron stimulation of ipsilateral motor neurons.
294
What does the mental status exam assess?
Higher cognitive functions such as memory, orientation, and language.
295
What is localization of function?
The concept that specific brain regions are responsible for specific functions.
296
Which hemisphere is typically associated with language functions?
The left hemisphere.
297
Which brain regions are involved in memory functions?
The medial temporal lobe, including the hippocampus and amygdala.
298
What are aphasias and which brain areas are associated with them?
Losses of language and speech functions, associated with Broca's and Wernicke's areas.
299
What is the purpose of asking a patient their name in a mental status exam?
To assess awareness, orientation, and the ability to interact.
300
How are the cranial nerves functionally grouped?
Sensory nerves, eye movement nerves, oral cavity/superior pharynx nerves, and neck movement nerves.
301
Which cranial nerve carries both sensory and motor information?
Trigeminal nerve.
302
Which nerves control extraocular muscles?
Oculomotor, trochlear, and abducens nerves.
303
What is tested by the vestibulo-ocular reflex?
Stabilization of gaze during head movements.
304
What is a dermatome?
A region of skin supplied by a single spinal nerve.
305
Which test assesses proprioception by requiring balance without visual feedback?
The Romberg test.
306
What is referred pain?
Visceral pain perceived in a different region of the body.
307
What does the motor exam assess?
The function of neurons and the muscles they control.
308
What does hypotonicity indicate?
A possible lower motor neuron issue with reduced muscle tone.
309
What brain region contains structures for planning, judgment, and working memory?
The prefrontal cortex.
310
What does the sensory exam evaluate?
Conscious somatic sensory perception.
311
What does the motor exam evaluate?
Neuronal and muscular function.
312
What are the two divisions of the autonomic nervous system (ANS)?
Sympathetic and parasympathetic divisions.
313
What is the main function of the autonomic nervous system?
To regulate involuntary body functions for homeostasis.
314
Which structure is the primary control center for the ANS?
The hypothalamus.
315
What does autonomic tone refer to?
The balance between sympathetic and parasympathetic stimulation.
316
What is the general pathway of autonomic motor output?
Preganglionic neuron → autonomic ganglion → postganglionic neuron → effector.
317
What is the primary role of the sympathetic nervous system?
Controls the 'fight or flight' response.
318
Where are the preganglionic neurons of the sympathetic system located?
In the lateral horns of the thoracic and upper lumbar spinal cord.
319
What are sympathetic chain ganglia?
Ganglia that run alongside the vertebral column and serve as relay points for sympathetic nerves.
320
What is a splanchnic nerve?
A nerve that carries visceral sympathetic and sensory fibers to collateral ganglia.
321
What cells in the adrenal medulla release adrenaline into the blood?
Chromaffin cells.
322
What is the primary role of the parasympathetic nervous system?
Controls 'rest and digest' responses.
323
Which division of the ANS increases heart rate and dilates pupils?
Sympathetic nervous system.
324
Which division of the ANS stimulates digestion and reduces heart rate?
Parasympathetic nervous system.
325
Where are the main anatomical components of the olfactory system located?
In the nasal cavity, specifically within the olfactory epithelium.
326
What are the three parts of an olfactory receptor cell?
Cell body, dendrite, and axon.
327
What is olfactory transduction?
The process through which a chemical stimulus (odorant) is converted into a neural signal.
328
What type of receptors are found in olfactory dendrites?
G protein–coupled receptors.
329
What role does the olfactory bulb play?
It receives axons from olfactory neurons and relays the signals to brain regions like the olfactory cortex and limbic system.
330
Why can smells trigger strong memories?
Because olfactory signals bypass the thalamus and connect directly to the limbic system.
331
What is the correct order of impulse propagation for olfaction?
Olfactory receptor → olfactory nerve → olfactory bulb → olfactory tract.
332
What are glomeruli in the olfactory bulb?
Globular tangles of nerve synapses where olfactory nerves synapse with bulb neurons.
333
What part of the olfactory receptor cell interacts directly with odor molecules?
The dendrite, specifically the olfactory cilia.
334
How often are olfactory receptor cells replaced?
Approximately every 50 days.
335
What is adaptation in the olfactory system?
The process by which sensitivity to smells decreases with prolonged exposure.
336
What is anosmia?
A condition characterized by a complete loss of the sense of smell.
337
What is hyposmia?
A reduced sensitivity to smells.
338
Where are taste cells primarily located?
On the tongue, soft palate, oropharynx, epiglottis, and inner cheeks.
339
What are the five basic taste sensations?
Sweet, salty, sour, bitter, and umami.
340
Which type of papillae do NOT contain taste buds?
Filiform papillae.
341
Which cranial nerve innervates fungiform papillae?
Facial nerve (VII).
342
Which cranial nerve innervates vallate and foliate papillae?
Glossopharyngeal nerve (IX).
343
What structures detect tastants dissolved in saliva?
Chemoreceptors on the microvilli of taste cells.
344
What are the three types of cells in a taste bud?
Basal cells, gustatory receptor cells, and supporting cells.
345
What is the function of gustatory hairs?
To increase the surface area exposed to tastants.
346
How often are gustatory receptor cells replaced?
Every 10 days.
347
Which ions are responsible for salty and sour tastes?
Na⁺ (salty) and H⁺ (sour).
348
What activates umami taste receptors?
The amino acid L-glutamate.
349
Which cranial nerves carry taste information?
Facial (VII), Glossopharyngeal (IX), and Vagus (X) nerves.
350
Where is the primary gustatory cortex located?
In the parietal lobe of the brain.
351
What is the function of the gustatory nucleus?
It relays taste signals to the thalamus, hypothalamus, and limbic system.
352
What are the three tunics of the eyeball?
Fibrous, vascular, and neural tunics.
353
Which structures make up the fibrous tunic?
Sclera and cornea.
354
What is the function of the ciliary body?
Adjusts lens curvature and secretes aqueous humor.
355
Which photoreceptors detect color?
Cone cells.
356
What is the fovea centralis?
The point of highest visual acuity in the retina.
357
What is the blind spot of the eye?
The optic disc, where no photoreceptors are present.
358
What fluid fills the anterior chamber of the eye?
Aqueous humor.
359
What is the function of the vitreous humor?
Maintains eyeball shape and supports retina.
360
Which structure controls pupil diameter?
Iris.
361
What is the function of eyelashes?
To protect the eye from airborne particles.
362
What is the role of the lacrimal apparatus?
Produces and drains tears.
363
Which cranial nerve controls the superior oblique muscle?
Trochlear nerve (IV).
364
What are the three regions of the ear?
External, middle, and inner ear.
365
Which bones make up the ossicles?
Malleus, incus, and stapes.
366
What is the function of the Eustachian tube?
Equalizes pressure in the middle ear.
367
What part of the ear contains the organ of Corti?
Cochlea.
368
What fluid fills the membranous labyrinth?
Endolymph.
369
What structure translates sound waves into neural signals?
Organ of Corti.
370
What is the modiolus?
The central pillar of the cochlea containing spiral ganglia.
371
What structure detects static equilibrium?
Maculae in the utricle and saccule.
372
What structure detects dynamic equilibrium?
Crista ampullaris in the semicircular canals.
373
What is the role of the cupula?
Detects rotational head movements by bending stereocilia.
374
Which nerve transmits equilibrium information to the brain?
Vestibular branch of the vestibulocochlear nerve (VIII).
375
Horns
In the nervous system, horns refer to regions of gray matter in the spinal cord that project outward in a horn-like shape on a cross-section.
There are three types of horns:
1. Dorsal (posterior) horns
• Located toward the back of the spinal cord
• Contain sensory neurons (receive incoming sensory information from the body)
• Associated with afferent pathways
2. Ventral (anterior) horns
• Located toward the front of the spinal cord
• Contain motor neurons (send signals out to skeletal muscles)
• Associated with efferent pathways
3. Lateral horns (only in thoracic and upper lumbar segments)
• Contain autonomic motor neurons (involved in involuntary control, like smooth muscle and glands)
• Part of the sympathetic division of the autonomic nervous system
So, “horns” in this context are anatomical structures in the spinal cord’s gray matter responsible for processing sensory, motor, or autonomic signals.
