Principles of the nervous system Flashcards
1
Q
How are the terms “dorsal” and “ventral” used in the brain?
A
In the brain, the terms “dorsal” and “ventral” have reversed meanings compared to the rest of the body. In the brain, “dorsal” signifies a direction that is upward, toward the top of the head, while “ventral” indicates a direction that is downward, toward the base of the skull.
2
Q
What do the terms “rostral” and “caudal” represent in the context of the brain?
A
In the brain, “rostral” refers to a direction that is toward the front or the beak-like end of the brain. “Caudal” signifies a direction that is toward the back or tail-like end of the brain.
3
Q
What are the two main components of the Central Nervous System (CNS)
A
Brain, ii) Spinal Cord
4
Q
What are the two main components of the Peripheral Nervous System (PNS)?
A
i) Cranial Nerves [12 pairs], ii) Spinal Nerves [31 pairs]
5
Q
How many pairs of spinal nerves are there?
A
31 pairs (8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal)
6
Q
Are the Olfactory (CN I) and Optic (CN II) nerves considered part of the CNS or PNS?
A
They are considered part of the CNS, although they are often grouped with the PNS on a structural level.
7
Q
What is the role of sensory organs/receptors in the nervous system?
A
Sensory organs/receptors detect and respond to stimuli, allowing us to perceive the world around us.
8
Q
What are the two main types of cells in the nervous system?
A
i) Neurons, ii) Glia cells (also known as glia and neuroglia)
9
Q
What is the function of neurons?
A
Neurons are excitable cells that are responsible for transmitting electrical and chemical signals within the nervous system.
10
Q
What are the three types of glia cells?
A
i) Oligodendrocytes, ii) Microglia, iii) Astrocytes
11
Q
Which type of glia cells are responsible for producing myelin in the central nervous system?
A
Oligodendrocytes
12
Q
: What is the role of microglia cells?
A
Microglia are the immune cells of the CNS and are involved in the defense and repair processes.
13
Q
What is the most numerous type of cell in the CNS?
A
Glial cells (or neuroglia) outnumber neurons at a ratio of approximately 10:1.
14
Q
How do neurons communicate with each other?
A
Neurons communicate with other neurons via chemical transmission, which involves the release and reception of neurotransmitters.
15
Q
How do individual neurons communicate internally?
A
Communication within an individual neuron is through electrical impulses.
16
Q
What is the function of a dendrite in a neuron?
A
The dendrite detects incoming information and conducts impulses toward the cell body.
17
Q
: What is the role of the soma (cell body) in a neuron?
A
The soma contains the organelles necessary for the neuron’s functions.
18
Q
What is the function of an axon in a neuron?
A
The axon conducts impulses away from the soma towards the axon terminal.
19
Q
Which cells are responsible for myelinating neurons in the central nervous system (CNS)?
A
Oligodendrocytes myelinate neurons in the CNS.
20
Q
Which cells are responsible for myelinating neurons in the peripheral nervous system (PNS)?
A
Schwann cells myelinate neurons in the PNS.
21
Q
What is the role of an axon terminal?
A
The axon terminal contains neurotransmitters to be released into the synaptic gap.
22
Q
What happens during neurotransmission at a synapse?
A
i) An action potential passes through the presynaptic neuron.
ii) This permits the vesicles carrying neurotransmitters to proceed to the synaptic gap.
iii) Neurotransmitters are released from the presynaptic neuron across the synaptic gap or synaptic cleft.
iv) Neurotransmitters are received by receptors at the postsynaptic neuron.
v) Any neurotransmitter not taken by the postsynaptic neuron remains in the synaptic gap until it is recycled by the presynaptic neuron or destroyed.
23
Q
What is saltatory conduction?
A
Saltatory conduction is the propagation of an action potential (AP) along a myelinated axon, specifically occurring at the nodes of Ranvier. It is faster than continuous conduction.
24
Q
Where does saltatory conduction take place?
A
Saltatory conduction occurs at the nodes of Ranvier along a myelinated axon.
25
What is continuous conduction?
Continuous conduction is the process of propagating an action potential within each gateway or segment of an axon. It takes a longer period of time compared to saltatory conduction.
26
How does the speed of saltatory conduction compare to continuous conduction?
Saltatory conduction is faster than continuous conduction.
27
What is the active site for saltatory conduction?
The nodes of Ranvier are the active sites where saltatory conduction occurs.
28
How is the action potential generated in a neuron?
The action potential is generated by an influx of sodium ions (Na+) into the neuron, followed by the release of potassium ions (K+) from the neuron.
29
How are CNS neurons interconnected?
CNS neurons are deeply interconnected, with each neuron having over 10,000 synaptic connections.
30
Are neurons capable of proliferating?
No, neurons are post-mitotic cells, which means they do not have the capacity to proliferate. However, there is evidence of adult neurogenesis in specific areas of the brain known as neurogenic niches.
31
What are the two types of junctions between the axon terminal and the target cell?
i) Electrical synapses, ii) Chemical synapses.
32
What occurs at electrical synapses?
Electrical synapses allow for direct electrical communication between cells, where ions can flow through gap junctions connecting the cells.
33
What occurs at chemical synapses?
Chemical synapses involve the release of neurotransmitters from the axon terminal of one neuron into the synaptic cleft, which then bind to receptors on the target cell to transmit the signal.
34
Can you provide an example of an area in the brain where adult neurogenesis occurs?
Neurogenic niches, such as the hippocampus, are regions in the brain where adult neurogenesis has been observed.
35
What is a unipolar neuron?
A unipolar neuron is a type of neuron that has a single axon only. It is typically found in primary sensory neurons, such as the cell bodies in dorsal root ganglia.
36
What is a ganglia?
A ganglia is a cluster of neuronal cell bodies.
37
What is a bipolar neuron?
A bipolar neuron is a type of neuron that has one axon and one dendrite. It is often found in specialized sensory neurons, such as those in the retina. An example of bipolar neurons in the retina is the bipolar cells that transmit signals from photoreceptors.
38
What is a multipolar neuron?
A multipolar neuron is a type of neuron that has one axon and multiple dendrites. They are the most common type of neurons in the brain. Motor neurons are also examples of multipolar neurons. There are three distinct types of multipolar neurons: a) Motor neurons found in the spinal cord, b) Pyramidal neurons found in the hippocampus, c) Purkinje neurons found in the cerebellum.
39
Can you provide an example of a pyramidal neuron?
Pyramidal neurons are found in the hippocampus. They are named for their pyramid-shaped cell body and are involved in processes related to learning and memory.
40
What is the role of astrocytes?
Astrocytes are glial cells that support and provide a suitable environment for neurons to function in the central nervous system (CNS).
41
What is the role of oligodendrocytes?
Oligodendrocytes are glial cells found only in the CNS and are responsible for the production and maintenance of the myelin sheath, which helps create white matter (WM). Each oligodendrocyte can myelinate multiple axons.
42
What is the composition of myelin?
Myelin is mainly composed of Myelin Basic Protein (MBP) and Proteolipid Protein (PLP), which make up approximately 80% of its structure.
43
What are microglia?
Microglia are a type of glial cell in the CNS. They have a delicate network of ramified cells and can be activated by pathogens. They are distributed throughout the CNS in a regular mosaic pattern and make up about 5% of all cells in the brain.
44
What are the functions of microglia?
Microglia serve as phagocytic and immune cells in the CNS. They play a role in promoting repair processes and respond to various stimuli by transitioning from a quiescent to an activated state.
45
What is the role of Schwann cells?
Schwann cells are the neuroglia of the peripheral nervous system (PNS). They myelinate axons through a process of spiral wrapping. They are important for axon regeneration and provide a substrate for axons to grow along.
46
How many axons does one Schwann cell myelinate?
One Schwann cell myelinates one axon.
47
What are the layers of myelin formed by Schwann cells called?
The layers of myelin formed by Schwann cells are referred to as dark bands.
48
What is the Node of Ranvier?
The Node of Ranvier is a gap between myelin sheaths along an axon where the axonal membrane is exposed.
49
Can axons be myelinated or unmyelinated?
Yes, axons can be either myelinated or unmyelinated. Myelinated axons have a diameter larger than 1 μm, while unmyelinated axons have a diameter smaller than 1 μm.
50
What is the significance of saltatory conduction?
Saltatory conduction is the process by which action potentials jump from one Node of Ranvier to another along a myelinated axon, allowing for rapid transmission of the signal.
51
What is the speed of conduction in myelinated axons compared to unmyelinated axons?
Conduction in myelinated axons is very rapid, with speeds up to 120 m/s. In contrast, unmyelinated axons have much slower conduction, typically less than 1.5 m/s.
52
What is the unit of measurement for micrometre?
The unit of measurement for micrometre is μm, which is equal to one millionth of a meter.
53
What are the anatomical components of the central nervous system (CNS)?
The central nervous system consists of the brain and the spinal cord.
54
What are the anatomical components of the peripheral nervous system (PNS)?
The peripheral nervous system includes the communication between the CNS and the periphery, which includes the viscera, muscles, joints, vessels, skin, and glands.
55
What are the divisions of the brain within the central nervous system?
The brain is divided into three main parts: the forebrain, midbrain, and hindbrain.
56
What are the specific components of the midbrain?
The midbrain includes structures such as the cerebral hemispheres, thalamus, hypothalamus, and brainstem.
57
What is the composition of the brain in terms of grey matter (GM) and white matter (WM)?
: The brain consists of both grey matter (GM), which includes neuronal cell bodies and synapses, and white matter (WM), which is composed of myelinated axons.
58
What structures are included in the hindbrain?
The hindbrain includes the cerebellum, which is responsible for coordinating voluntary movements and maintaining balance.
59
What is lobular organization in the context of the brain?
Lobular organization refers to dividing the brain into lobes based on anatomical landmarks.
60
What are gyri?
Gyri are ridges on the surface of the brain. They are elevated structures that form the outer contour of the brain.
61
What are sulci?
Sulci are depressions or grooves on the surface of the brain. They are shallow furrows that separate adjacent gyri.
62
What are fissures?
Fissures are the largest grooves on the surface of the brain. They are deep, prominent grooves that divide the brain into major regions or hemispheres.
63
What is the purpose of dividing the brain into lobes?
Dividing the brain into lobes based on gyri, sulci, and fissures helps in understanding the functional organization of different brain regions and their specific roles in processes such as cognition, sensation, movement, and perception.
64
Can you name some of the lobes of the brain?
Some of the major lobes of the brain include the frontal lobe, parietal lobe, temporal lobe, and occipital lobe.
65
What are the lobes of the forebrain?
The lobes of the forebrain include the occipital lobe, parietal lobe, and frontal lobe. Each lobe has different sensory or motor functions, exhibiting functional specificity.
66
What is the primary function of the temporal lobe?
The temporal lobe is involved in various functions such as the primary auditory cortex, primary olfactory cortex (smell), learning, memory, and executive functions.
67
What is the primary function of the cerebral cortex?
The cerebral cortex, which is the outer layer of the forebrain, processes motor and sensory information. It plays a significant role in cognition, including language, thinking, and following instructions.
68
What are the main components of the hindbrain?
The hindbrain consists of the cerebellum, pons, and medulla oblongata. These structures contribute to motor control, coordination, and vital functions such as breathing and heart rate.
69
What is the function of the hypothalamus?
The hypothalamus, located below the thalamus, plays a crucial role in homeostasis. It contributes to the control of the autonomic nervous system, endocrine system, thermoregulation, and satiety (suppression of hunger).
70
What is the role of the thalamus?
The thalamus is involved in relaying sensory and motor signals to and from the cerebral cortex. It acts as a sensory gateway for various types of information, including pain, touch, and proprioception.
71
What are the components of the brainstem?
The brainstem is formed by the midbrain, which is located in the middle, and the hindbrain, which is located at the posterior part of the brain.
72
What are the critical functions of the midbrain and hindbrain?
The midbrain and hindbrain are functionally critical for connecting the cortex to the spinal cord and controlling vital functions such as respiration and cardiovascular systems. Damage to these regions can be fatal.
73
What is the role of the cerebellum?
The cerebellum, often referred to as the "little brain," is responsible for coordinating and modifying muscular activity. It plays a crucial role in motor movements, regulating sensory systems, and maintaining balance and posture.
74
How is the cerebellar cortex structured?
The cerebellar cortex consists of tightly packed gray matter (GM) overlaying white matter (WM). The appearance of this structure is sometimes referred to as "Arbor Vitae" or "the tree of life" due to its branching and tree-like appearance.
75
What are some functions of the hindbrain?
In addition to the cerebellum, the hindbrain also includes structures such as the pons and medulla oblongata. It is involved in regulating vital functions, such as respiration and cardiovascular control.
76
How does damage to the brainstem typically affect an individual?
Damage to the brainstem, including the midbrain and hindbrain, can be life-threatening. It can disrupt crucial functions such as breathing and cardiovascular control, making it a critical region of the brain.
77
Where does the spinal cord extend from and to?
The spinal cord extends from the atlas, which is the first cervical vertebra (C1), to the first lumbar vertebra (L1).
78
Where is the spinal cord located?
The spinal cord is located within the vertebral canal, which is formed by the vertebral column (spine).
79
What are the structures that make up the vertebral column?
The vertebral column consists of individual vertebrae, which include spinous processes (bony projections), vertebral bodies (the main part of each vertebra), and the sacrum (a triangular bone at the base of the spine).
80
What is the function of the spinal cord?
The spinal cord serves as a major pathway for sensory and motor information between the body and the brain. It is responsible for transmitting signals to and from various parts of the body.
81
How is the spinal cord protected?
The spinal cord is protected by the vertebral column, which surrounds it and provides a bony enclosure. Additionally, it is surrounded by protective layers called meninges.
82
What is the significance of the C1 and L1 vertebrae in relation to the spinal cord?
The C1 vertebra (atlas) and L1 vertebra are important landmarks that indicate the upper and lower limits of the spinal cord's extent within the vertebral canal.
83
What are the two components of the peripheral nervous system (PNS)?
The PNS consists of the somatic (voluntary) component, which involves skeletal muscles, muscles, and joints, and the autonomic (involuntary) component, which involves organs, vessels, and autonomic responses.
84
What is the somatic component of the PNS responsible for?
The somatic component of the PNS is responsible for voluntary movements and sensory information related to muscles, joints, and the body's external environment.
85
What does the autonomic component of the PNS control?
The autonomic component of the PNS controls involuntary functions of the body, including the regulation of organs, blood vessels, and automatic responses such as heart rate, digestion, and breathing.
86
Are the somatic and autonomic components always anatomically separate in peripheral nerves?
No, many peripheral nerves contain axons from both the somatic and autonomic components. Therefore, they are not always anatomically separate.
87
Where do peripheral nerves arise from?
Peripheral nerves can arise from two sources: the brain or brainstem as cranial nerves, or the spinal cord as spinal nerves.
88
What is the difference between cranial nerves and spinal nerves in terms of their origin?
Cranial nerves originate from the brain or brainstem, while spinal nerves originate from the spinal cord. Both types of nerves contribute to the overall functioning of the peripheral nervous system.
89
What is the main function of the Autonomic Nervous System?
The Autonomic Nervous System controls the involuntary aspects of bodily functions and regulates the operation of internal organs to maintain the body's internal environment.
90
Where does the Parasympathetic division originate from?
The Parasympathetic division originates from the brainstem and the sacral region of the spinal cord.
91
Where does the Sympathetic division originate from?
The Sympathetic division originates from the thoracic and lumbar regions of the spinal cord.
92
What is the other term used to refer to the Parasympathetic division?
The Parasympathetic division is also known as the craniosacral division due to its origin from the brainstem and the sacral spinal cord.
93
What is the other term used to refer to the Sympathetic division?
The Sympathetic division is also known as the thoracolumbar division due to its origin from the thoracic and lumbar spinal cord.
94
How do the Parasympathetic and Sympathetic divisions differ in terms of their origin?
The Parasympathetic division originates from the cranial and sacral regions, while the Sympathetic division originates from the thoracic and lumbar regions of the spinal cord.
95
How many neurons are usually involved in the Autonomic Nervous System (ANS)?
The ANS typically involves two neurons: the preganglionic neuron and the postganglionic neuron.
96
Where is the adrenal medulla located in the ANS?
The adrenal medulla is a specialized structure associated with the sympathetic division of the ANS. It is located above the kidneys and is considered an extension of the sympathetic ganglia.
97
Which type of neurons have preganglionic axons only?
All preganglionic neurons, except those that supply the adrenal medulla, have preganglionic axons only. These axons synapse with postganglionic neurons in autonomic ganglia.
98
What are the effector organs of the ANS?
The effector organs of the ANS include smooth muscles, cardiac muscles, and glands. These organs are regulated by the autonomic nervous system.
99
Where do preganglionic neurons synapse with postganglionic neurons in the ANS?
Preganglionic neurons synapse with postganglionic neurons in autonomic ganglia. Ganglia are structures that contain several nerve cell bodies.
100
What is the Sympathetic trunk?
The Sympathetic trunk is a chain of interconnected paravertebral ganglia that extends the length of the vertebral column. It is part of the sympathetic division of the autonomic nervous system.
101
What is the function of the Sympathetic trunk?
The Sympathetic trunk serves as a major pathway for preganglionic sympathetic axons. It allows communication and coordination between different sympathetic ganglia.
102
Where do all preganglionic sympathetic axons enter?
All preganglionic sympathetic axons enter the sympathetic trunk.
103
What are somatic functions?
Somatic functions refer to voluntary control of bodily functions, particularly the contraction of skeletal muscles.
104
What is the role of somatic efferent neurons?
Somatic efferent neurons are responsible for generating, conducting, and coordinating motor commands that lead to voluntary movements, specifically the contraction of skeletal muscles.
105
What is the input and output of somatic efferent neurons?
Somatic efferent neurons receive input from sensory organs and transmit output to skeletal muscles.
106
What are the main components of the sympathetic pathway?
The sympathetic pathway includes the ventral and dorsal spinal nerves, the sympathetic trunk, splanchnic nerves, and prevertebral ganglia. It innervates the musculoskeletal system, abdomen, and organs in the heart, lungs, or head.
107
What are the main components of the parasympathetic pathway?
The parasympathetic pathway involves the brainstem, cranial nerves, ganglia located close to the effector organ, and the spinal cord (specifically the sacral region). It innervates organs in the head, heart, lungs, abdomen, and pelvic region.
108
What neurotransmitter is primarily used in the sympathetic pathway?
The sympathetic pathway primarily uses norepinephrine as its neurotransmitter.
109
What neurotransmitter is primarily used in the parasympathetic pathway?
The parasympathetic pathway primarily uses acetylcholine as its neurotransmitter.
110
What is the characteristic of the preganglionic and postganglionic axons in the parasympathetic pathway?
The parasympathetic pathway has long preganglionic axons and short postganglionic axons.
111
Where do the preganglionic axons of the sacral parasympathetic pathway exit?
The preganglionic axons of the sacral parasympathetic pathway exit via the pelvic splanchnic nerves.
112
Where do the preganglionic axons synapse with the postganglionic axons in the sacral parasympathetic pathway?
The preganglionic axons of the sacral parasympathetic pathway synapse with postganglionic axons on the pelvic organs.
113
Which organs are innervated by the sacral parasympathetic pathway?
The sacral parasympathetic pathway innervates the pelvic organs, including the bladder, rectum, and organs involved in sexual function.
114
What is the effect of the sacral parasympathetic pathway on the bladder?
The sacral parasympathetic pathway is responsible for promoting urination by stimulating the bladder muscles to contract.
115
What is the effect of the sacral parasympathetic pathway on the rectum?
The sacral parasympathetic pathway aids in defecation by coordinating the relaxation of the rectal muscles.
116
What is the effect of the sacral parasympathetic pathway on sexual function?
The sacral parasympathetic pathway plays a role in regulating sexual function and can contribute to the processes involved in sexual arousal and response.
117
What do spinal nerves provide to the body?
Spinal nerves provide motor (somatic motor) and sensory (somatosensory) supply to the whole body, except for the head and parts of the neck
118
Which part of the nervous system do spinal nerves also provide sympathetic supply to?
: Spinal nerves provide sympathetic supply to the whole body.
119
Which region of the body does the lumbar region of spinal nerves supply?
The lumbar spinal nerves supply the pelvis and lower limb.
120
What is the cauda equina?
The cauda equina is a bundle of spinal nerves and their roots that extends from the lower end of the spinal cord. It innervates the pelvis and lower limbs.
121
Which nerves are included in the cauda equina?
The nerves pertaining to L2-L5, S1-S5, and the coccygeal nerve are included in the cauda equina.
122
What is the function of the dorsal root of a spinal nerve?
The dorsal root of a spinal nerve carries afferent (somatosensory) information to the spinal cord.
123
What is the function of the ventral root of a spinal nerve?
The ventral root of a spinal nerve carries efferent (somatic motor/sympathetic) information away from the spinal cord.
124
Where are the cell bodies of the sensory neurons located in relation to the spinal cord?
The cell bodies of the sensory neurons are located in the dorsal root ganglia, which are clusters of cell bodies outside the spinal cord.
125
Where do the nerve roots of spinal nerves reside?
The nerve roots of spinal nerves reside within the vertebral canal.
126
What is the role of the dorsal primary ramus?
The dorsal primary ramus supplies the posterior (dorsal) body wall with motor and sensory innervation.
127
What is the role of the ventral primary ramus?
The ventral primary ramus supplies the anterior (ventral) body wall and the limbs with motor and sensory innervation.
128
What is the general pattern of spinal nerve division?
Spinal nerves divide into dorsal (posterior) and ventral (anterior) primary rami.
129
What is the intervertebral foramen?
The intervertebral foramen is the opening or passage through which spinal nerves exit the vertebral column.
130
What does the dorsal primary ramus innervate?
The dorsal primary ramus innervates the skin over the paravertebral gutter, erector spinae muscles, and facet joints of the vertebral column.
131
What does the ventral primary ramus supply?
The ventral primary ramus supplies the rest of the body, except for the head and parts of the neck, including the skin and musculoskeletal system.
132
What is a dermatome?
A dermatome is an individual area of skin that is innervated by a single spinal nerve (primary ramus). Each dermatome is responsible for sensory input to the dorsal root.
133
What is a myotome?
A myotome is an individual set of muscles that is innervated by a single spinal nerve (primary ramus). Each myotome represents a specific group of muscles.
134
How is segmental organization of spinal nerves related to dermatomes and myotomes?
Segmental organization of spinal nerves results in the formation of specific dermatomes and myotomes, where each spinal nerve supplies a distinct area of skin (dermatome) and a specific group of muscles (myotome).
135
What is the purpose of dermatomes?
Dermatomes help to map the sensory innervation of the body, allowing healthcare professionals to localize areas of sensory dysfunction or pathology.
136
What is the purpose of myotomes?
Myotomes help to identify the specific muscle groups innervated by each spinal nerve, aiding in the assessment of muscle strength and function.
137
How are dermatomes organized?
Dermatomes are organized in a strip-like pattern along the body, with each strip of skin being innervated by an individual spinal nerve.
138
What is the clinical importance of dermatomes?
Loss or altered sensation and/or pain in a specific dermatome can indicate possible injury to the corresponding spinal cord, nerve root, or spinal nerve.
139
What is a myotome?
A myotome is a group of muscles that are innervated by a specific, single spinal nerve.
140
What is the embryological significance of myotomes?
In embryology, myotomes refer to the segment of the somite that develops into the muscles of the body.
141
Why are myotomes more complicated in limbs?
Myotomes are more complicated in limbs because multiple spinal nerves innervate large muscle groups in the limbs.
142
How are muscles in the limbs innervated by spinal nerves?
Each muscle group in the limbs is innervated by an individual spinal nerve, allowing for coordinated movement and control.
143
Which nerves supply the intercostal muscles?
The intercostal muscles, which are located between the ribs, are supplied by the intercostal nerves arising from the T1-T11 spinal nerves.
