Nervous System And Brain Flashcards
1
Q
What are the three layers of the meninges?
A
Dura mater, Arachnoid mater, Pia mater
2
Q
What is the function of the dura mater?
A
Outermost tough membrane covering neural tissue
3
Q
How many layers does the dura mater have?
A
Two layers
4
Q
What are the two layers of the dura mater?
A
Outer Periosteal layer, Inner Meningeal layer
5
Q
What 3 supportive structures are formed by the dura mater?
A
Falx cerebri, Falx cerebelli, Tentorium cerebelli
6
Q
What does the falx cerebri do?
A
Divides the brain into left and right hemispheres
7
Q
What does the falx cerebelli do?
A
Divides the brain into left and right cerebellar hemispheres
8
Q
What is the role of the tentorium cerebelli?
A
Separates the cerebellum from the cerebrum
9
Q
What type of layer is the arachnoid mater?
A
Filamentous layer
10
Q
What is the pia mater?
A
Thin vascular layer adhering to the contours of the brain
11
Q
What fills all meningeal spaces?
A
All spaces are filled with cerebrospinal fluid.
12
Q
Where is the epidural space located?
A
Between the brain and the skull (dura mater + bone).
13
Q
What is the subdural space?
A
The space between the dura mater and arachnoid mater.
14
Q
Where is the subarachnoid space found?
A
Between the arachnoid and pia mater.
15
Q
What is cerebrospinal fluid?
A
A clear liquid similar to blood plasma.
16
Q
Where does cerebrospinal fluid fill?
A
It fills ventricles, canals, and the subarachnoid space.
17
Q
What are the functions of cerebrospinal fluid?
A
- Buoyancy (Support weight)
- Protection
- Chemical stability, removes waste.
18
Q
What is the function of the choroid plexus
A
Made of ependymal cells and secrete and circulate cerebral spinal fluid
19
Q
Where does CSF flow begin?
A
Choroid Plexus in lateral Ventricles
20
Q
What connects the lateral ventricles to the third ventricle?
A
Interventricular foramen
21
Q
What connects the third ventricle to the fourth ventricle?
A
Cerebral aqueduct
22
Q
Where does the fourth ventricle feed into
A
Central Canal / Subarachnoid space
23
Q
What regulates the Blood-Brain Barrier?
A
The Blood-Brain Barrier is tightly joined and highly regulated by Astrocytes.
24
Q
What types of molecules are permeable through the Blood-Brain Barrier?
A
Lipid soluble molecules (such as alcohol, nicotine, and anesthetics)
Small molecules (gases and glucose)
25
What types of molecules are impermeable to the Blood-Brain Barrier?
Large molecules such as proteins and antibiotics are impermeable.
26
What is the location of the Medulla Oblongata?
Anterior ventral to the 4th ventricle and cerebellum, superior to the spinal cord, inferior to the pons.
27
What types of tracts are found in the Medulla Oblongata?
Ascending and descending tracts.
28
What vital reflexes are controlled by the Medulla Oblongata?
Cardiac function, breathing, and vasomotor control (blood vessel diameter)
29
What system does the Medulla Oblongata contain part of?
The Reticular Activating System (RAS).
30
What is the function of the reticular activating system (RAS)?
Regulate sleep and waking up (conscious attention)
31
What is the function of the reticular activating system (RAS)?
Regulate sleep and waking up (conscious attention)
32
What is the location of the Pons?
Interior to the 4th ventricle and cerebellum, superior to the medulla, and inferior to the midbrain.
33
What is the function of the Pons?
Connection pathway between the cerebellum and cerebrum.
34
What is the location of the Midbrain?
Anterior to the 4th ventricle, anterior to the cerebellum, and superior to the pons.
35
What are the components of the Midbrain?
Cerebral Peduncles and Corpora Quadrigemina.
36
Function of cerebral peduncles
Voluntary motor fibers pass through here to skeletal muscle.
37
Function of corpora quadrigemina and its 2 parts
Superior colliculi (visual reflexes)
Inferior colliculi (auditory reflexes)
38
What is the Diencephalon?
The Diencephalon is a part of the brain that includes structures such as the thalamus and hypothalamus.
39
Where is the Thalamus located?
The Thalamus is located deep in the cerebrum, superior to the hypothalamus, surrounding the third ventricle.
40
What is the function of the Thalamus?
Nearly all sensory information travels through the Thalamus to the cerebral cortex, except for smell.
41
Where is the Hypothalamus located?
The Hypothalamus is located deep in the cerebrum, superior to the thalamus, surrounding the third ventricle.
42
What does the Hypothalamus control?
The Hypothalamus controls the Autonomic Nervous System (ANS), including sympathetic and parasympathetic responses, as well as the endocrine system.
43
What hormones does the Hypothalamus secrete?
The Hypothalamus secretes Antidiuretic Hormone (ADH) and Oxytocin.
44
What is the function of Antidiuretic Hormone (ADH)?
ADH helps retain water in the body.
45
What is the function of Oxytocin?
Oxytocin is involved in labor contractions.
46
What is the function of the pineal gland
Produce melatonin
47
What is the primary function of the Nervous System?
Works to maintain homeostasis
The Nervous System is the master controlling and communicating system of the body.
48
What are the three overlapping functions of the Nervous System?
1. Sensory input: Detects internal and external changes.
2. Integration: Processes and interprets information.
3. Motor Output: Activates effector organs to produce a response.
49
What are the two principal parts of the Nervous System?
1. Central Nervous System (CNS): Comprises the brain and spinal cord, serving as the integration and control center.
2. Peripheral Nervous System (PNS): Comprises nerves that branch off the brain and spinal cord.
50
What are the components of the Peripheral Nervous System (PNS)?
The PNS includes spinal nerves (to and from the spinal cord) and cranial nerves (to and from the brain).
51
What is a ganglion?
A ganglion is a swelling of cell bodies.
52
What is the role of sensory neurons?
Sensory (afferent) neurons detect changes in the body or external environment and transmit information away from receptors into the brain or spinal cord.
53
What is the function of interneurons?
Interneurons (association neurons) lie between sensory and motor pathways in the CNS, processing, storing, and retrieving information.
54
What do motor (efferent) neurons do?
Motor (efferent) neurons send signals out to muscles and gland cells, which carry out responses called effectors.
55
What are the divisions of the Peripheral Nervous System?
The Peripheral Nervous System has two divisions: Afferent Division (Sensory) and Efferent Division (Motor).
56
What does the Afferent Division (Sensory) do?
The Afferent Division conveys impulses to the CNS, including somatic sensory info from the skin and visceral info from internal organs.
57
What does the Efferent Division (Motor) do?
The Efferent Division conveys impulses away from the CNS, including somatic signals to skeletal muscles and visceral signals through the autonomic nervous system.
58
What are the two branches of the autonomic nervous system?
The autonomic nervous system has two branches: Parasympathetic and Sympathetic.
59
What are the properties of neurons?
excitability (responding to changes),
conductivity (producing traveling electrical signals),
secretion (releasing neurotransmitters when an electrical signal reaches the end of a nerve causes secretion
60
Define nuclei
Cluster of cell bodies in CNS
61
Define ganglia
Cluster of cell bodies and PNS
62
Define Tracts
Bundles of neuron processes in CNS
63
Define nerves
Bundles of neuron processes in PNS
64
What is a neuron process and what are the two types
An arm process that extends from the cell body.
Dendrites and axons
65
Explain axons vs dendrites
Axons Send or transmit info to the next cell
Dendrites receive information and transmit it to the cell body
66
Explain axons
Send or transmit info to the next cell
67
Define axon collaterals and axon terminals, and axon hillock
Axon collateral- axon with branches
Axon terminals- distal ends
Axon hillock- where nerve transmission action potential starts
68
Define axon collaterals and axon terminals, and axon hillock
Axon collateral- axon with branches
Axon terminals- distal ends
Axon hillock- where nerve transmission action potential starts
69
What are multipolar neurons?
neurons with many dendrites, one cell body, and one axon.
70
What are bipolar neurons and where are they found?
Bipolar neurons are for special senses such as vision and smell.
They have one dendrite, one cell body, and one axon.
Examples include olfactory neurons, retina, and ear neurons.
71
What are unipolar neurons?
sensory neurons where the branch splits into an axon and a dendrite.
transmit sensory information from skin and organs to spinal cord.
72
What are neuroglia?
support cells in the nervous system.
73
What are Schwann cells?
only in the axons of the PNS.
They create myelin (myelin sheaths) and are associated with white matter (adipose tissue)
74
Nodes of ranvier
Space between Schwann cell
75
Function of myelin
Increase speed of action potential(conduction)
76
What factors determine nerve signal speed?
diameter of the fiber
If myelinated.
77
What are A fibers?
A fibers have the fastest transmission
large and myelinated.
78
What are B fibers?
B fibers have medium transmission speed.
They are small and myelinated.
79
What are C fibers?
C fibers have the slowest transmission speed
They are small and unmyelinated.
80
What are the functions of slow signals?
supply the stomach and dilate the pupil.
81
What are the functions of fast signals?
supply skeletal muscles and sensory signals for vision and balance.
82
What are astrocytes?
Astrocytes are neuroglia in CNS
maintain the Blood Brain Barrier (BBB).
83
What are microglial cells?
Microglial cells are the immune cells of the CNS.
84
What are ependymal cells?
Neuroglia of CNS
synthesize and circulate Cerebral Spinal Fluid (CSF).
85
What are oligodendrocytes?
myelinate axons in the CNS.
86
What is voltage?
Voltage is a measure of potential energy generated by separated charge.
87
What is current?
Current is the flow of ions between two points.
88
What is resistance?
Resistance is the hindrance to charge flow.
89
What is an insulator?
An insulator is a substance with high electrical resistance.
90
What is a conductor?
A conductor is a substance with low electrical resistance.
91
What are the main types of ion channels?
leakage (nongated) channels
gated channels.
92
What are leakage channels?
channels that are always open.
93
What happens in gated channels?
Proteins change shape to open/close the channel.
94
What are the three types of gated channels?
chemically-gated,
voltage-gated,
mechanically-gated.
95
What are chemically gated channels?
Chemically gated channels (ligand-gated) only open when binding to a specific chemical.
96
What are voltage-gated channels?
Channels open in response to changes in membrane potential.
97
What are mechanically gated channels?
channels open/close in response to sensory receptors
98
What is the resting membrane potential of an axon inside the cell membrane
-70mV
99
Is the inside of an axon positive or negative charged
Negative
100
Is the outside of an axon membrane positive or negative charged
Positive
101
How is the resting membrane potential generated?
Difference of ion makeup inside vs outside the membrane
Difference in plasma membrane permeability
102
Explain ionic composition of ECF of an Axon
ECF has higher conc. of NA+
103
Explain ionic composition of ICF of an Axon
Higher conc. of K+
104
Explain sodium- potassium pump
Stabilize resting membrane potential
3Na+ out while 2K+ in
105
What are the two types of signals produced by changes in RMP?
Graded Potentials and Action Potentials
## Footnote
Action Potentials operate over long distances in axons.
106
What is depolarization?
A decrease in membrane potential towards zero, making the inside of the membrane more positive.
107
What is hyperpolarization?
An increase in membrane potential away from zero, making the inside of the membrane more negative.
108
What is repolarization?
The process of the membrane returning to resting membrane potential after depolarization.
109
Explain graded potentials?
Doesnt reach threshold
Short lived, localized and graded signals
Decremental: stimulus weakens the farther it spreads.
110
What are action potentials (APs)?
The principal way neurons send signals, occurring only in muscle cells and axons of neurons.
Signals don’t decay with distance.
111
Characteristics of action potentials
All or none law- voltage gates open or not
Don’t weaken with distance
Irreversible
112
What is threshold
Membrane voltage that must be reached during depolarization in order to generate action potential
-55mV
113
Steps to generate action potential
1. Resting state- channels closed
2. Depolarization- Na+ voltage channels open and Na+ into cell until -55mV then all Na+ channels open.
3. Repolarization- K+ channel open and K+ leaves (membrane more negative)
4. Hyperpolarization- K+ overshoot and excessive efflux (more negative than RMP)
114
Absolute refractory vs relative refractory
Absolute refractory period- no stimulus will trigger action potential
Relative refractory period- stronger than normal stimulus can trigger new action potential
115
Continuous conduction
Unmyelinated cells,
slow conduction
Sequential opening of an Na+ channels
116
Salfactory conduction
Melanated cells
Leapfrog between depolarizing nodes of Ranvier
117
Axodendritic vs axosomatic connections
Axodendritic- between axon terminals and dendrites
Axosomatic- between axon terminals and soma (cell body)
118
What is a synapse
Junctions that mediate information transfer
119
What is the chemical synapse?
Release chemical neurotransmitters
Electrical impulse change to chemical across synapse, then back into electrical
120
What are the steps for information transfer across a chemical synapse
1. AP arrive at axon terminal
2. Ca+ channels open and Ca+ into axon terminals
3.Ca+ cause synaptic vesicle to release NT
4. NT across synaptic cleft and bind to receptors on postsynaptic membrane
5. Ion channels open, generate AP
6. NT effects terminated
121
What are the three ways of terminating effects of a neurotransmitter?
Reuptake by astrocyte or axon terminal
Degradation by enzyme
Diffusion away
122
IPSP VS EPSP
IPSP- inhibit graded potential. Makes membrane more negative
EPSP- excitatory graded potential. Could be AP if strong enough
Both haven’t reach threshold
Both types of postsynaptic potentials
123
Temporal summation
Rapid fire impulses of EPSP’s that summate to reach AP
124
Spatial summation
Multiple presynaptic neurons fire at the same time to summate and reach AP
125
What are the two types of circus in neurons?
Divergent circuit- 1 neuron talks to many
Converging circuit - many neuron talk to 1
126
Explain the spinal cord
Information highway between brain and body
Functions : conduction, locomotion, reflexes
127
Cauda equina
Nerve roots that exit the spinal cord at L2 and bring nerves down to the sacrum and coccyx
128
What is Meninges
3 fibrous layers enclosing spinal cord
Outer layer- dura mater
Middle layer- Arachnoid mater
Inner layer- Pia mater
129
Gray vs white matter
Gray- unmylelinated, synapse junction found here. Synapses happens here
White- Myelinated, surround gray matter. Information travel
130
DAVE
Dorsal
Afferent
Ventral
Efferent
131
SAME
Sensory
Afferent
Motor
Efferent
132
What information is the Dorsal horn of the vertebra associated with
Afferent sensory information
133
What information is the ventral horn of the vertebra associated with
Motor efferent information
134
What kind of information does that mixed spinal nerve contain
Dorsal and ventral roots, bring sensory and motor information
135
Ascending tracts
Afferent sensory info sent to brain
136
Descending tracts
Efferent motor info sent to body
137
Explain the spinal reflex pathway
1.Receptor- site of stimulus
2.Sensory Afferent neuron- Afferent impulse to CNS
3. Spinal cord / integration center(brain)
4. Motor Efferent neuron- efferent impulse from brain to organ
5. Effector- muscle or gland response to impulse
138
What are the 2 types of reflexes
Somatic reflex- activate skeletal muscle
Autonomic (visceral) reflex- activate visceral effectors ( smooth/cardiac muscle or glands)
139
Monosynaptic reflex
2 neurons 1 synapse
Stretch reflexes
140
Polysnyaptic reflex
1 neuron many synapses
141
Polysnyaptic reflex
1 neuron many synapses
142
What are interneurons?
Interneurons are nerves that communicate sensory information to motor neurons during reflex actions.
## Footnote
They are located in the gray matter of the spinal cord.
143
What are the two kinds of interneurons?
The two kinds of interneurons are ipsilateral and contralateral.
## Footnote
Ipsilateral interneurons are involved in the withdrawal or flexor reflex, while contralateral interneurons are involved in the crossed extensor reflex.
144
What is the function of ipsilateral interneurons?
Ipsilateral interneurons facilitate the body's response to painful stimuli on the same side as the stimulus.
## Footnote
This is known as the withdrawal or flexor reflex.
145
What is the function of contralateral interneurons?
Contralateral interneurons are involved in the crossed extensor reflex, which coordinates the body's response to stimuli on opposite sides.
146
What triggers the Flexor (withdrawal) Reflex?
Itpainful stimulus, causing automatic withdrawal of the threatened body part.
Polysynaptic reflex: many muscles used to withdrawal
147
What is the Crossed Extensor Reflex?
The Crossed Extensor Reflex occurs with flexor reflexes in weight-bearing limbs to maintain balance.
## Footnote
Example: Stepping on a nail.
148
How many pairs of spinal nerves and how do they lay on the vertebra
31 pairs
Cervical nerves above vertebra
C8 is transition
Thoracic nerves below vertebra
149
Which way do sensory Afferent nerves travel?
Only toward CNS
150
Which way do motor efferent nerves travel
Only away from CNS
151
Which way do motor efferent nerves travel
Only away from CNS
152
Perineurium, endoneurium, endoneurium, fascicle
153
What does the Dorsal Ramus innervate?
The Dorsal Ramus innervates the skin and muscles of the back.
154
What does the Ventral Ramus innervate?
The Ventral Ramus innervates everything else from head to toe, including the trunk and limbs.
155
What are nerve plexuses?
Nerve plexuses involve Ventral Ramus/Rami that branch and merge repeatedly to form four nerve plexuses.
156
What are the four nerve plexuses?
The four nerve plexuses are:
1. Cervical plexus
2. Brachial plexus
3. Lumbar plexus
4. Sacral plexus.
157
What is the function of the Ventral Ramus in nerve plexuses?
The Ventral Ramus enters the plexus and leaves as 'Nerves'.
158
How do fibers behave within a plexus?
Within a plexus, fibers crisscross so that each branch contains fibers from several different spinal nerves.
159
What nerves associated with cervical plexus
C1- C5
160
What nerves associated with brachial plexus
C5- T1
161
What nerves associated with lumbar plexus
L1-L4
162
What nerves associated with sacral plexus
L4-S4
163
Cervical plexus
C1-C5
Inner care skin of neck, back of head, shoulders
Phrenic nerve - motor & sensory nerve of diaphragm
164
Brachial plexus
C5-T1
Inner gate upper limbs
Musckocutaneous nerve- bicep skin of forearm
Median nerve- forearm, thumb
Ulnar nerve- forearm pinky, ring
Radial nerve- extensor muscles
165
Lumbar plexus
L1-L4
Innervate thigh, abdominal wall, psoas muscle
Femoral nerve- quads and skin of anterior thigh, medial surface of leg
166
Lumbar plexus
L1-L4
Innervate thigh, abdominal wall, psoas muscle
Femoral nerve- quads and skin of anterior thigh, medial surface of leg
167
Sacral plexus
L4-S4
Innervate butt, lower limb pelvis, perineum
Sciatic nerve- Composed of tibial and common fibular nerve. Leg, foot, hamstring
168
Dermatome
Areas of the skin innervated by cutaneous branches of single spinal nerve
169
What parts of the brain are gray matter
Basal nuclei
Cerebral cortex
Limbic system
170
What makes up the white matter of the cerebrum
Projection fibers
Association fibers
Commissural fibers
