The Nervous System Flashcards
1
Q
What are the three functions of the nervous system?
A
- Monitor the body’s internal and external environments.
- Integrate sensory information.
- Direct or coordinate the responses of other organ systems to the sensory input.
2
Q
What are the major divisions of the nervous system?
A
- The central nervous system.
- The peripheral nervous system:
3
Q
The ____ consists of the brain and spinal cord, which occupy the ___ body cavity.
A
Central nervous system, dorsal.
4
Q
The integrating and command center of the nervous system - it interprets sensory input and dictates motor responses based on past experience, reflexes and current conditions.
A
Central nervous system.
5
Q
The part of the nervous system outside of the CNS, and consists mainly of the nerves that extend from the brain and spinal cord.
A
Peripheral nervous system.
6
Q
Carry impulses to and from the spinal cord.
A
Spinal nerves.
7
Q
Carry impulses to and from the brain.
A
Cranial nerves
8
Q
What are the sub-divisions of the peripheral nervous system?
A
- The sensory (afferent) division.
- The motor (efferent) division.
9
Q
Consists of nerve fibers that convey impulses to the central nervous system from sensory receptors located throughout the body.
A
Sensory (afferent) division.
10
Q
Sensory fibers conveying impulses from the skin, skeletal muscles, and joints are called ___.
A
Somatic afferent fibers.
11
Q
Fibers transmitting impulses from the visceral organs (organs within the ventral body cavity) are called _____.
A
Visceral afferent fibers.
12
Q
Transmits impulses from the CNS to effector organs, which are the muscles and glands.
A
The motor (efferent) division.
13
Q
The ______ is composed of axons that conduct impulses from the CNS to skeletal muscles. It is often referred to as the voluntary nervous system because it allows us to consciously control our skeletal muscles.
A
Somatic nervous system.
14
Q
Consists of visceral motor nerve fibers that regulate the activity of smooth muscles, cardiac muscles, and glands. This system is also referred to as the involuntary nervous system.
A
Autonomic nervous system.
15
Q
What are the two divisions of the autonomic nervous system?
A
The sympathetic and the parasympathetic.
16
Q
Mobilizes body systems during activity.
A
The sympathetic division of the ANS.
17
Q
Conserves energy and promotes housekeeping functions during rest.
A
The parasympathetic division of the ANS.
18
Q
How many neuroglia are there in the CNS?
A
Four.
19
Q
How many neuroglia are there in the PNS?
A
Two.
20
Q
What are the different neuroglia found in the central nervous system?
A
Astrocytes, microglia, ependymal cells, and oligodendrocytes.
21
Q
Shaped like delicate branching sea anemones, ____ are the most abundant and most versatile glial cells.
A
Astrocytes.
22
Q
____ are small ovoid cells with relatively long “thorny” processes.
A
Microglia.
23
Q
Their processes touch nearby neurons, monitoring their health, and when they sense that certain neurons are injured or in other trouble, the ____ migrate towards them.
A
Microglia.
24
Q
_____ range in shape from squamous to columnar, and many are ciliated.
A
Ependymal cells.
25
They line the central cavities of the brain and the spinal cord, where they form a fairly permeable barrier between the cerebrospinal fluid that cushions the brain and spinal cord.
Ependymal cells.
26
Though they also branch, the ____ have fewer processes than astrocytes.
Oligodendrocytes.
27
They line up along the thicker neuron fibers in the CNS and wrap their processes around the fibers, producing insulating coverings called myelin sheaths.
Oligodendrocytes.
28
Their numerous radiating processes cling to neurons and their synaptic endings, and cover nearby capillaries, supporting and bracing the neurons and anchoring them to their nutrient supply lines. They have a role in making exchanges between capillaries and neurons, in guiding the migration of young neurons, in synapse formation, and in helping to determine capillary permeability.
Astrocytes.
29
What are the two kinds of PNS neuroglia?
Satellite cells and Schwann cells.
30
___ surround neuron cell bodies located in the peripheral nervous system, but their function is still largely unknown.
Satellite cells.
31
____ surround and form myelin sheaths around the larger nerve fibers in the peripheral nervous system - they are vital to regeneration of damaged peripheral nerve fibers.
Schwann cells.
32
A chronic potentially debilitating disease that affects the myelin sheath of the central nervous system. Believed to be an autoimmune disease, the body directs antibodies and white blood cells against proteins in the myelin sheath surrounding nerves in the brain and spinal cord, which causes inflammation and injury to the myelin sheath.
Multiple sclerosis.
33
What structure/tissue is affected by multiple sclerosis?
Myelin sheath.
34
The billions of ___, also called nerve cells, are the structural units of the nervous system. They are highly specialized cells that conduct messages in the form of nerve impulses from one part of the body to another.
Neurons.
35
The ___ consists of a transparent spherical nucleus with a conspicuous nucleus surrounded by cytoplasm. The cells body ranges in diameter from 5 to 140 um. Except for centrioles, it contains the usual organelles.
Neuron cell body.
36
Bundles of neuron processes in the CNS.
Tracts.
37
Bundles of neuron processes in the PNS.
Nerves.
38
___ of motor neurons are short, tampering, diffusely branching extensions. They are the main receptive or input regions. They bristle with thorny appendages having bulbous or spiky ends, which represent close points of contact with other neurons. They convey incoming messages toward the cell body, known as graded potentials.
Dendrites.
39
Each neuron has a single ___. The initial region arises from a cone shaped area of the cell body, and then narrows to form a slender process that is uniform in diameter for the rest of it's length. In some neurons, it is very short or absent; in others, it is long and accounts for nearly the entire length of the neuron. Any long ___ is called a nerve fiber.
Axon.
40
These neurons have three or more processes. They are the most common neuron type in humans, and the major neuron type in the CNS.
Multipolar.
41
These neurons have two processes - an axon and a dendrite - that extend from opposite sides of the cell body. These rare neurons are found in some of the special sense organs. Examples include some neurons in the retina of the eye and in the olfactory mucosa.
Bipolar neurons.
42
These neurons have a single short process that emerges from the cell body and divides T-like into proximal and distal branches. The more distal process is often associated with a sensory receptor, known as the peripheral process, whereas that entering the CNS is the central process. These neurons are more accurately called pseudo because they originate as bipolar neurons.
Unipolar.
43
These neurons transmit impulses from sensory receptors in the skin or internal organs toward or into the central nervous system. Except for certain neurons found in some special sense organs, nearly all of these neurons are unipolar.
Sensory (afferent) neurons.
44
These neurons carry impulses away from the CNS to the effector organs (muscles and glands) of the body periphery. These neurons are multipolar, and except for some neurons of the autonomic nervous system, their cell bodies are located in the CNS.
Motor (efferent) neurons.
45
These neurons lie between motor and sensory neurons in neural pathways and shuttle through CNS pathways where integration occurs. Most of these neurons are confined within the CNS, and make up over 99% of the neurons in the body, including most of those in the CNS. Almost all of them are multipolar, but there is considerable diversity in both size and fiber-branching patterns.
Interneurons.
46
Where are sensory neurons found?
In sensory ganglia outside the CNS.
47
Where are motor neurons found?
Inside the CNS.
48
Where are interneurons found?
Confined within the CNS.
49
Periodic gaps in the insulating myelin sheaths of myelinated axons where the axonal membrane is exposed to the extracellular space.
Nodes of Ranvier.
50
How do Schwann cells form the myelin sheath and the neurilemma?
- To make the myelin sheath, Schwann cells wrap around an axon in a jelly roll fashion, and one cell forms one segment of myelin sheath.
- Neurilemma is the peripheral bulge of a Schwann cell, containing the nucleus and most of the cytoplasm of the Schwann cell.
51
Small cells that surround and wrap delicate neurons.
Neuroglia.
52
Excitable cells that transmit electrical signals.
Neurons.
53
Regions of brain and spinal cord with dense
| collections of myelinated fibers – usually fiber tracts
White matter.
54
Mostly neuron cell bodies and nonmyelinated fibers
Gray matter.
55
How do PNS nerve fibers regenerate?
- Separate ends seal themselves off, then swell.
- The axon and its myelin sheath distal to the injury site begin to disintegrate because they cannot recieve nutrients.
- The entire axon distal to the injury is degraded by phagocytes within a week.
- Surviving Schwann cells proliferate in response to the mitosis-stimulating chemicals released by macrophages
- Schwann cells release growth factors to stimulate axonal growth.
- Sprouts form on stumps of damaged nerve fibers, some grow into the endoneurial tubes
- As fibers grow in endoneurial tubes, Schwann cells surround and remyelinate regenerating axons.
- Increased blood supply to area where nerve is reaching.
- Sensory and motor functions return.
56
Why can't CNS neurons regenerate their fibers?
No Neurilemma is present to form a regeneration tube to guide growth of a severed axon
57
What is a synapse?
Functional junction or point of close contact between two neurons or between a neuron and an effector cell.
58
What is a ganglion?
A collection of nerve cell bodies outside of the CNS.
59
a complex system of nerves and networks in the brain, involving several areas near the edge of the cortex concerned with instinct and mood. It controls the basic emotions (fear, pleasure, anger) and drives (hunger, sex, dominance, care of offspring).
The limbic system.
60
What is saltatory conduction?
the propagation of action potentials along myelinated axons from one node of Ranvier to the next node, increasing the conduction velocity of action potentials.
61
What 2 factors influence impulse speed?
Myelin sheath and axon size.
62
How does a nervous impulse cross a chemical synapse?
One neuron releases chemicals in response to an action potential (nerve impulse). The chemicals travel across the synapse and stimulate an action potential in the next neuron.
63
How does a nervous impulse cross an electrical synapse?
In an electrical synapse, gap junctions, which are formed by the channel proteins connecting the presynaptic and postsynaptic membranes of two neurons, allow the current to pass directly from one neuron to the next.
64
Distinguish between a graded potential and an action potential?
Depending on the stimulus, graded potentials can be depolarizing or hyperpolarizing. Action potentials always lead to depolarization of membrane and reversal of the membrane potential.
65
What ions are involved in creating action potentials, and resting potentials?
Sodium and potassium.
66
Explain how a cell membrane becomes polarized:
An electrical signal is generated when the neuron allows sodium ions to flow into it, which switches the charges on either side of the cell membrane. This switch in charge is called depolarization. In order to send another electrical signal, the neuron must reestablish the negative internal charge and the positive external charge. This process is called repolarization.
67
What is the resting potential?
The resting membrane potential of a neuron is about -70 mV - this means that the inside of the neuron is 70 mV less than the outside. At rest, there are relatively more sodium ions outside the neuron and more potassium ions inside that neuron.
68
What is the Reticular Activating System?
The part of the reticular formation in the brainstem that plays a central role in bodily and behavioral alertness; its ascending connections affect the function of the cerebral cortex and its descending connections affect bodily posture and reflex mechanisms.
69
What are the three layers of the meninges?
- Dura Mater.
- Arachnoid Mater.
- Pia Mater.
70
What neuronal structures are found in the ganglion?
The Soma.
71
What is the neural tube/crest and what does it develop?
A dorsal tubular structure in the vertebrate embryo that develops into the brain and spinal cord. A tubular structure that results from the folding of tissue along the back of vertebrate embryos and develops into the brain and spinal cord.
72
What are the general functions of the cerebrum?
- Conscious thought.
- Memory storage and processing.
- Sensory processing.
- Regulating skeletal muscle contractions.
73
What are the general functions of the diencephalon?
The structural and functional link between the cerebral hemispheres and the rest of the CNS - the link between the nervous and endocrine systems.
74
What are the general functions of the midbrain?
- Regulates auditory and visual reflexes.
- Controls alertness.
- Can direct complex motor patterns at the subconscious level.
- Influences the level of activity in the entire nervous system.
75
What are the general functions of the pons?
- Connects the cerebellum to the brain stem.
| - Contains nuclei that function in somatic and visceral motor control.
76
What are the general functions of the medulla oblongata?
- Relays sensory information to other portions of the brain stem and to the thalmus.
- Regulate autonomic function, such as heart rate and blood pressure.
77
What are the general functions of the cerebellum?
- Coordinating and modulating motor commands from the cerebral cortex.
- Adjusting the postural muscles of the body.
- Programming and fine tuning movements controlled at the conscious and subconscious levels.
78
What connects the two hemispheres of the cerebrum?
Corpus callosum.
79
What are the general functions of the brain stem?
The brain stem has many basic functions, including regulation of heart rate, breathing, sleeping, and eating.
80
What are the functions of the thalamus?
- Involved in sensory and motor signal relay.
- Regulation of consciousness and sleep.
- All senses, excluding smell.
- Controlling the motor systems of the brain which are responsible for voluntary bodily movement and coordination.
81
What are the functions of the hypothalamus?
i. Centers controlling emotions, autonomic functions, and hormone production, appetite.
ii. In both the nervous and endocrine systems.
Creates hormones that are sent to the pituitary gland.
82
What are the functions of the pineal gland?
secretes hormone melatonin, regulates sleep
83
What is the fifth lobe?
Insula.
84
What are the four major lobes of the cerebrum?
Frontal, parietal, temporal, occipital.
85
What are the functions of the frontal lobe?
Front part of the brain; involved in planning, organizing, problem solving, selective attention, personality and a variety of "higher cognitive functions" including behavior and emotions.
86
What are the functions of the parietal lobes?
Processes sensory information that has to do with taste, temperature, and touch.
87
What are the functions of the temporal lobes?
The temporal lobe is involved in primary auditory perception, such as hearing, and holds the primary auditory cortex.
88
What are the functions of the occipital lobe?
- Visual percpetion.
| - Color recognition.
89
What are basal nuclei and what are their general function?
Basal nuclei are masses of gray matter that lie within each cerebral hemisphere, which provide subconscious control of skeletal muscle tone and help coordinate learned movement patterns.
90
The anterior (front) part of the brain is called the ____.
Prefrontal cortex.
91
What is meant by hemisphere dominance?
If one hemisphere is more heavily involved in a specific function, it is often referred to as being dominant.
92
What does the hippocampus do?
The hippocampus is associated mainly with memory, in particular long-term memory. The organ also plays an important role in spatial navigation.
93
Describe the Blood-brain barrier.
- Protects the brain from "foreign substances" in the blood that may injure the brain.
- Protects the brain from hormones and neurotransmitters in the rest of the body.
- Maintains a constant environment for the brain.
94
Describe how CSF is created, circulated and reabsorbed.
- Cerebrospinal Fluid is created by the choroid plexus, which secretes it into the ventricles of the brain.
- From the choroid plexus, it circulates through the ventricles, and fills the central canal (spinal cord)
- CSF is absorbed into the blood at sites called arachnoid granulations.
95
Describe the location of the 4 ventricles in the brain.
- The lateral ventricles are in the cerebrum.
- The third ventricle is located in the diencephalon.
- The fourth ventricle begins in the metencephalon and extends into the superior portion of the medulla, then narrows and becomes the central canal of the spinal cord.
96
In what part of the cerebrum is primary motor control performed?
Rear portion of the frontal lobe.
97
In what part of the cerebrum is motor speech control performed?
Broca's area - Left hemisphere, frontal lobe.
98
In what part of the cerebrum are primary somatosensory functions performed?
Parietal lobe.
99
In what part of the brain are vision functions performed?
Visual cortex - Occipital lobe.
100
In what part of the cerebrum are senses of hearing performed?
Auditory cortex - Temporal lobe.
101
In what part of the cerebrum are the functions of taste performed?
Parietal lobe.
102
In what part of the cerebrum is logic/reasoning performed?
The left side of the frontal lobe.
103
In what part of the cerebrum are general interpretive functions performed?
Wernecke's area - temporal, parietal and occipital lobes.
104
What is a plexus?
A network or braid of nerves or vessels in the body.
105
What is cranial nerve I?
Olfactory.
106
What is cranial nerve II?
Optic.
107
What is cranial nerve III?
Oculomotor.
108
What is cranial nerve IV?
Trochlear.
109
What is cranial nerve V?
Trigeminal.
110
What is cranial nerve VI?
Abducens.
111
What is cranial nerve VII?
Facial.
112
What is cranial nerve VIII?
Vestibulocochlear.
113
What is cranial nerve IX?
Glossopharyngeal.
114
What is cranial nerve X?
Vagus.
115
What is cranial nerve XI?
Accessory.
116
What is cranial nerve XII?
Hypoglossal.
117
What is the function of the olfactory nerve?
Smell - sensory.
118
What is the function of the optic nerve?
Sensory - vision.
119
What is the function of the oculomotor nerve?
Motor - eye movement and pupil constriction.
120
What is the function of the trochlear nerve?
Motor - movement of the eye.
121
What is the function of the trigeminal nerve?
Sensory - sensations of the mouth.
Motor - chewing.
122
What is the function of the abducens nerve?
Motor - moves the eye laterally.
123
What is the function of the facial nerve?
Sensory - taste.
Motor - facial expression, tear production, saliva production.
124
What is the function of the vestibulocochlear nerve?
Sensory - hearing and equilibrium.
125
What is the function of the glossopharyngeal nerve?
Sensory - taste.
Motor - swallowing, speech, saliva production.
126
What is the function of the vagus nerve?
Sensory - visceral sensations from thorax and abdomen.
Motor - swallowing, slowing of heart rate, increases GI activity.
127
What is the function of the accessory nerve?
Motor - swallowing, movement of the head, shrugging of shoulder.
128
What is the function of the hypoglossal nerve?
Motor - swallowing and speech.
129
What are the functions of ascending spinal cord tracts?
Carry information towards the brain.
130
What are the functions of descending spinal cord tracts?
Convey motor commands to the spinal cord.
131
The outermost covering of the nerve; consists of a dense network of collagen fibers.
Epineurium.
132
The middle layer of a spinal nerve; extends inwards from the epineurium. These connective tissue partitions divide the nerve into a series of fascicles.
Perineurium.
133
The innermost layer of a spinal nerve; consists of delicate connective tissues that extend from the perineurium and surround individual axons.
Endoneurium.
134
A slender strand of fibrous tissue that extends from the inferior tip of the conus medullaris to the second sacral vertebrae. It provides longitudinal support to the spinal cord as a compontent of the coccygeal ligament.
Filum teminale.
135
The tapered, conical portion of the spinal cord inferior to the lumbar enlargement.
Conus medullaris.
136
Innervates structures of the pelvis and lower limbs.
Lumbar enlargement.
137
Innervates the shoulder and upper limbs.
Cervial enlargement.
138
What is the function of the spinal cord?
To carry messages to the brain from the central nervous system.
139
Consists of a meshwork of elastic and collagen fibers that is firmly bound to the underlying neural tissue.
Pia mater.
140
This layer includes a simple squamous epithelium, called the arachnoid membrane, and the subarachnoid space that extends between the arachnoid membrane and the outer surface of the pia mater.
Arachnoid mater.
141
The outermost covering of the spinal cord; it contains dense collagen fibers that are oriented along the longitudinal axis of the cord. A narrow subdural pace seperates the dura mater from the arachnoid mater.
Dura mater.
142
The shallow longitudinal groove on the posterior (dorsal) surface of the spinal cord.
Posterior median sulcus.
143
Contains the axons of the neurons whose cell bodies are in the dorsal root ganglion.
Dorsal root.
144
Contains the cell bodies of sensory neurons whose axons carry information to the spinal cord. Each segment of the spinal cord has a pair of these, one on each . side.
Dorsal root ganglion.
145
Contains the axons of sensory and motor neurons. The sensory fibers enter the CNS through the dorsal root. The motor fibers emerge from the CNS within the ventral root.
Spinal nerve.
146
Contains the axons of motor neurons that extend into the periphery to control somatic and visceral effectors.
Ventral root.
147
Contains large numbers of myelinated and myelinated axons.
White matter.
148
Dominated by the cell bodies of neurons, neuroglia, and unmyelinated axons. It surrounds the narrow central canal and forms an H or butterfly shape.
Gray matter.
149
Responsible for supporting and protecting neurons.
Neuroglial cells.
150
How are spinal nerves formed?
From the union of ventral and dorsal roots.
151
The ventral root/anterior root consists of axons (nerve fibers) carring impulses ___ from the CNS. What type of fibers are these?
AWAY; motor fibers.
152
The dorsal or posterior root consists of axons carrying impulses ___ the CNS. What type of fibers are these?
TOWARD; sensory fibers.
153
As spinal nerves exit the vertebral canal, they divide into 3 branches...what are they?
dorsal ramus, ventral ramus, and meningeal branch
154
Describe Dorsal Ramus
It supplies the skin and deep muscles of the back. Usually divides into medial and lateral branches.
155
Describe Ventral Ramus
Describe Ventral Ramus LARGEST of the 3 branches; supplies skin and muscles of limbs, anterolateral trunk and neck, and superficial and intermediate back muslces
156
Describe Meningeal Branch
goes back into the vertebral canal and supplies meninges, blood vessels, ligaments, periostem, and intervertebral discs
157
The cervical plexus supplies the ____.
Neck.
158
The brachial plexus supplies the ____.
Upper limbs.
159
The sacral plexus supplies the _____.
Lower limb and perineum.
160
Describe the gross anatomy of the spinal cord.
- Enclosed within the vertebral column
- Extends from the foramen magnum to the upper border of L2
- Long and cylindrical.
- Has two enlarged portions.
-
161
What space of the spinal cord contains CSF?
Arachnoid mater.
162
What is the function and plexus of the radial nerve?
The brachial plexus - muscles of the arm and forearm; sensory from the skin over the posterolateral surface.
163
What is the function and plexus of the medial nerve?
Brachial plexus - Flexor muscles of the forearm, pronator muscles; sensory from skin over the anterolateral surface of the hand.
164
Plexus and function of the unlar nerve?
Brachial plexus - flexor muscles of the hand and the adductor pollicis muscle; sensory of skin over the medial surface of hand.
165
Plexus and function of the axillary nerve?
Brachial plexus - deltoid and teres minor muscles; sensory from skin of the shoulder.
166
Plexus and function of the Musculcutaneous nerve?
Brachial plexus - Flexor muscles of the arm; sensory from skin over the lateral surface of the forearm.
167
Plexus and function of the femoral nerve?
Lumbar plexus - anterior muscles of the thigh; skin over the anteromedial surface of the thigh, medial surface of leg and foot.
168
Plexus and function of the sciatic nerve?
Sacral plexus - two of the hamstrings ; adductor magnus muscle.
169
What is the difference between a stretch reflex and a tendon reflex?
The stretch reflex operates as a feedback mechanism to control muscle length by causing muscle contraction. In a Golgi tendon reflex, skeletal muscle contraction causes the agonist muscle to simultaneously lengthen and relax.
170
What receptors are involved in a stretch reflex?
Muscle spindles.
171
What is a muscles response to a stretch reflex?
Contract.
172
What receptors are involved in a tendon reflex?
Goldi tendon organs.
173
What is a muscles response to a tendon reflex?
Relax.
174
Receive and relay sensory information from peripheral receptors.
Sensory nuclei.
175
Issue motor commands to peripheral effectors
Motor nuclei.
176
____ reflexes are genetically or developmentally determined.
Innate.
177
____ reflexes are learned.
Acquired.
178
_____ reflexes control skeletal muscle contractions, and include superficial and stretch reflexes.
Somatic.
179
____ reflexes control actions of smooth and cardiac muscles, glands.
Visceral.
180
_____ reflexes occur with a single neuron.
Monosynaptic.
181
____ reflexes occur with the use of multiple synapses - INTERNEURON.
Polysnaptic.
182
What is the strongest stimulus for withdrawal reflexes?
Pain.
183
Describe the five parts of a reflex arc?
1. Receptor- Arrival of stimulus and activation of receptor.
2. Sensory Neuron- Activation of a sensory neuron.
3. Integration Center (CNS)- Information processing in CNS
4. Motor Neuron - Activation of a motor neuron.
5. Effector- muscles or visceral organ - Response by effector
184
The spread of information from one neuron to several neurons, or from one pool to multiple pools.
Divergance.
185
Occurs when several neurons or neuronal pools process the same information simultaneously. Divergence must take place before this processing can occur.
Parallel processing.
186
Information is relayed in a step-wise fashion, from one neuron to another, or from one neuronal pool to another. This pattern occurs as sensory information is relayed from one part of the brain to another.
Serial processing.
187
Several neurons synapse on a single postsynaptic neuron.
Convergence.
188
Collateral branches of axons somewhere along the circuit extend back toward the source of an impulse and further stimulate the presynaptic neurons.
Reverberation.
189
What are the three mechanisms that “turn off” a neurotransmitter? Which is fastest? slowest?
-----
190
When neuron is NOT actively sending message
Resting potential.
191
Local, temporary change, loses strength over distance.
Graded potential.
192
Long distance, high level currents; nerve impulse.
Action potential.
193
- Open and close when specific chemicals bind
| - Usually found on dendrites and soma
Chemically gated ion channels.
194
Open and close in response to changes in the transmembrane potential, typically found in axons.
Voltage gated ion channels.
195
Open and close in response to physical distortion of the membrane surface - important in the senses.
Mechanically gated ion channels.
196
At rest, most gated channels are ____.
Closed.
197
Describe a graded membrane potential.
They start local, are short lived, and have low level currents. They start with the opening of a gated channel, and may be either depolarizing or hyperpolarizing. The action potential dissipates rapidly with time and distance.
198
Where a neuron ends and communicates with another cell.
Synapse.
199
Concentration gradient for an ion across plasma membrane
Chemical gradient.
200
Attraction between opposite charges or repulsion between like charges (+/+ or –/–)
Electrical gradient.
201
When electrical and chemical gradients are equal and opposite, resulting in no net movement across membrane
Equilibrium potential.
202
A graded depolorization caused by the arrival of a neurotransmitter at the post synaptic membrane that shifts the membrane closer to the threshold. When that occurs, the membrane is said to be facilitated. The larger the degree of facilitation, the smaller the additional stimulus needed to trigger an action potential.
Excitatory postsynaptic potential (EPSP)
203
A graded hyperpoizaton of the postsynaptic membrane. It may result, for example, from the opening of chemically gated potassium channels. When membrane hyperpolarization occurs, the neuron is said to be inhibited, because a larger than usual depolarizing stimulus must be provided to bring the membrane potential to threshold.
Inhibitory postsynaptic potential.
204
The integration of the effects of graded potentials on a segment of the plasma membrane. If two different neurotransmistters arrive simultaneously, and both sets of channels open, the net effect may be no change in the membrane potential.
Summation.
205
Graded potentials that develop in the postsynaptic membrane in response to a neurotransmittter.
Postsynaptic potentials.
206
Occurs when a single synapse is activated repeatedly.
Temporal summation.
207
Involves multiple synapses that are active simultaneously.
Spatial summation.
208
How does a cholinergic synapse work?
- Depolarization of synaptic knob by arriving action potential
- Calcium ions enter the cytoplasm, and after a brief delay, ACh is released through the exocytosis of synaptic
vesicles
- ACh binds to sodium channel receptors on the postsynaptic membrane, producing a graded depolarization.
- Acetylcholinesterase (AChE, an enzyme) breaks down ACh
- The synaptic knob reabsorbs choline from the synaptic cleft and uses it to synthesize new molecules of ACh.
209
sensory receptors within the belly of a muscle that primarily detect changes in the length of this muscle. They convey length information to the central nervous system via sensory neurons. This information can be processed by the brain to determine the position of body parts.
Muscle spindles.
210
a proprioceptive sensory receptor organ that senses changes in muscle tension. It lies at the origins and insertion of skeletal muscle fibers into the tendons of skeletal muscle.
Goldi tendon organs.
