Exam 1 (Midterm) Flashcards
(113 cards)
1
Q
Dendrites
A
Input zone - cellular extensions that receive info from other neurons
2
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Soma (also cell body)
A
Integration zone - contains the cell’s nucleus, may receive additional synaptic contacts. Inputs are combined and transformed in the cell body
3
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Presynaptic neuron
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Initiating neuron
4
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Postsynaptic neuron
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Receiving neuron
5
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Schwann cell
A
- Located on axons of peripheral neurons (located in PNS)
- Glial cells that create myelin to sheath the peripheral neurons, enabling rapid mode of electrical impulse propagation called saltation
6
Q
What is the brain size of a 2-year-old compared to an average adult?
A
80% of adult brain size
7
Q
Satellite cells
A
Glial cells that provide physical support to neurons in the PNS
8
Q
Glial cells
A
Fxs:
- form myelin to insulate neurons from one another
- surround neurons and hold them in place
- supply nutrients and oxygen to neurons
- destroy and remove dead or injured neuron debris
9
Q
Mesencephalon (midbrain)
A
Structures include tectum, tegmentum, and cerebral aqueduct.
- Responsible for visual reflexes (superior colliculi) and auditory reflexes (inferior colliculi)
- Tectum is dorsal surface of midbrain
10
Q
Microglia
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Glial cell that digest parts of injured or dead neurons (similar to astrocytes) and provide active immune defense in CNS
11
Q
Resting membrane potential
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-70 mV
12
Q
Metencephalon
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Structures include Pons, Cerebellum, Reticular formation (4th ventricle)
13
Q
Lysosomes
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Found in cytoplasm of cells; contain enzymes for degradation of cell wastes
14
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Astrocytes
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Star-shaped glial cells in CNS that can turn into neurons; provide physical and nutritional support for neurons, clean up “debris”, transport nutrients to neurons, hold neurons in place, digest parts of dead neurons, regulate content of extracellular space
15
Q
Cerebellum
A
Responsible for movement, balance and posture; found in metencephalon
16
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Endoplasmic reticulum
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The extension of the nuclear membrane where the cell’s proteins are produced and assembled
17
Q
Mitochondria
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power generators of the cell, converting oxygen and nutrients into adenosine triphosphate (ATP) (i.e., supplies cell energy)
18
Q
Nissl body
A
- Located in cytoplasm of neurons, composed of rough endoplasmic reticulum (rER) or ribosomes used for protein synthesis (the endoplasmic reticulum is important of this synthesis)
19
Q
Microtubule
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Serve a transportation fx, as they are the routes upon which organelles move through the cell
20
Q
Neural plate
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1st sign of the developing nervous system and can be seen at the 16th day of development
21
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Neural tube
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By the 21st day of development, it is formed when the edges of the neural groove meet
22
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Neural crest
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Becomes the PNS
23
Q
Neural groove
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Trench in the neural plate
24
Q
True or False: Neurons can connect to a bone cell.
A
False
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Synapses
Junction where axons make contact with other cells
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Oligodendroglia
- Located on axons of neurons in CNS
- Glial cells that create myelin to sheath CNS neurons, enabling rapid mode of electrical impulse propagation called saltation
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Myelin
fatty white substance that surrounds the axon of some nerve cells, forming an electrically insulating layer. It is essential for the proper functioning of the nervous system
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Golgi apparatus
receives proteins and lipids (fats) from the rough endoplasmic reticulum. It modifies some of them and sorts, concentrates and packs them into sealed droplets called vesicles.
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Interneurons
link up sensory and motor neuron activity in CNS
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Electrochemical pulse
electrical signal moves through the neuron as a result of changes in the electrical charge of the axon
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Neocortex
outer part of the forebrain; composed of 6 layers of grey matter;
fxs: sensory perception, motor commands, spatial reasoning, conscious thought, and language
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What is the process in which, by the 7th week, the 3 major brain areas divide again?
Encephalization
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What is the insulating coat on axons?
Myelin sheath
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Where do summation of positive and negative charges take place?
Axon hillock
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Nodes of ranvier
Gap in myelin sheath along axon
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Rhombencephalon (hindbrain)
Comprised of metencephalon (structures: cerebellum, pons, and 4th ventricle) and myelencephalon (medulla oblangata, and 4th ventricle)
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How is the resting membrane potential maintained?
The process of moving sodium and potassium ions across the cell membrane is an active transport process involving the hydrolysis of ATP to provide the necessary energy.
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What is action potential and depolarization?
Action potential is explosion of electrical activity created by depolarizing current. Resting potential moves toward 0 mV and causes depolarization when reaches -55mV
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Absolute refractory period
A brief period immediately following the production of an action potential where no amount of stimulation can induce another action potential because the voltage-gated sodium ion channels are either still open or unresponsive
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Relative refractory period
Follows the absolute refractory phase. Only a very strong stimulation can produce another action potential because the potassium ions are still flowing out so the cell is temporarily hyper polarized after firing an action potential. The overall length of the refractory phase is what determines a neuron's maximal rate of firing
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Saltatory conduction
Propogation of action potential that jumps from node to node; increases speed of action potential (i.e., increasing speed of conduction)
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EPSP
(Excitatory Postsynaptic Potential)
- Channels permeable to Na+ and K+
- Inside of cell becomes more positive, causing depolarization potential in postsynaptic cell (i.e., generating action potential)
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IPSP
(Inhibitory Postsynaptic Potential)
- Channels permeable to Cl- and K+
- Inside of cell becomes more negative, causing hyperpolarization potential in postsynaptic cell (i.e., making it less likely that an action potential will be generated)
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Spatial summation
Occurs when multiple synapses in nearby locations are stimulated simultaneously
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Temporal summation
Occurs when the same channel is repeatedly opened, thereby altering the membrane potential further before it has the time to return to normal
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Process of synaptic transmission
process by which signaling molecules called neurotransmitters are released by the axon terminal of a neuron(the presynaptic neuron), and bind to and activate the receptors on the dendrites of another neuron (the postsynaptic neuron)
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The "lock-and-key" model of receptors
For a neurotransmitter to have an effect on the postsynaptic neuron, it has to bind successfully to the receptor that is embedded in the membrane of the postsynaptic neuron. For binding to occur, the neurotransmitter and the receptor site must have perfectly complementing shapes, as does a key that fits a lock.
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Transmission termination
End of transmission of signal or neurotransmitter
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Receptor response to neurotransmitter binding (2 general ways)
- Direct receptor channel (or ionotropic receptor): allows ions to pass through membrane; fast process
- Indirect receptor channel (or metabotropic receptor): binding of neurotransmitter to receptor channel causes release of a molecule (i.e., secondary messenger) that indirectly activates nearby ion channels; slow process
50
What are 3 major divisions of the Autonomic Nervous System (ANS)?
1. Sympathetic: preganglionic cells are found exclusively in the spinal cord (thoracic and lumbar regions). These cells send their axons a short distance to innervate the sympathetic chain – which is autonomic ganglia running along each side of the spinal cord.
2. Parasympathetic N.S. – preganglionic neurons are above and below those of the sympathetic n.s. – in the brain and sacral spinal cord. No chains … positioned near the affected organ.
3. The enteric nervous system (ENS), often referred to as “the second brain”.
The ENS has several functions which include: control of motility, regulation of fluid exchange and local blood flow, regulation of gastric and pancreatic secretion, regulation of gastrointestinal endocrine cells, defense reactions, and entero-enteric reflexes
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Brodmann's Classification System (and its areas)
A Brodmann area is a region of the cerebral cortex, in the human or other primate brain, defined by its cytoarchitecture, or histological structure and organization of cells.
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Brodmann's Classification System - What is Area 17?
Primary visual area
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Brodmann's Classification System - What is Area 44 and 45?
Broca's area (i.e., speech production)
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Pluripotency
refers to a stem cell that has the potential to differentiate into any of the three germ layer
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What is the "All-or-none" law?
the principle that the strength by which a nerve or muscle fiber responds to a stimulus is independent of the strength of the stimulus. If that stimulus exceeds the threshold potential, the nerve or muscle fiber will give a complete response; otherwise, there is no response.
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Cytosol
the liquid found inside cells
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Dopamine
- Dopamine tends to limit and select sensory information arriving from the thalamus to the fore-brain.
- In the brain, dopamine functions as a neurotransmitter—a chemical released by neurons (nerve cells) to send signals to other nerve cells. The brain includes several distinct dopamine pathways, one of which plays a major role in reward-motivated behavior.
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Axoaxonic synapse
the synaptic junction between an axon terminal of one neuron and either the initial axon segment or an axon terminal of another nerve cell.
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Termination
the neurotransmitters must be cleared from the synapse through one of several potential mechanisms including enzymatic degradation or re-uptake by specific transporters either on the presynaptic cell or possibly by neuroglia to terminate the action of the transmitter.
- Degradation: enzymes in synaptic cleft break down neurotransmitter
- Autoreceptors: decreases release of addition neurotransmitters when too many are in the synapse (i.e., decrease Ca2+ channels that open)
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thermally-induced oscillations
After binding, the neurotransmitter may diffuse away due to thermally-induced oscillations/vibrations of both it and the receptor, making it available to be broken down metabolically outside the neuron or to be reabsorbed
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Enzymes
Enzymes accelerate chemical reactions. Enzymes within the subsynaptic membrane may inactivate/metabolize the neurotransmitter.
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Reuptake pumps
Reuptake pumps may actively pump the neurotransmitter back into the presynaptic axon terminal for reprocessing and re-release following a later action potential.
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time frame for "clearing" neurotransmitters from the cleft
The time frame for these "clearing" processes varies greatly for different types of synapses, ranging from a few tenths of a millisecond for the fastest, to several seconds for the slowest.
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Exteroreceptors
Respond to stimuli arising outside the body. Sensitive to touch, pressure, pain, and temperature. Includes the special sense organs (eyes, ears, nose).
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Proprioceptors
Sensory neurons that monitor position and movement of body parts. Respond to degree of stretch of the organs they occupy. Monitor how much organs containing these receptors are stretched. Include muscles, tendons, and joint capsules. They can determine how much force is being applied to your limbs allowing you to pick something up without crushing it or dropping it.
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Conscious Proprioceptors
These receptors are located in the joint capsule, tendons, periosteum, and ligaments. They are responsible for one's kinesthetic awareness, or our ability to consciously perceive movements in terms of force, rate, direction, and range, including our position sense. This recognition of movement and joint positions allows us to regulate and monitor our posture and movement and is also used for motor planning and learning.
67
Unconscious Proprioceptors
These proprioceptors are found in the skeletal muscles. They too, carry information concerning force, rate, direction, and range of movement which is taken directly to the cerebellum. This information is not received directly by the higher cortical centers of the cerebrum which is why it is considered unconscious. However, this information does reach higher control centers indirectly through relays from the cerebellum.
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Enzymatic degradation
a specific enzyme changes the structure of the neurotransmitter so it is not recognized by the receptor. For example, acetylcholinesterase is the enzyme that breaks acetylcholine into choline and acetate.
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Vestibular Receptors
Vestibular receptors are located in the labyrinths of the inner ear. They are concerned with balance and equilibrium, that is, the maintenance of posture through learned reflexes that coordinate eye, head, neck, trunk, and extremity movements. The large myelinated fibers of the eighth cranial nerve supply the neural connections to the vestibular receptors.
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Phasic Receptors
The semicircular canals respond to movements of the head, especially rotary motions, or changes in acceleration and deceleration of the head in space.
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Static Receptors
The utricle and saccule respond to the force of gravity acting on the head and linear acceleration and deceleration of the head in space.
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Semi-permeability
A semipermeable membrane is a type of biological or synthetic, polymeric membrane that will allow certain molecules or ions to pass through it by diffusion—or occasionally by more specialized processes of facilitated diffusion, passive transport or active transport
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Bipolar neuron
- A single axon and dendrite arise at opposite poles of the cell body.
- Found only in sensory neurons, such as in the retina, olfactory and auditory systems.
- Vestibular fxs
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utricle and saccule
The otolith organs include the utricle and the saccule. The utricle senses motion in the horizontal plane (eg, forward-backward movement, left-right movement, or a combination thereof). The saccule senses motions in the sagittal plane (eg, up-down movement).
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neuronal reuptake
Reuptake is the reabsorption of a neurotransmitter by a neurotransmitter transporter of a pre-synaptic neuron after it has performed its function of transmitting a neural impulse.
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otolith: what does this mean?
In vertebrates, the saccule and utricle together make the otolith organs. Greek for “ear stone”
77
chemical synapse
Chemical synapses are specialized junctions through which cells of the nervous system signal to one another and to non-neuronal cells such as muscles or glands.
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synaptic bouton
The presynaptic terminal, or synaptic bouton, is a specialized area within the axon of the presynaptic cell that contains neurotransmitters enclosed in small membrane-bound spheres called synaptic vesicles (as well as a number of other supporting structures and organelles, such as mitochondria and endoplasmic reticulum).
79
postsynaptic density (PSD)
a protein dense specialization attached to the postsynaptic membrane. PSDs were originally identified by electron microscopy as an electron-dense region at the membrane of a postsynaptic neuron. The PSD is in close apposition to the presynaptic active zone and ensures that receptors are in close proximity to presynaptic neurotransmitter release sites.
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The basics about cranial nerves
- Cranial nerves are nerves that emerge directly from the brain, in contrast to spinal nerves which emerge from segments of the spinal cord. In humans, there are traditionally 12 pairs of cranial nerves. Only the first and the second pair emerge from the cerebrum; the remaining 10 pairs emerge from the brainstem.
- The 12 pairs of cranial nerves serve the sensory and motor systems of the head and the neck. These nerves pass through small openings in the skull to enter or leave the brain.
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Cranial nerves: Oh Oh Oh To Touch And Feel Virgin Girl’s Vagina And Hymen
I - Olfactory nerve (smell)
II - Optic nerve (vision)
III - Oculomotor nerve (eyelid and eyeball movement)
IV - Trochlear nerve/pathic nerve (innervates superior oblique - turns eye downward and laterally)
V - Trigeminal nerve/dentist nerve (chewing - face & mouth touch & pain)
VI - Abducens nerve (turns eye laterally)
VII - Facial nerve (controls most facial expressions, secretion of tears & saliva, taste)
VIII - Vestibulocochlear nerve/Auditory nerve (hearing, equilibrium, sensation)
IX - Glossopharyngeal nerve (taste, senses, carotid blood pressure)
X - Vagus nerve (senses aortic blood pressure, slows heart rate,stimulates digestive organs, taste)
XI - Accessory nerve/Spinal accessory nerve (controls trapezius & sternocleidomastoid, controls swallowing)
XII - Hypoglossal nerve (controls tongue movements)
82
What is the number of spinal nerve pairs?
31 pairs total
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What is the “cauda equina?”
“Horse’s tail”. It is a bundle of spinal nerves and spinal nerve rootlets, consisting of the second through fifth lumbar nerve pairs, the first through fifth sacral nerve pairs, and the coccygeal nerve.
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Dorsal (back) root
consists of sensory projections from the body to the spinal cord
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What are the 3 cranial nerves that are exclusively sensory pathways to the brain?
I: Olfactory
II: Optic
VIII: Vestibulo/Auditor
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What are 5 cranial nerves that are exclusively motor pathways from the brain?
```
III: Oculomotor
IV: Trochlear
VI: Abducens
XI: Spinal Accessory – controls neck muscles
XII: Hypoglossal – control the tongue
```
87
What cranial nerves have both sensory and motor fxs?
V: Trigeminal – facial sensations and chewing movements
VII: Facial – controls facial muscles and receives taste sensations
IX: Glossopharyngeal – throat sensation and movement
X: Vagus – from the head to the heart, liver, and intestines (“wandering”)
88
Ganglia
a nerve cell cluster or a group of nerve cell bodies located in the autonomic nervous system and sensory system.
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Voltage Gated Ca++ Channel
Found in the membrane of excitable cells (e.g., muscle, glial cells, neurons, etc.)
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Sodium channels
maintains resting membrane potential; responsible for action potential initiation and propagation in excitable cells, including nerve, muscle, and neuroendocrine cell types
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Depolarization
when inside of cell becomes more positive (generating action potential); Loss of difference in charge between the inside and outside of the plasma membrane due to a change in permeability and migration of sodium ions to the interior. Brings the membrane potential closer to zero
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Synaptic Vesicle
found in presynaptic terminals; contains neurotransmitters
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"docked" vesicles
Docking is the process during which the vesicle and pre-synaptic membrane line up in a fusion-ready state. Following docking, the membranes fuse to create a small opening which grows larger until the vesicle membrane collapses into the pre-synaptic membrane and exocytosis occurs.
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Telodendria
Axons of some neurons that branch to form axon collaterals, these can then be divided into a number of branches which are these. I.e. Is a distal branch of a neuronal axon that can further branch into axon terminals
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axon initial segment (AIS)
- Consists of specialized complex of proteins that form part of the proximal axon of a neuron
- It is unmyelinated and functions as site of action potential initiation (important role in maintaining neuronal polarity)
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multipolar neuron
- multiple dendritic processes, one axon (most numerous and common cell type in body, both CNS and PNS)
- Allow integration of information from other neurons
- Includes motor neurons and interneurons
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Prosencephalon (forebrain)
Consists of the telencephalon (structures include neocortex, basal ganglia, amygdala, hippocampus, lateral ventricles) and diencephalon (structures include thalamus, hypothalamus, epithalamus, third ventricle)
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Anion
Negatively charged atoms, more electrons than protons
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axon hillock
- The start of the axon extension from the cell body
- No neuron has more than one axon
- Axon hillock has lowest threshold for triggering an action potential
- Summation occurs here
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neurotransmitters are “cleaned up” how? (2 processes)
- Degradation: enzymes in synaptic cleft break down neurotransmitter
- Autoreceptors: decreases release of addition neurotransmitters when too many are in the synapse (i.e., decrease Ca2+ channels that open)
101
end-feet, neuropodia, terminal boutons
The somewhat enlarged, often club-shaped endings by which axons make synaptic contacts with other nerve cells or with effector cells
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phospholipid bilayer cellular processes
a sheet of lipids; lipids arrange into this structure due to the hydrophobic effect, which creates an energetically unfavorable interaction between the hydrophobic lipid tails and the surrounding water; thus, a lipid bilayer is held together by non-covalent forces that do not involve chemical bonds between molecules
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Hydrophilic Heads
points out to the water on either side of the lipid bilayer
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Hydrophobic Tails
points into the core of the bilayer
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Homunculus
a very small human or humanoid creature; location of motor and sensory homunculus
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Frontal lobe
The precentral gyrus, forming the posterior border of the frontal lobe, contains the primary motor cortex, which controls voluntary movements of specific body parts; The dopamine system is associated with reward, attention, short-term memory tasks, planning, and drive.
107
Parietal lobe
This lobe is divided into two hemispheres- left and right. The left hemisphere plays a more prominent role for right handers and is involved in symbolic functions in language and mathematics. Meanwhile, the right hemisphere plays a more prominent role for left handers and is specialized to carry out images and understanding of maps (i.e., spatial relationships). The parietal association cortex enables individuals to read, write, and solve mathematical problems.
108
Temporal lobe
involved in auditory perception and is home to the primary auditory cortex. It is also important for the processing of semantics in both speech and vision. The temporal lobe contains the hippocampus and plays a key role in the formation of long-term memory.
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Occipital lobe
visual processing center of the mammalian brain containing most of the anatomical region of the visual cortex; specialized for different visual tasks, such as visuospatial processing, color discrimination and motion perception.
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What does the limbic system consists of?
Hippocampus, Amygdala, and Septal nuclei
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Hippocampus
Required for the formation of long-term memories and implicated in maintenance of cognitive maps for navigation.
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Amygdala
Involved in signaling the cortex of motivationally significant stimuli such as those related to reward and fear in addition to social functions such as mating.
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Septal nuclei
the septal nuclei provide critical interconnections to the Limbic lobe. The septal nuclei play a role in reward and reinforcement along with the nucleus accumbens.
