Exam 1 Flashcards
Neuron
Neurons are cells arranged into circuits that underlie all forms of behavior;They receive input from cells, integrate the inputs, then distribute the processed info to other neurons
Neuron zones
Input zone: dendrites and dendritic spines; Integration zone: cell body (soma),axon hillock; Conduction zone: axon, myelin sheath, nodes of ranvier; Output zone: axon terminals. Make synapses with other neurons
Multipolar neuron
Have many dendrites and a single axon; Most common type of neuron
Bipolar neuron
Have a single dendrite at one end of the cell and a single axon at the other end; Common in sensory systems, like vision
Unipolar neuron
Have a single extension (process), usually thought of as an axon, that branches in two directions after leaving the cell body; Transmit touch info from the body into the spinal cord
Motor Neurons
Large neurons with long axons reaching out to synapse on muscles, causing muscular contractions
Sensory neurons
Specialized to gather sensory info
Interneurons
Small neurons that analyze info gathered from one set of neurons and communicate with others; Most of the neurons in our brain
Soma
The neuron’s cell body that integrates the info that has been received; In the integration zone
Dendrite
The neuron’s cellular extensions that help the it receive info via synapses from other neurons; Some neurons have dendritic spines which are small projections (like branches) that add additional space for synapses; In the input zone
Axon
The nerve fiber that carries the neuron’s own electrical signals away from the cell body; In the conduction zone, carrying the info to where it needs to go
Axon terminal
The specialized swellings at the ends of the axon that transmit the neuron’s signals across synapses to other cells; In the output zone
Myelin
A fatty substance that wrap around successive axons in order to insulate them; Myelination increases the speed with which the electrical signals pass down the axon; Myelin does not cover the Nodes of Ranvier, which the electrical signals jump quickly
Glial cell
Cells that protect and assist neurons; There are more glial cells than neurons in the brain
Astrocyte
Function in the brain; Help to form the tough outer membranes that coddle the brain; Some stretch between neurons and blood vessels to control local blood flow; Also secrete chemical signals that affect synaptic transmission and the formation of synapses
Microglia
Function in the brain; tiny and mobile cells that mainly contain and clean up sites of injury in the brain
Oligodendrocyte
Wrap myelin around axons in the brain and spinal cord (CNS)
Schwann Cell
Wrap myelination for everywhere BUT the brain and spinal cord (the PNS)
Ganglion (ganglia)
Groups of cell bodies in the PNS
Nuclei
Groups of cell bodies in the CNS
Nerves
Groups of axons in the PNS
Tracts
Groups of axons in the CNS
Central nervous system (CNS)
Consists of the brain and spinal cord
Peripheral nervous system
Everywhere BUT the brain and spinal cord
Somatic Nervous system
part of the PNS Consists of nerves that interconnect the brain and the major muscles and sensory systems of the bodies
Cranial nerves
Part of the somatic NS; 12 pairs (left and right) of cranial nerves that arise from the brain and innervate the head, neck, and visceral (other) organs directly, without ever joining the spinal cord
Sensory cranial nerves
Olfactory-smell; Optic-vision; Vestibulocochlear - hearing and balance
Motor Cranial Nerves
oculomotor - innervate muscles to move the eyes; trochlear - innervate muscles to move the eyes; abducens - innervate muscles to move the eyes; Spinal Accessory - control neck muscles; Hypoglossal - control the tongue
Cranial nerves with sensory and motor functions
trigeminal - transmit facial sensation, but also control the chewing muscles; facial - control facial muscles, but also receive some taste sensation; glossopharyngeal - receive additional taste sensations and sensations from the throat, but also control the throat muscles; Vagus- primary route by which the brain both controls and receies info from many visceral organs, also participates in varied functions like sweating, digestion and heart rate (extends from the head, running to other organs)
Spinal Nerves
Pair of 31 nerves; one on each side of body; Emerge through regularly spaced openings along both sides of the backbone
Spinal Nerves Number and location
8 cervical (neck); 12 thoracic (torso); 5 lumbar (lower back); 5 sacral (pelvic); 1 coccygeal (bottom)
Dorsal vs Ventral Spine Nerves
Dorsal spinal nerves enter thru the dorsal (back) side and carry sensory info from the body to the spinal cord (So they are afferent);Ventral spinal nerves exit from the ventral (front) side and carry motor signals from the spinal cord to the muscles and glands (So they are efferent)
Autonomic Nervous System
part of PNS; Consists of nerves that connect primarily to the viscera (internal organs); has parasympathetic and sympathetic systems
Parasympathetic Nervous System
Rest-and-digest response; Helps the body relax, recuperate, and prepare for future action; Nerves come from out of the brainstem
Sympathetic Nervous System
Responsible for flight or fight rxns; Blood pressure increase, heart rate increase, etc; Nerves come from out of the spine; Balance between the parasympathetic and sympathetic determines the state of organs at a given time
Afferent nerves
Carries information into a region of interest; Dorsal spinal nerves are afferent as they carry sensory signals to the spinal cord
Efferent nerves
Carries information away from a region of interest;Ventral spinal nerves are efferent as they carry motor signals away from the spinal cord
Anterior/rostral
Toward the front of the head (near eyes)
Posterior/caudal
Toward the back of the head for brain; Toward the ground for spinal cord
Dorsal
Towards the top of the head for brain;Towards the back for spinal cord
Ventral
Towards the body (down) for brain; Toward the front (belly button) for spinal cord
Medial
Towards the middle of the brain (left and right wise)
Lateral
Toward the sides of the brain (left and right wise)
Proximal
near
Distal
Far
Sagittal plane
Divides the brain into left and right portions (So you’re looking at the brain from the side)
Coronal plane
Divides front (anterior) from back (posterior) (So like you’re looking straight on from the face or back)
Horizontal plane
Divides between upper and lower parts (So like you’re looking from the top or from the bottom)
Four Lobes of the Brain
Frontal Lobe in front(Executive functioning); Parietal Lobe up top; Temporal Lobe bottom (receives auditory inputs and help in memory formation); Occipital Lobe in back (Crucial for vision)
Cerebral Hemispheres
The left and right halves of the forebrain; Contralateral control meaning the right hemisphere controls the left side of the body and vice versa
Corpus Callosum
A channel that allows axons of the left and right hemispheres to connect; Needed for complex processes
Cerebral cortex
The lumpy brain surface made of a thick sheet of tissue, mostly dendrites, cell bodies, and axonal projections of neurons; Is lumpy for more surface area = more brain stuffed into skull
Gyri
raised/ridged portion of the cerebral cortex
Sulci
Crevices that separate the gyri
Gray matter
In the outer layers of the cortex (in brain), inner part of the spinal cord ;darker grayish shade bc they contain a bunch of neuronal bodies and dendrites; Mostly receives and processes info
White matter
Found beneath the gray matter in the brain (under the cerebral cortex) and connects diff parts of gray matter together, Found on the outer part of the spinal cord, surrounding the gray matter;Is white bc it is made up of primarily myelinated axons; Mostly transmits info
Hindbrain
At the bottom of the brain where it connects to the spinal cord; Regulates essential life functions; includes medulla, reticular formation, cerebellum, pons
Medulla
Controls respiration and heart rate; The posterior part of the hindbrain, continuous with the spinal cord
Reticular Formation
Controls attention, arousal and sleep; Network of neurons that runs thru the core of the brain stem (thru medulla and pons) and extends into the midbrain
Cerebellum
Motor learning and memory; Behind the medulla and pons
Pons
Sensory and motor;Above the medulla and links the cerebellum to the rest of the brain
Midbrain
Acts as a relay center, integrating sensory info, particularly visual and auditory signals; Also plays role in motor control, alertness, and regulating reflexive movements; includes the Tectum and Tegmentum
Tectum (“roof”)
Forms the back part of the midbrain; Superior colliculus-Visual functioning; Inferior colliculus-Auditory functioning
Tegmentum (“floor”)
Forms the bulk of the midbrain in front of the tectum;substantia nigra-Critical for movement control and dopamine (Related to parkinsons);Periaqueductal gray-Pain modulation, fear, panic
Diencephalon
Positioned deep in brain between the midbrain and the cerebrum, forming part of the forebrain; includes Thalamus and hypothalamus
Thalamus
Above the hypothalamus; Sensory relay nuclei; Connects to cortex
Hypothalamus
Above pituitary gland; Endocrine (hormone) function; Motivated behaviors (feeding, drinking, temp regulation, sex, sleep)
Forebrain
contains the entire cerebrum as well as the telecephalon (cerebral cortex, hippocampus, basal ganglia, olfactory bulb) and diencephalon (thalamus and hypothalamus)
Important nuclei within the cerebral hemispheres made of gray matter include
Basal ganglia, hippocampus, fornix, limbic system, amygdala
Basal ganglia
Surrounds the thalamus, Plays a critical role in control of movement
Hippocampus
Important for memory
Fornix
Important for memory
Limbic system
Involved in emotion and learning
Amygdala
Involved in emotional regulation
Blood brain barrier
A semi-permeable barrier that separates the circulating blood from the brain and CNS; Protects the brain from toxins in the blood, but also lets in nutrients; Capillaries are tight and not leaky (like in the body because there are endothelial cells in the brain’s capillaries that are tightly joined together, supported by astrocytes
Meninges
3 protective membranes that surround the brain and spinal cord, providing a cushioning and supportive layer (Dura mater, arachnoid membrane, pia mater)
Dura mater
A tough outer layer
Arachnoid Membrane
Middle layer that makes an open space called the subarachnoid space; Subarachnoid space is filled with cerebrospinal fluid to protect the brain
Pia Mater
Layer that is tight against the brain and encloses the CSF
Ventricles
A system of four interconnected, fluid filled cavities within the brain that produce and circulate cerebrospinal fluid (CSF)
Lateral ventricles
One in each hemisphere
Third ventricle
In middle of brain below the lateral ventricles
Fourth ventricle
Between the brainstem and the cerebellum, connecting to the spinal cord
Choroid Plexus
A specialized membrane that lines lateral ventricles and produces CSF by filtering blood; Also helps filter out waste
CSF
Fluid that surrounds and cushions the brain and spinal cord to protect them; It also helps regulate intracranial pressure, delivers nutrients, and removes waste products; Circulates through the ventricles, around the brain and spinal cord, and is eventually reabsorbed into the bloodstream
The major function of Schwann cells is
myelination of axons in the PNS
The major function of oligrodendrocytes is
myelination of axons in the CNS
The plane that divides the brain into left and right halves is called the
sagittal
Which glial cells interact with blood vessels?
Astrocytes
The efferent nerves of the autonomic nervous system (ANS) go to
various organs in the body
What would be the consequence for a patient with damage to the eighth (VIII) cranial nerve?
impaired hearing
What does the nervous system coordinate in the body?
It coordinates every aspect of the functioning of the body, from automatic processes like heart rate to complex emotions and behavioral responses.
How many neurons are in the nervous system?
Nearly 100 billion neurons.
What are the three main structural elements of a typical neuron?
Dendrites, a cell body (soma), and an axon.
What are the four functional elements of neurons?
Input zone (dendrites and cell body), integration zone (axon hillock), conduction zone (axon), and output zone (axon terminals).
What are the functions of glial cells?
They myelinate axons, exchange nutrients with neurons, remove cellular debris, and participate in information processing.
Where does information transmission between neurons occur?
Across synapses.
What do axon terminals release in response to an impulse?
Neurotransmitters.
What does the nervous system consist of?
The central nervous system (brain and spinal cord) and the peripheral nervous system (somatic and autonomic systems).
What is the function of the somatic nervous system?
It connects muscles and sensory systems to the central nervous system.
What is the function of the autonomic nervous system?
It connects internal organs to the central nervous system.
What are the two divisions of the autonomic nervous system?
Sympathetic and parasympathetic divisions.
What is the function of the sympathetic nervous system?
It prepares body systems for action.
What is the function of the parasympathetic nervous system?
It tends toward relaxation.
What are the four major lobes of the cerebral hemispheres?
Frontal, parietal, temporal, and occipital lobes.
What are the prominent components found within the cerebral hemispheres?
Basal ganglia and limbic system.
What are the major divisions of the brain?
Forebrain, midbrain, and hindbrain.
What does the forebrain consist of?
The telencephalon (cortex, limbic system, and basal ganglia) and diencephalon (thalamus and hypothalamus).
What are the prominent parts of the midbrain?
Tectum and tegmentum.
What does the hindbrain consist of?
The cerebellum, medulla, and pons.
What protects the brain and spinal cord?
The three layers of the meninges: dura mater, arachnoid, and pia mater.
What suspends the brain and spinal cord?
Cerebrospinal fluid (CSF).
Where is cerebrospinal fluid produced?
In the choroid plexus of the lateral ventricle.
What is the main function of synapses?
To communicate information via neurotransmitters from the presynaptic neuron to the postsynaptic cell.
Name the major transmitter families.
Quaternary amines, monoamines, amino acids, neuropeptides, and unconventional transmitters.
What is the first identified neurotransmitter?
Acetylcholine.
What are the two types of effects that drugs can have on synaptic transmission?
Agonistic (enhancing) or antagonistic (blocking) effects.
What does the presence of a brain receptor for an exogenous drug imply?
That the brain makes an endogenous ligand for that receptor.
Name three ways drugs can affect presynaptic function.
Alteration in transmitter synthesis, alteration in transmitter storage, and alteration in transmitter release.
How can drugs affect postsynaptic function?
By activating or blocking postsynaptic receptors, altering second messenger activity, altering gene expression, or changing receptor density.
What do enkephalins and endorphins do?
They bind to opiate receptors and have morphine-like analgesic properties.
What is the active ingredient in tobacco, and what receptor does it bind to?
Nicotine, which binds to the acetylcholine nicotinic receptor.
Describe the two phases of alcohol’s effect on the nervous system.
An initial stimulant phase followed by a prolonged depressant phase.
What neurotransmission does alcohol antagonize?
Glutamatergic neurotransmission.
What neurotransmission does alcohol enhance?
GABAergic inhibition.
What is the active ingredient in marijuana?
Delta-9-tetrahydrocannabinol (THC).
What receptor does THC act on?
Cannabinoid receptors.
What physiological effects does THC produce?
Improved mood, pain relief, lowered blood pressure, nausea relief, and improvements in glaucoma.
How does nicotine affect the nervous system?
It binds to acetylcholine nicotinic receptors, enhancing cognitive performance and activating reward pathways.
What is the active ingredient in opium?
Morphine.
How do amphetamines affect synaptic transmission?
They cause the release of dopamine and block the reuptake of dopamine.
What neurotransmitter is associated with the effects of cocaine?
Dopamine.
How do hallucinogenic drugs affect sensory perceptions?
They alter or distort existing sensory perceptions.
Which neurotransmitter’s receptors do most hallucinogens target?
Serotonin receptors, especially 5-HT2A receptors.
What are potential outcomes of alcohol abuse on brain function and structure?
Impaired motor function, slurred speech, loss of consciousness, coma, and even death. Many effects are reversible after stopping alcohol use.
What neurotransmitter is involved in the psychoactive effects of stimulants like nicotine?
Acetylcholine.
What happens when drugs block reuptake of neurotransmitters?
It increases the concentration of neurotransmitters in the synaptic cleft, enhancing their effects.
What are endogenous opiate peptides?
Peptides like enkephalins and endorphins that bind to opiate receptors.
ionotropic receptors
receptors that are coupled to ion channels and affect the neuron by causing those channels to open, fast and short-lasting effects, used in rapid responses like muscle contraction and sensory processing
metabotropic receptors
receptors that are associated with signal proteins and G proteins, slower but longer-lasting effects than ionotropic responses
Enzymatic deactivation/degradation
Excess neurotransmitters are broken down by enzymes
What are the three things that can happen to a neurotransmitter after the postsynaptic response
Enzymatic degradation, reuptake into the pre-synaptic terminal, Neurotransmitters activate autoreceptors (acts like a break
Reuptake
a neurotransmitter’s reabsorption by the sending neuron, then they can be reused
autoreceptor
a receptor for a synaptic transmitter that is located in the presynaptic membrane, telling the axon terminal how much transmitter has been released
large neurotransmitters (neuropeptides)
assembled in the cell body, packaged in vesicles, and then transported to the axon terminal
small transmitters
Synthesized in the cytoplasm of the axon terminal and packaged by the Golgi apparatus
amino acids
come from food (ex. Glutamate and Gaba)
GABA effects on anxiety
Lowers anxiety as GABA receptors cause hyperpolarization leading to decrease in neural activity (benzos and alcohol work this way)
Monoamines
chemicals formed by a change in certain amino acids (serotonin, dopamine, norepinephrine
Acetylcholine (ACh)
A neurotransmitter that enables learning and memory and also triggers muscle contraction; made from dietary choline; linked to alzheimers
monoamine systems
Neuronal systems in the brain that produce monoamine neurotransmitters.
neuropeptides
short chains of amino acids made in the cell body; involved in analgesia and reward system (endorphins); have longer lasting effects compared to small NT
Catecholamines
dopamine, norepinephrine, epinephrine
Indolamines
serotonin
Glutamate
A major excitatory neurotransmitter; involved in memory
Agonist
a molecule that, by binding to a receptor site, stimulates a response
Antagonist
drugs that block the function of a neurotransmitter
exogenous substances
substances from outside the body
endogenous substances
substances that naturally occur within the body
ligand
any substance that binds to a receptor
Efficacy
the extent to which a drug molecule activates the receptor (agonists have high efficacy, antagonists have low efficacy)
Ways that drugs affect presynaptic processes
Effects on neurotransmitter production; Effects on neurotransmitter release (ex botox); Effects on neurotransmitter clearance (e.g., reuptake inhibitors)
Way drugs alter postsynaptic processes
Effects on neurotransmitter receptors.
Explain how drug effects on neurotransmitter receptors.
receptor antagonists bind directly to postsynaptic receptors to block them from being activated (ex. curare blocks nicotinic ACh receptors found in muscles leading to immediate paralysis); Receptor agonists bind to specific receptors and activate them, mimicking the natural NT at those receptors (ex. LSD at 5-HT2a receptors)
Reuptake inhibitors
work by blocking the presynaptic system that normally reabsorbs transmitter molecules after their release; This allows the transmitter molecules to stay longer in the synaptic cleft, having a greater effect on the postsynaptic cell
Botox effects on neurotransmitter release
blocks ACh release from axon terminals near the injection site, causing paralysis
What is the resting membrane potential?
The resting membrane potential is about -60 mV due to the differential concentrations of ions inside and outside the neuron.
Why is the resting membrane potential primarily influenced by potassium (K+) ions?
The membrane is primarily permeable to potassium (K+) ions, which move in and out of the neuron to maintain equilibrium.
How does the Na+/K+ pump help maintain the resting membrane potential?
The Na+/K+ pump actively pumps 3 Na+ ions out and 2 K+ ions into the cell to maintain the ionic balance.
What happens during hyperpolarization?
The membrane becomes more negative, decreasing the likelihood of an action potential.
What happens during depolarization?
The membrane becomes less negative (closer to zero), increasing the likelihood of an action potential.
What is an action potential?
An action potential is a rapid change in membrane potential that occurs when a neuron reaches its threshold.
What is the threshold for generating an action potential?
The threshold is usually around -55 mV.
How does an action potential follow the all-or-none principle?
Once the threshold is reached, an action potential will always occur with the same strength, regardless of stimulus size.
What happens to the membrane potential at the peak of the action potential?
The membrane potential approaches +40 mV due to the opening of voltage-gated Na+ channels.
What causes the membrane to repolarize after an action potential?
Potassium (K+) ions flow out of the cell, restoring the membrane to its resting potential.
What is the absolute refractory period?
It is the period after an action potential when Na+ channels are inactive and no new action potential can be generated.
What is the relative refractory period?
After the absolute refractory period, a very strong stimulus may trigger another action potential during this phase.
Where do action potentials arise?
Action potentials arise at the axon hillock and travel down the axon.
What is saltatory conduction?
Saltatory conduction is when action potentials jump between the nodes of Ranvier in myelinated axons, speeding up transmission.
What happens when an action potential reaches the axon terminal?
Voltage-gated calcium channels open, causing neurotransmitter release.
What is an EPSP?
An excitatory postsynaptic potential (EPSP) is a graded depolarization that increases the chance of an action potential.
What is an IPSP?
An inhibitory postsynaptic potential (IPSP) is a graded hyperpolarization that decreases the chance of an action potential.
How are neurotransmitters released into the synaptic cleft?
Calcium influx triggers synaptic vesicles to fuse with the presynaptic membrane, releasing neurotransmitters into the cleft.
What happens to neurotransmitters after they are released?
They bind to receptors on the postsynaptic membrane and alter the membrane’s permeability.
How are neurotransmitter signals terminated?
Neurotransmitter signals are stopped by enzymatic degradation or reuptake.
What is a ligand?
A ligand is a molecule (like a neurotransmitter or drug) that binds to a receptor, either activating or blocking it.
What is spatial summation?
Spatial summation occurs when EPSPs and IPSPs from different synapses add up to influence the neuron.
What is temporal summation?
Temporal summation occurs when multiple signals from the same synapse add up over time.
What is the role of voltage-gated calcium channels in synaptic transmission?
They allow calcium ions to enter the neuron, triggering neurotransmitter release.
How do EPSPs and IPSPs determine if a neuron fires an action potential?
If enough EPSPs outweigh IPSPs and the threshold is reached at the axon hillock, an action potential is triggered.
What is the role of the sodium-potassium pump?
It helps maintain the resting potential by pumping Na+ out and K+ into the cell.
Synapse
The site where communication happens between neurons.
Presynaptic membrane
The axon terminal of the presynaptic (transmitting) neuron.
Postsynaptic membrane
The membrane on the dendrite or cell body of the postsynaptic (receiving) neuron.
Synaptic Cleft
A gap of about 20-40 nanometers that separates the presynaptic and postsynaptic neurons.
Transmission at a chemical synapse
The process by which an action potential leads to neurotransmitter release and communication between neurons.
Steps in Neurotransmission
- Action potential-AP reaches the terminal
- voltage-gated calcium channel- opens allowing calcium ions to enter.
- Exocytosis- The influx of calcium ions triggers synaptic vesicles (filled with NT) to fuse with presynaptic membrane. this fusion causes exocytosis of NT into the synaptic cleft
4.Receptor Activation- The NT diffuse across the synaptic cleft and bind to specific receptor proteins on the postsynaptic membrane. This binding causes ion channels in the postsynaptic neuron to open or close depending on the type of receptor
- Postsynaptic potentials- The binding of NT to the receptors generates EPSPs or IPSPs. EPSPs may lead to another AP if it reaches the threshold
Cell membrane
A lipid-based membrane that blocks the passage of most substances, regulating what enters and exits the cell.
Ion channel
Proteins embedded in the cell membrane that allow ions to pass in and out of the neuron, helping maintain the electrical charge inside the cell. These channels can either be open all the time or controlled to open and close.
Voltage-gated calcium channels
Key channels at the presynaptic terminal that allow calcium ions to flow into the neuron in response to an action potential, triggering neurotransmitter release.
Resting Membrane Potential
The electrical charge difference across the membrane when a neuron is at rest, usually around -60 mV.
Distribution of Ions
Refers to the concentration of ions inside (intracellular) and outside the neuron (extracellular
Intracellular fluid distribution
Higher concentration of K+ (potassium ions) and negatively charged proteins (anions).
Extracellular fluid
Higher concentration of Na+ (sodium ions) and Cl- (chloride ions).
Concentration Gradient
Ions move from areas of high concentration to low concentration. For example, K+ tends to move out of the neuron, while Na+ tends to move in.
Electrical Gradient
Ions are influenced by their charge: opposite charges attract, and like charges repel. Positive ions (Na+ and K+) are attracted inside the cell because the inside is negatively charged.
Selective Permeability
The neuron’s membrane allows some ions to pass more easily than others. K+ can pass freely, while Na+ is blocked during resting conditions.
Sodium-Potassium Pump
Pumps 3 Na+ ions out and 2 K+ ions into the neuron, using energy (ATP). This helps maintain the resting potential by keeping Na+ high outside and K+ high inside.
Hyperpolarization
An increase in membrane potential meaning the inside of the neuron becomes more negative in comparison to the outside (like from -65 at resting potential to -75); makes it less likely for AP
IPSP (inhibitory postsynaptic potential)
synaptic potential that makes a postsynaptic neuron less likely to generate an action potential
Depolarization
The inside of the neuron becomes less negative; like from -65 to -50, needed for AP
EPSP (excitatory postsynaptic potential)
depolarizing graded potential in postsynaptic neuron in response to activation of excitatory synapse; depolarizes the membrane, increasing the chance of AP
Graded Response
Responses that vary depending on the strength of the stimulus. Occur in the dendrites and soma and weaken as they spread from the source (decremental); response from hyperpolarization or depolarization
Action Potential
A rapid, large change in membrane potential triggered when the neuron reaches a threshold (~-55 mV). It follows the all-or-none principle and propagates down the axon.
Voltage-Gated Ion Channel
Ion channels that open or close in response to changes in membrane voltage. Na+ channels open during depolarization, allowing Na+ to enter, followed by K+ channels opening to repolarize the cell.
Saltatory Conduction
The process in myelinated axons where action potentials jump from one node of Ranvier to the next, increasing the speed of transmission.
All-or-None Law
Once the threshold is reached, an action potential fires at full strength. The size of the action potential is always the same, regardless of stimulus strength.
Neurotransmitter
Chemicals that transmit signals across the synapse to another neuron. Examples include acetylcholine (Ach), dopamine, glutamate, and GABA.
Presynaptic and Postsynaptic Membranes
The presynaptic membrane releases neurotransmitters, and the postsynaptic membrane receives them, leading to EPSPs or IPSPs.
Excitatory vs. Inhibitory Postsynaptic Potentials (EPSP vs. IPSP)
EPSP: Depolarizes the neuron, increasing the chance of an action potential.
IPSP: Hyperpolarizes the neuron, decreasing the chance of an action potential.
Temporal Summation
Multiple EPSPs or IPSPs from the same synapse add up if they occur in rapid succession.
Spatial Summation
EPSPs or IPSPs from different synapses arrive at the same time and combine to influence the neuron.
AP peak
the membrane potential approaches +40 mV bc voltage-gated Na+ channels open, allowing sodium ions to flood into the neuron; these sodium channels close rapidly, and the K+ channels open, letting K+ ions to leave the cell; the outward flow of K+ repolarizes the membrane back to its resting state; inside of cell is more positive than outside
decremental vs. non decremental
Graded responses have decremental speed meaning that as the response spreads away from the sight of stimulation it gets weaker; AP has non-decremental meaning that it does not get weaker
Threshold
when neurons reach -55 mV it triggers an AP, so in order for an AP to be triggered the membrane needs to depolarize
APs result in the release of neurotransmitters at the _______, which can then create graded responses in the next neuron
axon terminal
What is the distribution of Na+, K+, Cl-, Ca2+, and proteins inside of the cell at resting potential.
Na+ few; K+ many; Cl- few; Ca2+ few; Proteins many
What is the distribution of Na+, K+, Cl-, Ca2+, and proteins in extracellular fluid at resting potential.
Na+ man; K+ few; Cl- man; Ca2+ many; Proteins few
A neuron can reach threshold if many EPSPs arrive at the axon hillock at the same time, but from different locations. This process is referred to as
Spatial summation
The most important difference between Inhibitory postsynaptic potentials and excitatory postsynaptic potentials is their:
direction of membrane polarization
The form of conduction that is used by myelinated axons is called
Saltatory conduction
The release of neurotransmitter molecules from terminals is triggered by
calcium ions entering the neuron
When a neurotransmitter molecule binds to an ionotropic receptor, the
associated ion channel opens or closes
The change in membrane potential from -60mv to -70mv would be
a type of hyperpolarization
T/F Negatively charged atoms (anions) are drawn to the intracellular fluid
t
T/F Do the concentration gradient and the electrostatic pressure/gradient encourage Na+ ions to enter resting neurons
t
During an action potential, the change in membrane potential caused by sodium ions entering the neuron triggers the
opening of potassium channels
