PNB Exam III

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When a motor neuron stimulates a muscle fiber to contract, the latent period refers to: the time between the closing of the inactivation gate of voltage gated sodium channels and the time that it reopens the time from development of end plate potential to the opening of the Ryanodine Receptor (RyR) A time in which only a fraction of the total number of sodium channels can be reopened The time between the firing of a neural action potential and a muscle action potential

The time from development of end plate potential to the opening of the Ryanodine Receptor (RyR)

If PCl is changed to 0.8, what happens to V?

t becomes more negative.

Sensory neglect is most often seen with the right parietal lobe damage associated with left hemiplegia. (T/F)

True

the major pathway of communication between the left and right cerebral hemisphere is the ___. A. Diencephalon B. Cerebral gyrus C. Central sulcus D. Corpus Callosum

The primary motor cortex A. is located on the pre central gyrus B. is in the frontal lobe C. is mapped somatotopically D. all of the above

Which of the following types of sensory information would most likely be transducer by a rapidly adapting receptor?A. Dull (aching) pain B. information traveling in the anterior spinothalamic tract C. temperature D. vibration

A decrease in sodium permeability through the membrane would have what effect on the membrane potential?

It would make it more negative.

An increase in potassium permeability through the membrane would have what effect on the membrane potential?

It would make the membrane more negative.

During the after-hyperpolarization phase of the action potential, _______________ . Threshold for action potential increases (more depolarized.) Voltage gated Na+ channels are in the inactivated conformation. K+ conductance (permeability) reaches its maximum All of the above

K+ conductance (permeability) reaches its maximum

Damage to the blood-brain barrier can cause _________ to move from blood to cerebrospinal fluid, leading to ___________ of neurons.

K+; depolarization

When a photon of light is absorbed by rod photopigment, closure of cation channels leads to decrease in Na+ and Ca++ influx and hyperpolarization of the rod. (T/F)

True

Diencephalon Overview

- "interbrain" : surrounded by hemispheres of cerebrum. 1) epithalamus (posterior/superior) 2) thalamus (superior) 3) hypothalamus (inferior/anterior) -Deeper is the diencephalon -Below the corpus collusom (white tract) connect left and right brains

Myosin ATP Hydrolysis regulates cross bridge formation

- ATP hydrolysis takes place on the myosin head - this is the second thing that determines whether interactions between actin and myosin - when ATP binds, the myosin has a very low affinity for actin. And this means that the cross bridge camp form. It also means that any existing cross bridges are essentially broken by the binding of ATP to myosin. - This is a short-lived state because myosin head is enzymatic and it can hydrolyze ATP into ADP and phosphate - ADP and phosphate stay bound to the myosin head and when they are bound, the myosin head twist to a higher energy confirmation and binds to Acton. The state is referred to as the contact confirmation because it's a high energy state and it's very similar to cocking the trigger of a gun - the phosphate is released and this allows the myosin head to stay bound but untwist and move into a low energy state. As it does this it pulls the act in to one position closer to the center of the sarcomere - In the low energy state, the ADP gets easily replaced by ATP that allows the cross bridge to break in this whole cycle can repeat a second time

Work is (energetically) expensive

- ATP is critical for contractile protein assembly & function GTP actin ATP polymerizes to --> F actin ATP Pi --> F actin ADP depolymerizes --> G actin ADP ADP/ATP exchange --> G actin ATP

motor and sensory cortex homunculus

- Both are organized by homunculus - The amount of real estate that different parts of the body get inside the brain is based upon their usage. - Not based on size - Hands have more cortical area (a large area dedicated to your hand allows a very sensitive sense of touch allowing us to do things like read braille) - This is true in both the primary motor cortex and in the primary somatosensory cortex. In there, having a large area dedicated to your face, allows you to produce really complex facial expressions. - important for nonverbal communication

primary language areas

- Brocas area is in the frontal lobe and it's important for speech production. - Wernicke's Area in the Temporel lobe is important for language comprehension. - broca's = frontal lobe - wernicke's = temporal lobe - Both are found only in the left hemisphere. They are laterally structured and they rely on fibers on the right side of the hemisphere. - But there are also association fibers running between them. - Arcuate fasciculus which is white matter, connects Broca's area to the Wernicke's area. Signal sent through this allow us to produce coherent spoken language. - Comprehending written language is used by angular gyrus. This is the collection of association fibers that connects to the visual cortex to Wernicke's area that allows you to make sense of the things you were reading..

Fiber tension: fatigue

- But if muscles stay in this state for too long, then the become fatigued and loose ability to make tension. - Depletion theory: muscle fiber runs out stuff to maintain contraction

Ventricles produce, circulate, and store CSF

- CSF provides physical and chemical stability for the neurons - CSF flows through the subarachnoid space to leave the brain, excess CSF flow into the the arachnoid villi, then drains into the dural venous sinuses - The composition of the CSF can directly impact the function of neurons in both the brain and spinal cord - Most of the cerebrospinal fluid is produced in structures in the brain called the ventricles.They are a CSF storage reservoir which are largeHaving fluid in the brain reduces the weight of it. - CSS is also circulated by the ventricles (they can move from the lateral ventricles to the third ventricle and travel through the cerebral aqueduct into the fourth ventricle and then to the central canal into the spinal cord. - CSF is continuous!! Which means it has a relatively uniform composition. - CSF travels to the median and lateral apertures. And circulated the rest of the brain.

Protection of the brain - skin - cranial bones - cranial meninges - cerebrospinal fluid

- Cranial cavity is physically protected by a number of things: - Superficially you have your skin which creates a physical barrier with the external environment - The bones that form the actual cranium. - Deep in the cranium we have meninges which protect the brain and the spinal cord. - The interstitial fluid of the brain which is called cerebrospinal fluid. It provides both physical and chemical potential.

Learning and memory: the case of H.M.

- Henry Molaison from Manchester, CT - Hippocampus was removed (located in the temporal lobe) He had changes associated with his memory. - memories prior to surgery were intact - short term memory was intact - unable to store new memories long term - but mirror drawing test he got better at through time - he did not recall fact information but learned new motor and visual skills

Cranial Meninges - dura mater (fibrous) - arachnoid (epithelial) - pia mater (fibrous)

- Meninges provide physical protection of the tissues of the CNS - dura: the outer most layer which is made of fibrous connective tissue. Strongest layer. - There are two layers of this. There are a lot of blood tissues that supply the tissues of the brain between them. - Subdural hemorrhage occurs here in response to head trauma - arachnoid: middle layer , which is made up of epithelial tissue - Cerebrospinal fluid is located in the space beneath this layer called cerebral arachnoid space. - Pia - inner most layer, thin layer of cells surrounded by a thin layer of connective tissue. - it is directly on top of the brain

excitation-contraction coupling

- Muscle fibers can then use the action potential to initiate the process of contraction. This transduction of an electrical signal into a mechanical force is referred to as excitation contraction coupling - The plasma membrane sarcolemma, represented in yellow, has a very special structure in muscle. In addition to being at the surface of the cell, it also travels deep down into the inner part of the muscle fiber creating a structure called a T tubules. They allow rapid exchange between the interstitial fluid in the deepest part of the muscle fiber - Sarcoplasmic reticulum , represented in bloom, is extremely well developed inside of muscle. This is the main calcium storage organelles inside of muscle. - triad is two or three total t-tubules. 1) excitation contraction begins with excitation. somatic motor neuron releases ACh at neuromuscular junction 2) net entry of Na+ through ACh receptor-channel initiates a muscle action potential 3) action potential in t-tubule alters conformation of DHP receptor (which is a voltage sensitive proteins). 4) DHP receptor opens RyR Ca 2+ release channels in sarcoplasmic reticulum and Ca 2+ enters cytoplasm 5) Ca 2+ binds to troponin, allowing actin-myosin binding. the calcium find troponin and moves tropomyosin out of the way and initial the process of filament sliding 6) myosin heads execute power stroke 7) actin filament slides toward center of sarcomere - you don't want your muscles to contract one time, relaxation stage is important - The concentration gradient has to be reset. But if we try to move the calcium out of the cytosol, then removing it against its concentration gradient. So that means we have to use active transport. - The calcium for muscle contraction came out of the SR, through the r receptor so I have to go back to the SR. But he cannot do so through a channel. Instead it goes to an active transport are known as SERCA.This active transporter is located on the membrane of the SR and he uses ATP to move calcium against its concentration gradient back into the SR. - The other requirement for muscle contraction is energy. ATP is also used in other ways inside of skeletal muscle. Skeletal muscles are one of the major consumers of glucose inside the body. This is because skeletal muscle fibers have a really high concentration of mitochondria, which allows them to meet these great energetic demands. - the important role of ATP is the regulation of cross-bridge formation

Integration of Synaptic Potential

- Soma receives many EPSPs and IPSPs at once and must try to make sense of these signals - if the neuron is able to produce enough depolarization (through summation of EPSPs), then an action potential can be produced - EPSPs are made into some channels and IPSPs are made into other channels, so the soma is necessary to integrate these changes in membrane potential that are occurring at the same time

frontal lobe of cerebrum (cortex)

- The frontal lobe is the largest and most well developed region of the brain - hypothesis generation - inhibitions - perseverance - planning/organizing strategy - primary motor cortex (M1) = precentral gyrus - It's primary job is in decision making or planning or organizing things we want to do - Also responsible for inhibitions that keeps us from acting on every urge and then tell us that we are feeling

cerebral features

- The race portions or the hills are called gyri or gyrus. - The grooves or valleys are sulcus or sulci. -Both of them increase the surface area for the exchange of ions with a CSF. - it helps to pack more brain tissue into the cranial vault.

Action Potential "Firing"

- a burst of electrical activity that rapidly propagates through the cell - action potentials are active electrical currents - able to maintain its strength overtime and over distance is not decremental

changes in membrane potential (graph included)

- a membrane at rest and experiences a positive change in membrane potential we call that a depolarization - when that membrane turns to rest from deep polarization it's known as a re-polarization - the membrane at rest which experiences a negative change in membrane and that's called a hyper polarization

axons

- action potential are sent through the axon - neurons have either one axon or no axon at all - the region where the axon connects to the cell body is the axon hillock - axons can be really short (like in the brain or spinal cord) or really long (like from the tip of your toes to your spine) - in some cases neurons don't have an axon at all (this can be seen in the visual system)

Phases of action potentials

- action potential is a changes in membrane potential over time - action potential starts off at a rest which is called the steady state, where the resting potentials are equal and opposite of each other creating no change in membrane potential - this happens because there is high permeability to K, Na, Cl or etc. - neurons will stay at this resting potential until they are given some kind of depolarization stimulus that moves them away from that resting potential - this depolarizing stimulus will be partially or temporarily summed EPSPs - this is followed by a steep repolarization back but if you look closely you can see that we actually go beyond resting membrane potential into a hyper polarized membrane potential - action potentials can happen over again (they are cyclical events) that depend on the combined effects of many K and Na channels working. - Depolarizations occurs with a increase in sodium permeability and the repolarization occurs with mostly with an increase in potassium permeability

The neuromuscular junction (NMJ) is example of synaptic transmission

- action potential that leads to the release of a chemical messenger which gives us a graded potential, creating an action potential - Alpha neuron is on the top and the muscle fibers at - action potential being fired in the motor neuron that depolarizes the axon terminal, brings the voltage gated calcium channels to threshold and allows calcium to enter the axon terminal so that the vesicles can dock and the neurotransmitter can get released into the synapse -specific type of neuron releases a specific type of neurotransmitter called acetylcholine. This can cross the synapse chemical messenger and that means that they are going to be receptors on the plasma membrane of the muscle fiber. The part of the skeletal muscle fiber that the skeletal part of the neuron is referred to as the motor end plate -acetylcholine receptor is a type of ligand gated ion channel and it opens when acetylcholine binds. This is a cat ion channel which means that it is selectively permeable for positive charges. So when it's open it allows both sodium and potassium to pass through it. However sodium is chemical driving force and it's electrostatic driving force pull it into the cell. Major effect is that sodium enters the muscle fiber which creates a graded potential. This would be an example of a action potential gets initiated in both directions and it travels away from those end plates. example of a EPSP. - action potential gets initiated in both directions and it travels away from those end plates.

post synaptic events

- after chemical messengers propagate through the synaptic cleft, the muscle action potential (MAP) begins - muscles are excitable cells specialized to transduce electrical energy into a contractile force - this process is commonly referred to as: excitation-contraction (EC) coupling

Action potentials travel forward

- after one segment of axon membrane is very depolarized, nearby membrane patches are also depolarized - the neighboring patch of membrane then goes through the action potential steps - sections that just finished the action potential are refractory - they are resistant to depolarization because the Na+ channels need time to recover - thus the action potential moves forward

Filaments have to be able to slide in order for a contraction to occur.

- at rest, low Ca2+, tropomyosin blocks the myosin binding site on actin, which prevents binding - when depolarized, high Ca2+, Ca2+ binds to TnC and causes ejection of tropomyosin so binding can occur - binding in actin and myosin is referred to as a cross bridge - tropomyosin regulates finding by blocking myosin binding site on actin which is present this is the situation where there is low intracellular calcium - when the calcium concentration inside the cell increases, the calcium binds to troponin. And this has a confirmational change that allows it to move the Tropomyosin out of the binding site. This makes it physically possible for cross bridges to form

pathology: - myasthenia gravis - lambert-eaton myasthenia syndrome (LEMS) - guillain-barre syndrome

- autoimmune disorder leading to the destruction of the ACh receptors - They might not be able to produce end plate potential to start the action potential because they don't have enough receptors to bind acetylcholine - droopy eyeballs - myasthenia syndrome - caused by defect in Ca V channels - leads to insufficient AcH release - autoimmune demyelinating disorders resulting in paralysis - auto immune disorder where the immune system attacks the glial cells that mylinate the inner nodes of the motor neuron. When this happens, conduction efficiency to the axon slows down. The conduction velocity slows down. And this means that action potentials don't always reach the axon terminal

Myocyte structure

- because muscle looks so different, its parts have been renamed - The cytoplasm of a muscle is called the sarcoplasm - The plasma membrane is sometimes called the sarcolemma. - The Endoplasmic Reticulum (ER) is called the sacroplasmic reticulum (SR)

brainstem: overview

- bidirectional passageway or all tracts extending between the cerebrum and the spinal cord - houses nuclei of many of the cranial nerves - contains many autonomic centers and reflex centers required for survival 1) midbrain (mesencephalon) : tracts, reticular formation, cranial nerve nuclei 2) pons : reticular formation, tracts (collection of axons in CNS), nuclei for cranial nerves - respiratory centers 3) medulla : pyramids (corticospinal tracts); pyramidal decussation (crossing), reticular formation (>100 nuclei: receive/project "all over") nuclei for cranial nerves - centers for cardiovascular regulation, respiration, and others -Deepest and most inferior part is brain stem - Controls basic autonomic centers - Impossible to survive if this is damaged. - Mid brain : cranial nerves are important.

dendrites

- branched processes protruding from the cell body - receive signals (using receptors) - dendrites receive many signals simultaneously (hippocampus) - contain really high density of receptors because they're constantly receiving signals from external and internal environments - signaling at the dendrites is incredible complex since the dendrites are highly benched and highly overlapping - there is a lot of variation in dendrites (some neurons have one or two, others have hundreds)

Model neuron structure

- dendrites are typically the region of signal input to the neuron - soma is the place where signals are integrated - the action potential is generated in the axon hillock and it spreads through the axon over a large distance into the axon terminal - this is where the synapse (chemical output) is formed in the signal gets relayed to the next cell which again could either be a neuron or some other type of cell

Initiation of the action potential

- density of NaV channels is highest at the axon hillock - action potentials originate in the axon hillock - it starts here because there's a very high density of voltage gated sodium channels in this region of cell channels are often abbreviated

Nervous System

- depends on concentration gradients in order to function so neurons have to have a very high capacity to generate ATP in order to keep the ions inside and outside the cell within homeostatic ranges

Excitatory (EPSP)

- depolarization if the membrane potential is more positive than Vm - any positive or depolarizing change from rest from the GHK equation and we can guess that a new EPSP could be produced for example by opening of sodium channel

Channelopathies

- diseases and disorders that are the result of ion channel dysfunction - voltage gated sodium channels are non-functional and control centers are never able to fire an action potential's which means that information about pain is never able to be related to control centers inside of the brain - or lightest touch sensation can produce really extreme pain and this is caused by a different mutation in the voltage gated sodium channel that causes action potential's to fire more frequently instead of less frequently

Repolarization

- during repolarization caused by K+ leaving the cell, the two gates reset to their original positions - decreasing sodium probability is enough to repolarize membrane potential - voltage gated potassium channels open more slowly than the voltage gated sodium channels and they also reach their peak permeability during repolarization phases of the action potential - potassium is at a different concentration gradient, so it's higher inside the cell and that means when potassium channels are open potassium ions actually leave the cell and they carried a positive charge out of the cell in that leads to the development of a negative potential inside the cell membrane (pulls membrane potential towards K+ negative equilibrium potential

Patho: - dystonia - blepharospasm

- dystonia: involuntary sustained muscle contractions resulting in twisting and repetitive movements or abnormal postures - blepharospasm: spasm of the muscle surrounding the tear duct -Muscle disorder: lack of tone: lack of muscle coordination.

lobes of the cerebrum

- frontal: motor, speech, memory formation, personality, emotion - partial: somatosensory cortex - occipital: visual processing and storing visual memories - temporal: hearing, speech and language, smell - contralateral control: cerebral hemispheres control opposite side of body - The largest and most superficial portion of the brain is this cerebral cortex - Structures on one side of the brain actually control structures on the opposite side of the body

Muscles are highly specialized

- generate action potentials to initiate contraction; this generates force. - muscles are constantly changing size due to their elastic properties (some muscles have a resting length but it does not lose membrane integrity when experiences large changes in size) - Muscle is also an extensible tissue so it can be safely stretched beyond its resting length

Synaptic potentials are Graded

- graded potentials decrease in strength as they spread out in all directions from the point of origin - graded potentials mean that these changes in membrane potential can have variable amplitude (they can be weak or strong) - graded potentials can decrease their intensity over time and over distance from the starting point because when a neurotransmitter binds to a channel on the dendrites ions are moving into or out of the channel through diffusion only from that spot so the movement through channels is passive always follows the rules of diffusion - membrane potential is a very localized effect. - If we measure other locations on the dendrite that are further away from that site where neurotransmitters being released in those channels are being opened or closed there's less of a change from rest and that's what it means to be decremental

temporal lobe

- hearing, language comprehension, memory formation, memory retrieval -This is the most lateral region of the cortex, and involved in sensation to some degree but more so in specialized senses hearing, learning and memory - Primary auditory cortex (A1) is located in the temporal lobe and that is where all sound information comes into the cortex. This region also contains neurons that are important for language comprehension. This happens in Wernicke's area

Refractory periods

- if ALL voltage gated sodium channels are inactivated then it's impossible to start a second action potential even if we gave a depolarizing stimulus, even if we have a strong depolarizing stimulus. This is known as the absolute refractory period. - however, if SOME channels are inactivated and SOME are closed, then a depolarizing stimulus would be able to start another action potential. This is know as the relative refractory period.

Goldman-Hodgkin-Katz in action

- if a neurotransmitter receptor opens and increases permeability to an Ion+, Vm will increase toward Eion - synaptic potential can be applied using this equation - That neurons are mostly permeable to potassium and a little bit permeable to sodium and a little bit permeable to chloride at rest and that gives them a resting membrane potential that's typically somewhere around -70 mV. When the ligand gated channels open or closed on the dendrites it changes permeability and that causes a shift in the steady state away from resting membrane potential.

Voltage Gated Na+ channels

- in neurons, the action potential is propagated by sodium ions by voltage gated sodium channels - the sodium channels are going to allow sodium to enter the cell because channels do passive transport (a pore) and so sodium follows its concentration gradient. It's higher outside but as the sodium comes in and brings with it is positive charge and that creates depolarization. The increase in sodium permeability moves the resting potential from rest towards sodium very positive equilibrium potential. - the activation gate is not voltage sensitive instead it is a probabilistic event (for example if the voltage gated channels are open longer, then the event of the inactivation gate closing increase) - the inactivation state means that one door is opened but the other is not opened so sodium ions cannot enter the cell since there is no pore being created. - the inactivation gate closes and this decreases the sodium probability to about zero in which causes the action potential to peak and cause it to begin to repolarize - decreasing sodium probability causes membrane potential to move away from sodium's equilibrium potential

The action potential is created by changes in permeability

- increase in potassium probability moves member potential closer to potassium's equilibrium potential in which creates a hyperpolarization of the action potential which is more negative than the resting membrane potential - this is because we have more leaky K channels that are open all the time, and having voltage gated K channels open as well - called repolarization - the transition from an active state back into the close state is actually happening anytime that membrane potential is back below threshold and continues through the hyper polarization phase

Whole muscle contraction

- isotonic: creates movement (force > load) - gradient between the amount of force being and the resistance objects being moved. - isometric: creates tension (load > force) - can't generate a force enough to move an object. The fibers are contracting but don't change the length. The tension is from the stretching.

Diencephalon: Thalamus

- major sensory relay center - sensory impulses from all sense converge on the thalamus except olfactory sense - principal and final relay for all sensory information - "switchboard" -90% sensory information we collect gets filtered and never makes it to the somatosensory cortex in the parietal lobe. - filtering happens here

Functions of muscle tissue

- movement:muscles are attached to bones and therefore when muscles contract they can create all sorts of motions - Muscles are contracted to some degree at least all the time. And those muscles are important for creating posture, supporting our posture inside the body. - Muscles are doing work when they contract, so when they do this they produce heat as a byproduct. And this makes muscle important for thermal regulation or maintaining temperature homeostasis inside the body. This is the reason why you shiver when you're cold

The neuromuscular junction

- muscle contraction begins when a motor neuron stimulates a muscle fiber - the neuromuscular junction (NMJ) is the synapse between a muscle fiber and a motor neuron - a motor unit consists of a single motor neuron and the muscle fibers it controls - a single motor unit controls only a few muscle fibers in a given muscle via the all-or-none principle - this also means that most muscles contain multiple motor units - efferent motor neurons fire their action potential, they release neurotransmitter that stimulates skeletal muscle fibers to fire their action potential. This initiates the process of contraction - presynaptic cell is a neuron and the postsynaptic cell is a muscle fiber. Every single skeleton muscle fiber is intervated in the axon terminal of a motor neuron

Myocyte development

- muscle is a terminally differentiated tissue but they still grow and need to be regenerate new muscle cells in body due to injury - Creating a muscle starts with a differentiation multi-potent stem cell within muscle tissue called and myosatellite cell, which becomes immature called myoblasts. - through the maturation process, the tiny myoblasts line up next to each other (end to end) and form tube-like structures called myocytes (or muscle fibers)

Muscle mechanics: contraction terminology

- muscle tension: force created by muscle - load: weight that opposes contraction - contraction: creation of tension in the muscle - relaxation: release of tension in the muscle -When the muscle contracts it delivers force intention whereas when the muscle goes through relaxation it decreases the tension.

Organization of muscles

- muscle tissue is comprised of a network of bundled fascicles, which are made up of muscle fibers that is held together by connective tissue wrapper - each individual muscle fiber contains myofibrils which are created from the arrangement of the contractile proteins inside the cell - there is muscle variability even within a single muscle, there can be differences in metabolic properties of muscle fibers

Axons are myelinated

- myelination increases the speed of conduction by (up to) a factor of 100 - Myelin is an insulating wrapper that's produced by supporting cells in the nervous system called glia - glial cells surround axon segments - these myelinated segments are called internodes and the ones that are NOT myelinated segments are called node of ranvier. - so the current spreads rapidly through the internodes and then pauses to recharges at the node of ranvier before spreading rapidly to the next internode. This is called saltatory conduction (action potential appears to goes from node to node - it does not jump).

"Cold shortening" of meat

- myocytes contract in response to cold temperatures - electrical pulses of prevent cold shortening - skeletal muscle contracts when it's cold to generate heat for the body - Deplete the muscle fibers of calcium by electricity which prevents the process of cold shortening from happening

Myocyte morphology and structure

- myocytes tend to be larger and thicker and more cylindrical than most other cell types inside the body - Since a muscle job is to contract it's only job is to contract. Skeletal muscle tries to cram as many myofibrils as possible into the inside of the cell. And this means that the inside of the cell has very little cytoplasmic space in comparison to other cell types in the body. - Most of the organelles in muscle cells tend to be pushed really far off to the periphery of the cell in order to make room for many my myofibrils as possible

Myofibrils are highly abundant

- myofibrils are made up of sarcomeres (contractile proteins of the cell) - basic units of the muscle contraction - One myofibrils contains many sarcomeres - three structures that make up a sarcomeres - There is a thick filament which is known as myosin. - There is a thin filament which is known as actin - There is a tiny elastic protein called Troponin -

Skeletal Muscle Fiber Subtypes

- myoglobin binds oxygen which causes a different color (subtypes) of the muscle fibers - Type One are the darkest fibers because they have the most myoglobin which means that they are good at binding and trapping oxygen in the tissue (they can stay contracted for a long time because they produce ATP) - Type One : postural and muscles that are used in endurance activities are typically made with a lot of these slow muscle fibers - The others rely on anaerobic respiration since they do not have a lot of myoglobin. This does not produce a lot of ATP. These fast fibers can only be used on short bursts of energy such as sprinting, weightlifting (have a limited ability to do aerobic respiration).

Neurons

- neurons are the basic unit of the nervous system - use changes in membrane potential throughout the entire body - characteristics: high metabolic rate, extreme longevity, and non-mitotic - we can replace neurons from the stem cell differentiation process - neurons have different morphology than most of their cell types inside the body.

What is a memory? Long term potentiation

- new memories require protein synthesis - if you learn something the there will be a greater amplitude greater than the initial response there (there will be more neurotransmitters and more ligand-gated channels - if you don't learn anything then the amplitude will be the same as it started (it will have an identical response)

whole muscle tension

- not all muscle cells in a muscle contract at the same time (only the ones activated by the same neuron) - the number of motor units that are activated determines the strength of the contraction - small number of units = weak contraction; large number of units at greater frequency = stronger contraction - muscle tone is the continued steady, low level of contraction that stabilizes joints and maintains general muscle health

cell body

- or the soma - contains nucleus and golgi apparatus - specialization in many mitochondria and many ribosomes - soma bodies contain high density of ribosomes in that accounts for the large amount of protein synthesis that neurons have to do (the soma is not the only place where proteins synthesis occurs inside of the neuron - like on the outside of the soma).

metabolic needs of the brain

- oxygen: passes freely across the blood brain barrier and brain receives 15% of blood pumped by heart (at rest) - glucose: brain consumes about half of body's glucose, membrane transporters move glucose from plasma into the brain interstitial fluid, progressive hypoglycemia leads to confusion, unconsciousness, and death - this is the reason why under normal circumstances the fifth of the body blood supply is going to the brain at any point. Glucose concentration in CSF is lower than concentration in the plasma since the neurons are consistently using glucose.

Synaptic Potentials Leads to action potential

- post synaptic potentials exhibit spatial and temporal summation - Summation can occur because channels that are close together on the membrane can be activated at the exact same time this is known as spatial summation - Also happen because channels open at the exact same time if they're stimulated with high frequency this is known as temporal summation - the temporal summation occurs first where all the EPSPs are being added together - then once you activate channels and adjacent parts of the membrane spatial summation occurs - summation does not only occur for EPSPs, it happens to all graded potentials (can happen to two IPSPs at same place, two IPSPs at same time, etc) - when IPSP and EPSP occurs at the same time, then they cancel each other out; making them be a breaking mechanism for the action potential to make sure that the action potential gets produced when it is absolutely necessary - if the neuron is able to produce enough depolarization then an action potential is produced

frontal lobe of cortex

- primary motor cortex (pre-central gyrus): when this region is stimulated your body will move - broca's area: speech - orbitofrontal cortex: decision making/adaptive learning - olfactory bulb: odor perception -Decision making comes from neurons that are located in the gray matter called the orbital frontal cortex. -It is involved in her sense of smell, speech because of Broca's area and contains most of the motor areas responsible for planning and executing many movements (motor cortex)

parietal lobe rois

- primary somatosensory cortex (postcentral gyrus): stimulus - somatosensory association cortex: processing

occipital lobe rois

- primary visual cortex - visual association area - interprets information acquired through the primary visual cortex

Soma (integration process)

- process of adding up all the graded or snapped a potential's is known as summation information is essential for starting the action potential - EPSP is just never going to produce enough of a change in membrane potential in order to spread from the dendrites all the way to the axon and that's because of limitations of diffusion - it is always going to make many channels openings or closings

occipital lobe

- processing, integration, interpretation of VISION and visual stimuli - The most posterior area of the brain is the occipital lobe. - This is the region that contains primary visual cortex (V1). And all the visual areas.

Whole muscle: how to generate more force?

- recruitment: more motor units stimulated (depending on need) - Heavier loads and more force, there are more motor units stimulated. - They don't have to be the same size - More motor units recruited but also the larger motor units - When generating greatest force you recruit the Type II.

Diencephalon: Hypothalamus

- regulates many homeostatic mechanisms throughout the entire body - sends "instructions" to brainstem centers 1) master control of the autonomic nervous system 2) master control of the endocrine system 3) regulation of body temperature 4) control of emotional behavior 5) control of food intake 6) control of water intake 7) regulation of sleep-wake (circadian) rhythms - Controller for endocrine system - Chemical responses in chemical systems

Proteins of the sarcomere

- regulatory elements are troponin (Tni, TnT, TnC) is a smaller protein made up of three subunits and it is the calcium binding proteins that is important for muscle contraction regulation and Tropomyosin blocks myosin binding site on Actin - without calcium binding, is physically impossible to contract, the tropomyosin is attached to actin and it's in the way so myosin does not have access. -when calcium (Ca) level of the cell increases, the calcium combined to the other regulatory proteins, troponin, will create a conformational change that will pull the Tropomyosin out of myosin binding site on actin. There's an bonding physically possible and the ATP cycle can kick in common which will ultimately generate the power stroke and allow the filaments to slide one position closer to the m line - contractile elements are myosin and actin - myosin has a head (contain an enzymatic domain that is able to break down or hydrolyze ATP to ADP and phosphate) and tail region. - actin is a globular protein; when it is a monomer its called G actin. It can polymerize to form long chains or filaments and in this state it is called F actin.

parietal lobe

- sensation and sensory integration - spatial awareness and perception - Located posteriorly to the frontal lobe - It is mostly involved in sensation because it contains the primary somatosensory cortex or the post central gyrus. - Sensory information is given to the sensory neurons that send information to the brain with the exception of smell and visual information - the primary somatosensory cortex would tell you that you were touching some thing but the association area might help you determine that you were touching something sharp. - primary somatosensory cortex (S1) = postcentral gyrus

the role to t-tubules

- t-tubules allow rapid ion exchange in isolated regions of myocyte

AP Propagation is local current

- the axon is divide into "segments" - there are three different regions of the axon that are, experiencing the same changes in membrane potential the action potential just a slightly different time - Segment one goes through its action potential first Milli second later segment two does in a millisecond after that etc.... - this is only possible because the action potential relies on voltage gated channels which are actually able to sense the change in voltage in their environment (not possible in gated channels) - each segment much go through all steps of the action potential

axon terminal

- the distal part of the axon which forms a synapse (connection) with another cell - axon terminals are really important for forming synapses for connections with other cell types, with other neurons, or non-neural cells inside the body - if a neuron synapses with another neuron then most commonly it's going to synapse with the dendrites of that neuron, that's known as an axle dendritic synapse - there's also some thing known as an axle axonic synapse which is where a dendrite synapses with the axon

CSF circulation

- the majority of the CSF is produced by ependymal cells in the choroid plexus (within ventricles) - the ependymal cells create a physical barrier between the blood vessels that supply the brain and the CSF. - they transport epithelium - Selective what they pass through the blood to CSF - Blood and CSF have different solute concentrations. - CSF lower concentration of protein, glucose, glucose and higher concentration of sodium which allows create a big concentration gradient that allows us to make it favorable to bring sodium to bring in the cell in action potential.

Synaptic Knob / Axon Terminal

- the neuron is the presynaptic neurons because it is the one that is sending the message to the next to trigger the release of neurotransmitters that are stored within membrane-bound vesicles inside the axon terminal - the signal is Ca - calcium allows the vesicles to move to the presynaptic membrane and attach or dock to family of proteins that at the membrane called snares - These vesicles are then exocytosis the neurotransmitters into the synapse on ligand gated channels on the postsynaptic dendrite can you start this entire process all over again. - Action potential which is due to Na, P and Ca which we need to release the neurotransmitter - calcium is it a relatively higher concentration outside the cell and relatively lower concentration inside the cytosol, when calcium channels open it allows calcium to enter the axon terminal and allows those vesicles to dock in to release neurotransmitters

spinal cord and brain are the same

- the spinal cord is made up of the white matter and gray matter - BUT THEY ARE REVERSED - gray matter is deeper inside and the white matter is located more towards the periferi - white matter axons are tracks - spinal cord has neurons leave to tissues and neurons come in to bring information to the system. nerves have to be myelinated to go out and get to the tissues

Rigor Mortis

- the stiffening of muscles once a person dies - it takes 48-72 hours for muscle proteins to breakdown & for the muscle to "relax" - body stops producing ATP which means that that the cross bridges between myosin and actin can't be broken down so the skeletal muscle gets frozen - concentration gradients breakdown. The resting membrane potential depolarizes and the calcium that's normally compartmentalized inside the sarcoplasmic reticulum gets released into the cytosol. This allows new cross bridges deformed as well - can determine how long person has been dead

synaptic potentials

- they are passive and primarly by ligand gated ion channels - binding of neurotransmitter causes receptors to open which increases the permeability to ions through that ion channel - Synaptic cleft is a point of communication between two different cells and separated by a really narrow space overseeing the axon terminal of the cell that's sending a message in the plasma membrane on a dendrite in the cell that's receiving the message - message from presynaptic neuron to post synaptic neuron is chemical - a neurotransmitter released into that really importantly another for the postsynaptic neuron to receive the chemical message it has to have like ligand gated ion channels on and that means that we have receptors for the neurotransmitter that's being released - there is no way for the postsynaptic neuron to receive the message if it was not chemical - if it is chemical then the channels will open or close; this is referred to as the synaptic potential

Fiber tension: length-tension relationship

- too much or too little overlap of contractile proteins results in decreased tension - multiple stimuli in a rapid amount of time do not allow a muscle fiber to relax, and causing tension to build - Individual skeletal muscles have individual lengths. This length is optimized to maximum tension - To have the optimum tension the sarcomere has to have overlap between action and myosin at rest. So cross bridges can easily perform when it gets initiated. - The tension generated by skeletal muscle can also be summed when stimulated at high frequency. - For a msucle to work properly it was receive maximum tension in each muscle fiber. As the frequency increased, the muscle will go through an event called the unfused tetanus, and the tension is building unevenly. - When held in state of contraction multiple muscle fibers work together.

Blood supply to the brain

Blood supply: - internal carotid arteries - vertebral artery - circle of willis blood return: - jugular vein - Blood supplying the brain is mostly consisting of the carotid artery, which branches out to supply the anterior and medial portion of the blood. - Due to the vertebral artery which supplies the posterior structures of the brain. - Nervous tissue has high requirements for oxygen and ATP because of all the active transporters - so it does not tolerate interruptions to blood flow very well. So one helpful inside the brain is the Circle of Willis which creates redundant or overlapping blood flow. - Having a circular type of arrangement of this there is a blockage or an interruption of blood flow on one side and blood can reroute and go in the other direction and still make it out to the tissues - Lack of oxygen can cause irreparable ischemic injuries to the brain (also lack of consciousness, confusion, death, etc.).

Drugs

curare - a competitive antagonist that binds to the acetylcholine receptor - it blocks the binding site for acetylcholine - Causes muscle paralysis without a loss of consciousness eserine (physostigmine) - an inhibitor of acetylcholine esterase - the enzyme that breaks down in acetylcholine - amplify the synaptic transmission through the NMJ because it increases the half life or the time that acetylcholine spends in the synapse - can cross the blood brain barrier (bbb) succinylcholine - ACh receptor agonist - activate acetylcholine receptor it mimics affects of acetylcholine but the reason why it's a paralytic is because it can't be broken down by Acet Esterase - does not allow for repeated signal transmission

Na V is a positive feedback loop (+)

cycle one: - depolarization is triggered, and causes Na+ channel activated gates to open rapidly, Na+ enters the cell, causing more depolarization - to stop the cycle, slower Na+ channel inactivation gate closes cycle two: - depolarization is triggered, slow K+ channels open, K+ leaves cell, then repolarization occurs

Blood brain barrier

endothelial cells of brain micro vessels exhibit complex tight junctions 1) control molecular traffic and keep out toxins 2) ion homeostasis 3) maintain low protein environment to limit proliferation 4) separate CNS: PNS neurotransmitter pools - Everywhere there is blood vessel there is a BBB which allows the difference of concentration between those compartments to be maintained. - From endothelial cells, lots of tight junctions.Astrocytes (glial cells) increase or decrease the tight junctions.

The cerebrum: intersections with eugenics

eugenicists: are "race realists" who believe in the false idea of biological race, and that the human gene pool can be improved by promoting reproduction in individuals that have desirable traits while at the same time limiting the reproductive freedoms of individuals with "undesirable" traits phrenology: pseudoscientific practice linking personality traits to cranial/brain shape craniometry: measurement of cranial capacity -Label individuals with traits/definitions claims about fitness/beauty/etc. - these ideas are still being researched today by some scientists

Learning and Memory

explicit/declarative memory: - hippocampus - parahippocampal region - medial temporal lobe - example: facial information (learning for classes) implicit/reflex/procedural memory: - stored elsewhere - example: procedural memories (motor memory like drawing and paying) - outside of hippocampus what is memory? it is long term potentiation

the cerebellum

functions: 1) adjust the postural muscles of the body 2) error correcting during movement 3) motor learning and adaptation 4) automating and optimizing behavior - Controls the structures on the same side so damage to left side of the cerebellum - damage: Trouble matching intended movement to the action - cannot correct trajectory. -receives visual, vestibular and proprioceptive input - cerebellar hemispheres: functions in skeletal muscle activity, timing, intensity, general coordination of contractions of individual muscles. - spinocerebellar tracts: mediate unconscious proprioceptions (prioprioceptive input that is sent to the cerebellum and integrated into movement control/coordination, without our being aware of it.

Lessons learned from H.M.

memory storage: - short term memory - long term memory factors: - repetition : hear or practice to get it to convert from short term to long term storage - intensity : strong emotional response to you will remember the details then you will the everyday things - exercise/age : Motivational component: academics in people excel in things they are interested in, they are more motivated to learn about them. but also memory formation decreases from age and exercise is promoted the memory formation.

Language and Aphasia

selected language dysfunctions: 1) aphasia 2) word deafness 3) conduction aphasia Aphasia: language disorders: understanding or producing speech. conduction aphasia:is a type of aphasia in which the main impairment is in the inability to repeat words or phrases. Other areas of language are less impaired (or not at all). It is also known as associative aphasia. A person with conduction aphasia can usually read, write, speak, and understand spoken messages but cannot produce speech for themselves

Regions of human brain

- cerebrum: higher brain functions - diencephalon: homeostatic controls - brainstem: autonomic/ reflex center - cerebellum: coordination of movement

Inhibitory (IPSP)

- hyper polarization if membrane potential more negative than Vm - any negative or hyperpolarizing change it from the resting membrane potential and again from the GHK equation we might predict that in IPSP can be produced by for example opening up a potassium channel.

CNS and PNS

CNS is brain and spinal cord PNS is everything else

white matter vs gray matter

white matter: - commissural fibers: connect hemispheres (left to right) - projection fibers connects cerebrum to other regions (same side) - association fibers are connections within cerebral hemisphere - White matter consists of myelinated axon's in the brain. This mostly describes the deeper aspects of the tissue. The whiteness comes from the myelin itself. - Axons in the white matter in the brain are referred to as fibers and they often connect different structures to each other. white fiber tracts - projection fibers: cortex --> periphery - commisural fibers: cross corpus callous; connect hemispheres - association fibers: connect sites within same hemisphere gray matter: - cerebral cortex - basal ganglia - Gray matter contains the cell bodies in synapses of neurons. Most of the regions the cortex are examples of gray matter structures. - internal capsule: between putamen-globus pallidus and thalamus. major projection fibers to /from cortex; common CVA site. - corpus callosum: connects hemispheres (with commissural fibers)

temporal lobe rois

- primary auditory cortex - Wernicke's area - primary olfactory cortex (deep)

The ___________ divides frontal from parietal lobe.

Central sulcus

If [K]in is changed to 1mM, what happens to V?

aIt becomes more positive.

the brainstem consists of _____

medulla, pons, midbrain

When I yawned, I felt the ( which answer?) moving anteriorly.

mandible

Which joint is the most frequently injured?

shoulder

Muscle classification: histology

- muscle tissues vary in morphology and internal structure (density, striation, nuclei, etc) - skeletal muscle is the only multi-nucleated cell - myoblasts have their own nuclei before becoming muscle fibers - skeletal and cardiac muscle have rectangular shape and have striations - skeletal muscle is densely packed tissue

Blood Brain Barrier

- quite difficult for many substances to enter the brain tissue - astrocytes with end feet on brain capillaries - tight junctions, continuous endothelium in brain capillaries - maintain highly controlled environment

reticular formation

- a core of gray matter extending throughout the brainstem. - it consists of >100 nuclei, receiving information from and sending information to "all over" the brain. - recall tracts are collections of ions within CNS, and nuclei are collections of cell bodies (and synapses) within CNS.

sensory/motor distribution of CNS (spinal and cranial nerve)

- dermatomes and myotomes - examples of major nerve plexuses: 1) cervical plexus: sensory/motor innvervation of neck 2) brachial plexus: sensory/motor innvervation of upper extremity 3) lumbosacral plexus : sensory/motor innvervation of lower extremity

cranial nerves

- nerves are a collection of axons, usually both afferent and efferent; OUTSIDE the CNS - cranial nerves are also PERIPHERAL nerves, and connect to the brainstem 1) olfactory: smell 2) optic : visual 3) oculomotor: eye movement 4) trochlear: eye movement 5) trigeminal: sensory/motor to jaw (chewing), face 6) abducens: eye movements 7) facial: sensory (facial); motor (facial expression; salivary glands) 8) vestibulocochlear (formerly "auditory" or "acoustic" or "statoacoustic") = hearing/equilibrium 9) glossopharyngeal - swallow (motor) 10) vagus - automatic nervous system (motor); sensory to viscera 11) spinal accessory - neck, pharyngeal muscles, swallow 12) hypoglossal - tongue, speech

basal nuclei: movement related

1) caudate nucleus: pattern and rhythm of limb movement (motor related) 2) putamen: subconscious muscle control (motor related) 3) globus pallidus: muscle tone (via thalamus) (motor related) - Can also play a role in sensation. Even unconscious processing stimuli.

basal nuclei: sensory related

1) claustrum: process visual information (sensory related) 2) amygdala: emotion/mood (sensory related) - important role in emotion and fear - fear conditioning - Monks have larger amygdala's than the serial killers. - Amygdala can be damaged by alcohol use - long term behavioral changes - sexual behaviors

brainstem: midbrain

1) cranial nerve nuclei pons: 1) respiratory centers 2) cranial nerve nuclei, tracts medulla: 1) CV & respiratory regulation 2) cranial nerve nuclei - respiratory system and cardiovascular control systems

spinal cord (anatomy)

1) spinal cord is enclosed by connective tissue and encased by the vertebral column. in adult, it ends at L1-L2 level, and spinal nerves below this level continue as caudate equine 2) cross section: gray matter (gray due to the presence of cell bodies; sites of synapses between neurons), white matter (axons and/or peripheral processes of sensory neurons), dorsal and ventral horns, dorsal (posterior) root and ventral root, dorsal root ganglion (gray matter due to cell bodies of unipolar sensory neurons - but no synapses) 3) spinal meninges (dura matter, arachnoid mater, pia mater) subarachnoid space

Arrange the sequence of structures making up the dorsal column system in the correct order, starting with transduction at the receptor and ending with primary somatosensory cortex (S1). A. muscle spindle; fasciculus gracilis; medical lemniscus; thalamus; S1 B. nociceptor; dorsal column nucleus; fasciculus cuneatus; thalamus; medial lemniscus; S1 C.Thermoreceptor; dorsal horn; spinothalamic tract; thalamus; internal capsule; S1. D. Meissner's corpusle; fasciculus cuneatus, medial lemniscus; dorsal column nucleus; thalamus; S1.

In order to focus upon _____ objects, the lens flattens when ____. A. Distant; ciliary muscles relax B. Distant; ciliary muscles contract C. Close; suspensory ligament tightens D. Close; ciliary muscles relax

Like the dorsal system, the anterolateral system _____. A. Carries sensory information B. Carries motor information C. Crosses in the corpus callosum D. Synapses in the spinal cord

Optic nerve axons arising from the left nasal retina _____. A. Cross at the optic chasm to the right cerebral hemisphere B. Do not cross and enter the left optic tract to project ti the left cerebral hemisphere C. Travel the same pathway as the optic nerve axons arising from the left temporal retina D. Both A and C are correct

Parkinson's Disease results from damage to the _____, which causes _____ as a symptom. A. Basal ganglia; cogwheel rigidity B. Primary motor Cortex; difficulty in initiating movement C. Nigrostriatal pathway; paralysis D. Cerebellum; resting tremor

The Optic nerve (cranial nerve II) is a ______ nerve. A. Sensory B. Motor C. Both sensory and motor

The ability to precisely localize the origin of a stimulus will be best with ____. A. small, overlapping receptive fields B. Large receptive fields that do not overlap C. Lateral inhibition wiring (neurons) between receptors D. Small receptive fields that do not overlap

The anterior corticospinal tract controls A. Axial muscles important in posture B. the fingers C. abnormal, involuntary movements D. All of the above

Transmission of ascending sensory information concerning pain may be interrupted by descending input from certain areas in the brainstem, which release opiate neurotransmitters. A. True B. False

When a rod absorbs a photon of light, _____ of glutamate binding to ____ receptors leads to ____ of on-bipolar cells. A. Decrease; mGluR (metatropic); activation B. Drecrase; ionotropic; inhibition C. Increase; mGluR (metatropic); inhibition D. Increase; ionotropic; activation

Which of the following transmits information about the static length AND rate of change of length of a skeletal muscle? A. Type Ia (primary) spindle afferents B. Type II spindle afferents C. Golgi tendon organs D. Both A and B are correct

A motor unit consists of: The population of motor neurons responsible for contracting an entire muscle A single motor neuron synapsed to multiple muscle fibers Multiple motor neurons synapsed to a single muscle fibers A group of muscle fibers that produce the same action

A single motor neuron synapsed to multiple muscle fibers

One of the visual association cortex areas contains neurons that fire in response to the human face. A. True B. False

The effects of angular acceleration when roaring your head are detected by A. Pacinian corpuscles in the semicircular canals B. Hair cells in semicircular canals C. The maculae of the saccule D. Hair cells in the saccule

The primary auditory cortex (A1) is contained in the _____. A. Parietal lobe B. Temporal lobe C. Frontal lobe D. Rhinencephalon

What prevents the action potential from propagating backwards? Local currents only flow one way Absolute refractory period Both of the above Neither of the above

Absolute refractory period

Turn your head right while looking at an object. The object ( and the rest of your visual world) stays stable because the ______ horizontal canal activates relax contraction of the ____ lateral rectus and ____ medial rectus muscles. A. right; right; left B. right; left; right C. left; left; left

Cellular respiration (ATP production) stops following death, which results in rigor mortis. This phenomenon is best explained by the fact that: Actin myosin cross-bridges cannot be broken The polymerization of G-actin to F-actin is inhibited The intracellular concentration of Ca2+ increases relative to extracellular Ca2+ The production of phosphocreatine stops

Actin myosin cross-bridges cannot be broken

By what process is sodium moved out of the cell?

Active transport

Brain region concerned with emotion such as fear and rage

Amygdala

Two-point discrimination is _____ on the lips than on the knee. One reason for this is that there is ______ representation of the lips in the primary somatosensory cortex. A. Worse; more B. Better; more C. Worse; less D. Better; less

A closer look at the muscle fiber subtypes in skeletal muscles responsible for supporting posture vs. those used for sprinting would likely reveal: An increased number of type IIb fibers & more myoglobin An increased number of type IIb fibers and less myoglobin An increased number of IIa fibers & more myoglobin An increased number of type I fibers & more myoglobin

An increased number of type I fibers & more myoglobin

What is the correct path visual information takes to travel from the retina to the primary visual cortex? A. Rods, bipolar cells; retinal ganglion cells; cones; optic nerve; optic tract; thalamus B. Rods; bipolar cells; retinal ganglion cells; optic nerve; optic tract; lateral geniculate nucleus

When is the activation gate of the voltage-gated sodium channel closed?

At resting membrane potential

A patient with an injury to the left brachial plexus would have what symptoms? A. loss of sensory and motor function to the right upper extremity B. loss of sensory and motor function to the left upper extremity C. loss of motor function to the right upper extremity and loss of sensory function to the left upper extremity D. loss of motor function to the left lower extremity

Assume you are recording from a primary (Ia) afferent neuron innervating a skeletal muscle, and you stretch the muscle and hold it at the new, longer length. To establish baseline, you record the frequency of action potentials before stretching the muscle. Which of the following statements describes what you expect to find? A. AP frequency during the stretch will be greater then baseline, and AP frequency at the new length would be greatest of all. B. AP frequency at the new length will be greater than baseline, but AP frequency during the stretch would be greatest of all. C. AP frequency would not change either during or after the stretch.

At what point does sensory information traveling in the spinoreticular tract cross the contralateral side? A. After synapsing in the thalamus B. Prior to entering the spinoreticular tract, in the spinal cord C. in the dorsal column nucleus D. none of the above-- information traveling in the spinoreticular tract does not cross.

Consider motor hierarchy. At which level of the CNS do we first find the circuitry (wiring) for the programming of the pattern of rhythms movements such as walking? A. Spinal nerve B. Spinal cord C. Brain Stem D. Primary motor cortex

Photons of light entering the eye are absorbed by rods or cones _____. A. Before passing through the amacrine cell layer B. After passing through four layers of neural cells in the retina C. Only after activating the optic nerve D. Immediately after passing through the vitreous humor

Skeletal muscle (extrafusal and intrafusal fibers included) is innervated by ____ type(s) of afferent and _____ type(s) of motor neurons. A. one;two B. two;two C. two;one D. one;one

The _____ is the motor pathway concerned with stereognosis. A. Reticulospinal tract B. Lateral corticospinal tract C. Spinotectal tract D. Fasciculus gracilis

The brain stem consists of the _____. A. Spinal Cord, medulla, midbrain, and pons B. Midbrain, pons, medulla C. Diencephalon, midbrain, and medulla D. Pons and medulla

When stereo cilia of hair cells bend back and forth, A. Ligand-gated channels in hair cells open and close B. Mechanicaly gated channels in stereocilia open and close C. Afferent neurons in cranial nerve VII (facial nerve) start firing action potentials

Which of the following are found in the ventral horn of the spinal cord? A. cell bodies of afferent (sensory neurons) B. cell bodies of alpha motor neurons C. Descending motor tracts D. All of the above

Which of the following functions is/are associated with cranial nerve XII, the Hypoglossal nerve? A. Taste and facial expression B. Speech and swallowing C. Eye movements D. Smell

Which of the following is the adequate stimulus for a simple cortical cell in V1 (primary visual cortex)? A. A spot of light in its excitatory center, assuming it is an on-cortical cell B. A bar of light oriented at a specific angle C. A bar of light oriented at any angle D. Diffuse light illuminating its entire receptive field.

Which retinal cells form connections between receptor and bipolar cells? A. Retinal ganglion cells B. Horizontal cells C. Vertical cells D. Amacrine cells

Which term best describes receptors that detect stimuli from the internal environment? A. Exteroreceptors B. Interoreceptors C. Pacinian corpuscles D. Nociceptors

Parkinsonâ s Disease results from damage to the ____________ , which causes __________ as a symptom.

Basal ganglia (nuclei); resting tremor

Two-point discrimination is _________ on the lips than on the knee. One reason for this is that there is _________ overlap of receptive fields on the lips.

Better; more

All of the following drugs act post-synaptically EXCEPT: Curare Succinylcholine Conotoxin Botulinum Toxin Eserine

Botulinum Toxin

A spinal nerve contains ______. A. Motor axons only B. Sensory axons only C. Both motor and sensory axons D. Motor and sensory axons, plus synapses between them

As a result of lateral inhibition, the ______ is increased. A. Firing rate of the primary afferents B. Firing rate of more strongly activated second order neurons C. Difference between firing rate of strongly activated and less-strongly activated second order neurons. D. Difference between firing rate of strongly activated and less-strongly activated receptors

GABA (gamma amino butyric acid) acts at _____ synapses by ______.A. Axo-somatic; blocking Ca++ channels B. Excitatory; opening K+ channels C. Axo-axonic; blocking Ca++ channels D. Axo-dendritic; opening Na+ channels

In V1 (primary visual cortex), simple and complex cortical cells A. have circular on-center and off-center receptive fields B. Produce a 'primal sketch' of the visual world with color and depth C. Construct a two-dimensional outline of objects with disconnected short-line segments D. All of the above

Increased intensity of a pressure stimulus (applied to the same spit on your finger) is coded by ____. A. Increased amplitude of a receptor potential B. Increased frequency of afferent action potentials C. Both of the above D. None of the above

Logarithmic compression enables A. Afferents to increase spike (AP) rate without limit B. Pain information to be conducted rapidly and precisely C. sensitivity over a large range of stimulus intensity D. Sensitivity over a large range of stimulus modality

Rods are sensitive to A. Motion B. Visual stimuli in low light C. both of the above D. none of the above

Sensory transduction is the process of converting ______. A. Stimulus energy from one modality (such as touch) into another modality (such as pain). B. Graded potentials into action potentials C. Stimulus energy into a change in membrane potential

The axons of ____ form the Optic nerve (cranial nerve II). A. Rods and cones B. Bipolar cells C. retinal ganglion cells D. Lateral geniculate cells

The primary somatosensory cortex (S1) is located in the _____. A. Frontal lobe B. Hippocampus C. Postcentral gyrus D. Precentral gyrus

This visual pathway is specialized for transmitting information about color: A. P-interblob pathway, which arises from the cones B.Optic tract, which arises from the optic chiasm C. P-blob pathway, which arises in the lateral geniculate nucleus D. M pathway, which arises in the retina

Brain damage due to stroke (CVA) or cerebral palsy causes spasticity, because the reticular formation____________. A. Activates basal ganglia to cause increased muscle tone B. Provides facilitation of tone in lower extremity flexor muscles. C. Is no longer inhibited by the cortex. D. Is damaged and no longer functions.

Which of the following statements correctly explains the relationship between Ca2+ and the contractile proteins found in skeletal muscle? Calcium binds to TroponinC. This removes Tropomyosin from the Myosin binding site on Actin. Calcium disrupts binding between Myosin and Tropomyosin. This allows Actin to bind to Myosin. Calcium binds to Tropomyosin. This moves Troponin so that Myosin can bind to Actin. Calcium disrupts binding between Troponin and Tropomyosin. This allows Actin to bind to Myosin.

Calcium binds to TroponinC. This removes Tropomyosin from the Myosin binding site on Actin.

Arrange the following terms into the order in which a compound must pass through to move from plasma to CSF. Capillary endothelium Extracellular matrix Pericyte Astrocyte

Capillary endothelium Extracellular matrix Pericyte Astrocyte

Sensory impulses from which sense converge on the thalamus and synapse in at least one of its nuclei? A. Touch B. Hearing C. Vision D. All of the above

Which of the following are found in the dorsal root ganglia of the spinal cord?

Cell bodies of primary afferent (sensory) neurons

Which of the following are found in the dorsal root ganglia of the spinal cord? Cell bodies of primary afferent (sensory) neurons Cell bodies of alpha motor neurons Synapses between primary afferent and motor neurons All of the above

Cell bodies of primary afferent (sensory) neurons

You meet a new patient without knowing her diagnosis and find her sitting quietly in the waiting room. You notice nothing remarkable about her until she reaches for a magazine, when you notice tremor. Which part of her brain is most likely affected?

Cerebellum

Match the CNS regions with its function

Cerebrum =Higher brain functions Homeostatic control= Diencephalon Information superhighway = Spinal cord Movement control= Cerebellum

After transduction, what is the correct path visual information takes to travel from the retina to the primary visual cortex?

Cones; bipolar cells; retinal ganglion cells; optic nerve; lateral geniculate nucleus; occipital lobe

The (which answer?) connects the two cerebral hemispheres, and the (which answer?) separates cerebral cortex from the cerebellum

Corpus callosum; transverse fissure

TOP HAT SUMMARY #2

Creating Membrane Potential - Excitability requires compartmentalization. Semi-permeable membranes allow cells to have different concentrations of charged ions on either side of the membrane. This concentration difference is known as a concentration gradient. - A typical cell has a relatively higher potassium concentration inside (intracellular), whereas sodium, chloride, and calcium concentrations are higher in the extracellular fluid. - Ions can cross the plasma membrane using transporters (e.g., primary active transport), which are important for setting and maintaining gradients. Ions can also cross the plasma membrane using channels (passive transport), which are essential for creating the rapid, predictable movement of ions from relatively higher to relatively lower concentrations. - Channel-mediated movements follow the rules of diffusion. The membrane is only permeable to ions when channels are in an open state, meaning there is a continuous path or pore through the plasma membrane. - In the closed state, ions are unable to move despite the existence of a gradient. - Channels can be gated or "opened" in response to a variety of stimuli such as the binding of a chemical messenger (ligand-gated), a change in the distribution of charges across the membrane (voltage-gated), or a change in the physical characteristics of the membrane (mechanically gated). Gating is a reversible process—channels can also be "closed." - Excitability also depends on interactions between charged particles like ions, or electrostatic forces. Similarly, charged particles repel, and opposite charges attract. - When there is a difference in charge distribution across the membrane, a form of potential energy known as membrane potential, measured in millivolts (mV), develops. The potential energy gradient can contribute to the movement of ions across the cell membrane. Changes in membrane potential can also trigger various cellular processes. Equilibrium Potential - In a typical cell at rest, any given ion is subject to chemical forces (attempting to balance the concentration gradient) and electrostatic forces (attempting to balance charge) across the cell membrane. - If the membrane is permeable to any given ion, and only to that ion, these two forces would reach equilibrium and create a voltage difference across the plasma membrane known as the equilibrium potential. - Equilibrium potentials only apply to a single type of ion (e.g., sodium) and can be described by (i.e., calculated by) the Nernst Equation. - In living cells, equilibrium potentials are relatively fixed, and they can only be altered by changes in the concentration gradient (which are opposed by homeostatic feedback mechanisms) or changes in ion charge (which are impossible in the body). Membrane Potential - A typical resting cell is permeable to multiple ions simultaneously but has the greatest permeability to potassium. It has significantly lower permeability to chloride and sodium. - Because the cell is permeable to multiple ions, each ion is attempting to reach its unique equilibrium potential. Ions drive the voltage across the membrane towards their equilibrium potentials in proportion to their permeability. - When the movements of all ions are balanced with an equal amount of each charge moving in both directions across the membrane, a voltage will develop across the membrane—this is theresting membrane potential. - Membrane potential can be calculated using the Goldman-Hodgkin-Katz (GHK) or Parallel Conductance equations. - Changing membrane potential requires a change in ion concentrations (which is opposed by homeostatic feedback mechanisms) or a change in permeability. - Because cells can change permeability relatively easily by opening and closing ion channels, this is the most common situation found inside the body and results in a transient change in membrane potential from its resting voltage - Membrane potentials are measured by comparing the charge inside the cell to the charge outside of the cell. Positive changes in membrane potential from the resting potential are known as depolarizations and make the intracellular space less negative (more positive), whereas negative changes in membrane potential from the resting potential are known as hyperpolarizations and make the intracellular space more negative (less positive). Neurons are Excitable Tissues - A stereotypical neuron consists of anatomically and functionally distinct regions: - Dendrites are processes that are stimulated by other cells or environmental conditions - The soma is the cell body - The axon hillock generates the action potential - The axon propagates the action potential - The axon terminal releases chemical messengers - A connection between neurons is a synapse. Any given neuron can be described as either pre-synaptic (i.e., the cell that is "sending" signals from its axon terminals) or post-synaptic (i.e.,the cell that is "receiving" a message on its dendrites). - Most neurons have a high density of ligand-gated channels on the dendrites and soma. When a neurotransmitter is released from a pre-synaptic cell, ligand-gated channels on the post-synaptic cell can open and close to create changes in permeability and membrane potential. These membrane potential changes are known as synaptic (graded) potentials. These changes diminish as they spread over time and membrane distance. - Depolarizing synaptic potentials are known as excitatory post-synaptic potentials (EPSPs) - Hyperpolarizing synaptic potentials are known as inhibitory post-synaptic potentials (IPSPs) - Summation is the additive effect of many small synaptic potentials occurring at the same time or in the same location on the plasma membrane. Action Potential - If a cell receives enough EPSPs, it will be able to initiate the action potential. - The action potential is generated at the axon hillock. In a typical neuron, this is because there is a high density of voltage-gated sodium channels in this region. - An action potential is generated if synaptic potentials create enough depolarization to reach threshold, which is the membrane voltage required to open or activate the voltage-gated sodium channels and allow sodium entry. - Synaptic potentials that do not reach threshold are not able to move the sodium channel from its resting closed state. - Due to the high density of voltage-gated sodium channels, reaching threshold creates a positive feedback loop. In other words, when voltage-gated sodium channels open due to depolarization, they allow entry of positively charged sodium, which creates sufficient depolarization to open more voltage-gated sodium channels. - This allows for rapid depolarization and the "rising" phase of the action potential. Depolarization also stimulates a delayed opening of voltage-gated potassium channels, allowing for relatively slower efflux of potassium. - At the peak of the action potential, after prolonged depolarization, the voltage-gated sodium channels enter an inactivation state, which reduces their permeability. - During the inactivation state, these channels cannot be opened, which causes the refractory period. - Low sodium permeability, and relatively higher potassium permeability, creates the repolarization or "falling" phase of the action potential. - Around the time that membrane potential is returning to rest, the voltage-gated sodium channels return to their resting closed state from their inactivated state. This allows them to be activated by a subsequent depolarizing stimulus and permits a new action potential to develop. - Action potentials are maintained over time and distance down the entire length of the axon because each membrane segment contains the voltage-gated channels necessary to create an action potential. Only the axon hillock requires the synaptic potential to generate the action potential. All other parts of the axon can use the sodium diffusing from the previous membrane segment to bring the voltage-gated sodium channels to threshold. - When the action potential reaches the axon terminal, voltage-gated calcium channels are triggered to open, allowing calcium influx into the axon terminal. - Calcium allows membrane-bound vesicles, containing neurotransmitters produced by this neuron, to attach to the post-synaptic membrane and be released into the synapse. - If the post-synaptic cell is a neuron, then the process will repeat when the neurotransmitter binds to ligand-gated ion channels on its dendrites.

A quick stretch (reflex hammer) to the quadriceps tendon activates ______ which synapse ______ with alpha motor neurons to the _______. A. Spindle afferents; indirectly via the excitatory interneuron; hamstrings B. Spindle afferents; indirectly via an inhibitory interneuron; quadriceps C. Golgi tendon organ afferents; directly; quadriceps muscle D. Spinde afferents; directly; quadriceps

High frequency sound waves cause A. high frequency vibrations of the tympanic membrane B. high frequency vibrations of the oval window C. a standing wave to peak close to the oval window D. all of the above

In low light, contraction of the ___ muscle acts to _____ the pupil. A. Ciliary; dilate B. Circular iris; constrict C. Radial iris; constrict D. Radial iris; dilate

Mechanoreceptors transduce which of the following stimulus modalities? A. position of head in space B. pressure C. sound D. All of the above

Consider transmission of a discriminatory touch stimulus. As a result of lateral inhibition, the ______________ is increased.

Difference between firing rate of strongly activated and less-strongly activated second order neurons

Consider transmission of a discriminatory touch stimulus. As a result of lateral inhibition, the ______________ is increased. Firing rate of the primary afferents (first order neurons) Difference between firing rate of strongly activated and less-strongly activated second order neurons Difference between firing rate of strongly activated and less-strongly activated first order receptors Firing rate of more strongly activated second order neurons

Difference between firing rate of strongly activated and less-strongly activated second order neurons

Initially, potassium concentration outside the cell (Ko) is 5mM, and potassium concentration inside the cell (Ki) is 100mM, and the equilibrium potential (Ek) under these conditions is -75mV. What would happen to this equilibrium potential if Ko were changed to 1mM?

Ek would become more negative

The hamstrings act to _ .

Extend the hip and flex the knee

Which term best describes receptors that detect stimuli from the external environment?

Exteroceptors

Which term best describes receptors that detect stimuli from the external environment? Exteroceptors Golgi tendon organs Proprioceptors Interoceptors

Exteroceptors

A person with Wernickeâ s aphasia cannot understand verbal speech; nor can he interpret body language or tone of voice. (T/F)

False

An on-center retinal ganglion cell responds equally to a spot of light illuminating its center or to illumination of its entire receptive field. (T/F)

False

Contraction of the biceps muscle activates ____________ , which act to keep the sensory region of the muscle spindle ____________ and responsive to muscle length.

Gamma motor neurons; biased

Consider a living neuron (that is, a real cell and not an artificial membrane) and assume equilibrium potential for Na+ is +55 mV. If we now open more and more Na+ channels, then membrane potential will ________________ +55mV. Become more negative (less than) Get closer and closer to Eventually reach Get more and more positive (greater than)

Get closer and closer to

Which retinal cells use lateral inhibition to refine information coming from receptors in the retina?

Horizontal cells

Elbow flexion / extension occur at the (which answer?) joint and pronation / supination occur at the (which answer?) joint.

Humero-ulnar; radio-ulnar

UNLIKE in skeletal muscle cells, neurotransmitters may affect neurons by causing ___________. Hyperpolarization Depolarization Graded potentials Action potentials

Hyperpolarization

The region(s) of the sarcomere containing only actin filaments is: I band A band H Zone Z disc Both the I band and the H zone

I band

At what point does sensory information traveling in the fasciculus cuneatus cross to the contralateral side?

In the medulla

Increased intensity of a pressure stimulus (applied to the same spot on your finger) is coded by ______ .

Increased frequency of afferent action potentials

a calcium binding protein that regulates muscle contraction is

troponin

In the dark,a(n) ______ of glutamate binding to _______ receptors leads to ________ of off-center bipolar cells.

Increase; ionotropic; activation

ncreased intensity of a pressure stimulus (applied to the same spot on your finger) is coded by ______ . Increased frequency of receptor potentials Increased amplitude of afferent action potentials Increased frequency of afferent action potentials All of the above

Increased amplitude of afferent action potentials

Which of the following stabilizes the shoulder (glenohumeral) joint? (There may be more than one correct answer.)

Infraspinatus tendon Contraction of the subscapularis

_ is required to inhibit the antagonistic knee flexors during the knee jerk reflex

Inhibitory transmitter released in the spinal cord

A rise in intracellular Ca2+ initiates smooth muscle contraction because: It binds to Troponin C to remove Tropomyosin from Actin It initiates the muscle action potential It activates enzymes that change the ATPase activity of the Myosin head It breaks Actin/Myosin crossbridges

It activates enzymes that change the ATPase activity of the Myosin head

If [K]in is changed to 150 mM, what happens to Ek?

It becomes more negative.

If PK is changed to 0.2, what happens to Vm?

It becomes more positive.

If PNa is changed to 0.4, what happens to Vm?

It becomes more positive.

If [K]out is changed to 150 mM, what happens to Ek?

It becomes more positive.

If [Na]out is changed to 160mM, what happens to Vm?

It becomes more positive.

If [K]in is changed to 5 mM, what happens to Ek?

It becomes zero.

Which of the following is TRUE of the power stroke? It results in the depolarization of voltage gated sodium channels It places myosin in a high-energy conformation It occurs only in smooth muscle It occurs while ADP is bound to Myosin

It occurs while ADP is bound to Myosin

An increase in sodium permeability through the membrane would cause the membrane potential to change in what manner?

It would become more positive.

______________, found on the motor end plate, produce the end plate potential in the presence of Acetylcholine. Ligand gated cation channels Voltage gated sodium channels Voltage gated calcium channels Ligand gated chloride channels

Ligand gated cation channels

Place the following structures in the order they would be encountered in a postsynaptic cell: Ligand-gated channels Dendrites Soma Axon hillock Voltage-gated channels Axon Axon terminal

Ligand-gated channels Dendrites Soma Axon hillock Voltage-gated channels Axon Axon terminal

A patient with an injury to the left brachial plexus would have what symptoms?

Loss of both sensory and motor function to the left upper extremity

A patient with an injury to the left brachial plexus would have what symptoms? Loss of both sensory and motor function to the right upper extremity Loss of motor function to the right upper extremity and loss of sensory function to the right lower extremity. Loss of only motor function to the left upper extremity Loss of both sensory and motor function to the left upper extremity

Loss of both sensory and motor function to the left upper extremity

UNLIKE graded potentials, action potentials ____________ . Occur in muscle cells Are changes in membrane potentialInvolve depolarization Measure the same amplitude at the stimulus site as they do further away from the stimulus site

Measure the same amplitude at the stimulus site as they do further away from the stimulus site

Cranial nerve nuclei and a respiratory control center are found in the

Medulla

Place the following areas in correct order from most inferior to the most superior. Medulla oblongata Pons Midbrain Cerebrum

Medulla oblongata Pons Midbrain Cerebrum

The center(s) for regulation of respiration is/are located in the ____ . (There may be more than one right answer)

Medulla of the brain stem Pons

The parallel conductance equation is used to predict _____________. Membrane potential at rest Equilibrium potential of just one ion at rest Conductance for an ion during an action potential Concentration of Na+ inside and outside the neuron

Membrane potential at rest

The ______________ branches from the internal carotid artery, and is a common stroke (Cerebrovascular Accident/CVA) location. A CVA involving this vessel will cause contralateral hemiplegia.

Middle cerebral artery

Assuming that a cell is permeable to Na, what would happen if the outside concentration of Na in the table below changed from 150 mM to 200 mM?

More Na+ ions enter the cell.

Hitting the quadriceps tendon with a reflex hammer (quick stretch) will activate _____________ , causing monosynaptic (direct) activation of motor neurons to _____________ muscles and activation of this sensory pathway: _________ .

Muscle spindles; ipsilateral quadriceps; fasciculus gracilis

All of the following are presynaptic disorders except: Myasthenia Gravis Multiple Sclerosis Eaton Lambert Syndrome Guillaine-Barre

Myasthenia Gravis

A sensory unit consists of

One afferent neuron and all its receptors

A sensory unit consists of __________ One receptive field and all afferent neurons wired to it One labeled line consisting of first, second and third order neurons One afferent neuron and all its receptors One receptor

One afferent neuron and all its receptors

Retinal ganglion cell axons from the nasal retina form part of the _______ and _______ to the opposite side at the optic chiasm.

Optic Nerve (II); cross

TOP HAT SUMMARY

Organization - The CNS embodies several fundamental organizing principles: - There is a hierarchy of organization, with information flowing from the spinal cord to the brain and vice versa. - Neurons with similar functions are found in the same place. - There is a topographical organization of neurons (e.g., neurons from neighboring fingers are co-located in the brain). - The CNS is plastic, changing as people change. - The CNS is composed of the brain and spinal cord. - The CNS is protected by the meninges—three layers of connective tissue that protect and support the CNS and also produce cerebrospinal fluid (CSF). CSF is a circulatory fluid that flows through the CNS, bringing nutrients to cells and taking away waste products. The CSF is kept separate and unique from the blood by the blood-brain barrier. Cell Physiology - The CNS is composed of neurons and non-neuronal cells known as glia. Neurons are excitable cells that transmit action potentials. - The most common type of neuron in the CNS is the multipolar neuron; the second most commom type of neuron is the pyramidal neuron. Multipolar neurons have many short dendrites and a single long axon, while pyramidal cells have large cell bodies shaped like a pyramid with much longer dendrites and axons. - Glia (non-neuronal cells) compose 90% of cells within the CNS and are responsible for the blood-brain barrier, removal of waste products, production of CSF, formation of neural circuits, formation of myelinated axons, repair of damage to neurons, and secretion and absorption of neurotransmitters in the synaptic cleft. - Glial cells include oligodendrocytes, astrocytes, microglia, ependymal cells, and oligodendrocyte precursor cells. - Growing neurons are attracted to their target organs through chemotaxis. The growth cone of a neuron is highly sensitive to attractive (or repulsive) chemical cues in the extracellular environment. - CNS neurons do amazing things like changing sensory information into information understandable by cells, integrating large amounts of information, and controlling the tissues inside the body. They also generate consciousness, sensory perception, language, reasoning, memory, and emotions. Circuits and Neuroplasticity - All of the bodily functions regulated by the CNS, like language and breathing, is dependent on the connections made between cells, i.e., circuits. The simplest circuit is made by one neuron communicating with another, which is rare. More common are neurons that communicate with 100s or 1000s of other neurons. - The types of neuronal circuits are: - Divergent: one neuron communicating with many others - Convergent: many neurons communicating with one neuronRhythm generating: a chain of interconnected neurons where the incoming stimulus travels from one to the next in a positive feedback manner (e.g., neurons regulating heartbeat) - Parallel after discharge: a single neuron sending a stimulatory or inhibitory signal to different chains of neurons, all of which impinge on a single cell - Neuronal circuits are formed during fetal and neonatal growth, underlie many reflexes, are maintained by use, and display plasticity. Their control of complex physiology is dependent on the correct communication between cells, and simple circuits can regulate complex physiology. - A reflex arc is a basic functional unit in the nervous system and the simplest circuit capable of receiving a stimulus and producing a response. The response time is faster because the action potential generated never travels to the brain for processing. Spinal Cord Anatomy - The spinal cord extends from the foramen magnum at the base of the skull to the cauda equina in your lower back. Within the cord, neurons and their axonal projections are organized into columns that carry information to and from the CNS. - Information enters the cord through dorsal root ganglia and exits the cord via ventral roots. Information that enters the cord is sensory, while information that exits the cord controls skeletal muscle via the somatic motor system and smooth muscle through the parasympathetic and sympathetic autonomic nervous system. - There is a specific organization of the flow of sensory information into the cord through the dermatome—a defined cutaneous sensory region. There is also a specific organization of the control of skeletal muscle known as the myotome. Brain Anatomy - The surface of the brain has classical landmarks—gyri (elevated ridges), sulci (small grooves), and fissures (deep grooves). - Within the brain, neuronal cell bodies are organized into grey matter, while axonal projections are organized into white matter. Axons carry information within a hemisphere of the brain, between hemispheres, and with the spinal cord. - The lowest portion of the brain is the brain stem, composed of the medulla, pons, midbrain, and thalamus and acts as a switching station that routes information coming into and out of the brain to its correct location. - The cerebellum plays a critical role in the control of skeletal muscle. - The cerebrum is the largest portion of the brain and contains the cerebral cortex, hippocampus, basal ganglia, and olfactory bulb. - The cortex collects information from the somatosensory cortex, gustatory cortex, auditory cortex, and visual cortex. It controls body functions through the motor cortex. - The hippocampus is associated with memory and the reticular formation with emotion.

The primary somatosensory cortex (S1) is located in the ____________ of the ______________ .

Postcentral gyrus; parietal lobe

Damage to the anterior corticospinal tract would cause problems with control of

Posture

Which ion has the greatest permeability at phase 1 on the graph above?

Potassium

QUESTIONS

What would happen to repolarization if the extracellular concentration of potassium was suddenly decreased?

Repolarization would take place more quickly because there would be a larger concentration gradient for potassium under these conditions.

Place the following phases of the action potential in the order that they would occur at the axon hillock.

Resting V[math]_m[/math] EPSPs are summed Membrane potential becomes more positive Membrane potential stops depolarizing Membrane potential becomes more negative Membrane potential is more negative than resting membrane potential Membrane potential becomes more positive to reach resting membrane potential

Visual information is heavily processed to create the visual world. This processing first occurs at which level of the visual hierarchy?

Retina

he most primitive muscle cell progenitor is: Satellite cell Muscle Fiber Myoblast Myosome

Satellite cell

Which of the following is NOT a part of the CNS? Microglia Schwann cells (neurolemmocytes) Astrocytes Spinal cord

Schwann cells (neurolemmocytes)

The treatment of CNS cancers and infections is hampered by the inability of most drugs to cross the BBB. What would be the dangers of altering the BBB so that drugs could more easily enter the CNS?

Several possibilities exist. Rabies virus particles might be able to bind to the surface of epithelial cells and then be pinocytosed into the cell and into the CSF. This is unlikely since the epithelium forming the BBB is incapable of pinocytosis. If the rabies virus particle was hydrophobic in nature, it might be able to pass through the BBB directly. Again, if the viral particle was hydrophobic, it wouldn't be able to pass easily through blood. Or it can infect peripheral nerve axons and enter the CNS by retrograde transport to the cell bodies of afferent or efferent neurons, which is how it enters the CNS to multiply.

Calcium is essential for signal propagation through the NMJ because it: Signals vesicle docking to the presynaptic membrane It is necessary for Acetylcholine (ACH) synthesis. Leaves the axon terminal, hyperpolarizing the cell. Binds to receptors on the postsynaptic cell, opening ion channels, and triggering graded potentials.

Signals vesicle docking to the presynaptic membrane

A patient with lung cancer is having his left lung removed. To remove the space remaining in the thoracic space and to assist breathing, the left side of the diaphragm will be paralyzed to allow the visceral organs to push upward. What nerve should be cut? Where should it be cut, and what other effects would the surgery have?

Since the phrenic nerve controls contraction of the diaphragm, severing the phrenic nerve on the left side will paralyze that portion of the diaphragm and remove its tone. The nerve should be severed as close as possible to the diaphragm to mitigate any influence on other tissues or organs. if done correctly, the surgery should have little effect on other organs.

Sarcomeric contraction

Sliding filament theory (model) - thin filaments slide across thick filaments towards the center of the sarcomere, resulting in shortening of the H zone and I zone. A-band does not change. The Z lines move closer together - Sarcomeres contract in a oscillatory manner which is very similar to the motion of a spring - The filament slide to form the structure and a contracted state. The myofibril is changed as more sarcomeres contract. This is known as the sliding filament model.

Starting with the receptor, put the following structures in the correct sequence

Spinal cord gray matter Lateral spinothalamic tract Thalamus Internal caspule Postcentral gyrus

The ability to identify an object using just touch is called __________________ and is only possible when sensory information reaches the _______________ .

Stereognosis; sensory association cortex

Sensory transduction is the process of converting

Stimulus energy into a change in membrane potential

Sensory transduction is the process of converting ___________ . Stimulus energy from one modality (such as touch) into another modality (such as pain.) Stimulus energy into a change in membrane potential Graded potentials into action potentials All of the above

Stimulus energy into a change in membrane potential

Unlike in the dorsal column system, the anterolateral system first order neurons ________ .

Synapse in the spinal cord

Match structure to function

Temporal lobe= Hypothesis generation Temperature regulation= Basal ganglia Muscle tone= Hypothalamus Medulla= Frontal lobe Hearing= Thalamus Sensory relay center= Regulation of breathing

The diencephalon contains the ________ .

Thalamus and hypothalamus

How does the density of voltage-gated sodium channels in the internode compare to the node?

The density of voltage-gated sodium channels is less in the internodes because of the electrical insulation that comes from myelin. Essentially, it takes fewer channels to produce the same effect.

Changes in membrane potential serve as signals to cells within the body—and can often be a drug target in the treatment of many diseases. However, membrane potential is also the target of many toxins that disrupt various cellular processes. Lethal injections, for example, commonly follow a three-step procedure: the first drug is a sedative, the second drug causes muscle paralysis, and the third drug, the one that actually kills, is potassium chloride. What happens to membrane potential when potassium is injected at this very high concentration?

The equilibrium potential for potassium becomes more positive, which causes resting membrane potential to become more positive. This causes excitable cells (like neurons and the heart muscle) to be held in a depolarized state indefinitely.

Why is a transport system necessary within the neuron?

The majority of protein synthesis takes place within the soma - but all regions of the neuron are important for carrying out its function. Proteins synthesized in the soma may include ion channels, transporters, signaling enzymes, and neurotransmitters that are needed in more distal portions of the cell (e.g., the axon terminal), and therefore must be transported anterograde.

During filament sliding, Z discs move towards the M line and:

The size of the H-zones become smaller

Why doesn't the spinal cord extend to the bottom of the spinal column?

The spinal cord doesn't extend to the bottom of the vertebral column because of differences in growth of the vertebral column and cord resulting in space for the lower spinal nerves to exit the cord, and to protect the cord from mechanical trauma because of the extra space and CSF.

Arrange the sequence of structures making up an anterolateral (AL) system tract in the correct order, starting with transduction at the receptor and ending with primary somatosensory cortex (S1).

Thermoreceptor; dorsal horn; spinothalamic tract; thalamus; S1

You step on a tack. Which of the following statements about the flexor withdrawal reflex is TRUE?

This reflex is coordinated by the spinal cord.

A person with Brocaâ s aphasia retains the ability to understand speech but is unable to produce fluent speech, due to damage to the left cerebral hemisphere. (T/F)

True

Cell bodies of alpha motor neurons to skeletal muscle are located in the ____________ of the spinal cord.

Ventral horn

Resting membrane potential (Vm) in a normal cell is -70mV. In this cell, the relative sodium permeability is 0.01, relative potassium permeability is 1, and the relative chloride permeability is 0.2. What would happen to Vm if sodium permeability were changed to 5?

Vm would become more positive

Place the following events in the order they occur, starting with the depolarization of the axon hillock:

Voltage gated sodium channels open in an internode segment Voltage gated calcium channels in the axon terminal open Acetylcholine enters the synapse Sodium enters through a ligand gated channel End plate potential develops Voltage gated sodium channels open on the sarcolemma Calcium levels in muscle increase Crossbridges form

During the depolarization phase of the action potential, _____________ . Voltage-gated Na+ channels are open A positive feedback cycle dramatically increases permeability to K+ K+ leak channels closeMembrane potential is moving toward threshold

Voltage-gated Na+ channels are open

A person's knee strength as assessed by the PT with a manual muscle test shows a 4+ (good+) grade for knee extension. What would you expect the strength to be if that same person lacked a patella?

Weaker (e.g., a 4 or good grade )

Inhibition of the sodium potassium pump:

Will cause resting membrane potential to become more positive

Functions lateralized to the left hemisphere typically include which of the following? (Choose all that apply.)

a Written language b Speech

What does the diencephalon do? a Acts as a transfer station for sensory information moving into the brain Your answer b Contains the thalamus c Contains the hypothalamus

a Acts as a transfer station for sensory information moving into the brain Your answer

What are the physiological consequences of sensory and motor pathways moving through the brainstem? Select all that apply. Multiple answers: Multiple answers are accepted for this question a Damage to the brainstem may interfere with breathing. b Damage the brainstem may interfere with touch sensation. Your answer c Increased number of synapses creates more opportunities for regulation of essential body processes. d Action potentials in the brain are not required to regulate movement.

a Damage to the brainstem may interfere with breathing. b Damage the brainstem may interfere with touch sensation. Your answer c Increased number of synapses creates more opportunities for regulation of essential body processes.

A young man is brought to the ER after being involved in a motor vehicle accident. The young man did not have his seat belt on and suffered cuts to his forehead and damage to the back of his head. He reports numbness in different parts of his body, difficulty swallowing, poor coordination, and slurred speech. He admits that he had been drinking prior to the accident and that he is a heavy smoker of marijuana. What is the likely problem the patient is suffering from? a Damage to the medulla Your answer b Damage to the vagal nerve c Alcohol intoxication d Damage to the cerebral cortex

a Damage to the medulla Your answer

Which of the following statements best differentiates between the roles of the cerebellum and diencephalon in human movement? a Find patients with movement disorders and look for changes or damage in either area. Your answer b Using fMRI, scan the active portions of the brain when people move. c Determine through staining which areas directly communicate with ∝-motor neurons in the spinal cord. d Determine through staining which areas receive proprioceptive information during human movement.

a Find patients with movement disorders and look for changes or damage in either area.

A patient with head trauma complains of not being able to smell anything. Where is the likely damage? a Frontal lobe Your answer b Parietal lobe c Occipital lobe d Insula

a Frontal lobe Your answer

Placing a neuron in a calcium free solution:

a Would prevent the action potential from firing b Would increase the speed of the action potential c Would result in a lower amplitude action potential d Would block synaptic transmission IDK ANSWER

How would a mutation that increases the threshold for the voltage gated potassium channel change the action potential?

a longer repolarization phase

little timmy has a mutation that reduces the permeability of his voltage gated potassium channels. in comparison to a normal person, his action potentials are likely to display:

a longer repolarization phase

Muscle tone is ________ the ability of a muscle to efficiently cause skeletal movements a state of paralysisa state of sustained partial contraction the muscle growth following athletic training.

a state of sustained partial contraction

____ is made of multiple globular molecules polymerized to form long chains or filaments

actin

__________ is made of multiple globular molecules polymerized to form long chains or filaments. Myosin Titin Actin Troponin Tropomyosin

actin

By increasing twitch frequency, muscles generate: More tension Unfused tetanus Fused tetanus All of the above

all of the above

Intrafusal muscle fibers __ . a Are sensory receptors b Are innervated by afferent (sensory) neurons c Are innervated by efferent (motor) neurons d All of the above e None of the above

all of the above

Voltage-gated K+ channels are closed during ___________ . the resting potential the after-hyperpolarization phase of the action potential all of the above

all of the above

In response to a stimulus, an excitable membrane produces an action potential whose peak measures +30 mV. If after the action potential is over, a second stimulus of greater intensity is delivered, the membrane will respond with an action potential whose peak is _________ +30 mV. Less positive than Also More positive than Either less positive than or more positive than

also

A patient reports numbness in his left arm and was severely burned when his elbow was too close to an open flame. What nerve plexus and nerve could be damaged? a Cervical plexus and the auricular nerve b Brachial plexus and any one of several nerves that innervate the arm Your answer c Lumbar plexus and the vagus nerve d Sacral plexus and the ischiadic nerve

b Brachial plexus and any one of several nerves that innervate the arm Your answer

During a breech birth (feet first instead of head first), the attending physician was forced to use forceps to grab the baby's leg and pull it out of the womb. Later examination of the baby revealed damage to the toes, which could not abduct or adduct, and the flexion of the ankle was impaired. What likely happened to the baby? a There was direct damage to spinal cord reflexes. b The common fibular nerve was damaged. Your answer c There was damage to the lumbar plexus. d The vagal nerve was damaged close to the knee.

b The common fibular nerve was damaged. Your answer

What conclusion can be drawn by the fact that CSF is colorless? a The CSF must be a thin layer covering the surface of the brain and spinal cord. b There cannot be hemoglobin within the CSF. c Oxygen must be stored with neuroglia. d The CSF is made up of the same proteins and cells that make up blood.

b There cannot be hemoglobin within the CSF.

A dermatome is defined as ________. a a rash located on the surface of the skin b a region of skin innervated by a particular spinal nerve c a functional muscle group innervated by a particular spinal nerve d a cluster of mechanoreceptors located on the surface of the skin

b a region of skin innervated by a particular spinal nerve

Neurotransmitters that cause presynaptic inhibition (inhibition of the cell "sending" a message) would have receptors located on the: a Postsynaptic membrane b Presynaptic membrane c Axonal membrane d Cell body

b Presynaptic membrane

Which of the statements comparing/contrasting muscle spindle and Golgi tendon organ (GTO) is FALSE? a Activating muscle spindles in an extensor muscle can produce an excitatory reflex to contract that muscle, while activating GTOs in same muscle can activate an inhibitory reflex. b Afferent information from spindles travels in Dorsal Column system, while information from GTOs travels in Anterolateral system. c Spindles transduce muscle length and GTOs transduce tendon tension. d Both muscle spindle and GTOs are proprioceptors. e Both muscle spindles and GTOs are receptors.

bAfferent information from spindles travels in Dorsal Column system, while information from GTOs travels in Anterolateral system.

If the concentration of extracellular calcium is changed to 1 mM, what happens to the concentration gradient?

bIt decreases

Two-point discrimination is _________ on the lips than on the knee. One reason for this is that there is _________ overlap of receptive fields on the lips. Better; less Worse; less Better; more Worse; more

better; more

Neurons that have exactly two processes attached to the cell body are called anaxonic bipolar unipolar multipolar

bipolar

Which of the following areas would you choose to investigate with the patient first? a Optic nerves b Ear canals c Cerebellum Your answer d Heart e Brain stem

c Cerebellum Your answer

Which fibers carry information from one brain hemisphere to the other? a Association b Projection c Commissural

c Commissural

This region of the diencephalon helps to regulate the human circadian cycle (24-hour cycle). a Hypothalamus b Epithalamus c Pineal body Your answer d Substantia nigra

c Pineal body Your answer

Damage to the ________ would prevent the flow of CSF from the spinal cord and brain. a meninges b nuclei c cerebral aqueduct d pia mater

c cerebral aqueduct

The cerebellum ________. a is superior to the brainstem. b is the seat of consciousness in humans. c plays a role in muscle movement. Your answer d is inferior to the brainstem.

c plays a role in muscle movement. Your answer

When the neuronal membrane is at the resting potential, the sodium channel inactivation gate is ________.

closed

What is a plexus? a The site outside the CNS where spinal nerves move in a dorsal or ventral direction b The site within the CNS where neurons and axons are organized into spinal nerves c The site outside the CNS where neuron cell bodies are collected d A braid-like structure intermingling motor, autonomic and sensory neurons e The region of the body innervated by a specific spinal nerve

d A braid-like structure intermingling motor, autonomic and sensory neurons Your answer

The role of CSF is to do which of the following? a Anchor the CNS to the pia mater b Provide direct contact between plasma and neurons within the CNS c Increase the weight of the CNS d To provide neutral buoyancy to the CNS

d To provide neutral buoyancy to the CNS

The dorsal root contains _ .

dBoth a ganglion and sensory axons

Compared to unmyelinated axons, action potential propagation in a myelinated axon involves which of the following? Voltage gated Na+ channels at the myelinated internodes in the myelinated axon Decremental currents that travel further in the myelinated axon Production of many more action potentials per unit distance All of the above

decremental currents that travel further in the myelinated axon

My shoulder joint can flex, extend, rotate, abduct and adduct. I am describing which feature of the shoulder joint?

degrees of freedom

The multiple thin, branched structures on a neuron whose main function is to receive incoming signals are the ______ . cell bodies axons dendrites synaptic knobs

dendrites

An excitatory postsynaptic potential (EPSP): depolarizes a neuron, increasing the likelihood of an action potential. hyperpolarizes a neuron, decreasing the likelihood of an action potential. hyperpolarizes a neuron, increasing the likelihood of an action potential. depolarizes a neuron, decreasing the likelihood of an action potential.

depolarizes a neuron, increasing the likelihood of an action potential.

The characteristic of muscles that allows them to return to their original resting shape after changing size is: Elasticity Excitability Extensibility Pliability

elasticity

Which muscle sheath contains neurons?epimysium apomysium perimysium muscle sheaths do not contain neurons endomysium

endomysium

Although classified as glial cells, ____________ are also ____________ that line the cavities in the brain and spinal cord and help form the choroid plexus. ependymal cells; epithelial cells microglial; phagocytes oligodendrocytes; epithelial cellsastrocytes; phagocytes

ependymal cells; epithelia cells

To ADduct the wrist, contract the _ . (There may be more than one correct answer.)

extensors

Basal Nuclei (aka Ganglia)

forebrain and midbrain structure that link complex motivational signals to motor function 1) caudate nucleus 2) putamen 3) globus pallidus 4) claustrum 5) amygdaloid body (amygdala) - role in sensory and motor functions (prevent unwanted movement, rhythmic movements) - baseline muscle tone is coordinated in the basal ganglia

Blood Supply to the brain

internal carotid arteries supply approximately anterior 2/3 of brain - anterior, middle and posterior cerebral arteries - middle cerebral artery is a common cerebrovascular accident (CVA/stroke) site - posterior cerebral artery vertebral arteries supply the rest of the brain circle of willis - collateral circulation venous sinuses; jugular vein for venous drainage

Assume you have an artificial cell, which is surrounded by fluid with a high concentration of NaCl, while the fluid inside the cell has a high concentration of KCl. The artificial membrane is made permeable to ONLY K+ ions. At equilibrium, the electrical force favoring movement of K+ _______ the cell will be ______ the chemical force favoring movement of K+ out of the cell. out of; equal to into;greater than out of; greater than into; equal to

into; equal to

A contraction generates force and moves a load is known as _____, whereas one that generates force without movement is known as_____. isotonic, eccentric isotonic, isometric isometric, eccentric isotropic, isometric isometric, isotonic

isotonic, isometric

which of the following is true about the cerebellum?

it compares movement in progress to the intended movement

The radius is ( ? ) to the ulna. There may be more than one right answer.

lateral

landmarks of the cerebrum

longitudinal fissure: - cerebral hemispheres (separates left and right hemispheres) transverse fissure: - cerebrum/cerebellum (separates cerebral cortex and cerebellum) Sylvian/lateral fissure: - frontal, parietal, temporal central sulcus: - parietal/frontal lobe

UNLIKE graded potentials, action potentials ______

measure the same amplitude at the stimulus site as they do further away from the stimulus site

protective structures of the brain

meninges: dura matter, arachnoid matter, pia mater ventricles: CSF within brain, CSF from choroid plexus of ventricles (where is formed by ependymal cells) through ventricles and central canal of spinal cord; then into subarachnoid space cerebrospinal fluid: bathes brain, the "ECF" of CNS; however CSF is not equal to the plasm. There is even less variation in constituents (i.e. even closer to homeostasis). compared to plasma, there is more Na, Cl, and less K, Ca

which of the following is not a characteristic of neurons /

mitosis

your neurologist taps your right patellar tendon with a reflex hammer, causing a quick stretch to the right quadriceps muscle. in response, there is ______ of the quadriceps muscle and _______ of the right hamstrings. (monosynaptic: one synapse; polysynaptic: more than one synapse)

monosynaptic excitation; polysynaptic inhibition

The knee jerk reflex requires ____ synapse(s) to activate quadriceps contraction in response to quick stretch of that muscle. The synapse(s) is/are found in the __ .

one, ventral horn

which is the correct association of cerebral structure or lobe and function?

parietal - somatosensory

electrical signals within neurons (passive electrical signals and active electrical signals)

passive electrical signals - a transient change in membrane potential that dissipates as it propagates in space and time, meaning it is specific to one region of the cell and only occurs for a very short period of time - e.g. a graded/synaptic potential active electrical signals - a change in membrane potential that is maintained over a long distance - e.g. an action potential

Rhinencephalon

phylogenetically "old" cortex - related to smell - olfactory bulb and tract - fornix - limbic system: amygdala ("end of caudate") and hippocampus (memory)

diencephalon: epithalamus

pineal gland: - secretes melatonin, a hormone that helps regulate day night cycles (circadian rhythm) habenular nuclei: - relay signals from the limbic system to the mesencephalon/midbrain and are involved in visceral and emotional responses to odor -Secretes hormone melatonin which is important for regulating circadian rhythms or sleep wake system - Emotional responses to smells/odors.

A student working in a lab accidentally injects himself with a drug that inhibits the L- type calcium channel (DHP). Which of the following processes will be most affected? The firing of a muscle action potentialThe depolarization of the motor end plate (end plate potential) The release of synaptic vesicles from the synaptic knob The removal of tropomyosin from myosin binding sites All of the above will be affected

removal of tropomyosin from myosin binding sites

Which of the following muscle tissues is striated and multinucleate? Skeletal Muscle Cardiac Muscle Smooth Muscle Both Skeletal and Smooth Muscle

skeletal muscle

a specialized structure of muscle fibers created by invagination of the sarcolemma is called the:

t-tubule

specialized structure of muscle fibers created by invagination of the sarcolemma is called the: t-tubule myofibril sarcosome sarcomere

t-tubule

Compared to the shoulder, the hip joint has ( ? ) degrees of freedom and ( ? ) range of motion.

the same, less

The length of the sarcomeres in resting muscles affects: the magnitude of the stimulus. the tension developed during a twitch. whether a muscle will fatigue. the ability to maintain a prolonged contraction.

the tension developed during a twitch.

spinal cord (fiber tracts)

tract = collection of axons running together within CNS 1) ascending (sensory) tracts - dorsal columns (fasciculus gracilis, fasciculus cuneatus) - anterolateral columns (spinothalamic) - spinocerebellar tracts 2) descending (motor) tracts - ventromedial system (VM) : reticulospinal, vestibulospinal, tectospinal tracts - dorsolateral system: oubrospinal tract - corticospinal ("pyramidal") tracts

Cell bodies of alpha motor neurons to skeletal muscle are located in the ____________ of the spinal cord. Dorsal root ganglion Ventral horn Dorsal horn Corticospinal tract

ventral horn

The regions of the central nervous system containing myelin are commonly referred to as white matter gray matter ganglia Neuroglia

white matter

Why aren't neuronal cells evenly distributed in the CNS? What advantage is gained by organizing neuronal cells in specific areas?

This allows for more efficient sharing of information between cells that regulate physiological processes, improving the control of those processes. It is also a consequence of how the CNS was organized during embryonic development.

PNB Exam III

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