PNB Exam 2

The Goldman Hodgekin Katz Equation (GHK) is different than the Nernst Equation because GHK takes into account: Answers: Ion solubility Ion charge Ion Permeability Ion concentration gradients Ion size

Ion Permeability

Relaxation

Release of tension

Cervical plexus

exits cervical, responsible for neck movement, head movement

Lumbosacral plexus

exits lumbar sacral region of spinal cord and innervates lower limbs

Brachial plexus

exits upper thoracic, innervates most of upper limb and part of chest

Na/K/ATPase pump maintains gradient by...

going AGAINST gradient using ATP (3 Na out for every 2 K in) → electrogenic process

Passive Electric Signals:

graded/synaptic potentials (dissipates over time/space) Decrease in strength Primarily ligand-gated channels These messages act simply to change permeability of ions

CIP

mutation of Na channel, it doesn't work - doesn't allow you to feel pain

if you were given a drug that made Ca concentration outside muscle cell zero, what would happen in the muscle cell?

nothing, Ca comes from SR (intracellular source) so crossbridges would still form and filaments would still slide SOURCE OF CALCIUM FOR MUSCLE CONTRACTION IS INTRACELLULAR!!**

Dendrites

receive

In a typical neuron, signal input primarily occurs at: Answers: The dendrites The soma The axon hillock The synaptic knob (axon terminal)

The dendrites

Interneurons

(most CNS neurons): connections to other neurons within CNS

Membrane

- membrane maintains the status quo - its goal is to maintain whatever the resting state concentration gradient is I.e. keep K inside cell and Na outside cell The concentration gradient will be mainly responsible for what diffusion takes place

Which of the following regions of the sarcomere does not change size during filament sliding? Answers: A band I band H zone Both A and B Both B and C

A band

Neuromuscular junction (NMJ)

A synapse between the axon terminals of a motor neuron and the sarcolemma of a muscle fiber (cell).

Absolute refractory period:

ALL VOLTAGE GATED NA CHANNELS INACTIVATED (can't respond)

Primary Active Transport:

ATP can be used as energy; broken down into ADP+P to transport molecule (k/na pump)

Secondary active transport

ATP is not consumed, but the energy comes from electrochemical gradient (glu/na pump)

__________________ is a filamentous muscle protein made up of polymerized globular proteins that contain binding sites for ________________ Answers: Myosin; Tropomyosin Actin; Tropomyosin Tropomyosin; Troponin Myosin; Calcium

Actin; Tropomyosin

Which of the following sequences correctly lists the density of voltage gated sodium channels from lowest to highest? Answers: Axon Terminal, Internode, Node Node, Axon Terminal, Internode Internode, Node, Axon Terminal Node, Internode, Axon Terminal Axon Terminal, Node, Internode

Axon Terminal, Internode, Node

Channelopathies:

CIP, PEPD

Motor (efferent) neuron

CNS connected to muscles/organs (brain telling me to move my finger)

Which of the following statements is TRUE about resting membrane potential? Potassium is entering the cell passively Sodium is leaving the cell passively Correct Ions are being moved by active transport All of the above are true statements

Correct Ions are being moved by active transport

Action potentials are created when...

DEPOLARIZATION (SUMMATION OF EPSPs IS POSITIVE) IS DRASTIC ENOUGH TO PASS THE THRESHOLD!!!**

How is membrane potential created?

Differential ion concentration across membrane Ions passively move down gradient through ion channels, but how can we maintain the resting potential? High stays high and low stays low via active transporters (moving against concentration gradient requires energy) Ions have an intracellular and extracellular concentration Ions to focus on: K, Na, Cl (and Ca2+)

A band

Entire length of myosin

Voltage gated sodium channels close during the peak of the action potential Answers: True False

False

Tyrion has a mutation in his sensory neurons that transmit pain information. The mutation increases the threshold of his voltage gated sodium channels. As a result, Tyrion will: Answers: Fire action potentials less often Fire action potentials of greater amplitude Fire actions potentials of smaller amplitude Fire action potentials more often

Fire action potentials less often

Relative refractory period:

IT'S POSSIBLE TO FIRE ANOTHER AP, IT'S JUST A LITTLE BIT HARDER (harder to respond)

The Na/K/ATPase or "pump" is inhibited by ouabain. Which of the following consequences may be expected in response to this inhibition? Answers: Depletion of intracellular sodium Increased cell volume Accumulation of potassium within cells Hyperpolarization All of the above

Increased cell volume

Assume inhibitory neuron 1 makes an axo-axonic synapse with neuron 2. What can you predict about the mechanism of its inhibition? Answers: Inhibitory neuron 1 will prevent neuron 2 from firing action potentials. Inhibitory neuron 1 will reduce the amount of transmitter released by neuron 2. IPSPs (inhibitory post-synaptic potentials) will be produced in neuron 2. All of the above

Inhibitory neuron 1 will reduce the amount of transmitter released by neuron 2.

In contrast to synaptic potentials in neurons, the release of neurotransmitter onto the motor end plate: Answers: Produces graded potential Brings extracellular calcium into the cell Is always depolarizing Brings voltage gated sodium channels to threshold

Is always depolarizing

How to predict changes in Ex

Is there a concentration gradient? Does it become larger or smaller? Which direction will ions move? What is the ion charge? Will this movement make the cell more negative or positive?

if Ko is 5 and Ki is 100, and you change the Ko to 1, what happens to Ek?

It becomes more negative

How does an action potential propagate?

It is a positive feedback cycle: DEPOLARIZATION LEADS TO MORE DEPOLARIZATION*** Stimulus (charged amino acids) trigger slow opening of Na channels (depolarization) which opens the activation gate wider as more Na floods in THE THRESHOLD IS THE POINT AT WHICH THE NA VOLTAGE GATED CHANNEL COMPLETELY OPENS***, AND THE POINT AT WHICH K CHANNELS OPEN COMPLETELY Na has a negative threshold, K has a positive one This then causes K channels to open slowly K leaves cell and eventually Na channels slowly close This leads to repolarization

What is electricity

It's a movement of charge Opposite charges attract, same charges repel The goal is electrical neutrality If we want to keep these charge apart, it requires energy

At rest, a cell must be most permeable to...

K

What impacts tension?

Length-tension relationship -- too much or too little overlap of contractile proteins decreases tension

Internodes vs. nodes

Less Na channels are required to recharge AP at internodes, while many thousands more are required to recharge at nodes****

EXCITATORY (EPSP):

MESSAGE CAUSES DEPOLARIZATION

INHIBITORY (IPSP):

MESSAGE CAUSES HYPERPOLARIZATION

Myelin sheath

Made by Schwann cells in PNS and Oligodendrocytes in CNS Internodes vs. Nodes of Ranvier Increased conduction velocity Are responsible for any regeneration that takes place

You are studying a cell that is permeable to sodium, chloride, and potassium. According to the G-H-K Equation (Parallel Conductance), if the cell DECREASES its permeability to sodium by a factor of 2: Answers: Membrane potential will become equal to EK Membrane potential will become more negative Membrane potential will become more positive Membrane potential will become zero Membrane potential will become equal to ENa

Membrane potential will become more negative

MUSCLE PHYSIOLOGY

Muscle is a contractile tissue (it can change size without damage) Excitability Conractibility Elasticity Extensibility Transduce AP(energy) into contractions (mechanical force)

Non-mitotic tissue

Muscle is built and repaired via a satellite (a muscle stem cell) Upon receiving signals, these satellite cells become myoblasts (a muscle precursor cell) Myoblasts mature (myocyte or muscle fiber is a muscle cell) and line up end to end All myoblasts then fuse together creating one very long cell (has many nuclei as a result)

Muscle Action Potential

Na coming in causing depolarization, but Ca needs to be released Excitation-Contraction Coupling (EC) - the link between the excitation (AP/Na) of the muscle cell and the contracting of the filaments (get the Ca to release)

Which of the following is a postsynaptic disorder? Selected Answer: Answers: Multiple Sclerosis Eaton Lambert Syndrome Guillaine-Barre Syndrome None of the above

None of the above (Myasthenia Gravis is the correct answer)

what happens if their is no extracellular Ca concentration outside the neuron?

Nothing because the calcium in muscle cells in stored in the sarcoplasmic reticulum, not outside the cell.

A motor unit consists of: Answers: One muscle fiber and all the neurons that control it. One axon terminal branch and the myofibrils it controls. The muscle fibers that make up a particular muscle group (e.g. rotator cuff) One neuron and the muscle fibers under its control

One neuron and the muscle fibers under its control

Na/K/ATPase Pump

Primary active antiport transporter Moves Na and K in opposite directions Na is outside and K is inside cell The ATP is required so that Na can be moved out where it's already high and K can be moved in where it's already high (moves against concentration gradient)

synaptic vesicles

Release neurotransmitter(acetylcholine)

Active transport:

Requires additional energy and enzymes (i.e. ion pumps)

How can you measure resting membrane potential in a cell?

Saline bath, and voltmeter with grounding and measuring electrodes outside and inside cell VOLTAGE ALWAYS DESCRIBES THE CHARGE INSIDE THE CELL****

The most primitive muscle stem cell is known as a Answers: Satellite Cell Myoblast Muscle Fiber Myofibril

Satellite Cell

Na/Glu Pump

Secondary active symport transporter Energy from sodium concentration gradient is used to transport glucose (because it's not energetically favorable to move glucose in)

The brachial plexus supplies ____________ innvervation to the _____________ . Answers: Sensory; neck Only sensory; upper extremity Sensory and motor; shoulder and neck Only motor; lower extremity Sensory and motor; upper extremity

Sensory and motor; upper extremity

Stimulus modality energy is converted to a receptor potential by the process of _________ . Answers: Presynaptic facilitation Analog to digital conversion Summation Sensory transduction. Motor transduction

Sensory transduction.

Unipolar Neuron

Sensory. Out in the skin/periphery, activated by sensory receptors/stimuli (pressure, feeling heat/cold)

what would happen to an action potential if the voltage-gated K channels had a congenital defect causing a higher threshold??

Slower repolarization or long depolarization Remember: K is associated with the right side of the action potential graph.. If the threshold (peak) at which point K channels open is higher, then they won't open at the point, and other things (i.e. pump) are going to very slowly move K out of cell

Skeletal muscle and smooth muscle differ because: Answers: Smooth muscle uses gamma motor neurons for contraction Smooth muscle does not have actin Smooth muscle is striated Smooth muscle has a single nucleus

Smooth muscle has a single nucleus

In a typical neuron, when neurotransmitter binds a single sodium channel, causing it to open: Answers: A positive feedback loop begins Sodium will enter the cell until membrane potential reaches +30mV Sodium enters the cell producing an EPSP All of the above

Sodium enters the cell producing an EPSP

Goldman Hodgkins Katz (GHK) equation

Summation of a weighted average of Ex for each permeable ion Membrane potential must fall between the "extremes" or the highest and low equilibria of all ions (i.e. between -75 mV and +58 mV) Ions with greatest permeability will have biggest effect on Vm, and therefore Vm will be closest to Ex for that ion****************

T-Tubules are an important specialization of muscle fibers because: Answers: T-Tubules allow muscles to store oxygen and prevent fatigue T-tubules store ATP T-Tubules are the units of force generation within muscle fibers T-tubules allow for communication between the plasma membrane and the sarcoplasmic reticulum

T-tubules allow for communication between the plasma membrane and the sarcoplasmic reticulum

ATP is critical for...

THE CREATION AND OPERATION OF CONTRACTILE PROTEIN (THEREFORE SO ARE MITOCHONDRIA)

Excitation contraction coupling begins when the action potential stimulates ______________ on the T-tubule to open the ________________ on the sarcoplasmic reticulum Answers: The RyR (Ryanodine Receptor); The DHP Receptor The RyR (Ryanodine Receptor); SERCA (Sarcoplasmic Ca/ATPase) SERCA (Sarcoplasmic Ca/ATPase); The DHP Receptor The DHP Receptor; SERCA (Sarcoplasmic Ca/ATPase) The DHP Receptor; The RyR (Ryanodine Receptor)

The DHP Receptor; The RyR (Ryanodine Receptor)

What is the best definition of the "receptive field" of afferent neuron X carrying information about touch or temperature? Answers: The area of the body innervated by the spinal nerve that contains neuron X. The area of the body that, when stimulated, leads to activity in neuron X. The number of interneurons with which neuron X's central process makes synaptic contact. The type of stimulus energy to which neuron X is most sensitive.

The area of the body that, when stimulated, leads to activity in neuron X.

What is important to determining an ions Ex?

The charge of the ion (valence) and the concentration gradient (Nernst's equation) If there is no concentration gradient, there is no movement, and Ex = 0

Know what hypothetical events can cause certain changes in membrane potential!! (i.e. what could cause depolarization? Hyperpolarization? etc)

The opening of channels that let positive ions flow into the cell can cause depolarization. Example: Opening of channels that let Na+ into the cell The opening of channels that let positive ions flow out of the cell (or negative ions flow in) can cause hyperpolarization. Example: Opening of channels that let K+ out or Cl- into the cell.

Sliding filament model

Thick filament slides over thin filament and M line and Z discs get closer together, H zone decreases, I band decreases, and A band does NOT CHANGE The myosin binds to the actin and pulls on it at the crossbridge (binding site) Contractile elements: actin and myosin Regulatory elements: troponin and tropomyosin Tropomyosin sits in the spot that myosin wants to bind to Troponin binds to actin, calcium, and tropomyosin When it binds to Ca it changes shape and can pull tropomyosin away so that myosin can bind to actin

A calcium binding protein that regulates muscle contraction is: Answers: Titin Actin Troponin Tropomyosin Myosin

Troponin

Dystonias are movement disorders that may result from loss of motor unit coordination Answers: True False

True

Intermediate fibers (Type 2A)

aerobic skeletal muscle

Occlusion state:

after solute binding, the carrier closes to both membrane faces, so no solute binding site is available (this also means that the solute is trapped inside the protein temporarily)** This is why carriers are slower than channels*** (slower transport rate than ion channels) RATE OF TRANSPORT: 1-3 molecules per confirmation cycle vs. thousands per second in channels

Motor end plate

area of muscle that forms synapse with nerve

Membranes =

batteries (which just means that they have different voltages!!)

AChE

breaks down ACh

Excitable cells

cells that respond to electricity Ex. Luigi Galvani and his creepy dead frog legs!!!

Plexuses

clusters of nerves that exit spinal cord in various areas. Name of plexus tells you where it exits from

Sensory transduction

converts stimuli energy into change in membrane potential

Contraction

created of tension in muscle

Sarcoplasm

cytoplasm (fluid inside membrane of cell)

Myocytes have very little...

cytoplasm because it is packed with myofibrils (and organelles are often shoved to the edges), which allows contraction

Sarcoplasmic reticulum = aka...

endoplasmic reticulum

Purpose of muscle

heat, movement, posture

Myelination:

insulation around some nerves Allows quicker firing of signals Some segments myelinated, some not

what happens to K when a K channel opens?

it moves down the gradient, or out of the cell via passive transport

Adequate stimulus:

least amount of energy to activate receptor

M line

middle of sarcomere

Sarcosome

mitochondria

ACh receptor

on motor end plate

Sensory unit

one afferent (sensory neuron) and all its sensors

A motor unit is....

one neuron and all the muscle fibers it has synapses with All muscle fibers in a motor unit act as one (ALL OR NONE PRINCIPLE - they all get neurotransmitters at the same time)

axon

one or zero which sends out branches

Proprioceptors

perception of movement, a mixture of external and internal (ex: closing your eyes and touching your fingers together - knowing whats happening)

Sarcolemma

plasma membrane

The muscle is the...

postsynaptic cell

The neuron is the...

presynaptic cell

Synapse

presynaptic membrane, synaptic cleft, and postsynaptic membrane (chemicals diffuse across this space)

Myosin is attached to...

protein called titin which is connected to z disc, myosin is in

Action potentials move forward, in one direction, due to...

refractory period (activation gates are closed, preventing repeated firing)

Bipolar neuron

retina

Most Ca comes from...

sarcoplasmic reticulum

Process of summation:

soma adds the EPSPs and IPSPs (spatial and temporal data) Is the sum positive? Negative? Do the SPs cancel each other out?

Cell body

soma, organelles

Satellite cells:

support soma in PNS/ganglia (metabolic/nutrient support)

Inactivation gate:

swings closed once depolarization reaches peak, which stops Na permeability even though activation gate is closed

Semipermeable membranes allow..

the ions to move in and out The membrane is therefore responsible for creating POTENTIAL ENERGY*****

Vm

the potential inside the cell vs. outside (i.e. resting membrane potential or RMP)

RMP is affected by...

the unequal distribution of ions, as well as the permeability of various ions****************

Fast fibers (Type 2B)

translucent (no myoglobin, anaerobic respiration, bursts of activity)

Slow fibers (Type 1)

very dark skeletal muscle. lots of myoglobin, postural muscles, oxidative - prolonged activity

Load

weight that opposes contraction (ex: lifting weights at gym)

Axon hillock

where the axon exits the soma, and where action potentials are generated

Equilibrium potential

(Ex)= concentration gradient and electrical potential are equal and opposite Net flux = influx - efflux So at Ek there is no net flux of K+ Ex = what would the charge of the cell be if the membrane was only permeable to one type of ion and the cell was allowed to just balance itself out?

This question refers to Figure 2. At which point are the votage gated sodium channels closed? Answers: 1 2 3 4

1

Z discs

Boundaries between sarcomeres

While characterizing the effects of medical marijuana, researchers have discovered a new type of ion channel that contains a binding site for the active ingredient, THC, on the outside of the cell. This new receptor could be classified as: Answers: A ligand gated ion channel A voltage gated ion channel A nociceptor A mechanically gated ion channel A stress gated ion channel

A ligand gated ion channel

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: Answers: An accelerated repolarization phase A longer repolarization phase A more negative threshold No depolarization An accelerated depolarization phase

A longer repolarization phase

Which of the following molecules is/are bound to the myosin head when it is in the low energy conformation, immediately after the power stroke? Answers: ATP ADP ADP + Pi Nothing

ADP

what would result from inhibiting opening of Na channels?

Action potentials cannot fire A great increase in extracellular K concentration can cause depolarization and a firing of AP (Fugu example)

During excitation contraction coupling, ions move into the sarcoplasmic reticulum by _______________ ; Ions move out of the sarcoplasmic reticulum by _______________; Answers: Diffusion; Active Transport Active Transport; Diffusion Active Transport ; Active Transport Diffusion;Diffusion

Active Transport; Diffusion

Increasing intensity of a pressure stimulus (applied to the same spot on your finger) is coded by ____ . (Assume threshold is met.) Answers: Increasing amplitude of receptor potential Increasing frequency of afferent action potentials Both of the above Neither of the above

Both of the above

Passive transport:

All channels (i.e. ligand gated, voltage gated, simple and facilitated/carrier diffusion) No energy required; driven by entropy

Schwann cells function to Answers: Secrete myelin in the peripheral nervous system Protect and support myelinated axons Protect and support unmyelinated axons All of the above

All of the above

The ability to precisely localize the origin of a stimulus is enhanced by ____________ . Answers: Overlapping receptive fields Small receptive fields Lateral inhibition wiring (neurons) at synapse sites in ascending pathway All of the above

All of the above

Which of the following is/are true about membrane potential? Answers: It is measured experimentally by comparing the inside of the cell relative to the outside It is due to unequal concentrations of ions inside and outside the cell It changes when ions move across the plasma membrane All of the above

All of the above

Muscles can generate additional force by:

Answers: Increasing the frequency of twitch Stimulating more motor units Recruiting larger motor units All of the above

UNLIKE nuclei, ganglia _______ . Answers: Consist of white matter Consist of gray matter Are located in the CNS Are located in the peripheral nervous system

Are located in the peripheral nervous system

dermatomes

Areas of innervation by same axons/spinal root

Saturation point

As the saturation of the solute/ion increases, so does the rate at which it is transported The point at which the rate stabilizes despite increasing concentration is called the SATURATION POINT This results from the number of binding sites at each carrier protein If all the binding sites are full, then no more solutes can bind, therefore saturation of solute will increase and things can get "backed up" I.e. hand-holding crossing guard analogy; why you urinate water soluble vitamins; etc.

Components of the NMJ

Axon terminal (synaptic knob) Synaptic vescicles (release neurotransmitter) Motor end plate (area of muscle that forms synapse with nerve) Synaptic cleft (space) ACh receptor (on motor end plate) AChE (breaks down ACh)

Alternating Access Model

Basically this model states that carrier proteins act in such a way that solutes bind cyclically, in such a way that only one side of the protein (on one side of the membrane) is open at a time (meaning only one area of a solute binding site is available at any given time) This also means that carrier protein is never a completely open tunnel between two sides of membrane** These are called CONFIRMATION CYCLES

Carriers vs. Channels

Both are proteins in cell membrane Carriers require interaction of ion with protein and can be passive or active Channels are passive Ion channels are faster than carrier proteins (ion binding is not required, so the process is less complex)**

At the axon terminal...

Ca2+ channels open when AP reaches them, allow influx of Ca ions, which allow the release of the neurotransmitter into the synaptic cleft Influx of Ca2+ moves vescicles to presynaptic membrane Ligand-gated channels on postsynaptic membrane have receptors for neurotransmitters AP changes to electrical signal once reaches soma of next neuron

The muscle contraction cycle:

Calcium ions initiate troponin binding to tropomyosin to release binding site ATP binds to myosin which breaks crossbridges Myosin head as ATPase (enzyme that breaks down ATP) The myosin then enters "cocked" phase (high energy state) when it is bound to ADP and P Myosin releases P, untwists and changes shape, and then slides the filaments ADP is released and process starts over This keeps happening until muscle is fully contracted **myosin walks on actin animation If you can't produce ATP your muscles can't relax (rigor mortis)

Calcium Cycling

Calcium leaves SR PASSIVELY Aids in muscle contraction then is released Brought back into SR via PRIMARY ACTIVE TRANSPORTER (via SERCA which is a pump requiring ATP) which allows muscle relaxation

Ions

Charged particles.

In the nervous system, communication through the synapse is most often: Answers: Chemical Mechanical Electrical None of the above

Chemical

How is RMP maintained?

Concentration gradient sends molecules in one direction while electrical forces pull them back in the other direction (TUG OF WAR ANALOGY) More positive ions being moved out, the more negative it gets, therefore the more ions get pulled back in This is how RMP is maintained!!!!!!!!************

Sensory system

Division with sensory receptors, their neural pathways, and the CNS neurons that process signals

Some primary afferent neurons synapse directly with dendrites of alpha motor neurons in the spinal cord. The afferent axons enter the spinal cord via the ____________ and the synapse would be located in the __________ of the spinal cord. Answers: Dorsal root; dorsal root Dorsal root; ventral horn Ventral root; dorsal horn Dorsal root; ventral root

Dorsal root; ventral horn

The touch receptors activated during a two-point discrimination sensory test (like we did in class) are examples of ____________ . Answers: Photoreceptors Exteroceptors Chemoreceptors Proprioceptors Interoceptors

Exteroceptors

Potassium reaches its equilibrium potential when there are equal concentrations of sodium inside and outside the cell Answers: True False

False

Order the following structures from LARGEST to SMALLEST: Answers: Fascicle > Myofibril > Muscle Fiber > Sarcomere Muscle Fiber > Fascicle > Myofibril > Sarcomere Fascicle > Myofibril > Sarcomere > Muscle Fiber Myofibril > Fascicle > Muscle Fiber > Sarcomere Fascicle > Muscle Fiber > Myofibril > Sarcomere

Fascicle > Muscle Fiber > Myofibril > Sarcomere

Which of the following statements is TRUE about graded potential: Answers: Graded potentials spread by diffusion Graded potentials always reach threshold Graded potential is the result of a positive feedback loop Graded potentials are produced when membrane potential reaches threshold All of the above

Graded potentials spread by diffusion

What is a muscle?

It is bundles of fascicles, which are bundles of muscle fibers/cells, all wrapped up in connective tissue Inside a single muscle cell, you have tubes of myofibrils bundled and tubelike contractile proteins Myoglobin binds oxygen to tissue (more myoglobin, more oxygen)

How Na/Glu pump and Na/K pump work together

Na/Glu symport uses Na gradient to bring in Glu Facilitated diffusion brings Glu out of cell Na/K pump brings Na out of cell to keep concentration low so that the process can continue

Resting Membrane Potential (Vm):

Net flux of ALL ions equals zero Steady state, NOT an equilibrium

Axons traveling together in the CNS make up _____________ . Answers: Ganglia Gray matter Nuclei Nerves Tracts

Tracts

Muscles in chicken legs that are constantly used for sustained contractions (e.g. posture) would be made primarily of _______ muscle fibers ("dark meat"), while the breast muscles, which are used for short intense bursts of wing flapping ("white meat") would primarily consist of ______ muscle fibers. Answers: Type 1 (oxidative); Type 2b (anaerobic) Type 1(oxidative);Type 1(oxidative) Type III (Delicious); Type III (Delicious) Type 2b (anaerobic) ; Type 2a (Intermediate) Type 2b (anaerobic); Type 1 (oxidative)

Type 1 (oxidative); Type 2b (anaerobic)

Afferent neurons carrying information about touch from your finger, including two-point discrimination; are categorized structurally as ___________. Answers: Unipolar neurons Multipolar neurons Bipolar neurons Mechanoreceptors Interneurons

Unipolar neurons

This question refers to Figure 2. Which of the following correctly describes the events taking place during phase 5 (hyperpolarization)? Answers: Voltage gated potassium channels are closed; Leaky Potassium Channels are closed Voltage gated potassium channels are open; Leaky Potassium Channels are open Voltage gated potassium channels are closed; Leaky Potassium Channels are open Voltage gated potassium channels are open; Leaky Potassium Channels are closed

Voltage gated potassium channels are open; Leaky Potassium Channels are open

What would happen if you were given a drug that blocked the binding of ACh?

Weakening of graded potential, no contraction of skeletal muscles

If an electrode is placed in the middle of an axon at resting membrane potential, and an above-threshold depolarization is applied, action potentials: Answers: Will start at that point and travel in both directions in the axon. Will start at that point and proceed only toward the cell body. Will start at that point and proceed only toward the axon terminal. Will not occur.

Will start at that point and travel in both directions in the axon.

Rate of transport graph

Y axis: rate of transport X axis: Concentration of transported substance Plateau point in line: Vmax/Point of saturation

The concentration of cation X(+) inside the cell is 150mM, and it's concentration outside the cell is 75mM. The equilibrium potential for cation X would be: Answers: Zero Negative Positive Equal to resting membrane potential

Zero

Thin filament

actin (rope-like, made of little spheres)

Active Electric Signals:

action potentials (long distance) A burst of electrical activity/currents that is all or nothing Starts at the axon hillock which has highest density of Na channels Opening of sodium channel causes rapid and severe depolarization until the peak positive potential is reached At peak, K permeability is increased and Na permeability is decreased to repolarize, and eventually hyperpolarize Resting membrane potential is reached again after K channels close Occurs rapidly, usually involves voltage-gated channels

Myofibrils

are numerous, and are made up of contractile structures (sarcomeres) which are repeating segments

Receptive field

area where when stimulated, activates one afferent neuron

I band

area with ONLY thin filament

H zone

area with only thick filament

at which point in the neuron does the analog signal convert to digital? (graded to action)

at the first node of ranvier

muscle contraction is completely dependent on...

calcium

Two classes of membrane transport proteins

carriers and channels - Both form continuous protein pathways across the lipid bilayer - Whereas transport by carriers can be either active or passive, solute flow through channel proteins is always passive

How do solutes/ions get through the membrane?

carriers and transporters (same thing, different names; these are the proteins that make up tunnels in cell membranes) or ion channels

Exteroceptors

come from outside stimuli

Movement of molecules against concentration gradient requires

energy

Muscle tension

force created by muscles

Activation gate

has a charge sensor which will open slowly until it reaches threshold, at which point it will open completely

Leaky potassium channels

help by easily letting K out

T Tubules

little pits in membrane of muscle to reach deep into tissue These are filled with extracellular fluid which aids in diffusion by bringing ions closer together

PEPD

lower threshold for action potentials - extreme pain disorder because threshold is low

Schwann's cells:

make myelin in the PNS

Interoceptors:

monitor internal things inside body

Antiport:

more than one type of molecule can be transported (in opposite directions**) (ex: K/na pump - sodium in potassium out)

Symport carrier/transporter protein

more than one type of molecule can be transported (in the same direction**) (ex: glu/na pump- both put into the cell in same direction)

Muscles are stimulated to contract by...

motor neurons (usually myelinated) which have a synapse between it and the muscle

Internode

myelinated segments

Thick filament

myosin (club-like)

Uniport carrier/transporter proteins

only transports one specific type of molecule

Sarcoplasmic reticulum

organelle that stores/releases calcium in muscle cells in response to voltage gated na channels opening

Voltage-gated Na channels

propagate action potentials via Na ions Closed Activated: open state, only time Na ions can pass through Inactivated: channels isn't closed but there's no Na permeability

Sensory (afferent) neuron

sensory neurons to CNS (ex: being touched, brain receives this message) - multipolar

Photoreceptors

sensory receptor - light (rods and cones)

Nociceptors

sensory receptor - pain

Chemoreceptors

sensory receptor - smell, taste, blood pH

Thermoreceptors:

sensory receptor - temperature

Mechanoreceptors:

sensory receptor - touch, pressure, vibration, sound waves

Saltatory conduction:

signal pauses at node and goes quickly through internode (there is no "jumping" of the AP)

Axon terminal

sometimes myelinated, used to send signal to next dendrite, forms synapses with other cells

Muscle tone

steady low level contraction that acts as stabilizing force (maintains general muscle health) Percentage of muscle fibers within group that are contracted Bigger load to move = muscle recruitment (more fibers involved)

Excitation-Contraction Coupling (EC)

the link between the excitation (AP/Na) of the muscle cell and the contracting of the filaments (get the Ca to release) It is the relationship between the sarcoplasmic reticulum and t tubules

Within sarcomeres, you have two filaments

thin filament, thick filament

Multipolar neuron

typical neuron, classic looking neuron - sensory - motor - interneurons

Nodes of Ranvier

unmyelinated segments

Neurons:

use changes in membrane potential to send signals in the form of action potentials They have high longevity, high metabolism (need ATP, have lots of pumps), and are non-mitotic (they don't regenerate)

Refactory period

when the voltage gated Na channels are closed and can't respond to stimuli (one segment at a time) Once first segment gets back to rest, another action potential can generate despite depolarization occurring further down the axon → THIS IS TO KEEP ACTION POTENTIALS MOVING IN ONE DIRECTION!!!

you have a cell with ion permeability of 0.2 for Cl, 0.1 for Na, and 1 for K. If you change permeability of Na to 5, what will happen to Vm?

will become more positive because Na has a positive charge