Exam 3 (Comprehensive)

The resting membrane potential is produced by the loss of positive ions from the cell and the subsequent attraction of large negative proteins to the inner membrane surface.

accept; definition

All cells are polarized at the same charge differential.

All cells are polarized at a charge differential ranging from -50 to -100 mv depending on cell type.

At the neuromuscular junction, ligand channels open when activated by ATP

At the neuromuscular junction, ligand channels open when activated by acetylcholine.

Both Curare and the botulism toxin result in no change in the polarized state of the muscle cell.

accept; point to ponder

Some ions are soluble in the bilipid cell membrane and can diffuse into and out of the cell without channels.

Ions are not soluble in the bilipid cell membrane and need channels go in or out of the cell.

The permeability of a cell to an ion is often due to the number of channels for that ion.

accept; definition of permeability

A membrane potential is a voltage differential. Voltage is always electrical potential energy resulting from the separation of oppositely charged particles.

accept; synthesis definition of membrane potential and voltage

Neurons have a -70 mV membrane potential because they are permeable to some Na+ too. (text)

accept; definition from reading

Voltage-gated Na+ channels are found along the entire sarcolemma while acetylcholine receptors are only part of the sarcolemma at the neuromuscular junction (NMJ).

accept; remember picture that was drawn

Several pesticides cause continual, rapid muscle contraction by inhibiting the outflow of K+ (from pt to ponder)

Several pesticides cause continual, rapid muscle contraction, but do not inhibit the outflow of K+

To produce a tonic contraction, a motor unit will only stimulate some of the muscle fibers in the unit.

To produce a tonic contraction, the motor units will be contracted asynchronously

Muscle tension can change by varying which motor units are recruited, the frequency of stimulation of motor units or adding motor units.

accept; definition

Incomplete tetanus - when a motor unit is stimulated at the end of relaxation.

Incomplete tetanus - when contraction happens before full relaxation.

Muscle twitch - the response of a muscle to a single stimulus.

accept; definition

Maximal contraction - when the largest motor unit causes the contraction.

Maximal contraction - when all muscle motor units are recruited simultaneously

The sodium-potassium pump is found throughout the entire sarcolemma

accept; definition

Ligand channels are only part of the sarcolemma at the NMJ.

accept; remember the picture

Ion pores are found throughout the entire sarcolemma.

accept; remember the picture

Voltage gated Ca++ channels are found at the axon terminal.

accept; defintion

ATP initiates and moves the action potential along the skeletal muscle cell.

A nerve impulse initiates and moves the action potential along the skeletal muscle cell.

ATP energizes the terminal cisternae to release calcium.

The action potential initiates the terminal cisternae to release calcium.

Calcium binding to troponin initiates the movement of tropomyosin which then unblocks the active sites on G actin.

accept; part of E-C coupling

Calcium is not directly used to detach the myosin head but is necessary for the recocking of the head into its high-energy configuration.

accept; recocking is done in the presence of calcium

The movement of the myosin head is called the power stroke

accept; definition of the power stroke

Chemical energy is changed to mechanical energy when the myosin head forms a cross bridge.

Chemical energy is changed to mechanical energy during the power stroke

In the Sliding Filament Theory, the myofilaments slide when Ca+ is actively transported back into the sarcoplasmic reticulum (text).

accept; definition from reading

In a strong isometric contraction, all myosin heads attach at the same time and then don’t detach (evaluation)

In a strong isometric contraction, tension increases until reaching peak tension, muscle doesn’t shorten or lengthen.

Relative refractory period - the period following a stimulus when a muscle fiber will not respond to a second stimulus no matter how strong it is

Relative refractory period - the period following a stimulus when a muscle fiber will respond to a second stimulus if it a strong enough stimulus

Latent period - time after contraction until the initiation of the relaxation of the microfilaments

Latent period - time before contraction until the initiation of contraction of the microfilaments

Myosin ATPase - myosin acts as its own enzyme to produce its high-energy configuration

accept; definition

Isotonic contraction - the initial increase in muscle tension for a muscle to lift a load

Isotonic contraction - the increase in muscle tension until peak tension

The asynchronous contraction of motor units is called cross bridge cycling.

The asynchronous contraction of motor units is called tonic contraction.

Even if it is not damaged, a muscle that is overstretched will still produce less force, because there is so little overlap between thin and thick filaments.

accept; stretched stay stretched

Wave summation occurs when a muscle is stimulated before it is fully relaxed, but only after the absolute refractory period is completed.

accept; definition of wave summation

A whole muscle response is a graded response. This contrasts with a muscle fiber response, which normally either fully contracts or does not contract at all.

accept; definition

Changing the frequency of stimulation can produce tetanus. Varying (asynchronous stimulation) of the motor units recruited can produce a tonic contraction.

accept; definition

Muscle fibers vary in their twitch duration. A whole muscle twitch duration varies with the % of fiber types in the muscle.

accept; definition

In our class analogy, all students with the same color candy and the student in the front with that same color represented a motor unit. Dr. T was not considered part of the motor unit.

accept; recall demonstration

A motor unit in an ocular muscle has very few (4-10) fibers. This allows these muscles to perform fine movements.

accept; application

In weight-bearing muscles, motor neurons are large

In weight-bearing muscles, motor units are large

Muscle fibers in a motor unit are spread throughout the muscle to function for cross innervation in case of muscle damage.

Muscle fibers in a motor unit are not spread throughout the muscle to function for cross innervation in case of muscle damage.

Both concentric and eccentric contractions are always isotonic

accept; definition

In an eccentric contraction, thin filaments are sliding in an opposite direction than they do in a concentric contraction, but in both eccentric and concentric contraction, force is generated. (evaluation)

accept; definition

In an isometric contraction, tension in the muscle increases but the muscle does not change length even though the muscle is using ATP, myosin heads are making cross bridges, detaching, and making more cross bridges.

accept; definition

Unlike rats, all humans have “mixed muscles” but % of the fiber types vary from individual to individual

accept; application

The brain functions to integrate and control the sensory and motor nerves traveling in the spinal cord.

The brain functions to integrate and control the nerve impulses traveling in the spinal cord.

The peripheral nervous system has both sensory and motor components while the autonomic nervous system is entirely motor.

accept; definition

Seven cranial nerve pairs have afferent function while nine cranial nerves have at least some efferent function.

accept; synthesis of numbers

Cardiac muscle is sped up by the sympathetic division, but smooth muscle can be sped up by either sympathetic or parasympathetic depending on the organ.

accept; remember chart

Half the mass of the brain does not have the property of conductivity (synthesis)

accept; definition

Astrocytes and microglial cells are types of neuroglia and are not neurons.

accept; definition

Ependymal cells are only in the CNS and circulate cerebrospinal fluid in the brain and spinal cord.

accept; defintion

The biosynthetic center of a neuron is its nucleus.

The biosynthetic center of a neuron is its nucleus and its cytoplasm

Nuclei - clusters of neuron cell bodies in the CNS. Only motor and interneuron cell bodies are in nuclei.

accept; definition

Dendrites - the part of an astrocyte which attaches neurons to capillaries.

Dendrites - receive signals from other neurons, highly branched

Saltatory conduction - electrical signals initiated by satellite cells

Saltatory conduction - electrical signals generated at next node, appearance of jumping

Nodes of Ranvier - the spaces of unmyelinated areas of axons which are associated as a feature of the definition of “myelin sheath”

accept; definition

Schwann cells protect and electrically insulate the axon but the cells themselves do not directly cause an increase in the speed of a nerve impulse.

accept; definition

In a healthy myelinated axon, action potentials are only propagated at the nodes.

accept; definition

Multiple sclerosis (MS) is a genetic disorder that causes axons to atrophy.

Multiple sclerosis (MS) is a genetic disorder that causes the myelin sheath to atrophy

Loss of oligodendrocyte cells due to an autoimmune disease will reduce saltatory conduction in the CNS

accept; point to ponder

Structurally, interneurons are classified as association neurons.

Functionally, interneurons are classified as association neurons.

Bipolar neurons are both afferent and efferent.

Bipolar neurons have one dendrite and one axon

Large motor neurons are usually myelinated and multipolar.

accept; definition

The cycle of Na+ in and K+ out through voltage-gated channels along successive points on a membrane is an action potential (synthesis)

accept; definition of an action potential

Ion channel - non-gated integral protein in a cell membrane that allows diffusion (leakage) of a particular ion

accept; definition

Cranial nerves - nerves that are part of the central nervous system attached to the brain

Cranial nerves - nerves that are not part of the central nervous system attached to the brain

The D division - the parasympathetic part of the autonomic nervous system that dominates in digestive and reproductive functions.

accept; definition

Mixed nerves are parallel bundles of axons, of both sensory and motor neurons

accept; definition

There are 31 pairs of spinal nerves as part of the PNS and they are connected to the spinal cord (CNS) by two roots (which are also PNS). (synthesis)

accept; definition

Interneurons are also in nerves.

Interneurons are not in nerves.

Nerves are just axons, no cell bodies or dendrites.

accept; definition

The sodium potassium pump is an integral protein with 2 different ion binding sites as well as 2 different shapes.

accept; definition

When it is open to the interior of the cell, 3 Na+ bind and a phosphate from ATP energizes the pump.

When it is open to the interior of the cell, 3 Na+ bind to the pump.

K+ ions move by an “electrochemical gradient”. As they follow their concentration gradient, they are also simultaneously being repelled by a similarly charged ion (evaluation).

accept; explanation of gradients

Synaptic vesicles bind to the presynaptic membrane and neurotransmitter binds to receptors on the postsynaptic membrane at the NMJ.

accept; definition

Only the ends of axons contain neurotransmitters (true statement), and this is the reason for one-way transmission of nerve impulses because axons can propagate action potentials both directions if electrically stimulated elsewhere due to the position of voltage-gated Na+ channels (evaluation)

accept; synthesis

Multiple sclerosis is a disease in which a type of neuroglia is attacked by the body.

accept; point to ponder

“Scleroses” are plaques that can damage the axons (cause paralysis) and impair saltatory conduction (speed of transmission)

accept; point to ponder

Rigor mortis muscle shortening is due to an abundance of intracellular calcium.

accept; point to ponder

Rigor mortis muscle tightness is due to a lack of ATP.

accept; point to ponder