A&P Lecture Exam 3

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.

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

All cells are polarized at the same charge differential.

Reject. Charge ranges from -50 to -100 mv depending on cell type.

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

Reject. The 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.

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

Reject. Ions need channels; there are three types of channels: ion, chemical, and voltage

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

Accept.

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

Accept.

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

Accept.

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.

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

Reject. They 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.

Reject. A motor unit is a motor neuron and ALL the muscle fibers it supplies.

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

Accept.

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

Reject. Incomplete tetanus: when contraction happens before full relaxation.

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

Accept.

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

Reject. Maximal contraction: when all muscle motor units are recruited.

The sodium-potassium pump is found throughout the entire sarcolemma

Accept.

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

Accept.

Ion pores are found throughout the entire sarcolemma.

Accept.

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

Accept.

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

Reject. The nerve impulse initiates this.

ATP energizes the terminal cisternae to release calcium.

Reject. The action potential initiates this.

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

Accept.

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.

The movement of the myosin head is called the power stroke

Accept.

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

Reject. This occurs during the power stroke.

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

Accept.

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

Reject. 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

Reject. Response requires a strong stimulus here.

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

Reject. latent period is delay between stimulus and response

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

Accept.

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

Reject. Isometric contraction: Tension increases until peak tension, no moving thin filaments.

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

Reject. This 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.

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

Accept.

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

Reject. Motor units must stimulate everything in their unit.

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.

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

Accept.

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

Accept.

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.

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

Accept.

In weight-bearing muscles, motor neurons are large

Reject. Motor UNITS are large, not motor neurons

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

Reject. Purpose is low grade contractions

Both concentric and eccentric contractions are always isotonic

Accept.

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.

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.

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

Accept.

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

Reject. it controls 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.

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

Accept.

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.

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

Accept.

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

Accept.

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

Accept.

The biosynthetic center of a neuron is its nucleus.

Reject. ***add why***

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

Accept.

Dendrites: The part of an astrocyte which attaches neurons to capillaries.

Reject. Dendrites: ***add definition***

Saltatory conduction: electrical signals initiated by satellite cells

Reject. Saltatory conduction: ***add definition***

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

Accept.

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.

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

Accept.

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

Reject. ***add definition***

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

Accept.

Structurally, interneurons are classified as association neurons.

Reject. They are classified as such FUNCTIONALLY

Bipolar neurons are both afferent and efferent.

Reject. ***add why***

Large motor neurons are usually myelinated and multipolar.

Accept.

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

Accept.

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

Accept.

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

Reject. they are part of the PNS, not the CNS.

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

Accept.

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

Accept.

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.

Interneurons are also in nerves.

Reject. Interneurons are only in the CNS.

Nerves are just axons, no cell bodies or dendrites.

Accept.

(about the sodium potassium pump) It is an integral protein with 2 different ion binding sites as well as 2 different shapes.

Accept.

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

Reject. ***add why***

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.

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

Accept.

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.

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

Accept.

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

Accept.

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

Accept.

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

Accept.