Anatomy and Physiology Chap 10-11

The amplitude (size) of a graded potential is determined by the stimulus strength, in other words, by the amount of neurotransmitter released at the synapse.

True

The contraction phase (cross bridge cycle) of muscle fiber contraction begins when calcium ions bind to troponin

True

interneurons are located mainly within the CNS

True

Which fibers have large quantities of ATP, myoglobin, mitochondira, and a well-developed blood supply?

Type 1 fibers

Gray matter of hte spinal cords?

Unmyelinated cell body, axons and dendrites

Which of the following is NOT one of the mechanisms for synaptic transmission termination?

Uptake of neurotransmitter into postsynaptic neuron

Which of the following are NOT correctly paired?

Voltage-gated K+ channel / receptor for acetylcholine

The channels that open when the axolemma reaches threshold depolarization are the:

Voltage-gated Na ion channels (Voltage-gated Na ion channels open at the threshold depolarization and Na influx causes a rapid depolarization to +30 mV.)

Ion channels that open and close in response to a change in membrane potential are called

Voltage-gated channel

Types of channel

Voltage-gated sodium and potassium ion channels open or close during action potential Voltage-gated calcium ion channels trigger exocytosis of synaptic vesicles Leak channels and Na+/K+ pump generate and maintain resting membrane potential

Metabotropic receptors

- G protein: make second messenger - Second messenger: cAMP

Smooth muscle

- Has dense bodies connected to intermediate filament - No myofibrils or sarcomere - Can contract 80% of its resting length - Capable of a latch state

All of these are true

- There is no mechanism to regulate the amount of tension produced by a single motor unit by changing the number of fibers in that unit that are contracting - The amount of tension produced by an individual muscle fiber depends on the number of cross-bridges formed during contraction - The amount of tension produced in the skeletal muscle as a whole is determined by the frequency of stimulation and the number of muscle fibers stimulated

Specific events of muscle relaxation

1. Acetylcholinesterase degrades remaining ACh 2. Sarcolemma returns to resting membrane potential 3. Calcium ions are pumped back into the SR 4. Troponin and tropomyosin block actin active sites

Contraction of smooth muscle events

1. Influx of extracellular calcium ions that bind calmodulin 2. Activation myosin light chain kinase (MLCK) 3. Activation of myosin ATPase 4. Crossbridge cycle

Actin and myosin are both found in the:

A-band

Electrons that are removed from fuel molecules during aerobic catabolism are transferred to oxygen, producing

ATP

Which is directly responsible for transmitting an action potential from a motor neuron to a skeletal muscle fiber?

Acetylcholine

Has a refractory period and all or none amplitude Propagates long distance and short-lasting Ions flow through voltage-graded channel Na and K Triggered by a threshold potential; axon hillock and axon

Action potential

What type of neuron carries information toward the central nervous system (CNS)?

Afferent

Which of the following is FALSE?

An excitable membrane contains chemically gated channels and is therefore capable of generating and conducting an action potential.

Which of the following neuroglia would be more likely to form a brain tumor because of their ability to rapidly divide following brain injury?

Astrocyte

Disuse of skeletal muscle causes ______________, which is defined as a decrease in the number of myofibrils and the size of each myofibril, along with a decrease in oxidative enzymes.

Atrophy

Regulation of heart rate, blood pressure, and digestive functions and Involuntary control of smooth and cardiac muscles and glands are carried out by the

Autonomic Nervous System- ANS

The conducting region of the neuron is the

Axon

Most sensory neurons such as the ones found in the special sense organs are

Bipolar neurons

Structural neurons

Bipolar: 1 dendrite and 1 axon Pseudounipolar: one process extending from cell body Multipolar: 1 axon and multiple dendrites

Which of the following characteristics makes myelin such an excellent insulator for axons?

High lipid content

Which of these ions triggers exocytosis of synaptic vesicles

Calcium - Ca ions bind to a complex of proteins responsible for the exocytosis of synaptic vesicles.

Calmodulin binds ______ in smooth muscle cells, resulting in contraction of the tissue.

Calcium ion

What is the most metabolically active part of the neuron?

Cell body (Soma)

Single unit (visceral) smooth muscle cells are connected by gap junctions and contract as a single unit.

True

Which sequence of structures indicates the direction in which an electrical signal is carried in a typical multipolar neuron?

Dendrites, cell body, and axons

Separation of charges across the plasma membrane is called

Electrical gradient

Which of the following characteristics is not associated with Schwann cells?

Envelops parts of several axons with multiple processes

What is the ciliated neuroglial cell that functions to circulate cerebrospinal fluid (CSF secretion)?

Ependymal cell

What link the events at NMJ and contraction?

Excitation-contraction coupling

An example of an eccentric isotonic muscle contraction would be picking a pen up off of a table.

False

Ca2+ is released into the sarcoplasm from the T tubules of the triads

False

Glycolysis is the aerobic breakdown of glucose to produce two molecules of pyruvic acid that occurs in the mitochondria of a muscle cell.

False

Rheumatoid arthritis is inflammation from uric acid crystal accumulation in joints.

False

Skeletal muscle hypertrophy involves the development of more muscle fibers per muscle, and each fiber is larger, with more myofilaments and mitochondria.

False

Skeletal muscle is voluntary, striated, multinucleate and branching.

False

Temporal summation of graded potentials occurs when postsynaptic potentials arrive close to the same time from different presynaptic neurons.

False

The tibial and fibular collateral ligaments of the knee limit the anterior and posterior movement of the femur and tibia.

False

Which of the following is NOT part of the knee?

Fibulofemoral joint

Loss of K ions from the cytosol will have the same effect as

Gain of Cl ions (Hyperpolarizing local potentials can result from loss of K ions or gain of Cl ions.)

No refractory period and variable amplitude Propagate short distance and long-lasting Ligand, chemical and mechanical gated channel Cell body and dendrites

Graded potential

Batrachotoxin produced by certain species of frogs is a toxin that permanently opens voltage-gated Na ion channels. The results of exposure to batrachotoxin will be:

Inability to generate action potential (Since the axolemma will not be able to repolarize, the neuron will be unable to generate more action potentials.)

Nicotine is addictive because it causes dopamine-releasing neurons to fire more action potentials. Nicotine will therefore cause:

Increased level of dopamine in the synaptic cleft

Which of the following characteristics is not associated with cardiac muscle?

It has many peripheral nuclei

During an action potential, hyperpolarization is caused by:

K+ efflux (Voltage-gated K ion channels are slow to close and efflux of K ions after returning to the resting potential results in hyperpolarization.)

Postsynaptic potentials are:

Local potential

The binding of neurotransmitter to receptors on the motor end plate cause

Local potential

Which structure occurs at the center of each sacomere?

M line

Interneuron function

Majority of neurons; multipolar; relay info between sensory and motor neurons within CNS

A fascicle is a bundle of

Muscle Fiber

White matter of brain and spinal cords in the CNS?

Myelinated axons

Another name for muscle cells is

Myocyte

The sarcoplasm of muscle cells contain cylindrical organelles called _____, which make up 50-80% of its volume.

Myofibrils

Muscle fibers are formed by the fusion of multiple cells called

Myogenesis

Which of the following events will cause an EPSP- depolarization?

Na ions enter postsynaptic cell

Depolarizing local potentials are caused by an influx of:

Na ions via gated ion channels (Depolarizing local potentials are caused by stimuli that open gated Na ion channels and as a result Na ions enter the cytosol driven by the electrochemical gradient.)

What structure contains the bulk of the Schwann cell's cytoplasm and organelles?

Neurolemma

The site where a somatic motor neuron releases acetylcholine and stimulates skeleton muscle fiber is called

Neuromuscular Junction

The synapse of a motor neuron with a muscle fiber is known as the __________.

Neuromuscular Junction

Cluster of neuron cell bodies in the PNS? CNS?

PNS: Ganglia; CNS: Nuclei

Bundles of axons in the PNS? CNS?

PNS: Nerves; CNS: Tracts

All of the following are TRUE regarding neurotransmitters except

Removal of neurotransmitters from the synaptic cleft is not essential

During an action potential, the loss of potassium ions from the cell results in:

Repolarization

The Na+/K+ pump helps a muscle cell maintain a state of

Resing membrane potential

3 stages of voltage-gated Na channel

Resting state: inactivation gate open, activation gate close Inactivated state: inactivation gate close, activation gate open Activated state: inactivation and activation gate open

The flow of materials from the synaptic terminus to the cell body is termed _______________ axonal flow.

Retrograde

Axonal transport

Retrograde: axon terminal to cell body; back toward cell body Anterograde: cell body to axon terminal; away from cell body

What is the functional contractile unit of

Sarcomere

The _____ contains cytosol and all of the organelles in the muscle cell.

Sarcoplasm

The storage and release of calcium ions is the key function of the?

Sarcoplasmic reticulum- SR

What neuroglial cells surround and support the cell bodies of neurons and have intertwined processes that link them with other parts of the neuron?

Satellite cells

What structure found in the peripheral nervous system (PNS) promotes regeneration of a damaged axon?

Schwann cells

Which of the following effectors is controlled by the somatic motor division?

Skeletal muscle

Which division of the PNS carried the signals from bones, joints, and organs of vision to CNS?

Somatic sensory division

Which characteristic is not descriptive of skeletal muscle tissue?

Surround hollow organs

Which of the following are part of the rotator cuff?

Teres minor Supraspinatus Infraspinatus Subscapularis

A thin filament consists of two strands of F actin, in which the individual G actin molecules are held together by nebulin.

True

A toxin that increases the release of neurotransmitter at synapses or the prevents the closing of postsynaptic sodium channels would lead to the overstimulation of the postsynaptic neuron.

True

Acetylcholine is released from the synaptic terminus into the synaptic cleft as a result of calcium influx through voltage gated channels in the membrane of the neuron.

True

Action potential propagation in a neuron is one way, from the axon hillock, down the axon, to the synaptic termini because sodium channels exhibit an absolute refractory period.

True

An IPSP is a graded hyperpolarization caused by the binding of a neurotransmitter to a chemically-gated membrane channel.

True

During Wallerian degeneration, the axon and myelin sheath distal to the injury disintegrate and are digested by phagocytes.

True

Dystrophin links the thin filaments of the sarcomere to integral membrane proteins of the sarcolemma.

True

Each muscle cell runs the length of the muscle, and is attached to bone (usually) by tendons at each end via connective tissue membranes that run through the layers of the muscle.

True

Excitation-contraction coupling refers to the events that link the events at the neuromuscular junction and the start of the muscle contraction.

True

Fractures of the femoral neck or between the greater and lesser trochanters are more common than hip dislocations, especially in the elderly.

True

Hyperpolarization is an increase in the membrane potential of a neuron, which reduces the probability of producing a action potential.

True

Luxations may be accompanied by torn ligaments, damaged articular cartilage and distorted joint capules.

True

Motor nerve axons branch to innervate each and every skeletal muscle fiber.

True

Nebulin is a protein that anchors the thin filaments to the Z discs.

True

Which structure occurs at the border between 2 adjacent sarcomeres?

Z discs

In order to keep a resting membrane potential, the active transport of the sodium and potassium pump must function to keep:

a high concentration of sodium outside the cell and a high concentration of potassium inside the cytosol

The _____ refractory period coincides with the period when Na+ channels are open or inactivated, before their return to the resting state.

absolute

In response to physical inactivity, we expect to see muscle

atrophy

In a _________________ neural circuit, several neurons relay information to a single neuron

converging

Depolarization to threshold during action potential propagation in axons is due to:

diffusion of Na ions down to the next segment of the axon (Diffusion of Na ions through the cytosol down to the next segment of the axon will depolarize this segment to threshold and it will generate an action potential.)

Activities such as cycling, jogging, cross-country skiing and distance swimming are all types of

endurance training

What is the basic function of all muscle tissue?

generate muscle tension

The acetabular labrum enhances the depth of the socket in the _______ joint.

hip

The relative refractory period is caused by:

hyperpolarization (During the relative refractory period, the axolemma is hyperpolarized and therefore further away from threshold and less likely to produce an action potential.)

Muscle fatigue, the inability to maintain a given level of intensity of a particular exercise, can result from all of the following except:

increased availability of oxygen to muscle fibers

The type of contraction in which length of the muscle fibers does not change is called

isometric

A muscle contraction in which a muscle develops tension and the muscle shortens (as in lifting an object) is termed a(n) ___ contraction.

isotonic concentric

What type of contraction requires the greatest amount of tension?

isotonic eccentric

A single motor neuron together with all the skeletal muscle fibers it innervates is called a

motor unit

Even when a muscle is at rest, it still has some degree of tension. This small amount of tension produces what is known as

muscle tone

If a neuron simultaneously receives a stimulus that results in local depolarization of 10 mV and a stimulus that results in a local hyperpolarization of 10 mV, the net effect would be

no net change in membrane potential (The depolarization caused by gain of positively charged ions will be cancelled out by the equal strength hyperpolarization resulting from loss of positively charged ions or gain of negatively charged ions.)

Through which ATP-generating mechanism can long-lasting muscle contractions be sustained?

oxidative catabolism

Smooth muscle propels materials through the hollow organs of the digestive, urinary and reproductive systems by a process known as

peristalsis

Which of the following choices is TRUE regarding an action potential in a muscle fiber?

potassium influx into the cell is responsible for the depolarization phase

The persistent increased rate of breathing following exercise and the time needed to return to the pre-exercise state is known as (the)

recovery period

The activation of additional motor units in order to produce a contraction with greater tension is known as

recruitment

Epilepsy

recurrent episodes of abnormal, disorganized electrical activity in brain (seizures)

The return of the sarcolemma to resting electrical conditions by the efflux (exit) of K+ through open voltage-gated channels is termed

repolarization

Activities that involve the use of free weights is a type of:

resistance training

The myofibril is the contractile organelle of skeletal muscle, and the ____________ is the functional (contractile) unit.

sarcomere

Diverging circuit

single input neuron axon; branches out to make contact with multiple postsynaptic

The predominant type of smooth muscle in the body found in nearly all hollow organs is the

single-unit smooth muscle

Which of the following is FALSE regarding types of muscle fibers?

slow oxidative fibers have little myoglobin, few mitochondria and blood vessels

Smooth muscle forms rings called ___________ that are usually contracted but relax periodically to allow substances to pass through them.

sphincters

If a drug inhibits neurotransmitter receptors on the postsynaptic cells:

the neurotransmitter will have no effect in the postsynaptic cell (If the neurotransmitter cannot bind to its post-synaptic receptors it will have no effect in the postsynaptic cell.)

Which contractile structure is attached to the Z disc?

thin filament

The elastic protein ________________ binds to the M line at the center of the sarcomere (within the thick filament) and to the Z discs at each end.

titin

In any skeletal muscle, some motor units are always active, causing muscle firmness, but not producing enough tension to cause movement. This is termed muscle

tone

Calcium ions bind to which regulatory protein?

troponin

Catecholamine neurotransmitters are synthesized from the amino acid

tyrosine

•amino acid neurotransmitters:

•Glutamate - most important excitatory neurotransmitter in CNS; binds to ionotropic postsynaptic receptors; opens channels that allow flow of both sodium and calcium ions; generate EPSPs in postsynaptic neuron •Glycine and GABA - both major inhibitory neurotransmitters; induce IPSPs on postsynaptic neurons by opening chloride ion channels; hyperpolarize axolemma

Neurotransmitter receptor

•Ionotropic receptors - components of ligand-gated ion channels; directly control movement of ions into or out of neuron when bind to neurotransmitter •Metabotropic receptors - within plasma membrane; associated with separate ion channel; connected to metabolic processes initiated when neurotransmitter binds

catecholamine subgroup (made from amino acid tyrosine)

•Norepinephrine (catecholamine; noradrenalin) - mainly in ANS; influences heart rate, blood pressure, and digestion; in CNS regulates sleep/wake cycle, attention, and feeding behaviors •Epinephrine (catecholamine; adrenalin) - also in ANS; similar functions as norepinephrine; more widely used as hormone by endocrine system. •Dopamine (catecholamine) - used extensively by CNS; movement coordination, emotion and motivation

3 main functional regions of neuron

•Receptive region - dendrites and cell body •Conducting region - axon •Secretory region - axon terminal

Functional neurons

•Sensory (afferent) neurons - carry information toward CNS; neuron cell bodies in PNS receive information from sensory receptors and relay information via axons to brain or spinal cord; usually pseudounipolar or bipolar •Interneurons (association) neurons - relay information within CNS between sensory and motor neurons; most neurons in body; multipolar; communicate with many other neurons •Motor (efferent) neurons - carry information away from cell body in CNS to muscles and glands; mostly multipolar

Biogenic amine: epinephrine, norepinephrine, dopamine, serotonin, histamine

•Serotonin - synthesized from amino acid tryptophan; most serotonin-secreting neurons are in brainstem; axons project into multiple areas of brain; functions include mood regulation, emotions, attention, feeding behaviors, and daily rhythms •Histamine - synthesized from amino acid histidine; regulation of arousal and attention

Division of nervous system

•Somatic sensory division (special sensory division) -carry signals from skeletal muscles, bones, joints, and skin; also from organs of vision, hearing, taste, smell, and balance •Visceral sensory division - transmit signals from viscera (heart, lungs, stomach, kidneys, and urinary bladder) •Somatic motor division - neurons transmit signals to skeletal muscle; voluntary control (aka voluntary motor division) •Autonomic nervous system (ANS) or visceral motor division: Neurons carry signals to thoracic and abdominal viscera; critical for maintaining homeostasis; Regulates secretion of certain glands, contraction of smooth muscle, and contraction of cardiac muscle; involuntary (aka involuntary motor division)

•Neuropeptides - group of neurotransmitters with wide variety of functions; must be synthesized in cell body and transported to axon

•Substance P - released from type C sensory afferents that carry information about pain and temperature; also released by other neurons in brain, spinal cord, and gut •Opioids - group of more than 20 neuropeptides; include endorphins, enkephalins, and dynorphins; all elicit pain relief; nervous system depressants •Neuropeptide Y - feeding behaviors; may mediate hunger or feeling full

•Summation - all input from several postsynaptic potentials are added together (EPSPs + IPSPs) to affect membrane potential at trigger zone

•Temporal summation - neurotransmitter released repeatedly from axon terminal of single presynaptic neuron; each local potential (EPSP) is short-lived; must be generated quickly to reach threshold and create action potential •Spatial summation - simultaneous release of neurotransmitters from axon terminals of many presynaptic neurons

Neuronal pools

•groups of interneurons within CNS •Composed of neuroglial cells, dendrites, and axons in one location and cell bodies in another location