BIO 351 TEST 3

________: composed of protein myosin that contains two heavy and four light polypeptide chains.

Thick filaments

________ in the utricle, saccule, and ampullae of the semicircular canals respond to motion of the head.

Sensory cells

________ are organized by motor programs.

Voluntary movements

________ depends on neurotransmitter released and type of receptor molecules.

Response

________: composed of fibrous protein actin.

Thin filaments

Load is greater than the ________ muscle can generate, so muscle neither shortens nor lengthens.

maximum tension

________ to cerebellum impairs standing, walking, or performance of coordinated movements.

Damage

________ are wrapped in myelin, which is compact and tight except near the nodes of Ranvier and at focal sites described as "incisures.

Peripheral axons

________ contain numerous Ca2+ channels that open to allow rapid influx of extracellular Ca2+.

Caveolae

________ spontaneously or in response to chemical stimuli that bind to G protein- linked receptors.

Depolarize

When nervous system stimulates ________, myosin heads are allowed to bind to actin, forming cross bridges, which cause sliding (contraction) process to begin.

muscle fiber

Shortening occurs when ________ generated by cross bridges on thin filaments exceeds forces.

tension

________ are spirally arranged, causing smooth muscle to contract in corkscrew manner.

Myofilaments

When a(n) ________ passes by, T tubule proteins change shape, causing SR proteins to change shape, causing release of calcium into cytoplasm.

electrical impulse

________ can be observed and recorded as a myogram.

Twitch

________ are specialized cell connections that allow depolarization to spread from cell to cell.

Gap junctions

________ contains pouchlike infoldings called caveolae.

Sarcolemma

________ line: line of protein (myomesin) that bisects H zone vertically.

M

________: ability to shorten forcibly when stimulated.

Contractility

________ on a dorsal root that contains cell bodies of afferent spinal nerve neurons.

Nodule

At the ________ ACh is released by exocytosis of synaptic vesicles at active zones in the nerve terminal.

neuromuscular junction

Actin is polypeptide made up of ________- shaped G actin (globular) subunits.

kidney

________: muscle fiber can not be stimulated for a specific amount of time, until repolarization is complete.

Refractory period

________ (responsiveness): ability to receive and respond to stimuli.

Excitability

Terminologies: Myo, mys, and ________ are prefixes for muscle.

sarco

Actin and ________ interact by sliding filament mechanism.

myosin

________ in the cleft rapidly terminates transmission by hydrolyzing ACh.

Acetylcholinesterase

________ consists of axon terminals, synaptic cleft, and junctional folds.

NMJ

________ flows across the synaptic cleft to reach receptors that are concentrated at the peaks of junctional folds.

Acetylcholine

________ integrates this information and modifies the motor outflow, exerting a coordinating and smoothing effect on the movements.

Cerebellum

________: muscle changes in length and moves load.

Isotonic contractions

________ are offset from each other, resulting in staggered array of heads at different points along thick filament.

▪ Myosins

________ proteins act as voltage sensors that change shape in response to an electrical current.

Tubule

________ binding causes either graded (local) potential or action potential.

Neurotransmitter

________ shows hexagonal arrangement of one thick filament surrounded by six thin filaments.

Sarcomere cross section

________ has an incidence of 1- 3 people per 100, 000 population.

ALS

________: control of voluntary movements, procedural learning, cognition, and emotions.

Basal ganglia

________: stripes formed from repeating series of dark and light bands along length of each myofibril.

Striations

________ does store intracellular Ca2+, but most calcium used for contraction has extracellular origins.

SR

________ (temporal) summation results if two stimuli are received by a muscle in rapid succession.

Wave

________ are stimulated by somatic motor neurons.

Skeletal muscles

Axons (long, threadlike extensions of motor neurons) travel from ________ to skeletal muscle.

central nervous system

control of voluntary movements, procedural learning, cognition, and emotions

Basal ganglia

dark regions

- A bands

lighter region in middle

▪ H zone

line of protein (myomesin) that bisects H zone vertically

- M line

lighter regions

- I bands

coin-shaped sheet of proteins on midline of light I band

▪ Z disc (line)

composed of fibrous protein actin

Thin filaments

composed of protein titin

Elastic filament

network of smooth endoplasmic reticulum tubules surrounding each myofibril

Sarcoplasmic reticulum

area formed from terminal cistern of one sarcomere, T tubule, and terminal cistern of neighboring sarcomere

Triad

muscle fiber cannot be stimulated for a specific amount of time, until repolarization is complete

Refractory period

events that transmit AP along sarcolemma (excitation) are coupled to sliding of myofilaments (contraction)

Excitation-contraction (E-C) coupling

simplest contraction resulting from a muscle fibers response to a single action potential from motor neuron

Muscle twitch

muscle changes in length and moves load

Isotonic contractions

muscle shortens and does work

Concentric contractions

muscle lengthens and generates force

Eccentric contractions

proteins that anchor filaments to sarcolemma at regular intervals

Dense bodies

responds to stretch only briefly, then adapts to new length

Stress-relaxation response

Morphological abnormalities in MG

NMJ disorders

* Part of the Motor System
* Named “extrapyramidal” to separate it from the tracts that originate in the cortex
* Originates in the brainstem
* Carries motor fibers to the spinal cord
* Responsible for involuntary movement

Extrapyramidal System

\

Peripheral nerve attached to the spinal cord

Spinal nerve

\

Axon directed toward central nervous system, conveying sensory information

Afferent axon

\

Nodule on a dorsal root that contains cell bodies of afferent spinal nerve neurons

Dorsal root ganglion

\

Axon directed away from the central nervous system, conveying motor commands to muscles and glands.

Efferent axon (eff ur ent)

\