| Question |
Answer |
| myofibrils |
one of the longitudinal parallel contractile elements of a muscle cell that are composed of myosin & actin |
| I band |
pale band across a striated muscle fiber that consists of actin; situated between 2 A bands, bisected by a narrow dark-staining Z line (isotropic band) |
| A band |
one of the cross striations in striated muscle that contain myosin filaments & appear darker under the light microscope & light in polarized light |
| alternating I & A bands along the length of aligned myofibrils give the muscle cell its ____ appearance |
striped |
| Z disc |
any of the dark bands across a striated muscle fiber that mark the junctions of actin filaments in adjacent sarcomeres |
| H zone |
narrow & less dense zone of myosin filaments bisecting the A band in striated muscle |
| M line |
a thin dark line across the center of the H zone, containing tiny protein rods that hold adjacent thick filaments together, in a striated muscle fiber (also called M Band) |
| sarcomeres |
any of the repeating structural units of striated muscle fibrils |
| ______ are aligned end to end like box cars |
sarcomeres |
| the arrangement of smaller structures, _____, within _____ produce the banding pattern |
myofilaments; sarcomeres |
| thick filaments |
a myofilament of 1 of the 2 types making up myofibrils; composed of the protein myosin |
| also called myosin filaments |
thick filaments |
| myosin |
fibrous globulin of muscle that can split ATP and reacts with actin to form actomyosin |
| thick filaments also contain _______ enzymes, which split ____ to generate power for muscle contraction |
ATPase; ATP |
| midparts of thick filaments are _____ but the end are _____ with small projections |
smooth; studded |
| cross bridges |
myosin heads; where they link the thick & thin filaments together during contraction |
| thin filaments |
composed of contractile protein actin, plus some regulatory proteins that allow/prevent myosin head-binding to actin |
| thin filaments are also called |
actin filaments |
| thin filaments are anchored to the ___ ___ |
Z disk |
| bare zone |
middle of a relaxed sarcomere; the H zone which lacks actin filaments & looks a bit lighter |
| when ____ occurs the actin-containing filaments slide towards each other into the center of the sarcomere; the light zones disappear because the ___ & ____ filaments are completely overlapped |
contraction; actin & myosin |
| it is the precise arrangement of the _____ in the myofibrils that produces the _____ pattern in skeletal muscles |
myofilaments; banding |
| sarcoplasmic reticulum |
SR - endoplasmic reticulum of skeletal striated muscle that functions especially as a storage & release area for calcium |
| the interconnecting ______ & sacs of the SR surround each _____ |
tubules; myofibril |
| excitability |
responsiveness or irritability; ability to receive & respond to a stimulus |
| contractility |
ability to shorten, forcibly, when adequately stimulated |
| extensibility |
ability of muscle cells to be stretched |
| elasticity |
ability to recoil & resume resting length after being stretched |
| motor unit |
motor neuron together with all the skeletal muscle fibers it stimulates |
| axon |
nerve fiber; long, thread-like extension of the neuron |
| axon terminals |
branches of axons which leading to junctions with sarcolemma of a different muscle cell |
| neuromuscular junctions |
junction of an efferent nerve fibers & the muscle fiber plasma membrane (myoneural junction) |
| nerve endings and the muscle cells' membranes never actually _____ |
touch |
| synaptic cleft |
space/gap between the nerve endings & the muscle cells' membranes, filled with interstitial fluid |
| a synaptic cleft is also called a |
synaptic gap |
| neurotransmitter |
chemical that transmits nerve impulses across a synapse |
| ______ is the specific neurotransmitter that stimulates skeletal muscle cells |
acetylcholine (ACh) |
| ACh ___ across the synaptic cleft & attached to the receptors that are part of the _____ |
diffuses; sarcolemma |
| action potential |
momentary reversal in the potential difference across a plasma membrane that occurs when a cell has been activated by a stimulus; also called spike potential |
| ________ by nerve causes myosin heads (molecules of protein containing ATP) to attach to binding sites on the _____ _____; Myosin heads then ______ to the next site of the thin filament |
activation; thin filament; bind |
| The calcium ion acts as the final trigger for _____ |
contraction |
| The result is that the muscle is _______ |
shortened (contracted) |
| graded responses |
the whole muscle reacts to stimuli with different degrees of shortening |
| muscle twitches |
single, brief, jerky contractions |
| fused/complete tetanus |
prolonged contraction of a muscle resulting from a series of motor impulses following one another too rapidly to permit intervening relaxation of the muscle |
| unfused/incomplete tetanus |
state that the muscle remains in until relaxation is achieved |
| creatine phosphate |
CP - unique high energy molecule found in muscle fibers but not other cells types |
| interactions of CP & ADP, as ATP is being depleted, result in a transfer of a high-energy phosphate group from CP to ADP; this allows for |
regenerating more ATP in a fraction of a second |
| aerobic respiration |
occurs in mitochondria & involves series of metabolic pathways that use oxygen; glucose is broken down completely to carbon dioxide & water; some energy captured as ATP when bonds are broken |
| oxidative phosphorylation |
synthesis of ATP by phosphorylation of ADP for which energy is obtained by electron transport & which takes place in the mitochondria during aerobic respiration |
| lactic acid |
dextrorotatory form of hygroscopic organic acid present normally in blood & muscle tissue as a product of the anaerobic metabolism of glucose & glycogen |
| anaerobic glycolosis |
occurring in the absence of free oxygen, the enzymatic breakdown of glucose /glycogen by way of phosphate derivatives with the production of pyruvic or lactic acid and energy stored in high-energy phosphate bonds of ATP |
| muscle fatigue |
when a muscle is unable to contract even in the presence of stimuli |
| oxygen deficit |
cumulative deficit of oxygen available for oxidative metabolism that develops during periods of intense bodily activity and must be made good when the body returns to rest |
| direct phosphorylation of ADP with creatine phosphate (CP) |
energy source: CPOxygen use: None Products: 1 ADP per CP, creatine Provision: 15 seconds |
| Aerobic respiration (oxidative phosphorylation) |
Energy Source: glucose, pyruvic acid, free fatty acids from adipose tissue, amino acids from protein catabolism Oxygen use: Required Products: 36 ATP/glucose. CO2, H2ODuration of energy provision: hours |
| Anaerobic glycolosis & lactic acid formation |
Energy source: glucose Products: 2ATP/glucose, lactic acid Provision: 30-60 seconds |
| Isotonic contractions |
The muscle shortens; "same tone"/tension; the myofilaments are successful in sliding movements, muscle shortens, and movements occur. |
| isometric contractions |
tension in muscles increase; muscle is unable to shorten; "same measurement"/length; myosin myofilaments are "spinning their wheels" and tension in muscles keep increasing; muscles trying to slide, but muscle pitted against some more/less immovable object |
| muscle tone |
some fibers are contracted even in a relaxed muscle; state of continuous partial contraction; contraction is not visible; result is a muscle remains firm, healthy & ready for action |
| good ___ ___important to maintain posture and produce body heat |
muscle tone |
| flaccid |
soft & flabby |
| atrophy |
wasting away |
| when the ___ ___ to a muscle is damaged/destroyed the muscle is no longer ______ & loses tone, becoming paralyzed |
nerve supply; stimulated |
| aerobic exercise |
results in stronger, more flexible muscles with greater resistance to fatigue; also makes the whole body metabolism more efficient, improves digestion, enhances coordination, strengthens bones & aides in better heart function. |
| endurance |
aerobic exercise creates |
| hypertrophic cardiomyopathy |
enlargement, especially of left ventricle, of the heart which may cause mitral insufficiency & blockages in the left ventricle |
| resistance/isometric exercises |
muscles are pitted against some immovable, or nearly immovable, object; causes the muscles to become larger; i.e. body builder vs. jogger |
| muscle movement |
is attained due to a muscle moving an attached bone |
| origin |
attachment to an immovable bone; end of the muscle that is attached to a fixed part |
| insertion |
attachment to a movable bone; end of the muscle that puts a body part into motion |
| muscles are attached to, at least, two points: |
origin; insertion |
| flexion |
bending; i.e. knee/elbow |
| extension |
straightening; i.e. knee/elbow |
| rotation |
motion around an axis; i.e. shaking your head no |
| abduction |
moving away; i.e. fanning the toes apart |
| adduction |
moving towards the midline; i.e. moving "fanned toes" together; add = together |
| circumduction |
combination of movements; i.e. circular movement of the arms at the shoulder joints |
| dorsiflexion |
lifting your foot up |
| plantar flexion |
pressing your foot down/pointing your toes down |
| inversion |
turning in of your foot |
| eversion |
turning our of your foot |
| supination |
palms of the hands facing anteriorly |
| pronation |
palms of the hands facing posteriorly |
| opposition |
thumb touches tips of the fingers on the same hand |
| prime mover |
muscle with the major responsibility for a certain movement |
| antagonists |
muscle that opposes/reverses a prime mover |
| synergist |
muscle that aids a prime mover in a movement & helps prevent rotation; stabilizes a joint |
| fixator |
stabilizes the origin of a prime mover; also called a specialized synergist |
| muscles are named based certain criteria, focusing on specific _____ or ____ characteristic |
structural; functional |
| muscle names are based on the location of the muscle ___ & ___ as well as the ___ & ___ of the muscle fibers |
origin; insertion; size; direction |
| muscle names are also based on the ___, ___ & ___ of the muscle |
shape; location; action |
| circular muscles |
pattern of the muscle when the fascicles are arranged in concentric rings & close by contracting; typically found surrounding exterior body openings |
| a general term for a circular muscle is a(n) |
sphincter |
| convergent muscle |
fascicles converge toward a single insertion tendon; triangular/fan-shaped |
| parallel muscle |
arranged so that the length of fascicles run parallel to the long axis of muscle; muscles are strap like |
| fusiform muscle |
spindle-shaped arrangement with expanded midsection |
| pennate muscle |
short fascicles attached obliquely to certain tendons |
| unipennate muscle |
fascicles insert into one side of a tendon |
| bipennate |
fascicles insert into opposite sides of a tendon |
| multipennate |
fascicles insert into several different sides of a tendon |
| muscle fascicle arrangement determines its ___ ___ ___ and ____ |
range of motion; power |
| muscle power depends on the total number of ___ ___ |
muscle cells |
| frontalis |
covers frontal bone, from cranial aponeurosis to skin of the eyebrows, where it inserts; motion of raising eyebrows |
| occipitalis |
posterior end of cranial aponeurosis; covers posterior aspect of skull & pulls scalp posteriorly |
| obicurlaris oculi |
fibers run in circles around the eyes; movements squint, blink, wink & closing the eyes |
| orbicularis oris |
circular muscles of the lips; "kissing muscle"; movements to close the mouth & protrude the lips |
| buccinator |
fleshy muscle running horizontal across the cheek, inserting into orbicularis oris; movements are flattening of the cheek (i.e. whistling) & compressing cheek to hold food between teeth during chewing "chewing muscle" |
| zygomaticus |
extends from corner of mouth to cheek-bone; "smiling muscle"; movement: raising corners of the mouth upward |
| masseter |
runs from zygomatic process of temporal bone to mandible, covering angle of lower jaw; closed jaw by elevating the mandible |
| temporalis |
fan-shaped muscle laying over temporal bone, inserts into mandible acting as a synergist of masseter while closing the jaw |
| platysma |
single sheet-like muscle covering the anteroelateral neck; originates from connective tissue covering of chest muscles & inserts in area around mouth; movement: pull corners of mouth inferiorly, producing downward sag of the mouth |
| sternocleidomastoid |
paired, two-headed muscles, on each side of neck; one arises from sternum & other from clavicle; muscle heads fuse before inserting into mastoid process of temporal bone; movement: contracting together they flex the neck bowing the head “prayer muscles" |
| torticollis |
during birth one of the sternocleidomastoid muscles are injured & develop spasms; also called wryneck |
| head and neck muscles are grouped into two categories: |
facial & chewing muscles |
| facial muscles |
insert into soft tissues as other muscle/skin |
Linnette Francois
on 2009-10-10
BIOL3326 Forms
