Chapter 9 Review Flashcards
fascia
-Sheet of dense connective tissue that encloses a muscle
myosin
- Protein that, with actin, forms the filaments that interact to contract muscle fibers
actin
-Protein in a muscle fiber that forms the thin filaments that slide between filaments of the protein myosin, shortening the muscle fibers
tendon
-Muscle to Bone
ligament
-Bone to Bone
aponeuroses
-Muscle to Muscle
myofibrils
-Overlapping parallel groups of thick and thin filaments in a repeating pattern; the underlying basis for the striation pattern
sarcomeres
-A repeating patter of units formed from striations
I bands
- light bands
- composed of thin actin filaments held by direct attachments to Z lines, which are in the middle of the I bands
Z lines
-Found in the middle of I bands
H zones
- part of the A bands
- consists only of thick filaments
A bands
- dark bands
- thick myosin filaments overlapping thin actin filaments
- includes: H zones and M lines
M lines
- part of the A bands
- consists of proteins that help hold the thick filaments in place
troponin
-three protein subunits and are attached to actin
tropomyosin
-rod-shaped and occupy the longitudinal grooves of the actin helix
sarcoplasmic reticulum
- corresponds to the endoplasmic reticulum. Membranous channels in the sarcoplasm of a muscle fiber that surrounds each myofibril and runs parallel to it.
transverse tubules
- A set of membranous channels that extends into the sarcoplasm as invaginations continuous with the sarcolemma and contains extracellular fluid
triads
-Region where the actin and myosin filaments overlap
neurotransmitters
- Biological messenger molecules that convey neural information
lower motor neurons
- Neurons that control effectors, including skeletal muscle fibers.
- Normally a skeletal muscle fiber contracts only upon stimulation by its motor neuron
neuromuscular junctions
- The synapse where a motor neuron axon and a skeletal muscle fibers.
- Here the muscle fiber membrane is specialized to form a motor end plate, where nuclei and mitochondria are abundant and the sarcolemma is extensively folded.
motor end plate
- Where nuclei and mitochondria are abundant and the sarcolemma is extensively folded.
synaptic cleft
- A small gap that separates the membrane of the neuron and the membrane of the muscle fiber
Acetylcholine(ACh)
- The neurotransmitter that motor neurons use to control skeletal muscle contraction.
myosin crossbridges
-A myosin head can attach to an actin binding site forming a cross-bridge, and bend slightly, pulling on the actin filament
sliding filament theory
- When sarcomeres shorten, the thick and thin filaments do not change length
ATPases
- An enzyme found in myosin heads
- it catalyzes the breakdown of ATP to ADP and a phosphate
lactic acid threshold
- anaerobic threshold
- glycosis breaks down glucose molecules to yield pyruvic acid, which would normally enter the citric acid cycle.
lactic acid
- dissociates rapidly to form lactate ion and hydrogen ion, both of which leave muscle cells by facilitated diffusion
- created from pyruvic acid when the oxygen supply is low
threshold stimulus
-the fiber remains unresponsive until it reaches a certain strength of stimulation
skeletal muscle
- multiple nuclei
- transverse tubules
- triads
- voluntary
cardiac muscle
- single nucleus
- transverse tubules
- intercalated disks
- diads
- involuntary
smooth muscle
- single nucleus
- lacks transverse tubules
- involuntary
intercalated disks
-Complex intercellular junctions that include components of desmosomes and gap junctions
peristalsis
- Alternare contractions and relaxations of the longitudinal and circular muscles.
- In the intestines it pushes food down the digestive tract
motor unit
- Together a motor neuron and a muscle fiber control it
synaptic vesicles
-tiny vesicles that stores neurotransmitters
