Muscular Tissue
What are the steps of the contraction cycle?
1. ATP hydrolysis. 2. Attachment of myosin to actin to form cross-bridges. 3. Power stroke. 4. Detachment of myosin from actin.
What are the properties of muscle tissue?
1. Electrical excitability 2. Contractility 3. Extensibitliy 4. Elasticity
What are the functions of muscular tissue?
1. Producing body movements. 2. Stabilizing body positions. 3. Storing and moving substances within the body. 4. Generating heat.
What are the three types of muscular tissue?
Skeletal, Cardiac and Smooth
Actin
Thin filament of protein found in muscles
tendon
a cord of dense regular connective tissue that attaches muscle to the periosteum of bone
Acetylcholine
a neurotransmitter that, among its functions, triggers muscle contraction
Myocin
a protien that forms Thick Myofilaments
endomysium
a sheath of areolar connective tissue that wrapes around individual skeletal muscle fibers
recovery oxygen uptake
amount of oxygen needed to restore the body's metabolic conditions back to resting levels after exercise
I band
area in the sarcomere where only thin filaments are present
H zone
area of only thick filaments
subcutaneous layer
areolar and adipose connective tissue that separates muscle from skin
twitch contraction
brief contraction of all the muscle fibers in a motor unit of a muscle in response to a single action potential in its motor neuron
fascicles
bundle of muscle fibers
What are the characteristics of cardiac muscle tissue?
cardiac muscle is striated, involuntary and forms most of the heart wall
M line
composed of supporting proteins holding thick filaments together at the H zone
aponeurosis
connective tissue elements extended as a broad, flat layer
eccentric isotonic contraction
contraction in which muscle lengthens
isometric contraction
contraction in which muscle tension is generated without shortening of the muscle
concentric isotonic contraction
contraction in which the muscle shortens
sarcoplasm
cytoplasm of muscle fibers
fascia
dense irregular connective tissue that lines the body wall and limbs and hold functional muscle units together
perimysium
dense irregular connective tissue that separates a muscle into groups of individual muscle fibers
the sliding filament theory
explains the mechanism of muscle contraction based on muscle proteins that slide past each other to generate movement.
sarcomere
functional unit of muscle contraction
muscle fatigue
inability of a muscle to maintain its strength of contraction or tension during prolonged activity
What are the characteristics of fast oxidative fibers?
intermediate in diameter, appear dark red due to large amounts of myoglobin and blood capillaries, can generate ATP by aerobic cellular respiration as well as by anaerobic glycolysis (due to high intracellular glycogen levels), and fast speed of contraction
transverse tubules
invaginations of the sarcolemma from the surface toward the center of the muscle fiber
wave summation
larger contractions resulting from stimuli arriving at different times
What are the characteristics of fast glycolytic fibers?
largest in diameter, generate the most powerful contractions (contain most myofibrils), appear white in color due to a low amount of myoglobin, blood capillaries, and mitochondria, generate ATP by glycolysis (contain large amounts of glycogens), and contract strongly and quickly
A band
middle area in the sarcomere where thick and thin filaments are found
muscle fiber
muscle cell
satellite cells
myoblasts that persist in mature skeletal muscle
What are the characteristics of skeletal muscle tissue?
skeletal muscle is striated, voluntary and move bones of the skeleton
What are the characteristics of slow oxidative fibers?
smallest in diameter, least powerful. appear dark red due to large amounts of myoglobin and blood capillaries, generate ATP (contain many large mitochondria) by aerobic cellular respiration, and have a slow speed of contraction
What are the characteristics of smooth muscle tissue?
smooth muscle is smooth (non-striated), involuntary, located in the walls of hollow internal structures and is also found in the skin
fused (complete) tetanus
sustained contraction of a muscle, with no relaxation between stimuli
unfused (incomplete) tetanus
sustained, but wavering contraction with partial relaxation between stimuli
neuromuscular junction
synapse between a motor neuron and a muscle fiber
Acetylcholinesterase
the enzyme that breaks down acetylcholine in the synaptic cleft
epimysium
the outermost connective tissue layer that encircles an entire skeletal muscle
Synaptic transmission
the process of transferring information from one cell to another at a synapse
stress-relaxation response
the smooth muscle action that allows the fibers to maintain their contractile function even when stretched
sarcoplasmic reticulum
Ca 2+ storing tubular system similar to the endoplasmic reticulum
myoglobin
oxygen-building protein found only in muscle fibers
sarcolemma
plasma membrane of the muscle fiber
motor unit recruitment
process of increasing the number of activated motor units
muscle tone
produced by the continual involuntary activation of small number of skeletal muscle motor units; results in firmness in skeletal muscle
Z discs
separates the sarcomeres from each other