Download Muscle Tissue: Skeletal, Cardiac, and Smooth Muscle Properties and Functioning and more Quizzes Physiology in PDF only on Docsity!
Skeletal muscle is?
striated, voluntary, attached to bone, skin and fascia.Description; long striated cells with multiple nuclei. Function; contraction for voluntary movements TERM 2
Cardiac muscle is?
DEFINITION 2 is striated, involuntary, auto-rhythmic (built in pacemaker). Description; branching, striated cells fused at plasma membrane. Common location; wall of heart. Function; pumping of blood in the circulatory system TERM 3
Smooth muscle is?
DEFINITION 3 non striated, involuntary, hair follicles in skin, makes the walls of hollow organsdescription; long spindle shaped cells each with a single nucleus.Common locations; in hollow organsFunction; propulsion of substances along internal passageways TERM 4
5 properties of muscle tissue
DEFINITION 4 Excitability (response to chemicals released from nerve cells.Conductivity (propogate electrical signals over membrane)Contractility (shorten and generate force)Extensibility (stretch without damaging the tissue)Elasticity (return to original shape after being stretched) TERM 5
Structure and function of neuromuscular
junction?
DEFINITION 5 Each myofiber receives a single axon terminal. The neuromuscular junction is called the motor end plate. Specialized region of sarcolemma, the neurotransmitter is Acetycholine.
structure and function of sacromere?
from Z disc to Z disc is a functional unit called the Sacromere. TERM 7
proteins in the sarcomere.
DEFINITION 7 the proper alignment of filaments with a sarcomere is ensure by two proteins: titin and nibbling. TERM 8
Titin
DEFINITION 8 is a huge elastic molecule and the largest known protein, composed of more than 25,000 amino acids. A single titian molecule stretches from Z disk to neighboring M line. TERM 9
Titins functions
DEFINITION 9
- it stabilizes the position of the contractile filaments and 2. its elasticity returns stretched muscles to their resting left. Titin is helped by Nebulin TERM 10
Sarcomere split up
DEFINITION 10 M line, the band represents proteins that form the attachment site for thick filaments, equivalents to the Z disk for the think filaments, equivalent to the Z disk for the think filaments. each M line divides an A band in half. M is the abbreviation for mittel, he German word for "middle".see page 404
Excitation-contraction Coupling and
relaxation
411, figure 12. TERM 17
Excitation-Contraction coupling
DEFINITION 17 is the process in which muscle action potentials initiate calcium signals that in turn activate a contraction-relaxation cycle. TERM 18
Contraction relaxation
DEFINITION 18 at the molecular level, a contraction-relaxation cycle can be explained by sliding filament theory of contraction. In intact muscle, one contraction-relaxation cycle is called a muscle twitch. TERM 19
power stroke
DEFINITION 19 The power stroke repeats many times as a muscle fiber contracts. The myosin heads bind, push, and release actin molecules over and over as think filaments move toward the center of the sarcomere. TERM 20
cross bridge formation
DEFINITION 20 Contraction is initiated by cross bridge formation between globular myosin heads and binding sties on actin.
ATP
is hydrolyzed before binding: ADP and Pi.New ATP must bind for bond with actin to be broken. New ATP required before cross bridge can release (4 to 5). dephospho rylation of ATP is required before cross bridge can attach. TERM 22
Why is ATP required for skeletal muscle
contraction and relaxation?
DEFINITION 22 ATP binding - myosin dissociates from actin.ATP hydrolysis - myosin head swings and binds to a new actinRelease of Pi initiates the powerstroke TERM 23
what is a motor
unit?
DEFINITION 23 a motor unit consists of one motor neuron and all the muscle fibers it innervates. A muscle may have many motor units of different types. muscles are composed of multiple motor units. TERM 24
what is recruitment?
DEFINITION 24 more motor units are activated when greater contraction is required TERM 25
What are the 3 factors which affect muscle
tension in a whole muscle?
DEFINITION 25
Frequence of stimulation># of motor neurons units recruited>Degree of muscle strength
what is summation?
If the interval of a time between action potentials is shortened the muscle fiber does not have time to relax completely between two stimuli, resulting in a more forceful contraction, known as summation. see figure 12.16 page 419 TERM 32
What is treppe?
DEFINITION 32 the graduated series of increasingly vigorous contractions that results when a corresponding series of identical stimuli is applied to a rested musclecalled also staircase effect, staircase phenomenon. TERM 33
Why does a muscle fatigue?
DEFINITION 33 with continued rapid stimulation there is a build up of acidic compounds which affect protein functioning, a relative but not total lack to ATP, and ionic imbalances resulting from membrane activities. These factors lead to muscle fatigue: the gradual inability of the muscle to respond to stimulation. TERM 34
What is quantal summation?
DEFINITION 34 what happens? increases the number of motor units. In vitro: increase the voltage of the stimulus. TERM 35
What is Frequency summation?
DEFINITION 35 what happens? Activated myofibers are stimulated to complete tetanus (contractions build on one another producing tetanus).In vitro: increase the frequency of the stimulus
What are the factors that influence the force
that a muscle can exert?
rate of change in length (force-velocity relationship_length of muscle (length-tension relationship) TERM 37
Elastic elements in muscle
DEFINITION 37 muscle has both contractile components (sarcomeres, shown here as a gear and ratchet) and elastic components.see page 423 TERM 38
What is an isotonic contraction?
DEFINITION 38 means to stretch. Any contraction that creates force and moves a load is an isotonic contraction. ex: once the elastic elements have been stretched and the force generated by the sacromeres equals the load, the muscle shortens in an isotonic contraction and lifts the load. TERM 39
What is meant by a concentric contraction?
DEFINITION 39 in isometric contractions, muscles create force without shortening significantly. when the sarcomeres shorten in an isometric contraction, the elastic elements stretch. this stretching of the elastic elements allows the fibers to maintain a relatively constant length even though the sarcomeres are shortening and creating tension. TERM 40
What is meant by an eccentric contaction?
DEFINITION 40 lengthening contraction. contribue most to cellular damage after exercise and lead to delayed muscle soreness.
Phasic smooth muscle
muscles that undergo periodic contraction and realization cycles are said to be phasic smooth muscles. ex: the wall of lower esophagus, which contracts only when food passes through it.page 426 TERM 47
Tonic smooth muscle
DEFINITION 47 muscles that are continuously contracted are called tonic smooth muscles because they are always maintaing some level of muscle tone.page 426 TERM 48
What characterizes single-unit and muscle
coordination?
DEFINITION 48 are connected by gap junctions, and the cells contract as a single unitpage 427 TERM 49
What characterizes multi-unit smooth muscle
coordination?
DEFINITION 49 are not electrically linked, and each cell must be stimulated independently. TERM 50
what is the typical smooth muscle resting
potential?
DEFINITION 50 -50 to -60 mV
what is the major ion channel in smooth
muscle?
L-type voltage gated Ca channels(get less participation of Na in the AP) TERM 52
what ion was important for skeletal muscle
contraction, but is not nearly as important in
smooth muscle contraction?
DEFINITION 52 Na TERM 53
What controls contraction in smooth muscle
and what role does calmodulin?
DEFINITION 53 see page 430 figure 12. TERM 54
what role does MLCK play in contraction?
DEFINITION 54 increase following Ca entry from the extracellular fluid and Ca release from the sarcoplasmic reticulum. the Ca ions bind to calmodulin obeying the law of mass action. Myosin light chain Kinase, the Ca2+ -calmodulin complex then activates an enzyme called MLCK.see page 430 figure 12. TERM 55
what role does MLCP play in contraction?
DEFINITION 55 dephosphorylation of the myosin light chain by thhe enzyme Myosin light chain phosphatase (MLCP) decreases myosin ATPase activitypage 431
How do alpha1 receptors affect smooth
muscle contraction?
-couple to phospholipase C (PLC) via G-proteins-PLC catalyzes hydroysis PIP2 to IP3 and DAG-IP3 diffuses into SR to cause Ca release>binds to channel in SR membrane that is a member of the same super-family as ryanodine receptors (SR Ca release channel)>channel is ligand-gated and releases Ca when IP3 binds to open it
