Exam 2 Flashcards
(242 cards)
What is found in cardiac muscle and is made of gap junctions that help transmit electrical signals to neighboring cells much quickly?
Intercalated discs
What is attached to bone, contractions are initiated by action potentials in MOTOR NEURONs, and is under VOLUNTARY control?
Skeletal muscle
What is found in walls of HOLLOW organs and TUBES; contraction supports internal movements; controlled by autonomic nervous system, hormones, other signals; and is controlled by INVOLUNTARY movement?
Smooth muscle
What is found in the heart, contraction propels blood through circulatory system; this is regulated by autonomic nervous system, hormones, and other signals; and is controlled by INVOLUNTARY movement?
Cardiac muscle
Label the structures in order from largest to smallest of skeletal muscle?
1) Muscle cell
2) Muscle fiber
3) Myofibril
4) Thick and Thin filaments
The thick and thin filaments are arranged in a pattern called?
Sarcomeres
What helps propagate action potentials through muscle cells?
T-tubule
1) Multi-nucleated
2) Many mitochondria
3) T-tubules
4) Myofibrils (thin and thick filaments) and sarcomeres
These are characteristics of what type of muscle?
Skeletal muscle
Sarcolemma
plasma membrane
Sarcoplasm
cytoplasm
sarcoplasmic reticulum
Smooth ER
What has heavy and light chains
Myosin
What is the light chain?
Myosin head
How many binding sites does the myosin (In skeletal muscle) head have and what is the function?
1) 2
2) one site binds to actin, and the other binds ATP
(Both together are called cross bridges)
Explain the mechanism of skeletal muscle contraction?
1) Motor neuron: generate AP
2) Ca2+ enters voltage-gated channels
3) Acetylcholine is released into neuromuscular junction
4) Acetylcholine binds to receptor and open ion channel on skeletal muscle
5) Na+ enters (causing depolarization of skeletal muscle)****
6) Local current between depolarized end plate and adjacent muscle plasma membrane
7) Muscle fiber AP initiation
8) Propagated AP in muscle plasma membrane
9) Acetylcholine degraded (Acetylcholinesterase)
what is defined as a motor neuron and all of the skeletal muscle fibers it innervates?
Motor unit
Can other motor units innervates other fibers of other motor units?
NO
This is the time it takes to assess the load by recruiting the muscle fibers
Latent period
(a better understanding is this is the period before excitation)
What are the drugs that block neuromuscular transmission and are sometimes used in small amounts to prevent muscular contractions during certain types of surgical procedures?
1) Succinylcholine
2) Curare (Rocuronium and Vecuronium)
This is agonist to ACE receptors and produces a DEPOLARIZING/desensitizing block?
(which means it is no longer activated, skeletal muscle will go into relaxation)
Succinylcholine
This is a nicotinic ACH receptor antagonist, a non-depolarizing neuromuscular junction blocking drug?
(which means it try’s to block ACH from binding to it and prevents the action of ACH causing relaxation)
Curare
(other similar drugs Rouronium and Vecuronium)
What blocks the release of acetylcholine from axon terminal, it is an enzyme that breaks down proteins of the SNARE complex that are required for the binding and FUSION OF ACH VESICLES with the plasma membrane of the axon terminal?
BOTOX (Botulinum toxin)
what is the sequence of events in which an action potential in the motor end plate of a muscle fiber causes actin-myosin cross bridge formation and contraction of the muscle?
Excitation-contraction coupling
How does action potentials in skeletal muscle fibers conduct their messages into the muscle fibers? This will initiate Ca2+ release from its storage site in the lateral sacs of what structure? Ca2+ ions then available for binding to Troponin an initiating the events of what? When Ca2+ increased in the ________________ near the actin and myosin muscle contraction occurs. At the end of an action potential, __________________________ return Ca2+ ions to the SR by active transport; this leads to decrease Ca2+ concentration around actin and myosin, which results in ________________________
1) Transverse tubules
2) Sarcoplasmic reticulum
3) Sliding filament mechanism
4) Sarcoplasm
5) Ca2+ -ATPase pump
6) Muscle relaxation