Skeletal Muscle And Nervous Tissue Flashcards
Contraction of muscle occurs when thin _____ microfilaments and thick _____ filaments slide past one another
Actin; myosin
Actin and myosin filaments are organized into structures called ______
Myofibrils
What are the 3 types of muscle tissue?
Skeletal muscle
Cardiac muscle
Smooth muscle
[differences in distribution, structure, and function]
_________ muscle is striated, voluntary, utilized in movement and posture, and makes up 40% of the body mass
Skeletal
_________ muscle is non-striated, involuntary, visceral organ tone and movement function, found in walls of hollow viscera, and blood vessels (vasodilation and vasoconstriction)
Smooth
_______ muscle is striated, involuntary, and pumps blood through the cardiovascular system
Cardiac
Is skeletal muscle striated/unstriated? Voluntary/involuntary?
Striated
Voluntary
Is cardiac muscle striated/unstriated? Voluntary/involuntary?
Striated
Involuntary
Is smooth muscle striated/unstriated? Voluntary/involuntary?
Non-striated
Involuntary
Skeletal muscle cells are called _______
Myocytes
[may also be called myofibers or muscle fibers]
Groups of myofibers form _______
Fascicles
3 layers of CT organize myofibers into an organ (a skeletal muscle). What are they?
Endomysium
Perimysium
Epimysium
__________ are separated by CT called endomysium
__________ are separated by CT called perimysium
____________ is the CT layer that surrounds the entire muscle
Myofibers
Fascicles
Epimysium
T/F: skeletal muscle cells are mononucleated cylinders commonly referred to as myofibers
False - myofibers are MULTINUCLEATED
Skeletal muscle cells are multinucleated; where are these nuclei located and why?
Nuclei are located in the periphery of the cell because the cytoplasm is primarily occupied by myofibrils
What is the basic structural unit of the myofibril?
Sarcomere
Each cell has thousands of them
The ______ is the transparent sheath that envelopes the fibers of skeletal muscles
Sarcolemma
What organelle associated with myofibers functions in calcium storage?
Sarcoplasmic reticulum
______ _______ are invaginations of the sarcolemma
Transverse tubules (t-tubules)
__________ ________ = dilated ends of sarcoplasmic reticulum that release calcium which triggers muscle contraction
Terminal cisternae
A single sarcomere extends from one _____-line to another
Z
T/F: When a muscle cell contracts, EVERY sarcomere shortens
True
What are the 5 components of a sarcomere?
Z-line I-band M-line H-zone A-band
_______ = the part of the sarcomere that serves as the anchor site for thin actin filaments
Z-line
_________ = the part of the sarcomere that contains only actin filaments
I-band
________ = the part of the sarcomere that serves as the anchor site for thick myosin filaments
M-line
______ = the part of the sarcomere that contains only thick myosin filaments
H-zone
______ = the part of the sarcomere that contains overlap of thick and thin filaments plus the H-zone
A-band
Describe the sliding filament mechanism of a typical sarcomere
When a muscle cell contracts, the thin filaments slide past the thick filaments toward the center, bringing the z-lines closer together
Every myofibril in a muscle cell shortens at the same time, thus the entire muscle cell contracts
T/F: the sliding filament mechanism of sarcomeres involves changes in length of the thin and thick filaments, leading to shortening of the sarcomere with contraction
False! The thin and thick filaments do not change in length, instead the degree of overlap does!
What is required for actin binding and release during muscle contraction?
ATP hydrolysis
__________ is a regulatory protein associated with skeletal muscle contraction that runs in the groove formed by F-actin strands and binds to the troponin complex
Tropomyosin
What are the 3 proteins that make up the troponin complex?
Troponin T
Troponin I
Troponin C
What component of troponin binds the complex to tropomyosin?
Troponin T
What component of troponin inhibits the binding of myosin to actin?
Troponin I
What component of troponin binds calcium?
Troponin C
Troponin C is only found in ______ muscle
Striated
Muscle fibers are categorized by what 2 factors?
Type of contraction generated (differ in power, speed, duration)
ATP supply
What type of skeletal muscle fibers are also known as slow oxidative fibers?
Type I fibers
What type of skeletal muscle fibers are also known as fast oxidative fibers?
Type Ia fibers
What type of skeletal muscle fibers are also known as fast glycolytic fibers?
Type IIb
What are the 3 types of skeletal muscle fiber types?
Type I fibers (slow oxidative)
Type Ia fibers (fast oxidative)
Type IIb fibers (fast glycolytic)
What type of skeletal muscle fibers is the largest and most prevalent?
Type IIb fibers (fast glycolytic)
Which type of skeletal muscle fiber contains slow ATPase, is red due to increased myoglobin, contractions are slow and not powerful, and can contract for long periods of time without fatigue?
Type I fibers (slow oxidative)
Which type of muscle fibers have fast ATPases which provide power and speed, primarily anaerobic, contract for short bursts, and lack myoglobin?
Type IIb fibers (Fast glycolytic)
What type of skeletal muscle fibers are least numerous, fast ATPases, primarily aerobic respiration with low O2 delivery rate, and contain myoglobin?
Type Ia fibers (fast oxidative)
[note that they contain less myoglobin than slow oxidative fibers]
What are the 2 basic cell types associated with nervous tissue?
Neurons
Neuroglia
Neurons are specialized for conduction of electrical impulses. What are the 2 major parts to a neuron?
Cell body (aka soma or perikaryon)
Cell processes (dendrites and axons)
Neuron clusters in the PNS are referred to as ________
Ganglia
Neuron clusters in the CNS are referred to as ______
Nuclei
[but sometimes ganglia]
_______ are neuron support cells
Neuroglia
Which are larger: neurons or neuroglia?
Neurons are much larger
________substance is abundant in the RER, reflecting the need to make lots of neurotransmitters and protein to maintain the large size of the neuron
Nissl
What part of the neuron processes the electrical information?
Cell body
What part of the neuron carries electrical signals toward the nerve cell body?
Dendrites
What part of the neuron carries electrical signals away from the nerve cell body?
Axon
What part of the neuron is where the electrical signals are transferred from the axon terminal of the nerve to an effector cell?
Synapse
What are the 3 structural classes of neurons?
Multipolar - many dendrites, one axon
Bipolar - one dendrite, one axon
Unipolar - one cell process from which branches a single axon and single dendrite
What cell type forms myelin in the PNS?
Schwann cells
What 2 cell types surround neurons in the PNS?
Satellite cells (“orbit” body of neuron)
Schwann cells (form myelin)
T/F: axons in the CNS and PNS can be myelinated or unmyelinated
True
What cell type forms myelin in the CNS?
Oligodendrocyte
T/F: even unmyelinated axons are physically associated with Schwann cells and oligodendrocytes
True
What is the purpose of nodes between myelin sheaths?
Transmission signal jumps from node to node, increasing the speed of conduction
The organization of CT surrounding peripheral nerves is similar to that of skeletal muscle.
What is the term for the CT between axons?
Endoneurium
The organization of CT surrounding peripheral nerves is similar to that of skeletal muscle.
What is the term for the CT surrounding clusters of axons forming fascicles?
Perineurium
The organization of CT surrounding peripheral nerves is similar to that of skeletal muscle.
What is the term for the CT surrounding several nerve fascicles?
Epineurium
What are the 4 parts of a chemical synapse?
Presynaptic knob (axon terminal)
Synaptic cleft
Presynaptic membrane
Postsynaptic membrane
_______ _____ in the presynaptic knob contain a neurotransmitter that’s released into the synaptic cleft by exocytosis
Synaptic vesicles
The neurotransmitter released from synaptic vesicles in the presynaptic knob bind to receptors on the postsynaptic membrane, stimulating the postsynaptic cell.
What are some examples of neurotransmitters?
Acetylcholine
Noradrenaline
T/F: every skeletal muscle cell, cardiac muscle cell, and smooth muscle cell receive an axon terminal
False: every skeletal muscle cell receives an axon terminal but not all cardiac or smooth muscle cells are directly innervated
What structure between axon and muscle cell allows entire muscle to contract vs. just one muscle cell?
Motor end plate
What structures associated with muscle cells monitor changes in length, rate of change, and tension of muscle?
Muscle spindle receptors
_________ fibers = specialized fibers inside the muscle spindle
Intrafusal
What are the 2 types of intrafusal fibers?
Nuclear bag fibers
Nuclear chain fibers
What type of intrafusal fibers are wrapped at their ends by type II nerve fibers and detect static muscle length?
Nuclear chain fibers
What type of intrafusal fibers are wrapped at the center by type Ia nerve fibers and detect change in length and degree of tension?
Nuclear bag fibers
_________ fibers = muscle fibers outside the muscle spindle
Extrafusal
What is the major type of extrafusal muscle fibers?
Alpha motor fibers