Skeletal Muscles & Nerve Tissue Flashcards
Muscle tissue is specialized for _________.
Contraction
Contraction occurs when thin _______ microfilaments and thick ________ filaments, organized into structures called ________ in the cytoplasm, slide past one another.
Actin
Myosin
Myofibrils
***Remember a group of Myofibrils make one Myofiber, which is one skeletal muscle cell!
What are the types of muscle tissue?
Skeletal
Smooth
Cardiac
This type of muscle tissue is striated and voluntary.
Skeletal muscle
This type of tissue is striated and involuntary.
Cardiac muscle
This type of tissue is non-striated and involuntary.
Smooth muscle
This type of muscle helps with movement and posture and makes up 40 percent of body mass.
Skeletal muscle
This type of muscle pumps blood through the CV system. It also contains intercalated discs.
Cardiac muscle
This type of muscle functions in visceral organ tone and movement, walls of hollow viscera, and blood vessels (vasodilation and vasoconstriction).
Smooth muscle
Skeletal muscle cells are called ________, myofibers, or muscle fibers.
Myocytes
A group of myofibers form a _________.
Fascicle
This is the layer of CT that surrounds individual myofibers.
Endomysium
A bundle of myofibers make a fascicle, and each fascicle is surrounded by what layer of CT?
Perimysium
Fascicles come together to form the whole muscle, and the entire muscle is surrounded by what layer of CT?
Epimysium
T/F. Skeletal muscle cells are mononucleated cylinders commonly referred to as myofibers.
False. Skeletal muscle cells are multinucleated cylinders commonly referred to as myofibers.
Where are the nuclei of skeletal muscle cells located?
In the periphery of the cell
What primarily occupies the cytoplasm of skeletal muscle cells?
Myofibrils
The basic structural unit of the Myofibril is a __________. Each cell has thousands of these.
Sarcomere
These two structures of the skeletal muscle cell function in Calcium storage and sleeves around each Myofibril.
Sarcolemma
Sarcoplasmic Reticulum
These are invaginations of the Sarcolemma.
Transverse Tubules (T-Tubules)
These are dilated ends of the Sarcoplasmic Reticulum that release Calcium. They trigger a muscle contraction.
Terminal Cisternae
When a muscle cell contracts, every Sarcomere (LENGTHENS/SHORTENS).
Shortens
A Sarcomere extends from what line to what line?
Z-line to the next Z-line
This part of the Sarcomere is the anchor site for actin (thin) filaments.
Z-line
This part of the Sarcomere ONLY contains actin (thin) filaments.
I-Band
***Remember, this and H-Zone shorten!
This part of the Sarcomere is the anchor site for the myosin (thick) filaments.
M-line
This part of the Sarcomere contains ONLY myosin (thick) filaments.
H-Zone
***Remember, this and I-Band shorten!
This part of the Sarcomere is an overlap of thick and thin filaments and includes the H-Zone.
A-Band
***Remember, this one doesn’t change in length!
When a muscle cell contracts, the (THICK/THIN) filaments slide past the (THICK/THIN) filaments toward the center of the Sarcomere, bringing the Z-lines closer together.
Thin
Thick
Every myofibril in a muscle cell shortens at the same time, thus the entire muscle cell _________.
Contracts
Do the thick and thin filaments change in length during a muscle contraction?
NO. Only the degree of overlap changes.
T/F. Myosin heads (thick filament) bind to Tropomyosin (thin filament).
False. Myosin heads bind to actin.
______ drives the movement of Myosin heads along Actin filaments.
ATP
In a thin filament, _________ runs in the groove formed by F-actin strands and binds to the ________ complex.
Tropomyosin
Troponin
This type of Troponin binds the complex to Tropomyosin.
Troponin T
This type of Troponin inhibits the binding of Myosin to Actin.
Troponin I
This type of Troponin binds Calcium.
Troponin C
Each molecule of Tropomyosin extends for the length of ________ Actin monomers.
Seven
How are muscle fibers categorized?
- Type of contraction generated and ATP supply
- - Contractions differ in power, speed, and duration
The following characteristics are describing what type of skeletal muscle fiber?
- Contains slow ATPase
- Red due to high myoglobin
- Contractions slower and less powerful
- Contract for long periods of time without fatigue
Type I fibers (slow oxidative)
The following characteristics are describing what type of skeletal muscle fiber?
- Largest and most prevalent
- Intermediate ATPase
- Provides power
- Primarily aerobic
- Intermediate fatigue
Type IIa fibers (Oxidative-Glycolytic)
The following characteristics are describing what type of skeletal muscle fiber?
- Fast ATPase
- Produces fast contractions
- Largely anaerobic
- Rapid fatigue
- Lower myoglobin content
Type IIb fibers (fast glycolytic)
Nerve tissue have two basic cell types, which are…
Neurons
Neuroglia (neuron supporting cells)
Neurons have two majors parts: the cell body and cell processes, which include ________ and ________.
Dendrites
Axons
Neuron clusters in the PNS are referred to as ________.
Ganglia
Neuron clusters in the CNS are referred to as ________.
Nuclei
________ are the “functional” cells of nerve tissue. They receive, process, and transmit electrical signals.
Neurons
When a neuron is stained to be viewed under a microscope, the _______ _______ is the abundant rER that take up the stain. It reflects the need to make lots of neurotransmitters and protein to maintain this large cell.
Nissl Substance
What part of the neuron processes the electrical information?
Cell body
(AXONS/DENDRITES) carry electrical signals toward the nerve cell body, while (AXONS/DENDRITES) carry electrical signals away from the nerve cell body.
Dendrites
Axons
How many axons are there per neuron?
One
This is where electrical signals are transferred from the axon terminal of the nerve to an effector cell.
Synapse
This class of neuron has many dendrites and one axon.
Multipolar
This class of neuron has one dendrite and one axon.
Bipolar
***See this in Retina
This class of neuron has one short cell process from which branches a single axon and single dendrite.
Unipolar
***See this in dorsal root ganglia sensory neurons
These cells surround the soma (cell body) of the neuron in the PNS.
Satellite cells
These cells form a myelin sheath around nerve fibers in the PNS.
Schwann cells
T/F. Axons in the CNS and PNS can be myelinated or unmyelinated.
True
How do Schwann cells and Oligodendrocytes differ in how they myelinate axons?
Schwann cells (PNS) – wraps itself around the axon
Oligodendrocytes (CNS) – wraps a cell process around the axon
Explain how myelination makes transmission signals faster?
Unmyelinated sections between myelination, called Nodes of Ranvier, makes the signal jump from node to node. Thus, by having myelination the signal moves faster because it jumps over those sections.
Organization of CT surrounding peripheral nerves is reminiscent of skeletal muscle. __________ CT is between axons, _________ CT surrounds clusters of axons forming fascicles, and __________ surrounds several nerve fascicles.
Endoneurium
Perineurium
Epineurium
What are the parts of a synapse?
1) Presynaptic knob (axon terminal)
2) Synaptic cleft
3) Presynaptic membrane
4) Postsynaptic membrane
Synaptic vesicles in the presynaptic knob contain a __________ that is released into the synaptic cleft by exocytosis.
Neurotransmitter
The neurotransmitter binds to receptors on the postsynaptic membrane, which stimulates the postsynaptic cell. What are examples of neurotransmitters?
Acetylcholine
Noradrenaline
T/F. All muscle types receive an axon terminal and are directly innervated.
False. Skeletal muscle receives an axon terminal, but not all cardiac or smooth muscle cells are directly innervated.
This the term for the ends of nerve fibers that store and release chemical messengers (neurotransmitters) at neuromuscular junctions.
Axon terminals
This is the space between the axon terminal and muscle cell plasma membrane (sarcolemma).
Synaptic cleft
ACh stimulates changes in the Sarcolemma that excite the muscle fiber. This stimulus is carried down the ________ to initiate fiber contraction.
T tubules
Some enzymes in the synaptic cleft will break down ACh and thus limit its action to what?
A single muscle twitch
What is the purpose of muscle spindle and tendon receptors?
Monitor changes in length, rate of change, and tension of muscles or tendons.
These are specialized fibers inside the muscle spindle that are made up of Nuclear Bag Fibers and Nuclear Chain Fibers.
Intrafusal Fibers
This type of Intrafusal Fiber is wrapped at the center by Type Ia nerve fibers and detects change in length and degree of tension.
Nuclear Bag Fibers
This type of Intrafusal Fiber is wrapped at their ends by Type II nerve fibers and detect static muscle length.
Nuclear Chain Fibers
These are specialized fibers outside the muscle spindle and are made up of Alpha motor fibers.
Extrafusal Fibers
This is the term for encapsulated receptors found within myotendinous junctions that sense tension within the tendon.
Golgi Tendon Organs