The Muscular System Flashcards
Muscle tissue is 1 of the 4 main tissue types and is responsible for __ and __ of force.
Movement; generation
Muscle tissue is composed of __ __ or __ that create a movement of the bone to which they are attached when they contract.
Contractile cells; fibres
Motion results when the muscles alternate b/w __ and __; the skeletal system provides the leverage and supportive framework for this movement.
Contraction; relaxation
List the 4 characteristics of muscle tissue
Excitability, contractility, extensibility, and elasticity
Excitability
Muscle tissue has the capacity to respond to the stimulation of nervous impulses or hormones
Contractility
Muscle tissue has the capacity to shorten or contract with force
Extensibility
Muscle tissue can stretch beyond (within reason) resting length
Elasticity
Muscle tissue returns (recoils) to resting length after being stretched
List the 3 types of muscle tissue
Skeletal muscle tissue, cardiac muscle tissue, smooth (visceral) muscle tissue
Skeletal muscle tissue
Is primarily attached to bones. It is striated and voluntary.
Cardiac muscle tissue
Forms the wall of the heart. It is striated and involuntary.
Smooth (visceral) muscle tissue
Is located in the viscera. It nonstriated (smooth) and involuntary.
Describe the 5 key functions of muscle
- Produces body movements
- Stabilizes body positions
- Regulates organ volume
- Moves substances within the body
- Generates heat
Superficial __ separates muscles from skin, functions to provide a pathway for nerves and blood vessels, stores fat, and protects muscles from trauma.
Fascia (sub Q layer)
Deep __, which lines the body wall and limbs and holds muscles w/similar functions together, allows for the free movement of muscles; carries nerves, blood vessels and lymph vessels; and fills the spaces between muscles.
Fascia
List the 3 types of connective tissue
Epimysium, perimysium, endomysium
Epimysium
Covers the entire muscle
Perimysium
Covers the fasciculi
Endomysium
Covers individual muscle fibres
__ and __ attach muscle to bone or muscle to other muscle.
Tendons; aponeuroses
__ (containing motor neurons) convey impulses for muscular contraction.
Nerves
__ provides nutrients and oxygen for contraction.
Blood
__ muscle fibres arise from myoblasts. A few myoblasts persist in mature skeletal muscle as satelite cells.
Skeletal
Skeletal muscle consists of fibres (cells) covered by a __.
Sarcolemma
__ __ are tiny invaginations of the sarcolemma that quickly spread the muscle action potential to all parts of the muscle.
T tubules
__ is the muscle cell cytoplasm which contains a large amount of glycogen for energy production and myoglobin for oxygen storage.
Sarcoplasm
Each fibre contains __ that consist of thin and thick filaments (myofilaments).
Myofibrils
The __ __ encircles each myofibril. It is similar to smooth endoplasmic reticulum in non muscle cells; and in the relaxed muscle, it stores calcium ions.
Sarcoplasmic reticulum
Myofibrils are composed of thick and thin filaments arranged in units called __
Sarcomeres
Sarcomeres are the basic functional units of a myofibril and show distinct dark (_ band) and light (_ band) areas.
A; I
A Z disc passes through the centre of the _ band.
I
Myosin
Main component of thick filaments functions as a motor protein.
Motor proteins __ or __ their cargo to achieve movement by converting energy from ATP into the mechanical energy of motion or force.
Push or pull
Actin
The main component of thin filaments, has myosin binding sites where myosin heads attach to produce the sliding together of the filaments.
Describe the neuromuscular junction (NMJ)
Muscle action potentials arise at the neuromuscular junction, which is the synapse between a somatic motor neuron and a skeletal muscle fibre.
A __ __ is a nerve and the muscle fibres it stimulates.
Motor unit
A __ is a region of communication between 2 neurons or a neuron and a target cell. The 2 neurons or a neuron and a target cell are separated by a gap, or a synaptic cleft.
Synapse
The neurotransmitters at an NMJ is __
Acetylcholine ACh
A __ __ __ elicits a muscle action potential through the release of acetylcholine, the activation of ACh receptors, the production of a muscle action potential and the termination of ACh activity
Nerve action potential
Watch the video on muscles to understand the sliding filament mechanism
Did you watch both parts you cheater?
A sustained partial contraction of portions of a relaxed skeletal muscle results in a firmness known as __ __.
Muscle tone
At any given moment, a few muscle fibres within a muscle are contracted, while most are relaxed. This small amount of contraction is essential for maintaining __.
Posture
List 3 sources for ATP production in cells
Creating phosphate, anaerobic cellular respiration, aerobic cellular respiration
Creating phosphate
Can power maximal muscle contraction for about 15 seconds and is used for maximal short bursts of energy. Creatine phosphate is unique to muscle fibres.
Anaerobic cellular respiration (glycosis)
Can provide enough energy for about 30-40 seconds
Aerobic cellular respiration (reactions requiring oxygen)
Completes the oxidation of glucose via cellular respiration and provides energy for prolonged activity
Muscle tissue has 2 sources of oxygen:
Diffusion from the blood and release by myoglobin inside muscle fibres
The inability of a muscle to maintain its strength of contraction or tension is called __ __ which occurs when a muscle cannot produce enough ATP to meet its needs.
Muscle fatigue
Define a twich
A twitch contraction is a brief contraction of all the muscle fibres in a motor unit in response to a single action potential.
A twitch contraction I closed 3 periods:
Latent, contraction and relaxation
__ __ is the increased strength of a contraction, which is the result of the application of a second stimulus before the muscle has completely relaxed after a previous stimulus.
Wave summation
A sustained muscle contraction that permits partial relaxation b/w stimuli is called __ (__) __.
Incomplete (unfused) tetanus
A sustained contraction that lacks even partial relaxation b/w stimuli is called __ (__) __.
Complete (fused) tetanus
On the basis of structure and function, skeletal muscle fibres are classified as:
Slow oxidative
Fast oxidative-glycolytic
Fast glycolytic fibres
Isotonic contraction
A contraction that occurs when the tension in the muscle remains the same but the muscle shortens.
Lifting a textbook from a table (or cup of coffee)
Isometric contraction
Is a contraction that occurs when tension is applied to a muscle but it does not shorten.
Carrying a box of books (trying to pick up a building)
Cardiac muscle tissue is only found in the __ __.
Heart wall
Cardiac muscle fibres connect to adjacent fibres by intercalated discs that contain __ and __ __.
Desmososomes; gap junctions
Cardiac muscle contractions last longer than the skeletal muscle twotch due to the prolonged delivery of __ __ from the sarcoplasmic reticulum and the extracellular fluid.
Calcium ions
Cardiac muscle fibres contract when stimulated by their own __ __.
Autorhythmic fibres
Smooth muscle tissue is non striated and involuntary. List it’s 2 types:
Visceral (single unit) smooth muscle
Multiunit smooth muscle
Visceral (single unit) smooth muscle
Found in the walls of hollow viscera and small blood vessels; it’s fibres are arranged in a network; and the fibres contract as a unit.
Multiunit smooth muscle
Is found in large blood vessels, large airways, arrector pili muscles, and the iris of the eye. The fibres operate singly rather than as a unit.
In smooth muscle, the regulator protein that binds calcium ions in the cytosol is __.
Calmodulin
The prolonged presence of calcium ions in the cytosol of smooth muscle fibres provides for smooth __ __, a state of continued partial contraction.
Muscle tone
Smooth muscle fibres can stretch considerably w/o developing tension; this phenomenon is called the __-__ __.
Stress-relaxation response
