30 Questions
What is the primary function of the sarcoplasmic reticulum in muscle cells?
Stores and releases calcium ions
Which protein serves as the attachment site on actin for calcium ions?
Troponin
In a sarcomere, where do you find the H zone?
Center of the sarcomere
During depolarization of a muscle fiber, what happens to the charge inside the cell?
Becomes more positive
What is the main function of the sodium-potassium pump in muscle cells?
Maintains cell resting potential
Where are M lines located in a sarcomere?
Where myosin are anchored
What is the role of Acetylcholine in muscle contraction?
Stimulates muscle fiber to contract
Where does the binding of Acetylcholine to receptor sites occur?
Synaptic cleft
What happens when Ca2+ binds to troponin during muscle contraction?
Tropomyosin uncovers active sites on actin myofilament
Which structure stores and releases neurotransmitters like Acetylcholine?
Synaptic vesicle
What is the primary function of a motor neuron in muscle contraction?
Carry action potentials to muscle fibers
What occurs when ATP binds to myosin during muscle contraction?
Myosin detaches from actin myofilaments
What is the term for the weakest stimulus needed to produce a muscle response?
Threshold
In which type of muscle contraction does the muscle remain contracted?
Isometric
Which type of muscle fibers contract slowly and fatigue slowly?
Slow Twitch Fibers
What is the function of myoglobin in muscles?
Facilitates oxygen binding in muscle
Which type of muscle fiber contracts quickly and fatigues quickly?
Fast Twitch Fibers
What determines the distribution of slow and fast twitch muscle fibers in humans?
Genetics
Which muscle in the upper limb is known as the 'flexing muscle'?
Brachialis
Which muscle is responsible for inverting the foot?
Tibialis anterior
How many origins does the triceps muscle have?
Three
Which muscle is located between the ribs and is responsible for elevating them?
Serratus anterior
Which muscle in the lower leg attaches to the ankle and flexes the foot?
Soleus
What type of muscle movement does the deltoid muscle primarily perform?
Abduction of upper limbs
What is the role of Ca2+ in the process of muscle contraction?
Ca2+ binds to troponin causing tropomyosin to move, exposing attachment sites for myosin
What happens when acetylcholine binds to receptor sites on Na+ channels during muscle contraction?
Na+ rushes into the postsynaptic terminal causing depolarization
Which organelle releases stored calcium in response to Na+ entering the postsynaptic terminal during muscle contraction?
Endoplasmic reticulum
What is the role of ATP in muscle contraction?
ATP is released from myosin heads, enabling them to bend towards the center of the sarcomere
What causes tropomyosin to move and expose attachment sites for myosin during muscle contraction?
Ca2+ binding to troponin
What causes muscle contraction to stop?
(Muscle contraction stops when) Acetylcholinesterase is released and Na+ channels close
This quiz covers essential elements of muscle contraction theory, including actin, myosin, sarcomeres, and the sliding filament theory. Test your knowledge on the key structures and functions involved in muscle contraction.
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