B15 Nervous Coordination and Muscles Flashcards
What is the resting potential of a neuron?
The resting potential is the electrical potential difference across the neuron’s membrane when it is not transmitting an impulse, typically around -70 mV, with the inside of the neuron being negative compared to the outside.
What causes the depolarization and repolarization phases of an action potential?
Depolarization occurs when sodium ions (Na⁺) rush into the neuron, making the inside more positive. Repolarization happens when potassium ions (K⁺) leave the neuron, returning the inside to a negative charge.
What is the function of the synapse in nervous coordination?
The synapse is the junction between two neurons. Neurotransmitters are released from the presynaptic neuron, travel across the synaptic cleft, and bind to receptors on the postsynaptic neuron to transmit the signal
How do neurotransmitters work at the synapse?
Neurotransmitters are chemicals that transmit signals from one neuron to another. They bind to specific receptors on the postsynaptic membrane, causing ion channels to open and influencing the likelihood of an action potential.
Describe the structure and function of the neuromuscular junction.
The neuromuscular junction is the synapse between a motor neuron and a muscle fiber. Acetylcholine is released here to trigger muscle contraction.
What is the sliding filament theory of muscle contraction?
The sliding filament theory states that muscle contraction occurs when actin and myosin filaments slide past each other, shortening the sarcomere and generating force.
What is the role of calcium ions in muscle contraction?
Calcium ions bind to troponin on the actin filaments, causing a conformational change that exposes binding sites for myosin heads, enabling contraction.
What is the role of Tropomyosin in muscle contraction?
Tropomyosin is a protein that blocks the binding sites on actin. When calcium ions bind to troponin, tropomyosin shifts, exposing the binding sites for myosin to interact with actin.
How does phosphocreatine contribute to muscle function?
Phosphocreatine provides a rapid source of phosphate to regenerate ATP during short bursts of high-intensity exercise, allowing for continued muscle contraction.
What is myelination, and how does it affect nerve impulse transmission?
Myelination is the process by which axons are covered with a fatty layer called myelin, produced by Schwann cells. This speeds up the transmission of nerve impulses by allowing the action potential to jump between the gaps in the myelin, called nodes of Ranvier (saltatory conduction).
What is the function of troponin in muscle contraction?
Troponin binds to calcium ions, causing a conformational change that shifts tropomyosin, exposing the myosin binding sites on actin, allowing muscle contraction to occur.
What is the role of myosin heads in muscle contraction?
Myosin heads bind to actin filaments to form cross-bridges. They then pivot, pulling the actin filaments toward the center of the sarcomere (power stroke), which shortens the muscle fiber.
What is summation in muscle contraction?
Summation occurs when multiple stimuli are applied to a muscle in quick succession, resulting in a greater force of contraction. This can be temporal summation (increased frequency of stimulation) or spatial summation (increased number of motor units recruited).
What is the H-band in a sarcomere?
The H-band is the region of the sarcomere that only contains myosin filaments. It shortens during muscle contraction as the actin filaments slide over the myosin filaments.
What is the M-line in a sarcomere?
The M-line is the central line of the sarcomere, located in the middle of the A-band. It anchors the myosin (thick) filaments and helps stabilize them during contraction.
