Muscle Anatomy and Function

<p>Multinucleated cells (C)</p> Signup and view all the answers

<p>Load exceeds muscle tension, lengthening muscle (B)</p> Signup and view all the answers

<p>Pump blood (D)</p> Signup and view all the answers

<p>Sarcoplasmic reticulum (C)</p> Signup and view all the answers

<p>Skeletal muscle (C)</p> Signup and view all the answers

<p>Sarcomere (B)</p> Signup and view all the answers

<p>A light area containing only actin filaments (C)</p> Signup and view all the answers

<p>Increased manoeuvrability (B)</p> Signup and view all the answers

<p>T-tubules (D)</p> Signup and view all the answers

<p>Involuntary control (A)</p> Signup and view all the answers

<p>The A-band remains the same length. (C)</p> Signup and view all the answers

<p>Tropomyosin (A)</p> Signup and view all the answers

<p>It provides energy for movement and breaks the actin-myosin link. (B)</p> Signup and view all the answers

<p>Too much overlap preventing cross-bridge cycling. (D)</p> Signup and view all the answers

<p>2.0-2.2 (B)</p> Signup and view all the answers

<p>Their heads protrude and tails wrap around each other. (A)</p> Signup and view all the answers

<p>To bind calcium ions and regulate the binding of myosin to actin. (C)</p> Signup and view all the answers

<p>H-zone (A)</p> Signup and view all the answers

<p>Calcium binds to the TnC subunit of troponin, facilitating contraction. (B)</p> Signup and view all the answers

<p>A twitch is a single, brief contraction in response to one action potential. (D)</p> Signup and view all the answers

<p>Tropomyosin moves deeper into the actin groove, exposing myosin binding sites. (A)</p> Signup and view all the answers

<p>The delay between action potential arrival and muscle contraction onset. (C)</p> Signup and view all the answers

<p>Tropomyosin (A)</p> Signup and view all the answers

<p>Two high affinity and two low affinity binding sites. (D)</p> Signup and view all the answers

<p>The arrival of an action potential. (B)</p> Signup and view all the answers

<p>A muscle fiber is stimulated repeatedly at a high frequency. (A)</p> Signup and view all the answers

Skeletal, cardiac, and smooth muscles are the three types of muscles in the body, each with different functions and characteristics.

Muscle movement is triggered by the interaction of actin and myosin filaments.

Long, thread-like structures within muscle cells, composed of myosin and actin filaments.

The functional unit of a myofibril; the repeating structural and contractile unit

Extensions of the muscle cell membrane that allow action potentials to reach the muscle fiber.

The internal storage organelle for calcium ions, crucial for muscle contraction.

Light band in a myofibril, containing only actin filaments.

Dark band containing both actin and myosin filaments.

The central region of the sarcomere, containing only myosin filaments.

Long protein chains (globular) coiled into a helix.

A protein that binds calcium ions, initiating muscle contraction.

A protein that covers the myosin-binding site on actin, preventing contraction until calcium levels rise.

Filaments with globular heads (protruding) and fibrous tails.

The length of a muscle where it can generate maximum force due to sufficient overlap of actin and myosin filaments.

ATP provides energy for movement and detaches myosin from actin, allowing the cycle to repeat.

Active transport of calcium ions from the sarcoplasm back into the sarcoplasmic reticulum.

Protein complex on actin, composed of TnT, TnC, and Tnl, that regulates muscle contraction.

Shortening of a muscle fiber due to the sliding of actin and myosin filaments.

A single, brief muscle fiber contraction in response to a single action potential.

Sustained muscle contraction due to high-frequency stimulation.

Delay between nerve stimulation and muscle contraction onset (approx. 10 ms).

Sequence of events linking nerve stimulation to muscle contraction.

Connection between a motor neuron and a muscle fiber.

Depolarization of the T-tubules activates voltage-gated calcium channels (DHP receptors).

Activation of the DHP receptors triggers the release of calcium ions from the sarcoplasmic reticulum by activating ryanodine receptors.

Calcium ions bind to troponin, triggering a conformational change that moves tropomyosin away from the myosin binding sites on actin, initiating the cross-bridge cycle and muscle contraction.

Muscle develops tension without changing length. This measures the tension generated by the muscle.

Muscle shortens while the load remains constant. This measures the rate of shortening.