1/8 - Chapter 6: Muscle, Bone, and Skin

In a synovial joint, the connective tissue holding the bones together are called...

• Tendons

• Osteocytes

• Ligaments

• Cartilage

Answer explanation

In a synovial joint, ligaments are the connective tissues that hold the bones together, providing stability and support. Tendons connect muscles to bones, while osteocytes are bone cells and cartilage is a smooth tissue that covers joint surfaces.

The ___ nervous system innervates involuntarily muscles, such as smooth and cardiac muscle.

• somatic

• motor

• autonomic

• central

Answer explanation

The autonomic nervous system controls involuntary muscles, including smooth and cardiac muscle, unlike the somatic nervous system, which innervates voluntary muscles. Therefore, the correct answer is 'autonomic'.

Skeletal muscle primarily stores energy in the form of ___, which is the first to be broken down during exercise.

• glucose

• fat

• glycogen

• protein

Answer explanation

Skeletal muscle primarily stores energy as glycogen, which is a polysaccharide. During exercise, glycogen is the first energy source to be broken down to glucose for immediate energy needs.

Tags

NGSS.HS-LS1-7

NGSS.HS-LS2-3

Which muscle is striated?

• Cardiac

• Smooth

• Skeletal

• A and C

Answer explanation

Striated muscles have a banded appearance. Cardiac and skeletal muscles are both striated, while smooth muscle is not. Therefore, the correct answer is A and C.

Select the correct order in the structure of muscle cells.

• Myofibril --> muscle fiber --> muscle fascicle --> muscle

• Muscle fiber --> myofibril --> muscle fascicle --> muscle

• Muscle fascicle --> muscle fiber --> myofibril --> muscle

• Myofibril --> muscle fascicle --> muscle fiber --> muscle

Answer explanation

The correct order is Myofibril --> muscle fiber --> muscle fascicle --> muscle. Myofibrils are the contractile units within muscle fibers, which group together to form fascicles, and multiple fascicles make up the entire muscle.

Tags

NGSS.HS-LS1-2

What neurotransmitter stimulates the action potential across the sarcolemma?

• Dopamine

• Serotonin

• Acetylcholine

• Epinephrine

Answer explanation

Acetylcholine is the neurotransmitter that stimulates muscle contraction by binding to receptors on the sarcolemma, leading to the generation of an action potential. This is crucial for muscle function.

In muscles, Ca+ is stored in the...

• Sarcoplasmic reticulum

• Mitochondria

• Cytoplasmic vesicles

• Actin filaments

Answer explanation

In muscles, Ca+ is primarily stored in the sarcoplasmic reticulum, which releases it during muscle contraction to facilitate the interaction between actin and myosin filaments.

Why is ATP important for muscle contraction?

• ATP causes tropomyosin to expose the binding sites, and allows for myosin binding

• ATP increases the levels of Ca+ in the sarcolemma

• ATP allows the myosin head to be released from the active site, and resets its position

• ATP forms cross-bridges between the thick and thin filaments

Answer explanation

ATP is crucial for muscle contraction as it allows the myosin head to detach from the active site on actin, enabling the myosin to reset its position for another contraction cycle.

Why is Ca+ important for muscle contraction?

• Ca+ binds to tropomyosin, causing troponin to expose the binding site

• Ca+ binds to troponin, causing tropomyosin to expose the binding site

• Ca+ binds to myosin, causing tropomyosin to expose the binding site

• Ca+ binds to tropomyosin, causing myosin to expose the binding site

Answer explanation

Ca+ is crucial for muscle contraction as it binds to troponin. This binding causes a conformational change that moves tropomyosin away from the binding sites on actin, allowing myosin to attach and initiate contraction.

Slow, oxidative twitch muscle fibers have a ___ resistance to figure, and are used primarily during ___ activity.

• high; short-term anaerobic

• low; short-term anaerobic

• high; aerobic

• low; long-term anaerobic

Answer explanation

Slow, oxidative twitch muscle fibers have a high resistance to fatigue, allowing them to sustain activity for longer periods. They are primarily used during aerobic activity, which relies on oxygen for energy.