Anonymous asked in Science & MathematicsBiology · 1 decade ago

BIO/ANATOAMY HELP!!!! any medicine/nursing majors?? 10 points!!!?

Which of the following statements is true?

A) Cardiac muscle cells can respire in aerobic and anaerobic environments

B) Cardiac muscle cells have many nuclei

C) Smooth muscle cells have T tubules

D) Striated muscle cells are long and cylindrical with many nuclei

The sliding filament model of contraction involves:

A) actin and myosin shortening but not sliding past each other

B) The Z discs sliding over the myofilaments

C) THE SHORTENING OF THICK FILAMENTS so that thin filaments slide past

D) actin and myosin sliding past each other but no shortening

The first thing that stops a contraction after the nerve stops sending Ach is:

A) the action potential stops going down the T tubule

B) the tropomyosin blocks the myosin

C) AChE destroys the Ach, and they are removed from the membrane receptors

D) calcium ions return to the terminal cisternae

Of the following muscle types, which has only one nucleus, no sarcomeres, and no gap junctions?

A) visceral smooth muscle B) multiunit smooth muscle C) skeletal muscle D) cardiac muscle

Skeletal fibers may be classified as either oxidative or glycolytic. Which of the following muscles

would be called glycolytic?

A) those with a high concentration of myoglobin

B) those with a large number of mitochondria

C) The dark muscle meat of poultry

D) those with the smallest diameters

E) the ones most easily fatigued

Duchenne muscular dystorphy is a sex-linked condition in humans that results from abnormal dystrophin protein. The condition results in progressive weakening and atrophy of muscles, usually beginning with the legs. This is most consistent with which of the following?

A) an abnormality of action protein distribution

B) a structural abnormality of the sacromere

C) a disturbance of smooth muscle

D) an abnormality of calcium channels

E) an enzymatic abnormality

When an organism dies, its muscles remian in a contracted state termed "rigor mortis" for a brif period of time. Which of the following most directly conributes to this phenomenon? There is no...

A) ATP to move cross-bridges.

B) ATP to break bonds between the thick and thin filaments

C) calcium to bind to troponin

D) oxygen supplied to muscle

E) glycogen remaining in the muscles

Which of the following does not form part of the thin filaments of a muscle cell?

A) actin B) troponin C) tropomyosin D) myosin E) calcium-binding site

I knwo 8 questions is a lot but 180 question anatomy packet for a high senior senior in a college class is also a lot and it doesnt make sense! please help me!

3 Answers

  • 1 decade ago
    Favorite Answer

    Hey love… great questions; I believe I may have answered some of these already but here it goes again. I disagree with some of the answers others have posted, so I've provided rationales for mine.

    D - We know that myofibers are some of the longest cells in the body, and are striated and multinuleate.

    D - Niether actin nor myosin shorten during muscle contraction. They slide past each other, bringing the z-discs closer together, increasing the a-band and decreasing the i-band.

    C - When an action potential arrives at the presynaptic terminal bud of a motor neuron, the change in membrane potential causes voltage-sensitive Ca2+ channels to open. As Ca2+ comes into the cell, synaptic vesicles containing ACh exocytose the neurotransmitter into the synaptic cleft, which bind to ligand responsive nicotinic-acetylcholine ion channels causing them to open and allow Na+ etc... It's thus, the presence of ACh in the synaptic cleft, that permits the change in local sarcolemma potential, that causes depolarization to occur. Therefore, in the absence of an AP, we rely on AChE to break down ACh into its substituents, and transport them back to the presynaptic cell.

    B - Multiunit smooth muscle cells (ie. iris and arrector pilli) are individually innervated with a neuromuscular junction. Therefore, they do not require gap junctions to transmit action potentials like visceral (single-unit) cells do.

    E - Glycolytic fibers rely on glycolysis for ATP production, which is very inefficient compared to aerobic respiration and produce biproducts that quickly accumulate and cause psychological fatigue. Therefore, these fibers tire quite easily.

    B - DMD fibers lack dystrophin, a cytoplasmic protein that links the cytoskeleton to the extraellular matrix and, like a girder, helps stabilize the sarcolemma. The fragile sarcolemma of DMD patients tears during contraction, allowing entry of excess Ca2+. The deranged calcium homeostasis damages the contractile fibers which then break down, and inflammatory cells accumulate in the surround connective tissue. As the regenerative capacity of the muscle is lost, and damaged cells undergo apoptosis, muscle mass drops.

    B - ATP binding to myosin causes cross-bridge detachment. Without a continual production of ATP, the sarcomere remains in a contracted state.

    D - Actin is composed of G-Subunits that having binding sites for myosin heads (which are not a part of actin), troponin (TnT-subunit connects to tropomyosin, TnI - inhibitory subunit binds to actin, TnC - binds calcium ions)

  • Anonymous
    5 years ago

    Bacteria varies on what it looks like. It's mostly microscopic and can only be seen through microscopes and sometimes hand lenses. They look like transparent jellybeans with whips and legs coming out of their bodies. It depends on the kind of bacteria. It doesn't take that long, because they're so small - they divide in half, so they make copies of their organelles and DNA, and then they split. Bacteria eat stuff. Pathogenic bacteria is... uh... bacteria? Pathogenic bacteria live... uh... places. Yeah. Uh huh.

  • 1 decade ago

    1) D

    2) C

    3) C

    4) A

    5) D

    5) B

    6) B

    7) D

    Source(s): Medical School Physiology
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