The skeletal muscle, responsible for voluntary contraction is composed of 1) Myofilaments 2) Myofibrilles 3) Muscle fibers 4) Muscle (from the left to the right in the image)
<h3>
What is the composition of the skeletal muscle?</h3>
The elements composing the skeletal muscle are,
- Myofilaments ⇒ Actine and miosine
- Sarcomere ⇒ It is the functional unit with the contractile apparatus. Composed of the Z band, A and I bands, and H zone.
- Myofibrilles ⇒ They have the Functional units
- Muscle fibers ⇒ Surrounded by endomysium
- Fascicle ⇒ Group of fibers surrounded by perimysium.
- Muscle ⇒ Group of fascicles surrounded by epimysium.
The sarcomere is the contractile unit in a skeletal muscle. The thick myosin myofilaments are located in the central region of the sarcomere, which corresponds to the A band.
Thin filaments united to the Z lines, extends to the interior of the A band until they reach the border of the H band.
The I band is formed solely of thin actin filaments, belonging to two sarcomeres adjacent to a Z line.
When the muscle contracts, the muscular fiber gets shorter and thicker due to the reduction in length of the sarcomere.
- The H line and the I band get shorter.
- The Z lines get closer to the A band, meaning that they get closer to each other. The A band keeps constant in length.
- This change is produced by movement mechanisms that involve a change in the relative position of actin and myosin filaments.
For a better understanding about muscle contraction, look at the attached files.
From the left to the right,
1) Myofilaments
2) Myofibrilles
3) Muscle fibers
4) Muscle
You can learn more about skeletal muscle structure at
brainly.com/question/11246024
brainly.com/question/12213587
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Answer:
Mucus is a liquid in your body and it protect you from pathogens
Explanation:
False is the answer ur conclusion is your summary hypothesis is a guess
Answer:
mutation rates can be used to design molecular clocks in order to estimate divergence times among species
Explanation:
In evolutionary biology, the substitution rates (also known as mutation rates) are used for the development of 'molecular clocks' which allow estimating the divergence times among species or among taxonomic groups. Molecular clocks can be designed by estimating the divergence rate of nucleotide sequences (either DNA or RNA) and amino acid (protein) sequences. These substitution rates can also be used to track how quickly viruses evolve (for example, in a pandemic situation).
Answer:
Sponges use <em><u>choanocytes</u></em> or <em><u>flagellated channels</u></em> to get nutrients from the feeding cells to other parts of their body.
Explanation:
Sponges are marine animals with a sac-shaped body. The epidermis is composed of polygonal flat cells called pinacocytes and pores protected by porocytes. Under the epidermis, there is a protein matrix called mesenchyme, which is composed of spicules and <em><u>amibocytes</u></em>. By the interior side of the sponge, there are the<em><u> choanocytes</u></em>. These are ovoid cells that can be shaping the spongocoele (internal cavity of the sponge), with an extreme attached to the mesenchyme and the other extreme projected to the spongocoele, or can be grouped in spaces called <em><u>flagellated channels</u></em>.
These animals depend on water to get oxygen and food to the inside of the sac and take excrements and reproductive cells to the outside. Sponges <em>feed on small detritus particles and suspending organisms</em> that get near the animal by water streams produced by choanocytes.
Particle size is essential. Only the small ones can get through the flagellated channels, where they get stuck to the choanocytes and are encapsulated by the cells. If the choanocytes are too small, the particle is transferred to the amibocytes for digestion. These last ones also act as food storages. Excrement products are dragged by a water stream.
