Maybe state laws since your signature is on your identification? Not sure.
Answer:
Alveoli.
Explanation:
Respiration may be defined as the process of exchange of gases between the environment, lungs and body tissues. Energy is given off during the process of respiration.
The alveoli is a ballon like structure present in the lungs when gases are inflated in the alveoli. The alveoli increses the surface area for the exchange of gases. Oxygen is transferred in the body tissue from the alveoli.
Thus, alveoli is the main site of gas exchange in the lungs.
Answer:
1. E) During muscle contraction all of the answers above are correct.
2. A) Myosin pulls actin filaments toward the M disk.
Explanation:
The mechanism of muscle contraction is also known as the sliding filament theory. It explains the activities which occur during contraction of muscles.
Muscles are made up of functional units called sarcomeres and these sarcomeres made up of myofibrils which are long and thin strands of protein. Myofibrils contain thin filaments called actin and thick filaments called myosin. Interactions between the thin and thick filaments results in contraction.
The I band contains thin filaments. The H band is the area of no thin filaments. The M line is the midline of the thick filaments. The Z line is the boundary between adjacent sarcomeres and the A band is the area of thick filaments.
Contraction occurs when muscle fibres are activated by neurons through the release of calcium ion. On stimulation, the H and I band get smaller, the zone of overlap gets larger and the Z lines move closer together and the A band remains constant. This the thin filaments slide towards the center resulting in the shortening of the sarcomeres and the muscle fibres as a whole.
