Answer:
In muscles contraction the correct order of the steps are: A (Nerve impulse reaches the muscle), B (Action potential travels down T-tubules), C (Calcium binds to troponin), D (Tropomyosin moves).
Explanation:
Skeletal muscle contractions are based on different physiological and biochemical phenomena that happen in every cell. These phenomena are due to stimulation produced by somatic motor neurons, which axons get in contact with muscle fibers through a neuromuscular synapse. In rest, attraction strengths between myosin and actin filaments are inhibited by the tropomyosin. When an action potential is originated in the central nervous system, it travels to the somatic motor neuron membrane: the muscle fiber, and activates the calcium channels releasing it in the neuron. Calcium makes vesicles to fuse with the membrane and release the neurotransmitter named acetylcholine (Ach) into the synaptic space in the juncture. Then, Ach binds to its receptors on the skeletal muscle fiber. This causes the ion channels to open, and positively charged sodium ions cross the membrane to get into the muscle fiber (sarcoplasm) and potassium get out. The difference in charges caused by the migration of sodium and potassium makes the muscle fiber membrane to become more positively charged (depolarized). The action potential caused by this depolarization enters the t-tubules depolarizing the inner portion of the muscle fiber. This activates calcium channels in the T tubules membrane, that make the calcium be released into the sarcolemma. At this point, tropomyosin is obstructing binding sites for myosin on the thin filament. When calcium binds to the troponin C, the troponin T alters the tropomyosin by moving it and then unblocks the binding sites. Myosin binds to the uncovered actin-binding sites, and while doing it ATP is transformed into ADP and inorganic phosphate. Z-bands are then pulled toward each other, thus shortening the sarcomere and the I-band, and producing muscle fiber contraction.
Answer: Tincture
Explanation:
A tincture can be defined as an extract of plant or animal material which is dissolved in ethanol commonly known as ethyl alcohol.
The solvent concentration is 25-60% are commonly used but it can be increased upto 90%.
Other solvents that is uswed to produce tincture are vinegar, propylene glycol, glycerol.
Explanation:
What is stem ?
= Stem is the part of the plant which grow above the ground....
<h3>Function : </h3>
The major function of stem are production and support to the branches , leaves , buds , flowers , seeds etc. It also helps in conduction of water , minerals and foods in different part of the plant...
Besides this primary functions , the stem of some plants are modified into different shapes , size and structure and perform some special functions as an perennation , vegetative propagation, storage , food production etc....
An onion is a plant so it would have a cell wall, but a human cell is an animal cell so it doesn't have a cell wall. I'm not sure if that's the type of answer you're looking for though.
