I would say it is true and if it isn’t then I’m sorry.
Considering answers;
-fever
-constricted veins
-swollen veins
-confusion
Answer;
Swollen veins
Swollen veins might be a symptom of a person whose vein valves are not functioning properly and are causing fluid it flow away from the heart.
Explanation;
Valves are structures that are found in the circulatory system both in the heart and the veins.
They function to prevent the back flow of blood.
They do so by ensuring the continuous flow of blood in one direction.
If the valves are not functioning properly it may lead to various effects such as swollen veins due to the back flow of blood which may lead to the pooling of blood in the extremities.
The answer to your question would be (<span>barter)</span>
Vestigial structures are taken as an example of evolution because they give us an indication of structures that, due to the adaptation to the environment, disappeared.
At the end of the vertebral column, we have the coccyx as an example of this. Its believed that it could have formed a tail and currently, is only a small bone without any specific function, even some individuals are born without it.
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.
