<u>Answer:</u>
<em>There are innermost serious membranes that cover the heart is Parietal Pericardium.</em>
<u>Explanation:</u>
Heart is <em>covered by pericardium</em> in two sides, inner and outer sides. The inner membrane is parietal pericardium and the outer one is visceral pericardium. Pericardium is made up of <em>fiber tissues</em> that strongly protect the heart from all around.
The<em> main function of pericardium</em> is to protect the heart from any injuries and prevent the infections. The serious pericardium helps in<em> lubricating the heart. </em>
Answer:
The correct answer is 3: "<em>High levels of Ca2+ are expected to be found </em><em>within the sarcoplasmic reticulum</em>".
Explanation:
Muscular contraction is a highly regulated process that depends on free calcium concentration in the cytoplasm. Amounts of cytoplasmic calcium are regulated by <u>sarcoplasmic reticulum</u> that functions as a storage of the ion.
When a nerve impulse reaches the membrane of a muscle fiber, through acetylcholine release, the membrane depolarizes producing the entrance of calcium from <u>extracellular space</u>. The impulse is transmitted along the membrane to the sarcoplasmic reticulum, from where calcium is released. At this point, <em>tropomyosin is obstructing binding sites for myosin on the thin filament</em>. The calcium channel in the sarcoplasmic reticulum controls the ion release, that activates and regulates muscle contraction, by increasing its cytoplasmic levels. When <em>calcium binds to the troponin C</em>, <em>the troponin T alters the tropomyosin by moving it and then unblocks the binding sites,</em> making possible the formation of <em>cross-bridges between actin and myosin filaments.</em> When myosin binds to the uncovered actin-binding sites, 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.
All the cells in a person's body have the same DNA and the same genes. However, the difference between cells in different tissues and organs is that the "expression" of the genes differs between cells. ... For example, liver cells have different proteins than skin cells, even though their DNA is the same......this is a google search i hope it helps
The brain which, along with the spinal cord gathers informationand responds to changes in the environment.