That is true because that’s where it’s mostly are
Answer:
The correct option is E) Contraction still occurs because Ca2+ can enter the cell directly through Ca2+ channels in the plasma membrane and bind to calmodulin.
Usually, the calcium ions are released from the sarcoplasmic reticulum of a cell during a muscle contraction, but if those are blocked, the contractions is an cell can still arise through the calcium ions which are present in the cell membrane of a cell.
Organ System, Organ coll, tissue
1. In the heart, an action potential originates in the (E) sinoatrial node.
The cardiac action potential is a term referring to the change in the membrane potential of heart cells causing the heart to contract. Cardiac action potentials are created by a group of specialized cells capable of generating automatic action potentials and are located in the right atrium of the heart. These cells are called sinoatrial node and sometimes are referred to as the natural pacemaker of the heart. This characterization originates from the fact that sinoatrial node continuously provides action potential and sets the rhythm of the heart function.
2. The sequence of travel by an action potential through the heart is (A) sinoatrial node, atrioventricular node, atrioventricular bundle, bundle branches, Purkinje fibers.
As explained above, the cardiac action potential originates from the sinoatrial node. This action potential then travels through the atrioventricular node, which belongs to the electrical conduction system of the heart and is located between the atria and the ventricles. It is responsible for the electrical connection between the right atrium and the right ventricle. The action potential then travels to the atrioventricular bundle (or bundle of His), another part of the electrical conduction system of the heart. The atrioventricular bundle transmits the electrical impulses from the atrioventricular node to the bundle branches. The bundle branches then send the signal to the Purkinje fibers which send the electrical impulses to the ventricles, causing them to contract.
3. The correct answer is A.
The generation of an action potential in the sinoatrial node causes the contraction of the atria. When the action potential passes from the sinoatrial node to the atrioventricular node, it slows down. This causes the transport of the electrical impulse from the atria to the ventricles to slow down. This delay enables the blood (from the contraction of the atria) to fill the ventricles before their contraction.
4. This statement is true.
The interventricular septum is a structure which divides the two ventricles of the heart and it is composed of two branches, the left bundle and the right bundle branch. When the action potential reaches the interventricular septum, it then travels to the apex of the heart from where it travels upwards along the walls of the ventricles and the ventricular contraction begins.
5. This statement is true.
The bundle branches gradually become Purkinje fibers located in the interior of the ventricular walls. Purkinje fibers are specialized cells and are responsible for conducting cardiac action potentials from the bundle branches to the ventricular walls. This signal transduction causes the muscle of the ventricular walls to contract.
Answer:
B) FADH2 -- FMN of Complex I -- Fe-S of Complex II -- Q -- Fe-S of Complex III -- Cyt c -- Cyt a of Complex IV -- O2
Explanation:
FADH2 and NADH give their high energy electrons to the terminal electron acceptor molecular oxygen via an electron transport chain. As the electrons move through electron carriers of the electron transport chain, they lose their free energy. Part of the free energy of the electrons is used to pump the protons from the matrix into the intermembrane space. Therefore, part of the energy of electrons is temporarily stored in the form of a proton concentration gradient.
NADH gives its electrons to FMN of complex I while FADH2 gives its electrons to the Fe-S center of complex II. Both the complexes are oxidized by coenzyme (Q) which in turn reduces Fe-S centers of complex III. Cyt c of complex IV obtains electrons from complex III and passes them to CuA center, to heme "a" to heme "a3-CuB center" and finally to the molecular oxygen.
So, the compounds arranged with respect to the energy content of electrons in descending order are as follows: FADH2 -- FMN of Complex I -- Fe-S of Complex II -- Q -- Fe-S of Complex III -- Cyt c -- Cyt a of Complex IV -- O2.
