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.
A) a large group of cells that grew without regulation.
A tumor is where there is a mutation that causes cells to lose their ability to self regulate, so they reproduce too fast and become unspecialised, causing a tumour.
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Answer:
There are many reasons why manned space probes to Saturn are simply unachievable. Getting to space is incredibly hard. The force of gravity is very hard to escape. If you wanted to, you would have to invest trillions upon trillions of dollars to create a space shuttle that may or may not explode. Second, we simply don’t have the technology to make it that far with a manned probe. Saturn is more than a billion miles away. It would take more than several years to go that far. To keep astronauts alive, entertained, and sustained is also a big challenge. In conclusion these are some reasons why a manned space probe to Saturn is unachieveable.
Explanation:
U’d better give me that brainly.
Answer:
Pleiotropy
Explanation:
Pleiotropy is a genetic condition in which a single gene conditions the expression of multiple phenotype. There are different types of pleiotropy depending on the underlining mechanism
- <em>gene pleiotropy</em>
- <em>developmental pleiotropy</em>
- <em>selectional pleiotropy</em>
- <em>antagonistic pleiotropy </em>
<em>Phenylketonuria is a disease characterized by increased level of amino acid phenylalanine in the blood. It caused by mutation to the gene responsible for breaking down phenylalanine in the blood. Elevated level of phenylalanine causes other issues such as mental problems, urine coloration and reduction in skin pigmentation. This is a clear case of pleiotropy.</em>
