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:
At the bottom of the sequence
Explanation:
According to the "principle of superposition of strata", the oldest rocks are formed at the bottom of sedimentary rock sequences.
The oldest rock layer would contain the the oldest fossil. Weathering, erosion, transportation and deposition would bring all sediments which includes rock materials and remains of living organisms to the basin where they would be lithified to form sedimentary rocks. This makes the oldest fossil to be at the bottom of the sequence. As time progresses, the fossil sequence would continue to accumulate and young upwards as the strata becomes relatively younger. Also, we know that fossils succeed one another in a definite manner.
This why relative dating of rocks can be possible.
Answer:
The (rough) endoplasmic reticulum
Explanation:
The endoplasmic reticulum is a system of interconnected membranes that functions in the synthesis of several membrane-related proteins and lipids. There are two types of endoplasmic reticulum in the eukaryotic cell;
- Smooth endoplasmic reticulum
- Rough endoplasmic reticulum
The smooth endoplasmic reticulum is actually smooth because it has no ribosome attachment while the rough endoplasmic reticulum appears rough due to the attachment by ribosomes.
<em>Therefore, the name of the specific organelle that is studded with ribosomes in eukaryotic cell is endoplasmic reticulum.</em>
In a turbite bed sediments is deposited chronologically.
Answer:
Below:
Explanation:
Your Answer is "Phagocytosis".
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