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:
Georgia is the world's leading producer of Kaolin (china clay).
Explanation:
Kaolin or china clay contains the mineral kaolinite mainly. It also contains varying amounts of other minerals like muscovite, feldspar, quartz, etc. In order to prepare it for commercial use, the clay in its natural form is then chemically treated and washed with water to remove the other minerals.
Kaolin is extensively used in the ceramic industry and the paper-coating industry. The high fusion temperature and white burning characteristics are used in the ceramic industry for the manufacture of chinaware, porcelain, and refractories. In the paper-coating industry, the kaolin is mixed with the cellulose fiber in the paper sheet. This gives the paper its color, opacity, and printability. It is also used as a pigment additive in paints, as a filler in plastic and rubber compounds, and in pharmaceuticals.
Photosynthesis takes place<span> inside plant cells in small things called chloroplasts. Chloroplasts (mostly found in the mesophyll layer) contain a green substance called chlorophyll. Below are the other parts of the cell that work with the chloroplast to make </span>photosynthesis happen<span>.</span>
Answer: The vulnerable embryo must be sheltered from desiccation and other environmental hazards. In both seedless and seed plants, the female gametophyte provides protection and nutrients to the embryo as it develops into the new generation of sporophyte.
Explanation:
i think this may help
Trees are a crucial part of the<span> carbon cycle</span>, a global process in which carbon dioxide constantly circulates through the atmosphere into organism and back again. Carbon is the second most valuable element to life, you know, after water. Anyway, trees take carbon from the atmosphere through <span>photosynthesis </span>in order to make energy. This carbon is then either transferred into oxygen and released into the air by <span>respiration </span>or is stored inside the trees until they decompose into the soil. Therefore, the absence of trees would result in significantly HIGHER amounts of carbon dioxide in the air and LOWER amounts of oxygen! The filthy air would also be full of airborne particles andpollutants like carbon monoxide, sulfur dioxide and nitrogen dioxide and its temperature may increase by up to 12 F.
