Oxygen-poor blood enters the heart through the right atrium. From there blood flows through the tricuspid valve into the right ventricle. When the heart contracts during the diastolic phase, this blood is pumped out through the pulmonary arteries that run toward the lungs. At the lungs, the blood is circulated through a series of progressively smaller arterioles until it flows through capillaries lining the lungs' alveolar sacs. It is here that gas exchange takes place as oxygen is taken up by the blood, and carbon dioxide is released into the waste air.After oxygenation, the fresh blood is circulated back through the bronchial veins and into the pulmonary veins. These run from the lungs and drain into the heart's left atrium. During the systolic phase of the heartbeat, the mitral valve under the left atrium opens and permits blood to pass into the left ventricle. This chamber is heavily muscled and it has the power to pump the oxygen-rich blood out through the aorta and into the rest of the body.
The process is ocurring by steps, starting with depolarization.
1- Na+ permeability > K+ permeability
2- Vm (membrane potential) approaches ENa+ (quilibrium potential for potassium)
3- K+ permeability > Na+ permeability
4- Vm (membrane potential) approaches EK+ (quilibrium potential for potassium)
Evolution by natural selection.
survival of the fittest=natural selection
Answer: TRUE
Explanation:
Sound waves enter the OUTER EAR and travel through a narrow way up to the eardrum, where it vibrates.
The vibrations are sent to the bones of the MIDDLE EAR where they are amplified, and passed to a structure called COCHLEA in the INNER EAR.
Finally, it reaches the sensory cells that passes it to the auditory nerve that transmit the sound to the brain as electrical signals (neural messages) for proper interpretation.
So, it is True because from OUTER EAR to MIDDLE EAR, to INNER EAR.
Answer:
traits that hinder survival eventually disappear
Explanation:
living things adapt to their surroundings
