Sodium in biologyTubuloglomerular feedbackand Sodium-calcium exchanger The homeostatic mechanism which controls the plasma sodium concentration is rather more complex than most of the other homeostatic mechanisms described on this page. The sensor is situated in the juxtaglomerular apparatus of kidneys, which senses the plasma sodium concentration in a surprisingly indirect manner. Instead of measuring it directly in the blood flowing past the juxtaglomerular cellsthese cells respond to the sodium concentration in the renal tubular fluid after it has already undergone a certain amount of modification in the proximal convoluted tubule and loop of Henle. In response to a lowering of the plasma sodium concentration, or to a fall in the arterial blood pressure, the juxtaglomerular cells release renin into the blood.
For example, rock layers show the sequence of geological events, and the presence and amount of radioactive elements in rocks make it possible to determine their ages. Analyses of rock formations and the fossil record are used to establish relative ages. In an undisturbed column of rock, the youngest rocks are at the top, and the oldest are at the bottom.
Rock layers have sometimes been rearranged by tectonic forces; rearrangements can be seen or inferred, such as from inverted sequences of fossil types. The rock record reveals that events on Earth can be catastrophic, occurring over hours to years, or gradual, occurring over thousands to millions of years.
Records of fossils and other rocks also show past periods of massive extinctions and extensive volcanic activity. Although active geological processes, such as plate tectonics link to ESS2.
B and erosion, have destroyed or altered most of the very early rock record on Earth, some other objects in the solar system, such as asteroids and meteorites, have changed little over billions of years. Page Share Cite Suggested Citation: A Framework for K Science Education: Practices, Crosscutting Concepts, and Core Ideas.
The National Academies Press. Major historical events include the formation of mountain chains and ocean basins, volcanic activity, the evolution and extinction of living organisms, periods of massive glaciation, and development of watersheds and rivers. Because many individual plant and animal species existed during known time periods e.
C By the end of grade 2. Some events on Earth occur in cycles, like day and night, and others have a beginning and an end, like a volcanic eruption. Some events, like an earthquake, happen very quickly; others, such as the formation of the Grand Canyon, occur very slowly, over a time period much longer than one can observe.
By the end of grade 5. Earth has changed over time. Understanding how landforms develop, are weathered broken down into smaller piecesand erode get transported elsewhere can help infer the history of the current landscape.
Local, regional, and global patterns of rock formations reveal changes over time due to Earth forces, such as earthquakes. The presence and location of certain fossil types indicate the order in which rock layers were formed.
By the end of grade 8. Major historical events include the formation of mountain chains and ocean basins, the evolution and extinction of particular living organisms, volcanic eruptions, periods of massive glaciation, and development of watersheds and rivers through glaciation and water erosion.
Analyses of rock strata and the fossil record provide only relative dates, not an absolute scale. By the end of grade Radioactive decay lifetimes and isotopic content in rocks provide a way of dating rock formations and thereby fixing the scale of geological time. Continental rocks, which can be older than 4 billion years, are generally much older than rocks on the ocean floor, which are less than million years old.
Tectonic processes continually generate new ocean seafloor at ridges and destroy old seafloor at trenches. B and erosion, have destroyed or altered most of the very early rock record on Earth, other objects in the solar system, such as lunar rocks, asteroids, and meteorites, have changed little over billions of years.
Weather and climate are shaped by complex interactions involving sunlight, the ocean, the atmosphere, clouds, ice, land, and life forms. Earth is a complex system of interacting subsystems:But it puts me in the mind of pondering the delicate balance of life on this earth and, though the artwork in the video is beautiful, I suspect that the presence of rings would dramatically alter life on this earth, perhaps even annihilate it.
By way of disclaimer, let me say I am not a geologist or astronomer. Friday, November 9, Time Sensitive Situation Update. Delta Option plan has triggered many different and strong responses and thus requires a little clarification.
"Biodiversity hotspots" take up just % of the Earth's surface and yet they account for over 50% of plant species and 42% of terrestrial vertebrates.
They include Madagascar, the Himalayas, the mountains of Central Asia and south-west Australia.
The Delicate Balance on Earth The earth is a living planet where many complex systems run perfectly without stopping at all. When compared to other planets, it is evident that in all its aspects the earth is specially designed for human life.
Built on delicate balances, life prevails in every spot of this planet, from the atmosphere to the depths of the earth. Exploring only a few of the millions of these delicate balances would be sufficient to show that the world we live in is specially designed for us.
The earth is a living planet where many complex systems run perfectly without stopping at all. When compared to other planets, it is evident that in all its aspects the earth is specially designed for human life. Built on delicate balances, life prevails in every spot of this planet, from the atmosphere to the depths of the earth.