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3 years ago

Which seismic waves are felt first at a seismic station

1 answer:

8 0

Question-
Which seismic waves are felt first at a seismic station

Answer-
Seismic waves are the waves of energy caused by the sudden breaking of rock within the earth or an explosion. They are the energy that travels through the earth and is recorded on seismographs.

There are several different kinds of seismic waves, and they all move in different ways. The two main types of waves are body waves and surface waves. Body waves can travel through the earth's inner layers, but surface waves can only move along the surface of the planet like ripples on water. Earthquakes radiate seismic energy as both body and surface waves.

BODY WAVES
Traveling through the interior of the earth, body waves arrive before the surface waves emitted by an earthquake. These waves are of a higher frequency than surface waves.

P WAVES
The first kind of body wave is the P wave or primary wave. This is the fastest kind of seismic wave, and, consequently, the first to 'arrive' at a seismic station. The P wave can move through solid rock and fluids, like water or the liquid layers of the earth. It pushes and pulls the rock it moves through just like sound waves push and pull the air. Have you ever heard a big clap of thunder and heard the windows rattle at the same time? The windows rattle because the sound waves were pushing and pulling on the window glass much like P waves push and pull on rock. Sometimes animals can hear the P waves of an earthquake. Dogs, for instance, commonly begin barking hysterically just before an earthquake 'hits' (or more specifically, before the surface waves arrive). Usually people can only feel the bump and rattle of these waves.

P waves are also known as compressional waves, because of the pushing and pulling they do. Subjected to a P wave, particles move in the same direction that the the wave is moving in, which is the direction that the energy is traveling in, and is sometimes called the 'direction of wave propagation'. Click here to see a P wave in action.

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In response to action potentials arriving fiom the transverse tubules, the surcoplasmic reticulum releases

sveta [45]

Answer:

D. Calcium ions.

Explanation:

Here we are talking about the mechanism of muscle contraction. The most accepted theory of muscle contraction is sliding filament theory. It was given by Huxley and Huxley. During the process actin filaments slides over myosin filament by forming cross bridges. The sequence of events are as follows:

a. An action potential propagates through the motor nerve and reach the nerve endings on the muscle fiber at neuro-muscular junction.

b. Neurotransmitter called acetylcholine is released by the nerve endings.

c. Acetylcholine binds to the receptors on muscle fiber and opens the gated channels which causes flow of Na+ ions into the muscle fiber.

d. This influx of sodium ions initiates an action potential in the muscle fiber which reaches the T- tubules or transverse tubules. Here it causes the sarcoplasmic reticulum to release large amounts of calcium ion.

e. Calcium ions are responsible for initiating the attractive forces between actin and myosin filaments. Cross bridges are formed, actin slides over myosin causing the contraction of muscle.

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4 years ago

from which cells or islets of langerhans the glucagon andinsulin are secreted?how tdo their effects are antagonistoc

Nadya [2.5K]

Answer: I think this may be the answer....

Explanation:

The islets of Langerhans contain alpha cells which secrete glucagon and beta cells which secrete insulin. Insulin and glucagon are hormones that work to regulate the level of sugar (glucose) in the body to keep it within a healthy range.

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3 years ago

Which structure is composed of the filaments actin and myosin?

bagirrra123 [75]

Myofibril. Thick filaments consist of myosin, held in place by titin filaments

4 0

4 years ago

Read 2 more answers

A type of aneurysm in which blood leaks between layers of the vessel wall, tearing them apart, is called

olga2289 [7]

An aneurysm that divides the three layers of the artery wall, as opposed to inflating out the entire wall, is known as a dissecting aneurysm.

<h3>What causes an aneurysm to form?</h3>

Multiple circumstances that lead to the breakdown of the well-organized structural elements (proteins) of the aortic wall, which maintain and stabilize the wall, can result in an aneurysm. Uncertainty surrounds the precise cause. Aneurysmal disease is thought to be significantly influenced by atherosclerosis, which is the hardening of the arteries with plaque.

Surgical intervention can be required since an aneurysm may continue to grow in size and the arterial wall may deteriorate over time. One of the objectives of therapy is to prevent aneurysm rupture. The risk of an aneurysm rupturing increases with its size (bursting). A rupture could lead to fatal hemorrhage (uncontrolled bleeding), which is life-threatening.

For more information regarding arterial wall, visit:

brainly.com/question/14015132

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2 years ago

Recall that C4 plants tend to have higher rates of photosynthesis when compared with C3 plants (under normal 21 percent O2 atmos

Effectus [21]

Answer:B

Explanation:

In C3 plant fixation of carbon occurs rubisco the Calvin cycle enzyme that add CO2 to ribulose bisphosphate to produce a three carbon compound 3-phosphoglycerate.

C4 plants have an alternate mode of carbon fixation that forms a four-carbon compound as its first products. In C4 plants there are two distinct types of photosynthetic cells; bundle-sheath cells and mesophyll cells. The Calvin cycle is confined in the chloroplasts of the bundle-sheath cell.

In the first step of this mechanisms an enzyme present only in the mesophyll PEP carboxylase adds CO2 to PEP to form oxaloacetate a four-carbon products.

The four-carbon is exported to the bundle-shealth cells where it releases CO2, which is reassimilated into organic material by rubisco and the Calvin cycle. The same reaction regenerate pyruvate. ATP is used to convert pyruvate to PEP, allowing the reaction cycle to continue.

In C4 plants ATP is the price for concentrating CO2 in the bundle-shealth. C4 photosynthesis has higher ATP requirements than the C3 pathway.

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3 years ago