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AVprozaik [17]
4 years ago
13

The following lists are nations with mixed economies. In which list is the free market most dominant?

Biology
1 answer:
Svetradugi [14.3K]4 years ago
6 0

The correct answer is B. United States, United Kingdom, Singapore, Hong Kong

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List all the electrical and mechanical events that occur within 1 heartbeat (in order). Also be able to state which are occurrin
eimsori [14]

Answer:

 Phases of the Cardiac Cycle are Diastole and Systole

Explanation:

<h2><em>Cardiac Cycle Phases           </em></h2>
  • <u>(First Phase)  Atrial contraction </u>

This is the phase of atrial contraction.

In this fase, 80% of ventricular filling has been done passively even before the onset of atrial contraction, and the remaining 20% of ventricular filling is due to atrial contraction. The active filling of ventricles becomes valuable during physical activity.

When pressure in the atrium increases, blood rush into the ventricles through the opened mitral valve. During left atrium contraction, pressure and volume are transferred into left ventricle through opened mitral valve. Aortic valve is closed because pressure in aorta is greater than the pressure in left ventricle at this moment.  

  • <u>(Second Phase)  Isovolumetric Contraction </u>

The early phase of ventricular systole. When ventricles contract, there is a progressive increase in intraventricular pressure. This wil leads to closure of mitral valve. That produces first heart sound (S1) and little bulging of mitral valve into atrium causing the slight increase in the atrial pressure.

Intraventricular pressure progressively increases upto 80mmHg altought it is not competent enough to open the aortic valve.

At this moment ventricle is contracting with closed mitral and aortic valves. Meanwhile, intra atrium pressure is gradually increasing due to accumulation of blood returning from lungs into the left atrium. During the same phase, aorta pumps whatever blood it contains into more peripheral part of arterial tree due to its elastic nature.  

This is the stage of ventricular contraction when backward valves are closed yet the forward valves are not opened. Ventricle is contracting as a closed chamber without any change in volume and size of the ventricle. We call it isovolumetric contraction of early part of ventricular systole.

  • <u>(Third Phase) Rapid Ventricular Ejection </u>

When pressure reaches to 81mmHg, aortic valve opens. This starts third phase of cardiac cycle. Ventricles keep on contracting, and there is a progressive increase in intraventricular pressure upto 120mmHg. During this phase, aortic valve opens and blood is ejected quickly into the aorta. At this point left ventricle and aorta behave as a single chamber.

The pressure changes occurred in the ventricles results in the transmission of pressure to aorta. Meanwhile left atrium continues receiving blood from the lungs.  

  • <u>(Fourth Phase)  Slow Ventricular Ejection </u>

In this phase atrium is still behaving as reservoir of blood and the pressure is keep on building. Mitral valve is closed. Ventricles are still contracting but intraventricular pressure starts falling, due to ejection of blood . Hence, pressure in aorta also starts falling, but intraventricular pressure is still more than aortic pressure.

Aortic valve remains open leading to slow ejection of blood into aorta. Elastic aorta keeps on squeezing the blood and pumps it into peripheral arterial tree.

  • <u>(Fifth Phase) Isovolumetric Relaxation </u>

In this phase ventricles start relaxing. Intraventricualr pressure falls quickly. In the beginning, as soon as the ventricular pressure becomes less than pressure in aorta, aortic valve closes.

Even though pressure in ventricle is falling, it is still high enough compared to pressure in atrium. Ventricle is relaxing with closed valves and it is known as isovolumetric relaxation. During this phase atrium is still behaving as reservoir of blood.

  • <u>(Sixth Phase) Rapid Passive Ventricular Filling </u>

When left ventricle start relaxing, pressure in left ventricle start dropping  until it reaches the point where pressure in the ventricle becomes less than the pressure in atrium, leads to opening of mitral valve. Blood which was previously accumulated in atrium will rush into ventricle. This quick filling is done without atrial contraction.

  • <u>(Seventh Phase) Slow Passive Ventricular Filling </u>

As atrioventricular valve open, blood coming to atrium rushes into the ventricle. Here atrium is not acting as reservoir.

<u></u>

7 0
4 years ago
Explain the difference from producers and consumers and give 3 EXAMPLES of each.
alexdok [17]
Producers make things like; bees making honey, factory making paper, or  plants making oxygen are all producers
Consumers are the ones who use what producers make like; people eating honey, anyone that uses paper, and anything that needs oxygen are all consumers
5 0
3 years ago
A plant with round seeds is crossed with another plant with round seeds. Round are dominant over oval seeds. When two heterozygo
ASHA 777 [7]

Answer:

Round will appear 75% of the time

Explanation:

Rr*Rr punnet square

Results

RR round

Rr round

Rr round

rr oval

25% round homozygous

50% round heterozygous

25% oval homozygous

7 0
4 years ago
Read 2 more answers
The term Southern Oscillation most nearly refers to which of the following?
Yuki888 [10]

The term Southern Oscillation most nearly refers to a reversal of wind direction

Answer: Option D

<u>Explanation: </u>

Southern Oscillation, a component of the atmosphere in one large-scale interaction called El Niño / ENSO. The equatorial cycle fluctuates after irregular periods of about many years in response to alter in atmospheric pressure in the tropical Indo-Pacific.

With the weakening of the east-west wind during the southern oscillation phase, warm water may slide back west, increasing the flow of the equator up. Surface water temperatures and sea levels fall west and rise east, which is why this event is called El Niño.

6 0
3 years ago
Read 2 more answers
which of the following fossil is best described as forming when minerals replace all of the organisms ​
Andrei [34K]

I think it is a petrified fossil but you didn't give any choices

8 0
4 years ago
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