True, a person can have two conflicting attitudes.
Answer:
The prolonged electrical depolarization of cardiac muscle cells -that occurs during contraction- is due primarily to the persistent influx of calcium ion
Explanation:
The action potential of the heart muscle is longer with respect to skeletal muscle (around 300 milliseconds), and this is due to the activity of calcium (Ca⁺⁺ ) in the intracellular compartment.
The initial depolarization of cardiac muscle fiber depends on the entry of sodium (Na⁺) into the cell. However, for the action potential to occur and be maintained, Ca⁺⁺ must increase its cytoplasmic levels, which depends on:
- The increase in intracellular sodium induces the release of Ca⁺⁺ from the sarcoplasmic reticulum.
- Calcium entry from the extracellular space through the voltage dependent Ca⁺⁺ channels.
- The entry of extracellular Ca⁺⁺ causes the release of more Ca⁺⁺ ions by the sarcoplasmic reticulum, further increasing its intracellular concentration.
This is how the ion that guarantees the duration of the action potential of the cardiac muscle cell is the Ca⁺⁺.
Learn more:
Calcium, sodium and cardiac muscle cells brainly.com/question/4473795
Answer:
The correct answer is: <em>C. Increased average lifespan to 78 in the US.</em>
Explanation:
Science has impacted human health by increasing the average lifespan to 78 in the US. Over the last couple of decades, the life expectancy of Americans has increased significantly than what it was 200 years ago. This can be attributed to:
1. Vaccinations- Since the invention of vaccinations, diseases such as tuberculosis, cholera and polio which were major causes of death 200 years ago have virtually been eradicated in the US.
2. Abundant and safer foods available- Commercial and large scale farming has made a wide variety of nutritious foods easier to obtain.
3. Improved sanitation- Safer drinking water, sewage treatment and stricter food inspection has significantly reduced the rate of illnesses due to poor hygiene and sanitation.
In these ways, science has impacted human health by increasing the average lifespan to 78 in the US.
Explanation:
The membrane would be too rigid. The unsaturated fatty acids allow the membrane components to maintain their fluid mosaic structure-the components slip past each other freely and adjust to changes in osmotic pressure within the cell.
Further Explanation:
Lipids consist of fatty acids forming the hydrophobic tail and glycerol forming the hydrophilic head; glycerol is a 3-carbon alcohol that is water-soluble, while the fatty acid tail is a long chain hydrocarbon (carbon-backed hydrogen) of up to 36 carbohydrates.
Their polarity or arrangement can confer hydrophilic and hydrophobic properties on these non-polar macromolecules. Small water molecules can pass through the phospholipid bilayer through diffusion into the extracellular fluid or cytoplasm as a semi-permeable membrane, both of which are hydrophilic and contain large concentrations of polar water molecules or other water soluble compounds. The heads of the bilayer are hydrophilic the bilayer are attracted to water while their water-repellent hydrophobic tails face towards each other- allowing molecules of water to diffuse across the membrane along the concentration gradient.
Other components include:
- Cholesterol: The comparatively rigid cholesterol anchors other molecules attached to the membrane, maintains membrane stability or structural integrity, and helps to separate some lipids, helping with membrane fluidity at low ambient temperatures.
- Transmembrane proteins are embedded from the extracellular fluid into the cytoplasm within the membrane, and are sometimes attached to glycoproteins (proteins attached to carbohydrates) that function as cell surface marker.
Learn more about membrane components at brainly.com/question/1971706
Learn more about plasma membrane transport at brainly.com/question/11410881
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