Heart Dissection

1. Compare the structure of the atria and ventricles - How are they different? Why is that?

Ventricles are thick walled muscular, which is essential because they must be strong enough to to push blood away from the heart and through the body. The atria are thinner because blood flows into the atria, and very little force is needed to move blood through the atria.

2. Did you notice a difference between the veins and the arteries entering and leaving the heart? How is their structure different?

The pulmonary arteries carry blood from the heart to the lungs. Pulmonary veins carry blood from the lungs to the heart. Arteries have thick walls, and veins have thinner walls. Other than that, we did not notice much of a difference. 

3. Describe the valves that you found in the heart - what are their functions?

The valves we found are the aortic semilunar valves, and the pulmonary semilunar valves. The blood flows through the semilunar valves on its way out of the heart. The right ventricle has a pulmonary semilunar valve, since it pumps blood out through the pulmonary artery. The left side has an aortic semilunar valve, since it pumps out blood through the aorta. They prevent blood from flowing back into the ventricles.

4. What surprised you about dissecting the heart? Why?

What surprised me is how similar it was to a human heart. The pictures and diagrams we have seen in class match the heart we dissected. I was expecting some differences.

How much blood is pumped by the heart?

As we all know, the heart is the strongest muscle in our body, and is also the most vital. The million dollar question is: how much blood does the heart pump?

The average human heart beats :

• 72 times a minute
• 100, 000 times a day
• 3, 600, 000 times a year
• 2.5 billion times a lifetime

• A healthy human heart pumps 2, 000 gallons of blood through 60, 000 miles of blood vessels every day.
• A kitchen faucet would need to be turned on all the way for at least 45 years to equal the amount of blood pumped in an average lifetime.
• The volume of blood pumped by the heart can range from five to 30 litres per minute.
• The heart creates enough energy, per day, to drive a truck 20 miles. That is equal to driving to the the moon and back in a lifetime.
• During an average lifetime, the heart will pump about 1.5 barrels of blood, which is enough to fill 200 train tank cars.

Source

How does blood flow through the heart?

What is Asthma?

Asthma is a respiratory condition marked by spasms of the bronchi in the lungs, which causes difficulties in breathing. Asthma causes recurring periods of wheezing, chest tightness, shortness of breath, and coughing. The coughing often occurs at night or early in the morning. People who have asthma have inflamed airways, making them swollen and very sensitive; they tend to react strongly to certain inhaled substances. When the airways react, the muscles around them tighten. This narrows the airways, causing less air to flow into the lungs. Cells in the airways might produce more mucus than usual; this chain reaction can result in asthma symptoms. Symptoms can happen each time the airways are inflamed. 

There are many factors which contribute to asthma, such as:

• low birth weight
• exposure to tobacco smoke
• allergies
• pollution
• pregnancy
• stress
• genes
• airway hyperactivity
• atopy

Some triggers:

• mould
• animal dander
• pollen
• cockroaches
• dust mites
• chemicals, fumes, odours
• respiratory viral infections
• weather
• smog
• excessive, strenuous physical activity

Although asthma cannot be cured, it can be controlled by avoiding asthma triggers, taking medication, and following an asthma action plan.  

Source #1 Source #2 Source #3 Source #4

Vital Capacity

We tested our vital capacity earlier this week and I can store up to 2800 cc or 2.8 L. I am happy with this result, as 2.7 L is the average for a 17 year old girl. Vital capacity is what it is depending on how much we use our lungs. Some of the highest vital capacities out of the girls were from those in band; the band kids had higher lung capacities because they have conditioned and strengthened their lungs. A usual breath consists of 500 mL. The reason we do not exhale our entire vital capacity each time is to conserve energy; it would be exhausting to force out all the air each time we need to exhale. The purpose of exhaling is to rid the body of carbon dioxide to prevent our blood from becoming toxic. Breathing is meant to be an autonomic process to allow us to concentrate on other things. Activities such as playing a sport or an instrument are beneficial to our lungs because it allows them to become stronger. The lungs are like any other muscle in our body, they become stronger the more they are exercised.