Heart Dissection w/ Thomas

 Answer the following questions about the structures and functions of the heart & post to your blog:

1. Compare the structure of the atria and ventricles - how are they different?  Why is that?
    The right atria is only 2 mm thick, but the right ventricle is 4-5 mm thick. The left atria is 3 mm thick, while the left ventricle is 8-15 mm thick. The atrias are about one third the size of ventricles.

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

Both the arteries and veins have 3 layers in them, but the arterial walls are much thicker than the veins. 

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

The valves that we found were small tissues near the pulmonary arteries, veins, and between the atrias and ventricles. Their functions are to prevent backflow of blood into the aorta. 

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

Thomas and I were surprised at how big the heart was, and how strong the chordae tendinae were. I was also surprised on how small the atria were compared to the ventricles. 

Arrythmia

What causes irregular heartbeats, and why is it so dangerous?

First of all, heartbeats are caused by electrical impulses that happen in the atria. Cells called sino-atrial nodes (SA nodes) generate the first pulse. The signal travels to another node called the AV node that causes the heart to contract and make a heartbeat. These electrical impulses stimulates the atria, contracts the muscles and allow blood to be pumped. Irregular heartbeats are called arrythmia. Tachycardia is an irregularly fast heartbeat. Ventricular fibrilation occurs when the heart doesnt beat properly. Instead of sending out thr electrical impulses, the heart just jiggles in place, doing nothing. This is caused by disordered electrical impulses. Although the heart moves, there isn't enough impulse to move blood through the heart, failing to circulate blood throughout the body. Symptoms include rapid heartbeats, chest pain, nausea, and dizziness. Medicine can be used to control the heart, and if it gets serious, an external defibrillator can be used to change the heartbeat back to its normal rhythm.

Links:

http://www.medicalnewstoday.com/articles/188837.php

http://www.nlm.nih.gov/medlineplus/ency/article/007200.htm

Heart video

http://www.youtube.com/watch?v=Qj7NtrnBZ0U&feature=youtu.be

What is Emphysema, and why is it so dangerous?

Emphysema is a long term lung disease that is caused by smoking, and long term exposure to air pollution. Some people also get by having a rare decease where they are missing an enzyme that protects their lungs. Some symptoms include, wheezing, shortness of breath, and feeling tired all the time. What emphysema actually does, is that it destroys tissues that are needed to protect the lungs. The alveoli are destroyed, lose thier elasticity and they can't take their regular shape when a person exhales. When exhaling, the alveoli do not expand and shrink properly, making it harder for oxygen to travel, and thus making it harder to breathe. The capillaries also break and do not completely surround the alveoli anymore because of the alveoli being bigger.  Currently, there is no cure for emphysema and medications are the only way to treat the disease.

Links:
http://www.lung.ca/diseases-maladies/a-z/emphysema-emphyseme/index_e.php

http://chealth.canoe.ca/channel_condition_info_details.asp?disease_id=51&channel_id=2022&relation_id=16451

Pictures:

Vital Capacity

1. How does your vital capacity compare to others in the class? Describe some reasons why you think your vital capacity is what it is. Why are the highest and lowest vital capacities the way they are?
Compared to others in the class, my vital capacityis above average. I believe this is due to my size. I am bigger than most of the people in the class. I think the smaller you are, the less vital capacity you will have.


2. How much air is in a usual breath? Why are our breaths the volume that they are?
For guys that are around 18 years old, their usual breath is on average, 4 litres and for girls, it is 2.75 litres. A breath's volume depends on health, age and how big or small the person is.

3. How is the mechanism of exhaling forcefully different than a usual exhalation? Why would practice at this via exercise/instrument playing/singing make you better at it?
Usual exhalation and forceful exhalation is different because during forceful exhalation, the diaphragm does not relax, but instead strains the diaphragm and thoracic cavity. The dipahragm is a muscle, and iwth any muscle, it gets stronger with use. By exercising, playing an instrument, or singing, it strengthens your diaphragm and increases your vital capacity.

Homemade Lungs

The process of inspiration occurs when the intercostal muscles receive nerve impulses that causes them and the diaphragm to contract. The diaphragm goes down and increases the size of the thoracic cavity. The lung inflates because the thoracic cavity and the lungs are attached. The lungs deflate when the diaphragm relaxes and goes back up into its original position. The volume of the thoracic cavity decreases and this compresses the lungs. The process of the diaphragm contracting only happens during inspiration.