Transport System

Blood
There are some components in our blood, such as plasma, erythrocytes(red blood cell), leukocytes(white blood cell), and platelets.



job of red blood cell

 

• erythrocytes: produced in bone marrow and transport O₂and CO₂
• leukocytes: produced in bone marrow and have a role of defense against bacteria or foreign body substance by phagocytosis
• platelets: help blood clotting
• plasma: contain water, salts, plasma proteins, and transport nutrients, urea, gases(CO₂and O₂), hormones, and heat

 

job of white blood cell



Human Heart
Our heart has two sides with different functions. Right side is for receiving blood and pumping it to the lungs, and left side is for receiving blood and pumping it to around the body. Moreover, each side has two chambers that are atrium and ventricle.

• Right atrium: It is connected to superior vena cava and inferior vena cava, and blood with carbon dioxide enters.
• Right ventricle: Blood is collected in right ventricle with carbon dioxide. And it is connected to pulmonoary artery and blood goes to lung.
• Left atrium: Blood from lung enters with oxygen.
• Left ventricle: Blood is collected in here with oxygen and it is pumped to around the body through the arteries.

Since right side and left side have different jobs, the structures are a little bit diffrent each other. Left side has to pump blood around the body, so it has thick muscle and it is hard. On the other hand, right side has thin mucle and soft.

Blood Vessels

There are three types of blood vessles in our body.

• Arteries: It carries blood with a lot of oxygen to the body. So the pressure inside the arteries is really high. To endure the high pressure, they have thick wall, and elastic fibers, and they have outer fibrous coats to prevent arteries from rupturing. Also they have lumen small to maintain high pressure.
• Veins: It carries blood with carbon dioxide to lung. The pressure inside the veins is lower than arteries. So they have thin wall, more collagen, and small muscle. And they have lumen large to facilitate blood flow.
• Capillaries: They are thinner and smaller than arteries and veins. To do fast exchange, they have pores and wall is one cell thick.

Flow of Blood

1. Blood is carried through superior/inferior vena cava to right atrium. When blood is collected and pressure increases enough, atrio-venticular valve opens and blood can enters to right ventricle.
2. Blood is collected in right ventricle. When the pressure inside ventricle increases, semi-lunar valve opens and blood is pumped to lung through pulmonary artery.
3. Blood comes to left atrium from lung with oxygen through pulmonary veins. When pressure becomes high, atrio-ventricular valve opens.
4. In left ventricle, blood is collected. After pressure increaases, the semi-lunar valve opens. And blood can be carried to the body through aorta.

Heart Beat
Heart is made up cardiac muscle, and this muscle contracts and relaxes spontaneously. This is known as myogenic contraction.

1. Sino-Atrial node(SA node) generates electrical impulse frequency.
2. That impulse goes to both atria and atria contract together.
3. Atrio-Ventricular node(AV node) picks up that impulse and conduces to ventricles through fibers.
4. Ventricle contracts.

Also during exercise, we can feel that our hearts move faster than usual. It is because when we are doing exercise, cell metabolism produces more CO2, and that CO2 is dissolved in blood as forming H2CO3 that makes blood pH lower. So the receptors in the brain perceivedecreasing of the pH in the blood and send signals to increase hertbeat.

Coronary Heart Disease

This is a disease that cardiac muscle cannot get enough blood. Inside coronary arteries, lipid and cholesterol(plaque) are built up. So arteries become harder and less flexible and the spaces for blood to pass become narrow. This disease is cased by many factors. Forexample, age, gender, cholesterol levels, smooking, stress, and so on. The researcher said that stoping smoking can dcrease risk of coronary heart diesase effectively.

Dissection of pig heart!
In a class, we dissected pig's heart with scissors and knife. The heart had a lot of fats, and we could see blood vessels. We cut the heart from top to bottom. We saw that muscle on the left side of heart was bigger and thicker and riht side was small. Also left side was much harder than right side.