After we finished our sheep heart dissection,
we made a video explaining the parts of the heart, their functions, how
the blood flows through the heart, and how the heart beats. The video is below and can also be found on YouTube here and here:
Monday, November 16, 2015
Thursday, November 12, 2015
2015.11.01 Sheep Heart Dissection
Today we dissected a sheep's heart. We were able to observe all the structures on the outside and inside the heart. As we studied the heart we answered questions that our teacher gave to us. The answers are below, and the question numbers are in parentheses ().
On the outside of the heart is the pericardium, a two-layered membrane sac that protects the heart and secretes a fluid that lubricates the heart to reduce friction. It also keeps the heart together as it continuously contracts and relaxes (1).
There are many blood vessels that connect to the heart. Blood vessels that take blood from the heart to the body are called arteries. Blood vessels that take blood from the body to the heart are called veins. Arteries are more elastic than veins, and their walls are thicker and contain more smooth muscle than the walls of veins. This lets the arteries expand and contract under the pressure that the heart exerts against the artery walls as it pumps blood (2).
The inside of the heart is divided into four chambers, two atria and two ventricles. The four chambers are divided into left and right. Each side (left or right) has one atrium and one ventricle. The right side of the heart pumps blood only to the lungs, so it is not as large and muscular as the left side of the heart, which pumps blood to the whole body. The right side of the heart contains deoxygenated blood, while the left side of the heart contains oxygenated blood (12).
The atria are the superior chambers that receives blood from the veins and pumps it into the ventricles. On top of each atrium is a dogear-like pouch that increases the blood volume of the atria so they can receive more blood from the veins (3). Since the atria only have to pump blood to the ventricles, their walls are not as thick and muscular as the walls of the ventricles, which have to pump blood to the lungs or to the whole body (4).
The atria are separated from the ventricles by atrioventricular valves, which prevent blood in the ventricles from flowing back into the atria when the ventricles contract. The atrioventricular valves, which are the tricuspid and bicuspid (mitral) valves, are "anchored" by the chordae tendinae, which are long fibers that trail off the valve, and the papillary muscle, which attach the chordae tendinae to the wall of the ventricle. This makes sure the valves close properly and keeps the valves from swinging backwards into the atria so that blood does not leak backwards into the atria. If valves are not anchored properly, blood could leak backwards instead of going where it needs to go, which could cause health problems like fatigue, swelling, or heart palpitations (irregular heartbeat) (7).
The semilunar valves are the valves that separate the ventricles from the arteries that leave the heart. Just like the atrioventricular valves, they prevent blood from flowing backwards. The semilunar valves prevent blood flow back into the ventricles and keeps the blood flowing in the arteries away from the heart (9).
Valve failure on different sides of the heart has different effects. If valvular heart disease occurs on the right side of the heart, swelling in the feet and ankles occurs because blood that is pumped into the right ventricle by the right atrium does not stay in the right ventricle. Instead, it flows back into the right atrium, backing up the blood flow and not letting blood from the body flow into the right atrium. As a result, blood collects in the feet and ankles, causing them to swell up (10a).
If valvular heart disease occurs on the left side of the heart, the body would not be able to get as much blood. Body cells would not get as much oxygen, which would cause fatigue. This is because blood in the aorta that is supposed to be pumped to the body by the left ventricle instead flows back into the left ventricle and does not go to the body (10b).
At the very end of the dissection, we made a frontal cut through the heart to separate the anterior (front) and posterior (back) sides. This way we were able to see all the structures inside the heart.
On the outside of the heart is the pericardium, a two-layered membrane sac that protects the heart and secretes a fluid that lubricates the heart to reduce friction. It also keeps the heart together as it continuously contracts and relaxes (1).
There are many blood vessels that connect to the heart. Blood vessels that take blood from the heart to the body are called arteries. Blood vessels that take blood from the body to the heart are called veins. Arteries are more elastic than veins, and their walls are thicker and contain more smooth muscle than the walls of veins. This lets the arteries expand and contract under the pressure that the heart exerts against the artery walls as it pumps blood (2).
The inside of the heart is divided into four chambers, two atria and two ventricles. The four chambers are divided into left and right. Each side (left or right) has one atrium and one ventricle. The right side of the heart pumps blood only to the lungs, so it is not as large and muscular as the left side of the heart, which pumps blood to the whole body. The right side of the heart contains deoxygenated blood, while the left side of the heart contains oxygenated blood (12).
The atria are the superior chambers that receives blood from the veins and pumps it into the ventricles. On top of each atrium is a dogear-like pouch that increases the blood volume of the atria so they can receive more blood from the veins (3). Since the atria only have to pump blood to the ventricles, their walls are not as thick and muscular as the walls of the ventricles, which have to pump blood to the lungs or to the whole body (4).
The atria are separated from the ventricles by atrioventricular valves, which prevent blood in the ventricles from flowing back into the atria when the ventricles contract. The atrioventricular valves, which are the tricuspid and bicuspid (mitral) valves, are "anchored" by the chordae tendinae, which are long fibers that trail off the valve, and the papillary muscle, which attach the chordae tendinae to the wall of the ventricle. This makes sure the valves close properly and keeps the valves from swinging backwards into the atria so that blood does not leak backwards into the atria. If valves are not anchored properly, blood could leak backwards instead of going where it needs to go, which could cause health problems like fatigue, swelling, or heart palpitations (irregular heartbeat) (7).
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| drawing of aortic semilunar valve (11) |
Valve failure on different sides of the heart has different effects. If valvular heart disease occurs on the right side of the heart, swelling in the feet and ankles occurs because blood that is pumped into the right ventricle by the right atrium does not stay in the right ventricle. Instead, it flows back into the right atrium, backing up the blood flow and not letting blood from the body flow into the right atrium. As a result, blood collects in the feet and ankles, causing them to swell up (10a).
If valvular heart disease occurs on the left side of the heart, the body would not be able to get as much blood. Body cells would not get as much oxygen, which would cause fatigue. This is because blood in the aorta that is supposed to be pumped to the body by the left ventricle instead flows back into the left ventricle and does not go to the body (10b).
At the very end of the dissection, we made a frontal cut through the heart to separate the anterior (front) and posterior (back) sides. This way we were able to see all the structures inside the heart.
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| drawing of interior of heart (13) |
Tuesday, November 10, 2015
Unit 3 Reflection: The Circulatory System
Unit 3 was about the circulatory system and the respiratory system. The essential questions of this unit included:
We learned about different parts of the heart in detail in this unit. To help us learn about the heart's structure, we went outside, drew a diagram of the heart on the ground, and made a video explaining the path a red blood cell takes through the heart.
All this drawing of the heart helped us prepare for our sheep's heart dissection, which was very interesting and let us see what an actual heart looked like. There was some fat on the heart, which we did not really expect because diagrams of the heart don't really depict fat, and the anatomy of the heart was a little bit different since it wasn't a human heart.
We also learned about blood vessels. There are three main kinds of blood vessels: arteries, which take blood from the heart to the body; veins which take blood from the body to the heart; and capillaries, which connect the two. Arteries are the ones that expand and contract as the heart beats (this is how you feel you pulse). Veins have valves in them that prevent blood from flowing backwards (e.g. blood in your leg has to flow against gravity to get back to your heart). The capillaries are where the exchange of nutrients, wastes, and gasses actually occur.
In the blood vessels flow the blood, which is made of plasma and cells. Plasma itself is made of water and dissolved solutes. Blood cells include red blood cells, which carry oxygen, and white blood cells, which are part of our immune system and help fight infections. There are many different kinds of white blood cells, including neutrophils, basophils, eosinophils, lymphocytes (B-cells and T-cells), and monocytes (which mature into macrophages). Blood also contains platelets, which help the blood clot if you get cut.
What we learned about heart diseases tied into our past unit about health. Mostly we learned about atherosclerosis (the buildup of plaque, or fatty material, in the blood vessels) and aneurysms (the weakening of a blood vessel wall due to blood getting in between the layers of the wall and making it swell up). Atherosclerosis is caused by chronic inflammation; excess sugars, omega-6, and LDL ("bad") cholesterol; and too little HDL ("good") cholesterol. When little microtears form in the blood vessel wall, this excess LDL becomes stuck in the wall. If there is too little HDL to clean it up, white blood cells think that the body is under attack, come to engulf the LDL, and become stuck as well. This forms a plaque in the artery that restricts blood flow. A blood clot can form around the plaque and cut off blood flow entirely. If this happens in a coronary artery that provides blood to the heart muscle, it is called a heart attack. If this happens in the brain, it is called a stroke (strokes can also be caused by aneurysms). Good nutrition lowers your risk of atherosclerosis (since atherosclerosis is caused by excess sugars, omega-6, and LDL) and therefore the diseases associated with it. Exercising, managing stress, and controlling your weight also prevents atherosclerosis.
We also learned about the respiratory system, since it is connected to the circulatory system (oxygen-poor blood is pumped from the heart to the lungs to exchange carbon dioxide for oxygen, then returns back to the heart to be pumped to the rest of the body). Air enters the respiratory system through the nose, then travels down the pharynx (throat), larynx (voice box), trachea (windpipe), bronchus, broncial branches, and finally into the lungs. The lungs themselves are made of tiny air sacs called alveoli, which are covered with capillaries and are where the actually gas exchange takes place. Breathing in occurs when the diaphragm contracts and flattens out from its relaxed, curving-upward state (this is interesting; I didn't know about how the diaphragm actually moved down before), and the intercostals (muscles between the ribs) contract and pull the ribcage out.
This unit was a pretty good unit for me, since I understood what was taught in class. I felt more comfortable with this unit's material than with last unit's on health; I suppose I am better at learning about the larger things that I can see and feel than I am at learning about the little things that I can't really see for myself. The active studying method that we discussed in class also helped, especially relating concepts to each other by drawing concept maps.
Last unit we made a chart of health goals. My goals were to:
- What are the major features of the circulatory system?
- What are the structures of the heart and their functions?
- What are the (dys)functions of the blood vessels?
- What are the different components of blood and what are their functions?
- What are heart attacks and strokes? What causes them, how are they identified, and how are they treated?
- What are the functions of the respiratory system?
We learned about different parts of the heart in detail in this unit. To help us learn about the heart's structure, we went outside, drew a diagram of the heart on the ground, and made a video explaining the path a red blood cell takes through the heart.
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I also drew a diagram of the heart by myself to help me learn about the heart. This was after we had learned more about the structures of the heart and their functions, so it is more accurate (the papillary muscle in the above diagram is incorrectly labeled).
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| my diagram of the heart |
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In the blood vessels flow the blood, which is made of plasma and cells. Plasma itself is made of water and dissolved solutes. Blood cells include red blood cells, which carry oxygen, and white blood cells, which are part of our immune system and help fight infections. There are many different kinds of white blood cells, including neutrophils, basophils, eosinophils, lymphocytes (B-cells and T-cells), and monocytes (which mature into macrophages). Blood also contains platelets, which help the blood clot if you get cut.
What we learned about heart diseases tied into our past unit about health. Mostly we learned about atherosclerosis (the buildup of plaque, or fatty material, in the blood vessels) and aneurysms (the weakening of a blood vessel wall due to blood getting in between the layers of the wall and making it swell up). Atherosclerosis is caused by chronic inflammation; excess sugars, omega-6, and LDL ("bad") cholesterol; and too little HDL ("good") cholesterol. When little microtears form in the blood vessel wall, this excess LDL becomes stuck in the wall. If there is too little HDL to clean it up, white blood cells think that the body is under attack, come to engulf the LDL, and become stuck as well. This forms a plaque in the artery that restricts blood flow. A blood clot can form around the plaque and cut off blood flow entirely. If this happens in a coronary artery that provides blood to the heart muscle, it is called a heart attack. If this happens in the brain, it is called a stroke (strokes can also be caused by aneurysms). Good nutrition lowers your risk of atherosclerosis (since atherosclerosis is caused by excess sugars, omega-6, and LDL) and therefore the diseases associated with it. Exercising, managing stress, and controlling your weight also prevents atherosclerosis.
We also learned about the respiratory system, since it is connected to the circulatory system (oxygen-poor blood is pumped from the heart to the lungs to exchange carbon dioxide for oxygen, then returns back to the heart to be pumped to the rest of the body). Air enters the respiratory system through the nose, then travels down the pharynx (throat), larynx (voice box), trachea (windpipe), bronchus, broncial branches, and finally into the lungs. The lungs themselves are made of tiny air sacs called alveoli, which are covered with capillaries and are where the actually gas exchange takes place. Breathing in occurs when the diaphragm contracts and flattens out from its relaxed, curving-upward state (this is interesting; I didn't know about how the diaphragm actually moved down before), and the intercostals (muscles between the ribs) contract and pull the ribcage out.
This unit was a pretty good unit for me, since I understood what was taught in class. I felt more comfortable with this unit's material than with last unit's on health; I suppose I am better at learning about the larger things that I can see and feel than I am at learning about the little things that I can't really see for myself. The active studying method that we discussed in class also helped, especially relating concepts to each other by drawing concept maps.
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| active studying |
- eat seafood at least three times a week.
- exercise at least three times a week.
- sleep at least eight hours every day.
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