The simplest form of animal circulatory pump consists of a blood vessel down which passes a wave of muscular contraction, called peristalsis , that forces the enclosed blood in the direction of contraction. While ciliary respiratory currents are sufficient to supply the requirements of animals with simple epithelial tissues and low metabolic rates, most species whose bodies contain a number of organ systems require a more efficient circulatory system. Where as hyperhydration or a gain in body fluid intake of water usually results in a reduction of blood tonicity and an increase in blood volume. Oxygenated blood arrives in…. When you run around a lot, your body needs a lot more oxygen-filled blood. Increased risk of heart disease. The two chambers on top are called the atria say:
There are networks of capillaries in most of the organs and tissues of the body. These capillaries are supplied with blood by arterioles and drained by venules.
Capillary walls are only one cell thick see diagram , which permits exchanges of material between the contents of the capillary and the surrounding tissue. Function is to supply tissues with components of, and carried by, the blood, and also to remove waste from the surrounding cells … as opposed to simply moving the blood around the body in the case of other blood vessels ;.
Exchange of oxygen, carbon dioxide, water, salts, etc. Venules are minute vessels that drain blood from capillaries and into veins. Many venules unite to form a vein.
The walls outer structure of veins consist of three layers of tissues that are thinner and less elastic than the corresponding layers of aerteries. Veins include valves that aid the return of blood to the heart by preventing blood from flowing in the reverse direction. The heart is located slightly to the left of the centre of your chest between the 2 lungs. It is made of cardiac muscle and is surrounded by a double membrane called the pericardium.
There is fluid between these 2 membranes called pericardial fluid. This fluid helps to reduce friction when the heart beats. The heart is about the size of a clenched fist. The human heart is primarily a shell. There are four cavities, or open spaces, inside the heart that fill with blood. Two of these cavities are called atria. The other two are called ventricles. The two atria form the curved top of the heart.
The ventricles meet at the bottom of the heart to form a pointed base which points toward the left side of your chest. The left ventricle contracts most forcefully, so you can best feel your heart pumping on the left side of your chest. The left side of the heart houses one atrium and one ventricle.
The right side of the heart houses the others. A wall, called the septum, separates the right and left sides of the heart. A valve connects each atrium to the ventricle below it. The bicuspid valve connects the left atrium with the left ventricle.
The tricuspid valve connects the right atrium with the right ventricle. The semilunar valves allow the blood to flow out of the heart into the 2 main arteries aorta and pulmonary artery. They prevent blood from returning to the heart. The top of the heart connects to a few large blood vessels.
The largest of these is the aorta, or main artery, which carries nutrient-rich blood away from the heart. Another important vessel is the pulmonary artery which connects the heart with the lungs as part of the pulmonary circulation system.
The two largest veins that carry blood into the heart are the superior vena cava and the inferior vena cava. The inferior is located beneath the superior. From the moment of development through the moment of death, the heart pumps. The heart, therefore, has to be strong. As the cardiac muscle contracts it pushes blood through the chambers and into the vessels.
Nerves connected to the heart regulate the speed with which the muscle contracts. When you run, your heart pumps more quickly. When you sleep, your heart pumps more slowly. Considering how much work it has to do, the heart is surprisingly small. The average adult heart is about the size of a clenched fist and weighs about 11 ounces grams. Located in the middle of the chest behind the breastbone, between the lungs, the heart rests in a moistened chamber called the pericardial cavity which is surrounded by the ribcage.
The diaphragm, a tough layer of muscle, lies below. As a result, the heart is well protected. Day and night, the muscles of your heart contract and relax to pump blood throughout your body. When blood returns to the heart, it follows a complicated pathway. If you were in the bloodstream, you would follow the steps below one by one. Superior and inferior vena cava deoxygenated 2. Pulmonary veins oxygenated 9. The heart has a double circulation system.
The pulmonary circuit pumps blood to the lungs and the systemic circuit pumps blood to the body systems i. The head limbs, and trunk. The right ventricle pumps blood through the shorter pulmonary circuit while the left ventricle pumps blood through the longer systemic circuit.
Nearly one-forth of the blood that is pump into the Aorta by the Left Ventricle flows to the Kidneys. Excess nutrients are stored in the Live for future needs. The Liver receives oxygenated blood from a large Artery that branches of the Aorta. The heart also needs a supply of blood for its nourishment. It does not use the blood it pumps for itself. The blood flowing through the heart does not directly serve the heart. Like all other organs the heart muscle has its own blood circuit.
The heart gets blood from the coronary arteries that emerge directly from the aorta. Two coronary arteries arise from the aorta just beyond its semilunar valve. The right coronary artery mostly serves the right atrium and right ventricle. The left coronary artery is much larger and supplies the left atrium and left ventricle. Venules then carry the blood to the coronary veins and back to the right atrium. The pumping action of the heart is controlled by the pacemaker also known as the sino-atrial node SA.
It is in the wall of the right atrium. The pacemaker receives messages from the brain. Two nerves from the medulla oblongata connect to it influencing its rate of contraction. One nerve quickly accelerates the heart rate and the other can quickly reduces it back to resting rate. These messages are transmitted as electrical impulses that cause the atria both left and right to contract. They also allow for the study of fetal circulation , which differs from that of an adult.
Secondly, fetal pigs are easy to obtain because they are by-products of the pork industry. Fetal pigs are the unborn piglets of sows that were killed by the meat packing industry.
Fetal pigs not used in classroom dissections are often used in fertilizer or simply discarded. Fourthly, fetal pigs are easy to dissect because of their soft tissue and incompletely developed bones that are still made of cartilage. As long as the pork industry exists, fetal pigs will be relatively abundant, making them the prime choice for classroom dissections. Several peer-reviewed comparative studies have concluded that the educational outcomes of students who are taught basic and advanced biomedical concepts and skills using non-animal methods are equivalent or superior to those of their peers who use animal-based laboratories such as animal dissection.
Three studies at universities across the United States found that students who modeled body systems out of clay were significantly better at identifying the constituent parts of human anatomy than their classmates who performed animal dissection.
Another study found that students preferred using clay modeling over animal dissection and performed just as well as their cohorts who dissected animals. The size of the fetal pig depends on the time allowed for the mother to gestate:. However, there is a correlation between a mother pig having a nutritious diet containing proteins, vitamins and minerals during gestation period and the survival rate of piglets.
The correlation, however, is not statistically different. Weight is also not a factor of survival rate because a healthier diet does not lead to a heavier offspring or a greater chance of live birth.
The placenta is used as a means of transferring nutrients from the mother to the fetus. The efficiency at which nutrients are transferred dictates the health and growth of the fetus.
FRP, or fetal weight: However, increasing FPR does not prove to increase litter size. Instead, a more accurate way of determining fetus growth is through certain characteristics of the placental lining. The width and length of the placenta folds are positively related and increase as gestation progresses.
The width of the placental folds decreases until day 85 of gestation. From here, the width increases with gestation and is at its largest around day The rate at which these folds increase is negatively related to fetus size.
Thus, greater fold widths will be seen in smaller fetuses. Although increasing placental fold width does increase the interaction between fetus and mother, nutrient exchange is not most efficient in smaller fetal pigs, as would be expected.
Many other factors, including depth of placental folds, are also responsible for these interactions. The prenatal development of the fetus includes all the tissue and organ development. Within hours of mating, the sperm and egg undergo fertilization in the oviduct and three days later the egg moves into the uterus. The cells begin to specialize by day six, and attach themselves to the uterus lining by day eleven.
From fertilization to day 18, the endoderm , ectoderm and mesoderm have been forming inside the embryo, and are completely formed by day 18, the same day the placenta forms. The endoderm transforms into the lungs, trachea, thyroid gland, and digestive tract of the fetus. The ectoderm has a greater role in the development of the fetus. It forms into the skin, nervous system, enamel of the teeth, lining of the intestine, mammary and sweat glands, hoofs, and hair.
The mesoderm forms the major organ components that help keep the fetus alive. It forms the muscles and connective tissues of the body, blood vessels and cells, the skeleton, kidneys, adrenal glands, heart, and the reproductive organs.
By day 20, most of the major organs are visible, and the last half of gestation focuses greatly on increasing the size of the fetuses. The development of the lymphatic system and the formation of blood circulation occur at different stages of fetal pig development.
The first lymphatic organ to become present is the thymus. Lymphocyte builds up in the spleen on the 70th day. By day 77, the thymus is already completely developed and is distinguishable from other organs. Also, follicles are present on the tongue and intestines on day On the 84th day, Periarteriolar lymphoid sheaths appear in the fetal pig.
By this time, the liver and bone marrow are active and functional. Studies have shown that litter size, the amount of floor space during the growing period, and the number of pigs the gilt, or female pig, is placed with while growing affect the reproduction rates of the gilts. Data from a study in by Nelson and Robinson showed that gilts from a small litter size ovulated more than the gilts from the larger litters.
The study suggests stress plays a role in impacting the reproduction. The amount of floor space has been shown to impact the time it takes gilts to reach puberty. An adequate amount of floor space allowed the higher percentage of gilts to reach puberty sooner than those gilts who had less floor space.
The gilts placed in smaller groups bore one more pig per litter than gilts in larger groups. Still, the environment in which the fetal gilt develops is significant to the reproductive and physiological development. Fetal pigs are often preserved in formaldehyde [ citation needed ] , a carcinogenic substance.
A study found that exposure to formaldehyde could possibly cause nasal cancer in rats, leading to research on whether this was possible in humans or not. The anatomy of a fetal pig is similar to that of the adult pig in various aspects. Systems that are similar include the nervous, skeletal , respiratory neglecting the under developed diaphragm , and muscular. Other important body systems have significant differences from the adult pig.
There are only a few differences between the circulatory system of an adult pig and a fetal pig, besides from the umbilical arteries and vein. There is a shunt between the wall of the right and left atrium called the foramen ovale. This allows blood to pass directly from the right to left atrium.
There is also the ductus arterius which allows blood from the right atrium to be diverted to the aortic arch. Both of these shunts close a few minutes after birth. The monogastric digestive system of the fetal pig harbors many similarities with many other mammals. The fetal pig's digestive organs are well developed before birth, although it does not ingest food.