Learning Elementary Biology for Class 8: Biology - Circulatory system Flashcards

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created 7 weeks ago by Reeth2008
Biology, Science. Part of PT-3
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Provide details about the heart.

The heart is located in the chest cavity towards the left, enclosed in a double-walled sac called the pericardium. Pericardial fluid is present between the heart wall and pericardium. The fluid protects the heart from shocks and jerks during contractions. The heart is made of muscle cells called cardiac muscle fibers.


Explain more about auricles and ventricles.

The upper 2 chambers are the right and left auricles and the lower two are the right and left ventricles. The auricles are called the receiving chambers because they receive blood from different parts of the body. They are smaller than ventricles and have thin walls.


What are ventricles?

The ventricles are the distributing chambers, as they pump blood into the lungs and blood vessels that distribute the blood everywhere. They are larger than auricles and their walls are thick, elastic, and muscular to help efficiently pump blood into different parts of the body


How is the heart divided into different parts?

The right and left sides are separated by a membrane called the septum. The blood on the right side never mixes with the left side. The left auricle opens into the left ventricle through the left auriculo-ventricular aperture and vice versa.


What are the 4 valves in the heart?

  • The tricuspid valve guards the opening between the right auricle and the right ventricle. It has 3 cusps.
  • The bicuspid valve guards the opening between the left auricle and the left ventricle. It has 2 cusps.
  • Aortic semilunar valves are located at the point of origin of the aorta from the left ventricle and are 3 in number.
  • Pulmonary semilunar valves are located at the opening of the right ventricle into the pulmonary artery and are 3 in number.

What is the sino-atrial node and what does it do?

The heart is a muscular organ made up of specialized cardiac muscles. Contraction and relaxation are a result of an electrical impulse that originates in a mode called the sinoatrial or SA node. The sino-atrial node is situated in the wall of the right atrium. The impulse of the heartbeat starts here. It is also called the pacemaker of the heart. The impulse is relayed to the ventricles with the help of special conducting fibers.


Provide detail on pacemaker and septum.

Sometimes the pacemaker becomes faulty causing heart trouble. An artificial pacemaker can be attached to the heart to treat the problem. Septum is the portion of the human heart that separates the two left chambers from the right. The upper part is called atrial septum and the lower part is called inter-ventricular septum.


Explain about the major blood vessels in the heart.

Aorta; carries the oxygenated blood from the left ventricle to other parts of the body.

Pulmonary artery: The right vetricle forces blood into the pulmonary aorta which carries the deoxegenated blood to lungs purification.

Pulmonary vein: Left atrium receives oxygenated blood from lungs through this.

The Coronary artery carries the blood to the heart muscles.

The Coronary vein collects the blood from the heart muscles.


Explain the vena cava and the pulmonary trunk.

The right atrium receives deoxygenated blood of the whole body through the superior and inferior vena cava. the superior brings in deoxygenated blood from the upper parts of the body while the inferior brings deoxygenated blood from the lower part.

The pulmonary trunk is the major blood vessel of the human heart. It originates from the right ventricle and branches into the left and right pulmonary arteries. These arteries carry deoxygenated blood to the lungs.


What is double circulation?

As the blood flows twice through the heart, it is called double circulation. The circulation of blood from the right ventricle to the lungs and from the lung to the left auricle is called the pulmonary circulation. In pulmonary circulation, deoxygenated blood from the right ventricles is pumped through pulmonary arteries to both lungs. oxygenated blood comes back to the pulmonary veins.


What is a cardiac cycle?

Systemic circulation is the circulation of oxygenated blood from the left ventricle through the aorta to and from body parts by veins to the right auricle. Both circulations occur in a rhythmic manner one after the other. They form a cardiac cycle.


What are conditions related to the heart?

  • palpitation is rapid, forceful beating of the heart. The patient is conscious during this period
  • Cardiac arrest happens when there is a blockage in the heart and a cardiac muscle dies. reduced blood flow is caused due to cholesterol or calcium buildup in the arteries.
  • Hypertension is when the blood pressure in the arteries is elevated. It is caused by emotional or nervous stress and increases the risk of a heart attack.

Explain the Lymphatic system

The capillaries are not the only route by which the tissue fluid returns to circulation. Some return through the lymphatic system. Most tissue fluid enters another set of minute channels named lymph vessels. the walls of these vessels are more permeable than blood capillaries. Lymph vessels have valves to prevent back flow. All lymph vessels flow towards the upper thorax, passing through various lymph nodes that filter bacteria and cell debris.


What are the functions of lymph?

Nutritive supplies nutrition and oxygen to those parts where blood cannot reach.

Drainage drains excess tissue fluid and metabolites and helps return proteins to the blood from tissue fluid.

Defense: Lymphocytes of the lymph perform the function of defense. these remove bacteria from the tissues. Lymph nodes help in localizing the infection and prevent it from spreading to the whole body.