Biology Ch 6 Circulatory System PDF

# Syllabus 1. Internal structure of the heart in detail (including valves, septum, pacemaker). 2. Schematic diagram of the heart. 3. Blood vessels - aorta, pulmonary trunk, coronary artery and vein, vena cava. 4. Circulation of blood as double circulation. 5. Blood Groups (A, B, AB and O): uni...

# Syllabus 1. Internal structure of the heart in detail (including valves, septum, pacemaker). 2. Schematic diagram of the heart. 3. Blood vessels - aorta, pulmonary trunk, coronary artery and vein, vena cava. 4. Circulation of blood as double circulation. 5. Blood Groups (A, B, AB and O): universal donor and universal acceptor. 6. Conditions related to the functioning of the heart: palpitations, cardiac arrest and hypertension. 7. Introduction of lymphatic system as a parallel circulatory system. # Human Circulatory System Both human beings and animals need food and oxygen to keep themselves alive. Simultaneously, their bodies produce certain harmful substances like carbon dioxide and metabolic wastes. The transport of nutrients and oxygen, and the removal of the above-mentioned wastes is carried out through blood by a transport system called circulatory system. The circulatory system comprises of the heart, blood and blood vessels which circulates blood throughout the body, thereby helping in the transport of nutrients, oxygen and carbon dioxide. Transportation is mainly carried out by the blood and the lymph. The blood is transported to all parts of the body by a pumping organ, i.e. the heart, through the blood vessels. Lymph is transported by the lymph vessels which run alongside the blood vessels of the circulatory system. # Fluids In Our Body There are three principal fluids in our body: 1. **Blood:** It is contained in the heart and the blood vessels (arteries, veins and capillaries) of the circulatory system. 2. **Tissue fluid:** It occupies the spaces between the individual cells of the body and is also known as the interstitial fluid. 3. **Lymph:** It is contained within the lymph vessels and lymphatic organs. ## Heart - The Pumping Organ The heart has the size of one's folded fist and weighs about 225-340 grams. It is located in the centre of the chest cavity, with its tip slightly tilted to the left side. It is enclosed within a protective double-layered membrane called pericardium. The space between the two membranes is filled with a fluid called pericardial fluid which protects the heart from shocks, jerks or any mechanical stress. The main function of the heart is to receive and pump blood and to keep it circulating in the body through blood vessels. Internally, the heart is divided vertically into a left and a right portion by a membrane or a septum. Each half is further divided horizontally into two chambers - an upper chamber called atrium and a lower chamber called ventricle. Therefore, heart has four chambers in all - two auricles and two ventricles. The atria are the "receiving chambers" as they receive blood from different body parts. They are smaller and have thin walls. The ventricles, on the other hand, are the "distributing chambers" as they pump blood into lungs and blood vessels that distribute the blood to all parts of the body. Ventricles are bigger in size and their walls are thicker, elastic and muscular so as to efficiently pump blood to different parts of the body. The right atrium opens into the right ventricle, this opening is guarded by the *tricuspid valve* (having three cusps or flaps). Similarly, the opening between the left atrium and the left ventricle is guarded by the *bicuspid valve* (having two cusps or flaps). These valves regulate the flow of blood in one direction i.e., from auricles into the ventricles. The blood flows from the right ventricle into the pulmonary artery and from the left ventricle into the aorta (the largest artery). The flow of blood from the ventricles into these two arteries is also regulated by valves. These valves resemble a half moon, hence they are called *semi-lunar valves*. These valves are present at the opening where the pulmonary artery and aorta leave the right and left ventrides respectively. They ensure that the blood does not flow back into the ventricles. ## Pacemaker The heart is a muscular organ made up of specialized muscles called *cardiac muscles*. These muscles show continuous contraction and relaxation, without any rest throughout the lifetime of a person. This contraction (and simultaneous relaxation) is a result of an electrical impulse which originates in a node called the *sinoatrial or SA node*. This node is located in the upper right corner of the right atrium and is responsible for setting a rhythm for the contractions and relaxations of the heart or simply the *heart beat*. Hence, it is also called as the "**natural pacemaker of the heart**". ## Blood Vessels of the Heart 1. *Vena cavae:* These are the two large veins bringing deoxygenated blood to the right atrium. The *superior vena cava* brings in deoxygenated blood from the upper parts of the body, such as the head and shoulders. The *inferior vena cava* brings in deoxygenated blood from the lower parts of the body, such as the trunk and legs. 2. *Pulmonary veins:* They bring in oxygenated blood from the right and left lungs. These veins open into the left atrium. 3. *Pulmonary trunk:* It arises from the right ventricle carrying deoxygenated blood to the lungs for oxygenation. (The pulmonary trunk branches into a left and right pulmonary artery, each going into the respective lung.) 4. *Aorta:* Leaves the left ventricle carrying oxygenated blood to all parts of the body through its branches. The *coronary artery* is the blood vessel that distributes oxygenated blood to the walls of the heart. It is a branch that arises from the aorta. The *coronary veins* they bring back deoxygenated blood from the walls of the heart and pour it into an opening in the right atrium. # Blood Circulation 1. The deoxygenated blood from different parts of the body is received in the right atrium. Simultaneously, the oxygen-rich blood returning from the lungs is received in the left atrium. 2. The right atrium contracts and pumps deoxygenated blood into the right ventricle. Simultaneously, the left atrium contracts and pours oxygented blood into the left ventricle. 3. The atrio-ventricular valves close with a sound when the ventricles are full (end of an auricular contraction). At the same time the semi-lunar valves open. 4. The right ventricle begins to contract. The deoxygenated blood is pushed into the pulmonary artery, which transports this blood to the lungs for oxygenation. Similarly, the left ventricle contracts and oxygenated blood is pumped into the aorta with great pressure because the blood has to reach all parts of the body. 5. The semi-lunar valves close with a sound when the blood in the ventricles has been pushed into the arteries (end of a ventricular contraction). It should be remembered that when the heart chambers relax they are filled with blood and when they contract blood is pushed out of them. Both auricles relax and contract together. Similarly, both ventricles too, relax and contract together. The contraction of the atria is quickly followed by the contraction of the ventricles. This goes on in a rhythmic manner, about 72 times per minute. Also remember that the right half of the heart (i.e. the right atrium and the right ventricle) receives deoxygenated blood, while the left half (i.e. the left atrium and the left ventricle) receives oxygenated blood. The blood on the right side of the heart never mixes with that on the left side. ## Double Circulation The blood flows through the heart twice to complete one full circulation throughout the body. 1. At first, blood flows from the right side of the heart to the **lungs** and then returns to the left side of the heart (Pulmonary circulation). 2. The second time, the blood flows from the left side of the heart to all parts of the **body** and then returns to the right side of the heart (Systemic circulation). # Tissue Fluid and Lymph 1. **Tissue fluid (or intercellular fluid):** As the blood flows in the capillaries of the tissues, the plasma and the leukocytes "leak out" through their walls and bathes the cells. This fluid is called the *tissue fluid* or the *intercellular* or *extracellular fluid*. It is from this fluid that the cells absorb oxygen and other required substances, and in turn, give out carbon dioxide and other wastes back into it. 2. **Lymph and lymphatic system:** Some of the tissue fluid may be reabsorbed into the blood vessels, but most of it enters into another set of minute channels named *lymph vessels* and is then called *lymph.* The lymph flows in these vessels due to contraction of the surrounding muscles. The lymph vessels on the way drain lymph into lymph nodes from where fresh lymph channels arise. These channels ultimately pour the lymph into the major anterior veins close to their entry into the right auricle, and it is then in circulation again. The lymphatic system consists of lymphatic organs, such as the spleen and the tonsils, a conducting network of lymph vessels and the circulating lymph. ## Composition of Lymph: Lymph consists of a cellular part and a non-cellular part. 1. **Cellular part:** It contains only leukocytes (mostly lymphocytes). Blood platelets or red blood cells are absent. 2. **Non-cellular part:** It is made up of mostly water (about 94%) and the rest is made up of proteins, fats, carbohydrates, enzymes, antibodies, etc. (about 6%). ## Functions of Lymph: 1. **Nutritive:** It supplies nutrition and oxygen to those parts where blood cannot reach. 2. **Drainage:** It drains away excess tissue fluid and metabolites and returns proteins to the blood from tissue spaces. 3. **Absorption:** Fats in the intestine are absorbed through lymph vessels (or lymphatics). 4. **Defence:** Lymphocytes and monocytes of the lymph function to protect the body. The lymphatics also remove bacteria from the tissues. We often experience painful swellings in our groins or in the axils of our arms when we get a boil or injury in the limbs. This is a protective sign. The lymph circulation begins at the blind ends of the lymphatic capillaries. # Blood Groups Karl Landsteiner in 1900 identified different types of blood groups in humans. These blood groups are differentiated on the basis of proteins (antigens) found on the surface of the RBCs. There are two types of antigens – A and B. A person's blood group is 'A' if the antigen present on his RBCs is 'A', and 'B' if the antigen is 'B'. The persons whose RBCs have both types of antigens belong to the 'AB' blood group and those with no antigen i.e. neither A nor B have the 'O' blood group. ## Matching of Blood Groups Matching of blood groups (compatibility) under the ABO system for donation is done as follows (√ = Yes, × = NO): | Blood group of donor | Blood group of recipient | A | B | AB | O | | ------------------------ | ------------------------ | - | - | - | - | | A | | √ | × | √ | × | | B | | × | √ | √ | × | | AB | | × | × | √ | × | | O | | √ | √ | √ | √ | What do you conclude from the above matchings? 1. The blood of A group can be given to a person with A and AB groups. 2. The blood of B group can be given to a person with B and AB groups. 3. The blood of AB group can only be given to AB group, but a person with AB type of blood can receive blood from all types, and is therefore called a **universal recipient**. 4. The blood of O group can be given to all the groups. Hence, a person with O blood group is called a **universal donor**. ## Activity 1 To collect information about the blood group of persons around you, and to know about blood transfusion. The activity is based upon the information you have to collect from your own family members as well as from some of your friends. Write the type of blood groups in the columns provided in the table. In case, the person does not know his/her blood group, place a “dash" (–) in the column. You should also ask the blood donors if they have ever given blood to other persons or received it from others. Also, ask whether any matching of the blood groups of the donor and the recipient was earlier done or not. The matching of blood groups is also called blood group compatibility. **Chart For Recording Blood Groups** | Serial No. of family | Member of the family | Blood Group | | ----------------------- | --------------------------------------- | ----------------- | | Family No. 1 (Own family) | Father | | | | Mother | | | | Brother (Anyone) | | | | Sister (Anyone) | | | Family No. 2 | Father | | | | Mother | | | | Brother (Anyone) | | | | Sister (Anyone) | | | Family No. 3 | Father | | | | Mother | | | | Brother (Anyone) | | | | Sister (Anyone) | | **Conclusion:** Based on the above survey, you can find out who can donate blood to whom or who can receive it from whom under the ABO system. In the table given below, indicate the matching blood groups by a (√) and a (×) for non-matching blood groups. | Blood group of donor | Blood group of recipient | A | B | AB | O | | ------------------------ | ------------------------ | -- | -- | -- | -- | | A | | √ | × | √ | × | | B | | × | √ | √ | × | | AB | | × | × | √ | × | | O | | √ | √ | √ | √ | [Sometimes, people may respond by saying “B (+)" (B-positive) or "B (-)" (B-negative). In such cases, "positive" or "negative" refers to another blood group system called "Rh" system. You will learn about it in your higher classes.] # Objective Type Questions 1. Put a tick mark (√) against the correct alternative in the following statements: a) The vein which brings oxygenated blood to the heart from the lungs: (i) Renal vein (ii) Superior vena cava (iii) Pulmonary vein √ (iv) Coronary vein b) The path which the blood flows through during pulmonary circulation is: (i) RA → RV → Pulmonary arteries → Lungs → Pulmonary veins → LA √ (ii) LA → LV → Pulmonary veins → Lungs → Pulmonary arteries → RA (iii) LA → LV → Aorta → Body → Vena Cavae → RA (iv) RA → RV → Vena Cavae → Body → Aorta → LA 2. Match the items in Column A with those in Column B. **Column A** | **Column B** ----------- | ----------- (a) Sino atrial node | (iii) Pacemaker (b) Pulmonary veins | (v) Oxygenated blood (c) Pulmonary artery | (i) Deoxygenated blood (d) Tricuspid valve | (ii) Between right atrium and ventricle (e) Biscuspid valve | (iv) Between left atrium and ventricle 3. Name: a) The membranous structure which divides the heart into a right and a left portion. b) The structure responsible for starting electrical impulses that cause the heart to contract and relax in order to keep pumping blood. c) The scientist who identified different types of blood groups. # Short Answer Questions: 1. Name the following: a) Three components of circulatory system b) Four blood groups on the basis of antigens c) Two phases of double circulation d) Three principal fluids of human body e) Three kinds of blood vessels f) Two types of blood circulation the human body. 2. Define the following terms: a) Circulatory system b) Blood c) Lymph d) Artificial pacemaker 3. In which organ of our body does blood get oxygenated ? 4. Which side of the heart (left or right) contains oxygenated blood ? 5. Write important role(s) of each: a) Pericardial fluid b) Aorta c) Vena cavae 6. Give the functions of lymph. # Long Answer Questions (Write the answers in your notebook): 1. Differentiate between the following pairs on the basis of what is indicated within the brackets: a) Pulmonary artery and pulmonary vein (kind of blood) b) Artery and vein (direction of blood flow) c) Closed and open vascular system (definition) d) Bicuspid and tricuspid valve (location) e) Blood and lymph (composition) 2. Name any four heart-related conditions that occur commonly in humans. Briefly explain the cause and symptoms of each of them. 3. Explain: a) Universal donor b) Universal recipient 4. During surgical operations or during accidents, the patient may be given blood from outside to save his life. What is the technical name of this process? Briefly explain the precautions to be observed and taken in this process. 5. Given alongside is a diagram of the human heart showing its internal structure. Label the parts marked 1 to 6, and answer the following questions. [Include an image here in the format of your choice (e.g. .png, .jpg, .svg)] a) Which type of blood is carried by the blood vessel marked 2 ? b) Name the main artery which takes the blood from heart to different parts of the body. c) Which chamber of the heart receives deoxygenated blood from the body?