Plus One Zoology Notes Chapter 7 Body Fluids and Circulation is part of Plus One Zoology Notes. Here we have given Kerala Plus One Zoology Notes Chapter 7 Body Fluids and Circulation.
|Text Book||NCERT Based|
|Chapter Name||Body Fluids and Circulation|
|Category||Kerala Plus One|
Kerala Plus One Zoology Notes Chapter 7 Body Fluids and Circulation
- All living organisms have a specialized system to transport nutrients and other necessary materials to the cell and wastes away from the cell by blood. This is called circulation.
- Different groups of animals have evolved different methods for this transport.
♦ Circulatory system
- The system responsible for circulating blood and lymph throughout the body, that supplies nutrients and oxygen to the cells and removes various waste products from the cells is called the circulatory system.
- Sponges and coelenterates use water for circulation.
- Complex organisms, like humans, use body fluids (blood & lymph) for circulation.
- It is a special connective tissue and chief transporting medium in the human body.
- Blood is a slightly alkaline fluid of pH 7.4.
- It consists of a fluid matrix, plasma and formed elements.
→ Plasma (55%)
→ Formed elements (45%)
- Straw colored.
- Viscous fluid constituting nearly 55% of the blood.
- It contains various components performing different functions.
Components of plasma & their function
|Water ( 90-92%)||It is a good solvent
It transports vitamins, hormones, enzymes, nutrients.
|Plasma proteins (6-8 %)|
|1. Fibrinogen||Clotting or coagulation of blood.|
|2. Globulin||Defend the body against diseases.|
|3. Albumin||Maintains osmotic balance.|
|Calcium (Ca++)||Clotting of blood, regulation of muscle activity.|
|Glucose, Aminoacids, Lipids||Nutrition|
|Na+, Mg++, HCO3 CI, Phosphates||Maintains osmotic balance|
- Plasma without the clotting factors is called serum.
- Erythrocytes (RBC), Leucocytes (WBC) and Platelets are collectively called formed elements.
- It constitutes 45% of blood.
1. Erythrocytes or RBC (Red blood cells)
- Most abundant cells in the blood.
- Its count is about 5 5.5 million /mm3 of blood.
- It is formed in the RRedbonemarrow in adults.
- Average life span is 120 days.
- Biconcave in shape & devoid of a nucleus,
- Red colored, iron-containing complex protein is presently called Haemoglobin.
→ Normal hemoglobin level 12 16g/100 ml of blood
- Hemoglobin carries oxygen and transports it to all parts of the body.
- RBCs are destroyed in the spleen, hence spleen is called the graveyard of RBCs.
- Involved in the transport of respiratory gases.
2. Leucocytes or WBC
- Also called WBC (White blood cells). They are colorless due to the lack of hemoglobin
- They are nucleated and are lesser in number. Its count is 6000 8000 mm3of blood.
- Formed in bone marrow, lymph glands, and spleen
- Average life span is 115 days, are short-lived.
- Major role to play defense the stem of the body.
- WBC’s are classified into two,
- WBC with granular cytoplasm.
- Lobed nucleus.
- It is of three types:
a. Neutrophil (60 – 65 %)
- Most abundant cells
- Many lobed nuclei with fine granules.
- Phagocytic ingest and destroy foreign organisms.
b. Eosinophil (2 3%)
- A bilobed nucleus with granules in the cytoplasm.
- Resist infections and associated with allergic reactions.
c. Basophil (0.5 1 %)
- Three-lobed nucleus, c Secrete histamine, serotonin, heparin (anticoagulant).
- Involved in inflammatory reactions.
- WBC with agranular cytoplasm.
- The nucleus is not lobed.
- They are of two types,
- Smallest WBC with a large round nucleus.
- They form 20 25 % of the total WBC.
- They are of two major types:’ B’ and ‘ T’ forms.
- Responsible for the immune responses of the body.
- Largest WBC.
- They form 6 8% of total WBC.
- Phagocytic ingest and destroy foreign organisms.
- Also called thrombocytes.
- They are fragments of large cells called megakaryocytes(special cells in the bone marrow).
- Blood normally contains 1,500,00 3,500,00 platelets mm-3.
- It involved in coagulation or clotting of blood.
- A reduction in platelet number can cause clotting disorders which will lead to excessive loss of blood from the body.
- Blood of human differs in certain aspects though it appears to be similar.
- Human blood can be grouped into two:
- ABO grouping
- Rh+ or Rh– grouping
- It is based on the presence or absence of two surface antigens (A & B) on the RBCs.
- Antigens are chemicals that induce an immune response.
- Plasma contains two antibodies, namely antibody A and antibody B.
- Antibodies are proteins produced in response to antigens.
- In man, there are 4 types of blood groups: A group, B group, AB group, and O group.
- During blood transfusion the blood of a donor has to be matched with the blood of a recipient, to avoid problems of clumping.
- Because of the presence of antibodies, a recipient cannot receive any group of blood. He can only receive a particular group or groups that match with his own group.
Human ABO blood group & their compatibility
|Blood group||Antigens on RBC||Anti-bodies in plasma||Donor’s group||Reciever’s group|
|A||A||anti – B||A, O||A, AB|
|B||B||anti – A||B, O||B, AB|
|AB||A, B||Nil||A, B,
|O||Nil||anti – A
anti – B
- Persons with ‘O’ group are called Universal donors because they can donate blood to persons with any other blood groups.
- A person with ‘ AB ‘ group is called Universal recipients because they can accept blood from all groups.
- Another antigen present on RBC’s of the majority of people is called the Rh factor.
- Individuals with Rh factor are Rh+ and those who do not have Rh factor are Rh negative.
- Nearly 80% of humans are Rh+ve.
- If Rh+ve blood is given to Rlrve individual, the recipients’ blood will produce anti-Rh antibodies against Rh antigens.
♦ Erythroblastosis Fetal
- It is an Rh incompatibility between the Rh blood of a pregnant mother and Rhtve blood of the fetus.
- Rh antigen does not get mixed with maternal blood in the first pregnancy because placenta separates the two types of blood.
- But at the time of first delivery, there is a possibility of exposure of the maternal blood to small amounts of the Rh+ve blood from the fetus.
- This induces the formation of Rh antibodies in maternal blood.
- In case of her subsequent pregnancies, the Rh antibodies from the mother can leak into the fetus and destroy the fetal RBC’s.
- This could be fatal to the fetus or could cause severe anemia and jaundice to the baby. This condition is called erythroblastosis fetal.
- Avoided by administering anti-Rh antibodies to the mother immediately after the delivery of the first child.
Coagulation of blood
- Blood exhibits coagulation or clotting in response to an injury or trauma. This is a mechanism to prevent excessive loss of blood from the body.
- At the site of injury, blood platelets rupture and release thrombokinase.
- Blood contains an inactive protein, prothrombin which is converted into active form thrombin in the presence of calcium ions and thrombokinase.
- The protein fibrinogen is converted into fibrin thread in the presence of thrombin.
- Fibrin thread to trap dead cells and form a blood clot.
Lymph (Tissue fluid)
- Lymph is a colorless fluid containing specialized lymphocytes which are responsible for the immune responses of the body, they are present in the lymphatic system.
- When blood passes through the capillaries, some of the fluid parts of the blood passes from the capillary into the space between the cells. This fluid is tissue fluid or lymph.
- It has the same mineral distribution as in plasma.
- Lymphocytes in the lymph protect the body from disease.
- It carries nutrients and hormones.
- Fats are absorbed into the lymph in the lacteal of the villus.
- Two types of circulatory system are present, they are
1. Open circulatory system
2. Closed circulatory system.
Open circulatory system Closed circulatory system Blood flows through open spaces or body- cavities called sinuses.
Eg., Arthropods, and Molluscs
Blood flows through the closed network of blood vessels.
Eg., Annelids, and Chordata
♦ Evolution of vertebrate heart
All vertebrate possess a muscular chambered heart.
- A heart is 2 chambered with an atrium and a ventricle.
- In fishes, heart pumps out deoxygenated blood which is oxygenated by gills.
- This is supplied to the body parts and from where deoxygenated blood is returned to the heart, it has only single circulation.
2. Amphibians & Reptiles (except crocodiles)
- Heart possess two atria and a single ventricle ie. 3 chambered, a. The left atrium gets oxygenated blood from the gills or lungs or skin.
- The right atrium receives the deoxygenated blood from different parts of the body.
- Blood gets mixed up in the single ventricle & which pumps out mixed blood.
- So it is incomplete double circulation.
3. Birds, Mammals & crocodiles
- A heart is 4 chambered.
- The left atrium receives oxygenated blood and right atrium receives deoxygenated blood.
- Blood passes on to ventricles of the same sides.
- Each ventricle pumps out blood without mixing, the two separate circulatory pathways are present in these organisms it is called Double circulation.
Human circulatory system
- It is also called blood vascular system.
- It consists of muscular 4 chambered heart, a network of closed branching blood vessels and blood, the fluid which is circulated.
- Mesodermally derived organ.
- Situated in the thoracic cavity in between the lungs.
- It has the size of a clenched fist. It is protected by a double-walled membranous bag called pericardium, enclosing the pericardial fluid.
- The heart is 4 chambered, two atria & two ventricles.
- A thin muscular wall called interatrial septum separates the right and left atria similarly interventricular septum separates the right & left ventricle.
- Atrium and vehicles of the same side are separated by a thick fibrous tissue called atrioventricular septum.
♦ Tricuspid valves
The valves formed of three muscular flaps or cusps, which guard the opening between the right atrium and the right ventricle.
♦ Bicuspid valve or mitral valve
The valve which guards the opening between the left atrium and the left ventricle made up of two flaps.
♦ Semilunar valves
- The valves present at the opening of the right and left ventricles and allow the entry of blood into the pulmonary artery and the aorta.
- These valves prevent any backward flow
Conduction of cardiac impulses
- A human heart is made of cardiac muscles.
- Sino Atrial Node (SAN) is present on the right upper corner of the right atrium.
- The nodal musculature is auto excitable and produces action potential called cardiac impulses.
- The action potential directly spread throughout atria from the SA node.
- The conduction of impulses through ventricle occurs along a conducting system consisting of Atrioventricular node (AVN), AV bundle, bundle branches and finally through Purkinje fibers in order to spread over ventricle.
- This delays conduction of impulses through the ventricle.
- That is why atrial systole commences first and then ventricular systole.
- To begin with, all the four chambers of the heart are in a relaxed state, i.e., they are in joint diastole.
- When the tricuspid and bicuspid valves open, blood from a pulmonary vein and vena cava flows into left and right ventricles through left and right atria.
- The SAN generates an action potential which stimulates both the atria to undergo contraction. This is known as atrial systole.
- The atrial systole increases the flow of blood into the ventricles by about 30%.
- The action potential is conducted to ventricular side by AVN and AV bundle from where a bundle of His transmit it through the entire ventricular musculature.
- This causes the ventricular muscle to contract is called ventricular systole.
- he atria undergo relaxation (diastole).
- The ventricular systole increases the ventricular pressure causing,
- Closure of bicuspid and tricuspid valves due to attempted backflow of blood into the atria.
- Semilunar valves open. So deoxygenated blood enters the pulmonary artery from the right ventricle and oxygenated blood enters the aorta from the left ventricle.
- The ventricles now relax and ventricular pressure falls causing,
- . The closure of semilunar valves
- which prevents the backflow of blood into the ventricles.
- The bicuspid and tricuspid valves are opened by the pressure in the atria.
- The ventricles and atria again undergo joint diastole and above processes are repeated. This is called the cardiac cycle.
- A cardiac cycle is completed in 0.8 secs.
- The volume of blood pumped out by each ventricle during a cardiac cycle is called stroke volume, it is about 70 ml.
♦ Cardiac output
- It is the volume of blood pumped out by each ventricle per minute.
→ Stroke volume × Heart rate
- The value of the cardiac output of a normal person is about 5000 mL or about 5L per minute.
- Cardiac output of an athlete is very high.
♦ Heart sounds
During each cardiac cycle, two prominent sounds are produced.
1. Lubsound: It is the first heart sound or systolic sound.
- It is associated with the closure of tricuspid valves during ventricular systole.
- Closure of these valves prevents the entry of blood from ventricles to atria.
2. Dub sound: Second heart sound or diastolic sound.
- It is associated with the closure of semilunar valves during joint diastole.
- Closure of these valves prevents them entry of blood from greater ties to the ventricle.
- The stethoscope is the instrument used to hear heart sound.
- ElThe electrocardiographs an instrument used to obtain electrocardiogram.
- Electrocardiogram is the graphical representation of the activity of the heart during the cardiac cycle.
- An ECG has 5 peaks P, Q, R, S, and T
- It is composed of a ‘ P’ wave, ‘QRS’ wave and T wave.
- To get an ECG, a patient is connected to the machine with 3 electrical leads that monitor the hearts activity.
- For a detailed evaluation of the heart’s function, multiple leads are attatched to the chest region.
- Each peak of the electrocardiogram corresponds to a specific electrical activity.
- P wave represents the electrical excitation of the atria called depolarisation, which leads to the contraction of both the atria.
- The QRS complex represents the depolarisation of the ventricles, which initiates the ventricular contraction.
- The T wave represents repolarisation of the ventricle.
- The deviation in the ECG indicates the abnormality or disease. So ECG has clinical significance.
- The blood flows through the heart twice for completing a circuit. Such a blood circulation is called Double circulation.
Schematic plan of blood circulation
- It involve two main circulations.
1 Systemic circulation.
2. Pulmonary circulation.
♦ Systemic circulation
- The circulation of blood between the heart and various body parts except for the lungs.
- The left ventricle pumps oxygenated blood into the aorta.
- The aorta supplies it to the various body tissue through a number of arteries .
- The deoxygenated blood from these tissues is returned to the right atrium through superior vena cava and inferior vena cava.
- Distribution of Os and other essential nutrients to the various body tissues.
- Removal of CO, and other harmful nitrogenous wastes from a tissue.
- The circulation of blood between the heart and lungs .
- The deoxygenated blood pumped into the pulmonary artery is passed onto the lungs.
- In the lungs oxygenation takes place.
- The oxygenated blood is carried by four ilmonary veins into the left atrium.
- Oxygenation of blood.
- Removal of CO, from blood
Regulation of cardiac Activity
- Normal activities of a heart are autoregu lated by nodal tissues, so the heart is myogenic.
- Autonomic nervous system (ANS) regulates the heart activity.
- Neural centre is present in medulla oblongata to moderate the process.
- Sympathetic nerves of ANS increase the rate of heart beat, the strength of ventricular contraction and cardiac output.
- Parasympathetic nerves of ANS decrease the heart beat, conduction of action potential and the cardiac output.
- Adrenal medullary hormones increase the cardiac output.
Disorders of the Circulatory System
♦ Hypertension(High Blood Pressure)
- In this disorder, the blood pressure is higher than normal systolic (pump ing) pressure (120 mm Hg), i.e. above 120/80 mm Hg.
- BP is 140/90 or above, it is hypertension. It leads to heart diseases and also affects vital organs (brain, kidney etc).
- It results from narrowing of the arterial lumen and reduced elasticity of arterial walls in old age. It can cause rup turing of capillaries. It is a silent killer.
♦ Coronary Artery Disease (CAD) or Atherosclerosis: ‘
- In this disorder, the deposition of calcium, fat cholesterol and fibrous tissue occurs in coronary arteries which makes the lumen of arteries narrower and thereby affect the blood supply.
♦ Angina (angina pectoris)
- Angina is an acute chest pain when no oxygen is reaching heart muscles.
- It occurs d ue to improper blood flow.
- It is common among middleaged and elderly.
♦ Heart Failure(congestive heart failure)
- It is the condition in which the heart is not pumping blood enough to meet the needs of the body.
- Congestion of the lungs is the main symptom.
- Heart failure is not the same as a cardiac arrest or a heart attack.
♦ Heart attack
It is caused when the heart muscle is suddenly damaged by an inad equate blood supply.
♦ Cardiac arrest
It is the state in which the heart stops beating.
|It is a red colored fluid due to the presence of hemoglobin||Interstitial fluid present in the lymphatic vessel. Responsible for the immune response.|
|It contains plasma, plasma protein, RBC, WBC and platelets||Plasma proteins, RBC and platelets are absent.|
|It transports materials from one organ to other||It transports materials from tissue cells into the blood|
|The row of blood is fast||Lymph flows very slowly|
♦ Systole and diastole
The contraction of auricles and that of the ventricles. The relaxation of cardiac chambers is called diastole.
♦ Atrial systole and diastole
Contraction of atria is called atrial systole. Just after the atrial systole, the atria relax. It is called the atrial diastole.
♦ Ventricular systole diastole
Contraction of ventricles is called ventricular systole. At the end of ventricular systole, the ventricle also relax it is called ventricular diastole
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