Transportation in Animals and Plants Science Class 7
The body of multicellular organisms is made up of millions of cells. To stay alive all living organisms need to transport materials like food, water and oxygen to various parts of the body.
Oxygen and food are transported to all the cells in the body for respiration and growth. and waste products are transported from the cells to the organs to excrete them.
There are various methods by which materials are transported in living organisms in which circulatory system is very important.Circulatory system helps living organisms to transport and excrete the material.
Transportation in Animals and Plants Science Class 7
What is Circulatory?
The circulatory system is the transport system of our body.
It carries oxygen, food, water, hormones, and other substances to all parts of the body and removes waste materials like carbon dioxide and urea.
How many types of circulatory system?
There are two types of circulatory system
1- Blood vascular system
2- Lymphatic system
What is Blood vascular system?
The blood vascular system is the network of organs and tubes in our body through which blood circulates. It mainly consists of, heart, Blood and Blood vessels. There are three types of blood vessels Arteries, Veins and Capillaries.
Blood
Blood is a red-colored fluid that flows in our body through blood vessels. It is an important part of the circulatory system and acts as a transport medium.An adult human has 5-6 litres of blood.
Function of blood
1- Blood Carries oxygen from lungs to all parts of the body.
2-Blood Carries carbon dioxide from body cells to lungs for removal.
3- Blood Transports digested food and water to body cells.
4-Blood Transports waste products to kidneys for excretion.
5-Blood Protects the body against infections (WBCs).
6-Blood Helps in blood clotting during injury (platelets).
What is plasma?
How many types of blood cells?
1- Red blood cells
2-White blood cells
3-Platelets
Red blood cells (RBCs) - Red blood cells are circular biconcave cells which are red in colour .Their red colour is due to the presence of a red coloured pigment called haemoglobin.Haemoglobin is the carrier of oxygen.It binds with oxygen and transports it to all parts and cells of the body.Life span of RBCs is 120 days. They are destroyed and replaced every second in our body.New RBCs are formed in the bone marrow of bones.
White blood cells(WBCs)- They are colourless blood cells of different shapes and sizes.They are larger than red blood cells .Their life span is from 12 hours to several days.They destroy germs and help in fighting infection.Hence,They are also called the soldiers of the body.
Platelets- Platelets are smaller than red blood cells.They help the blood to clot whenever there is a wound on the body.This blocks the flow of blood and prevents blood loss.
Blood vessels
Blood circulates across the body through a network of tubes called blood vessels. There are three types of blood vessels -arteries, veins and capillaries.
Arteries:- Arteries are the blood vessels which carry blood from the heart to the various organs of the body. Arteries generally contain oxygen-rich blood. The walls of arteries are thick and elastic. There lumen is narrow. Most of the arteries are deep seated hence, they can not be easily seen. Blood flows in arteries with jerks due to pumping activity of heart. The blood in arteries is at high pressure.
veins:- They are the blood vessels which carry blood from various organs of the body to the heart.veins generally contain carbon dioxide-rich blood. The walls of veins are thin and less elastic. Their lumen is wide. Most of the veins are superficial, i.e., they can be easily seen. The greenish blue lines we see just below the skin of our hands are veins only. Blood flows smoothly and slowly inside the veins. The veins have valves which prevent the back flow of blood.
Capillaries:-
Capillaries are the thinnest and narrowest blood vessels in our body.
They connect arteries and veins.
Their walls are only one cell thick, which allows easy exchange of materials.
Functions of Capillaries
Exchange of gases – Oxygen passes from blood to body cells, and carbon dioxide passes from cells to blood.
Supply of nutrients – Digested food and other nutrients in blood move into body cells.
Removal of wastes – Waste materials from body cells move into blood through capillaries.
Connection – Capillaries join arteries (which bring blood) to veins (which carry blood back to heart).
Heart
The heart is the pumping organ of the blood vascular system.It pumps blood to all the parts of the body through the blood vessels.Human heart is a conical, hollow and muscular structure of the size of our fist.It is reddish in colour and is present in between the lungs.Its broad base is upwards while narrow pointed end is downwards and tilted towards left.Heart is four-chambered.The two upper chambers are called atria (singular : atrium).Atria are smaller and thin walled.The lower two chambers are called ventricles. They are larger and thick walled.The atrium opens into the ventricel of its side. Its opening is guarded by valves.The blood enters the heart through atria and leaves it through ventricles.The left atrium receives oxygenated blood from the lungs and the left ventricle sends it to various parts of the body The right atrium receives deoxygenated blood from the body and the right ventircle sends it to the iungs for oxygenation.The septum prevents the mixing of oxygenated and deoxygenated blood. Heart is covered by a narrow fiuid filllled membranous sac called the Pericardium - the fluid protects the heart from external shocks internally. The heart is completely separated from its left side by means of a wall called septum
Circulation of blood
Circulation of blood takes places through the pumping action of th heart. From the heart, the blood is pumped to the rest of the body.
oxygenated blood is received by the left auricles from the lungs. From the left auricle, it enters the left ventricle which distributes blood to various organs and tissues of the body through the arteries.The carbon dioxide-rich deoxygenated blood collected by two major veins.These are superior vena cave and inferior vena cave.Blood from these veins enterrs the right auricle, The right auricle contracts and passes the blood into the right ventricle.Then, it is pumped into the lungs by pulmonary artery. In the lungs the blood get oxygenated and enters the left auricle by the pulmonary vein.From the, left auricle , oxygenated blood passes to the left ventricle.The oxygen-rich blood is then pumped to all parts of the body.
Heart Beat-Heart contracts and relaxes rhythmically throughout the life of an organism. The contraction and relaxation of heart is due to rhytmic contraction and relaxation of muscles present in the walls of the heart.One contraction of hearts followed by its relaxation is called a heartbeat. In a normal healthy adult, the heart beats 70-72 times per minute. how ever its speed may change depending on activities. for example, It can increase to about 200 times per minute during exercise. This is because the demand for oxygen and other substances increase during exercise.
The heart beat can be observed with the help of an instrument called a stethoscope. It amplifies the sound of a heartbeat so that it can be heard clearly, A stethoscope consists of three parts
1-A chest piece- It is sensitive to heart beats and is placed by the doctor on your chest.
2- Two ear pieces- The doctor puts it in his ear to hear the heart beats.
3- A connecting tube- It joins the ear pieces with the chest piece
Pulse- Contraction of left ventricle forces blood into arterices at high pressure.This causes the arterise to expand.When the left ventricle relaxes, pressure inside the arteries reduces, as a result of which they relax.This rhythmic contraction and relaxation of arteries can be felt in the arteries running over a bone in the form of rhythmic throbbing movement called pulse.Pulse can be easily felt over wrist.It can also be felt in neck, temple and ankle.The number of throbs per minute is called pulse rate.The pulse rate is the same as the heart rat,70-72 times per minute.It increases during excitement, fever, exercise ,etc.
Blood Pressure- The pressure exerted by the forceful flow of blood on the walls of arteries is known as blood pressure.
It is measured by an instrument called sphygmomanonmeter. A higher value of pressure is called hypertension while a lower values is called hypotension. Both hypertension and hypotension are harmful.
Lymphatic system
Lymphatic system is another circulatory system. It comprises of lymph nodes, lymph vessels and a circulating fluid called lymph. Lymph is a light yellow viscous fluid which flows in blood lymph vessels. It collects substances which cannot pass directly into the blood. It always flows from the tissues to special types of veins .It acts as a middleman between blood and tissues.
Transportation of materials in small animals
In unicellular organisms such as amoeba, paramecium, etc. Food and oxygen are transported throughout the body by the simple process of diffusion.
Simple multicellular organisms like hydra, sponges, etc do not possess well-developed circulatory system. The water in which they live brings food and oxygen as it enters the bodies. The waste materials and carbon dioxide diffuse out of their body into the water at the same time. These excretory substances are moved out as the water leaves the body. Thus these animals do not need a circulatory fluid like the blood.
Excretion in organisms
A number of wastes are produced in the body of organisms as a result of various metabolic activities. Accumulation of these are toxic in nature. Hence they need to be removed periodically. The removal of these metabolic wastes from the body is called excretion. Carbon dioxide, water, urea acid, excess of vitamins, drugs, etc are common examples of such metabolic wastes. The various body parts involved in the process of excretion together constitute the excretory system.
Excretion in animals
Various organisms have developed different methods of removing their wastes.
1- In simple organisms like amoeba, paramecium, etc. the waste products are removed from the entire body surface by the process of diffusion.
2- In flukes, tapeworms, etc the waste products are removed by specialised excretory organ called flame cells.
3- Earthworms, leeches, etc. have coiled tubules called nephridia for removeal of metabolic wastes.
4-Insects like cockroaches, scorpions and spiders have malphigian tubules for removing their wastes.
5-Kidneys are the major excretory organ of vertebrates.
Human Excretory system - In human beings, excretiory mainly occurs through excretory system or urinary system.
Human excretory system consists of
1-A pair of kidneys
2-An urinary bladder
3- A pair of ureters
4- An urethra
Kidneys- Kidneys are bean- shaped structures located just above the waist.Each kidney consists of a large number of coiled tubes called nephrons. They act as filters and filter waste products from the blood which reaches the two kidneys. The useful substances are absorbed back into the blood. Waste products dissolved in water from the liquid urine. The urine contains 95% water , 2.5% urea and 2.5% other waste products.
Ureters- A narrow tube called ureters runs from the inner sides of each kidney. The two ureters from the two kidneys are connected to a large sac called bladder. Urine passes out from the kidney through the two ureters into the urinary bladder.
Urinary bladder- It is a pea-shaped sac that receives urine from the ureters. Its function isto store urine brought by the ureters. It can store about 300-800ml of urine.
Urethra- It is a tube that carries the urine out of the body. It starts from the lower parts of urinary bladder and opens to the outsides by urinary opening.
Kidney Failure- Sometimes kidney may stop working due to infection or injury.This condition is termed as kidney failure. There are two method of solving this problem.
1-Artificial kidney or dialysis machine- This is a temporary method to solve the problem. It does not cure the kidney but only filters the blood just like a kidney.Dialysis is a process of separating smaller solutes or ions from the large particles with the heip of an ultrafilter. Artificial kidney machine is based on the process of dialysis. The blood of the person with damaged kidney is cleaned periodically with the help of dialysis machine.
2-Kidney transport- It is a long term solution for kidney failure. In it, the damaged kidney is removed and a matching kidney donated by a healthy person is transported in its place by surgery.
Transportation of material in plants
The food that is prepare in plants by photosynthesis , water that is observed by root and dissolved minerals observed by roots need to be transported to the different parts of plant. For this plants have a transporting system that is made from tissues xylem and phloem. These tissues are in the form of long tubes extending in all parts of the plant.
Transportation of water and minerals in plants
Plants absorb water and dissolved minerals with the help of hair-like extensions present on root. These extensions are known as root hairs increase the surface area of the root for the absorption of water and mineral nutrients dissolved in it. They absorbs water along with dissolved minerals. This water and absorbed minerals passes from cell to cell and finally reaches the root xylem vessels. Water is absorbed by the root hairs from soil by the process called osmosis. Osmosis is the process in which water move from its region of higher concentration to a region of its lower concentration through a semi-permeable membrane is one that allows only some substances to pass through it
Transportation of food
The food prepared in the leaves is transported to all parts of the plants. The vascular tissue that transports food is called phloem. it is present along with the xylem inside the plant body. The food is transported from leaves to various other parts in the form of the aqueous dilute solution. As the food prepared by leaves enters the phloem, it can move upwards as well as downwards. Not only food, but various hormones synthesized at shoot tips are also transported through the phloem. Xylem and phloem together from the vascular tissue.
Transpiration
Plant absorb a large amount of water from the soil. Only a fraction of this water is utilized by plant in various activities. The rest of it is lost from the aerial parts of the plants in the form of water vapour. This loss of water in the form of water vapour from the aerial parts of the plant is knows as transpiration. All aerial parts of the plants transpire. However, most of the transpiration takes place through leaves. Transpiration is both advantageous as well as disadvantageous. Hence, it is called a necessary evil. It helps in ascent of sap, absorption of water, and transportation of minerals salts. It helps in development of mechanical tissue and root system of plants. It in disadvantageous as a lot of energy is utilized in the absorption of water and transpiration. Excessive transpiration can retard growth and reduce the yield of crop plants. It also leads to stunted growth of plants.
Excretion in plants
Plants do not have a special excretory system like animals. so, these waste products are stored up in old leaves , barks or vacuoles. Some of the waste products plants secrete are very harmful to us as given below: carbon dioxide and water produced during respiration, and oxygen produced during photosynthesis are removed through stomata present on surface of leaves. A lot of toxic wastes are stored in dead tissues of plants.. A lot of wastes get collected in leaves, bark and fruits of the plants. Plants remove these wastes by shedding off leaves, peeling off barks and falling fruits. Wastes like gums, latex, essential oils, etc. are stored in special tissues and glands. Some waste products are excreted by plants into the soil arounds them. A number of plant wastes like latex, gums, essential oils, oxygen, etc. are useful for human beings.
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