Transportation in Animals and Plants

IMPORTANT TERMS

Pulse                 The throbbing sensation that occurs in the arteries due to the flow of blood is called pulse.

Plasma              The fluid part of the blood is known as plasma.

Heartbeat          The rhythmic contraction and relaxation of the muscles of heart constitute a heartbeat.

Haemoglobin     A red-coloured pigment which makes the blood appear red.

Dialysis              An artificial process by which waste products are removed from the blood.

Diffusion            The movement of particles from a region of high concentration to low, until they are evenly spread out.

Arota                 The largest artery in the human body.

Auricles (Atria)   The upper chambers of the heart are known as auricles or atria.

Ventricles           The lower chambers of the heart are known as ventricles.

Septum              The muscular wall that separates the heart into two halves.

Nephrons           Tiny filtering units in Kidney, which filter and remove the wastes from the blood.

Translocation     The process by which prepared food is transported to the other parts.

 

CIRCULATORY SYSTEM

In multicellular organisms such as human beings, there is a transport system which carries substances to all parts of the body. It transports substances such as food, oxygen and waste products to different parts of the body. This transport of substances is done by the circulatory system. It consists of heart, blood and blood vessels.

BLOOD

Blood is the fluid which flows in the blood vessels. It transports substances such as digested food, oxygen, water and waste products to other parts of the body. Blood has various kinds of cells suspended in it. The following functions are performed by blood:-

  • Blood carries oxygen to various parts of the body and to each body cell.
  • Blood transports waste substances such as urea to the kidneys for filtration.
  • Blood helps in maintaining a constant body temperature.
  • It transports carbon dioxide to the lungs for elimination from the body.

The following are the cells present in the blood:-

Red blood cells (RBC) are disc-shaped cells. They contain a red-coloured pigment called haemoglobin, which makes the blood appear red. This pigment combines with oxygen and transports it to all parts of the body.

White blood cells (WBC) are colourless cells. They protect the body by fighting against the germs that may enter the human body.

Platelets are colourless cells that help in clotting of blood whenever there is bleeding due to any injury.

BLOOD VESSELS

Blood vessels are tube like structures which transport blood to various parts of the body. There are three types of blood vessels: veins, arteries and capillaries.

Arteries are the blood vessels that carry oxygen-rich blood from the heart to all parts of the body.They have relatively thick walls because the heart pumps blood rapidly and with high pressure into the arteries. So the thick walls enable them to withstand the pressure of blood pumped from the heart.

Veins are the vessels which carry carbon dioxide-rich blood from all parts of the body back to the heart. The walls of the veins are thin because the blood travels at low pressure. They have valves which allow blood to flow only towards the heart.

Capillaries are the blood vessels that connect the arteries and the veins. They are extremely thin so the oxygen, nutrients and waste products can easily pass to and from the tissue cells.

HEART

Heart is a muscular organ that pumps blood into the blood vessels. It is located in the chest cavity with its lower tip slightly tilted towards left. Its main function is to pump blood to all parts of the body.

The heart consists of four chambers:-

Right Auricle (Atrium) - The right auricle gets deoxygenated blood from all parts of the body through veins and pumps it into the right ventricle.

Right Ventricle – It pumps deoxygenated blood into the pulmonary artery that takes the blood to the lungs for oxygenation.

Left Auricle (Atrium) - It receives oxygenated blood by the pulmonary vein and sends it to the left ventricle.

Left Ventricle- The left ventricle receives oxygenated blood from the left auricle which it pumps to the rest of the body.

EXCRETORY SYSTEM IN HUMANS

The process of removal of wastes from the body of the living organisms is known as Excretion. The excretory system is responsible for the removal of waste produced in the cells, such as urea, water vapour and undigested food.

The excretory system consists of kidneys, ureters, urinary bladder and urethra.

Kidneys

The kidneys are the main organs of excretion. The kidneys are a pair of organs located in the back of the abdomen, one on either side of the spine. Each kidney has about a million tiny filtering units known as nephrons. They filter and remove the wastes from the blood. The blood brings the waste to the kidneys which are removed from the blood with the help of nephrons. The useful substances are absorbed back into the blood and the waste substances get dissolved in water and are removed as urine from the body.

Ureters are the connecting tubes which carry urine from the kidney to the urinary bladder.

The urine that is formed is temporarily stored in the urinary bladder.

Urethra is the muscular tube that leads from the bladder and transports and expels urine outside the body.

EXCRETION IN ANIMALS

Some land animals such as birds, snakes and lizards excrete a semi-solid, white coloured compound called uric acid, which contains the waste nitrogen.

Aquatic animals such as fishes excrete nitrogenous waste as ammonia which directly gets dissolved into the water.

TRANSPORT OF SUBSTANCES IN PLANTS

Plants absorb water and minerals from the soil through the root hair.

The water and minerals absorbed by the roots have to be transported to the leaves for preparing food. Then, the food prepared by the leaves has to be transported to all the other parts of the plant.

Plants have pipe-like vessels for transportation of water and nutrients from the soil. These vessels are made of special cells forming the vascular tissues.

Xylem tissue forms a continuous network of channels that connects roots to the leaves through the stem and branches, transporting water and dissolved minerals to the entire plant.

Phloem is the vascular tissue which carries the prepared food and transports it to all parts of the plant.

The process by which food is carried to all parts of the plants by the phloem is called translocation.

TRANSPIRATION

Transpiration is the process by which plants release excess water in the form of water vapour through the stomata present in leaves.

Transpiration is necessary for the plants in following ways:-

  • The evaporation of water from leaves generates a suction pull. This suction pull can pull water to a great height in tall trees.
  • Transpiration cools the plant and protects the cells from the heat of the sunlight.

EXCRETION IN PLANTS

The following products are excreted by the plants:-

Plants absorb water from the soil but all of it is not utilised by the plants. The excess water is released in the form of water vapour through tiny openings called stomata.

Carbon dioxide which is formed as a result of respiration by plants (during night) is released through stomata and lenticels.

Oxygen which is formed as a result of photosynthesis is released through stomata.

Plants also release their toxic wastes in the form of resins, gums and latex.

INTERESTING FACTS

  • Blood is actually blue in color. It turns red when exposed to oxygen because of a substance called haemoglobin.
  • It takes about 20 seconds for the blood to take an entire trip around the human body.
  • One drop of blood contains more than 250 million red blood cells, 375,000 white blood cells, and 16 million platelets.
  • Due to the heart having its own electrical impulse, it will continue to beat even when removed from the body as long as it has an adequate supply of oxygen.
  • All of the blood vessels in the human body could reach up to a length of 100,000km (60,000 miles) if they are stretched out, enough to go around the world four times.
  • Though weighing only 11 ounces on average, a healthy heart pumps 2,000 gallons of blood through 60,000 miles of blood vessels each day.
  • If the nephrons in both kidneys are taken out and placed end to end horizontally, they will cover a distance of 16 kilometers.
  • Though there are two kidneys in the human body and both of them have to work, but we can lead a healthy life even if one of the kidneys is removed.