Transport/ circulation - notes

 Transportation

• Transportation in human beings-
• Components of Circulatory system:
• a)Heart            b) Blood vessels       c) Blood

§  Heart-    (Refer to figure 6.10 page no. 106 of N.C.E.R.T  Text book)

      (i) It is a muscular organ, which works as a pump in the circulatory system.

                       (ii)  It is the size of our fist.

                       (iii)  It has two sides, which are separated by a partition so that the oxygenated and

                              deoxygenated blood do not get mixed up.

                       (iv)  It has four chambers-

        Two upper chambers called Atria. 

        Two lower chambers called Ventricles.    

Atria                                                                 Ventricle

                               a) Small in size (volume)                                       a) Large in size

                               b) Have thin walls.                                                b) Have thick walls.

§  Working of heart-

                         Left side- (i)  Left atrium relaxes & the  Oxygenated blood enters it from

                                               the lungs through the pulmonary vein.

   (ii)  Left atrium contracts & the blood enters the left ventricle

           through the valve.
 (iii) Left Ventricle contracts and the blood is pumped into the

       largest artery ‘Aorta’ and is carried to all parts of the body.

                  Right side- (i) Right atrium relaxes & the deoxygenated blood from the body enters                                                it through superior and inferior Vena cava.

      (ii)  Right atrium contracts & the blood enters the right Ventricle through

               the valve.

                                             (iii) Right Ventricle contracts and the blood is pumped into the                                                                        Pulmonary artery and is carried to lungs.

§  Valves- Unidirectional to prevent the backward flow of blood.

§  Pulmonary vein is the only vein that carries Oxygenated blood.

§   Pulmonary Artery is the only artery that carries Deoxygenated blood.

§  Double circulation in man- because the blood passes through the heart twice in one complete cycle of the circulation.

§  Higher animals-  E.g., birds, mammals.                                                       

(i)                   Oxygenated blood & Deoxygenated blood are completely separate for efficient Oxygen supply.  

(ii)                This is  to fulfil higher energy needs and to maintain body temperature (warm blooded animals). 

§  Amphibians & reptiles- have 3 chambered heat where little mixing of  Oxygenated blood & Deoxygenated blood takes place. Therefore their body temperature varies with the temperature of the environment. (cold blooded animals)    
Fishes have 2 chambered heart- blood passes through heart only once in one complete cycle of circulation.(Single Circulation)

                                                                   

§  Blood vessels-
 (i) Arteries          (ii) Veins             (iii) Capillaries

Arteries	Veins
1.  Thick walled. 2.  Deep seated. 3.  Carry blood away from the heart. 4.  Carry Oxygenated blood. 5.  Valves absent.	1.  Thin walled. 2.  Superficial.  3.  Carry blood to the heart. 4. Carry Deoxygenated blood. 5.  Valves present

§  Capillaries- (i)  Form the connection between arteries & veins.

                                           (ii) Walls are one cell thick only for easy exchange of

                                                  nutrients, gases and other substances.

§  Blood- (i) It is a fluid connective tissue.

                                ii)Components- (1) Fluid medium- Plasma transports food, Oxygen,               

                            Carbon dioxide, Nitrogenous wastes, etc.

                          (2)  Red blood corpuscles- transports oxygen with the help of                                            haemoglobin protein.

                                                    (3)  White blood corpuscles- fight against infections/ defence                                                              mechanism of  the body.

                               (4)  Platelets – Plug the leaks of arteries and veins by clotting the                                                            blood.

                           Functions of blood- (i) Transport of respiratory gases.

                         (ii) Transport of nutrients.

                         (iii) Transport of waste products.

                         (iv)  Defence against infection

§  Lymph- Extracellular fluid similar to plasma but colourless with lesser protein.

§  Function of lymph-  (i) Transportation of digested & absorbed fats from

                                            the small intestine.

                                       (ii)  Drains excess fluid from the intercellular spaces

                                              back in the blood.

• Transportation in plants-

§  Plants need less energy needs- because they do not move and therefore have a slow transport system

§  Transport of water- 

(i)                  Takes place by xylem tissue present in roots, stem, leaves and is therefore interconnected.

(ii)                Root cells take up ions from the soil, which creates a concentration difference between root and soil. Water absorbed by osmosis.
 iii)     Water pressure develops in roots pushing column of water upwards.(Root pressure)

iv) In very tall plants- transpiration creates a suction pressure, which pulls the water upwards.(Transpirational pull)

§  Transpiration is loss of water in form of water vapors from stomata present on leaf surface

§  Importance of transpiration-

(i)                  Helps in upward movement of water in plants.

(ii)                It regulates the temperature in plants.   

§  Transport of food-

(i)                  Takes place by phloem tissue.

(ii)                Movement of prepared food in plants is called translocation.