Notes of Ch 11 Transportation in Animals and Plants Class 7th Science

Revision Notes of Ch 11 Transportation in Animals and Plants Class 7th Science

Topics in the chapter
  • Circulatory System
  • Blood
  • Lymph
  • Blood vessels
  • Heart
  • Excretory system
  • Transport in plants
  • Excretion in plants
Circulatory System

→ All multicellular organisms have a specialized system to transport nutrients and other necessary materials to the cell and the wastes away from the cell. This system is known as circulatory system.

→ Circulatory system is the transportation system of human body. It has three major parts:
(i) Blood
(ii) Blood vessel
(iii) Heart

Blood

→ It is a fluid connective tissue that is pumped throughout the body by heart.

Functions of Blood

→ It transports oxygen and nutrients to various parts of the body.

→ It also transports wastes for removal from the body.

Composition of Blood

→ It contains plasma, red blood cells, white blood cells, and platelets.

→ Plasma is the fluid part of blood.

→ Red blood cell contains a pigment called haemoglobin. It carries oxygen and transports it
to all parts of the body.

→ White blood cell protects body against infections. These are also known as leucocytes.

→ Platelets help in clotting of blood.

Lymph

→ Lymph is a watery clear fluid. It is blood minus RBC.

→ This fluid distributes immune cells and other factors throughout the body.

→ It also interacts with the blood circulatory system to drain fluid from cells and tissues.

→ The lymphatic system contains immune cells called lymphocytes, which protect the body against foreign antigens (viruses, bacteria, etc.) that invade the body.

Heart


→ It is the main pumping organ of our body that beats continuously.

→ It pumps oxygen-rich blood to all parts of the body and carbon dioxide-rich blood to the
lungs. .

→ Human heart is four chambered as shown in the figure below, and located in the chest
cavity.

→ The upper two chambers are called atria while lower two chambers are called ventricles.

→ A muscular wall between the chambers prevents the mixing up of blood rich in oxygen and blood rich in carbon dioxide.

→ The rhythmic contraction and expansion of heart is the heart beat.

→ Doctors use stethoscope for listening to the heart sounds.

→ The human heart beats about 70 to 80 times per minute in an adult.

Blood vessels
There are three types of blood vessels:
(i) Arteries
(ii) Veins
(iii) Capillaries

Arteries

→ Arteries carry oxygen-rich blood from the heart to various organs of the body.

→ Pulmonary artery is the only artery that carries CO2-rich blood from heart to lungs.

→ The walls of arteries are thick and elastic in order to tolerate high pressure of the blood.

→ Pulse is the rhythmic contraction and expansion of arteries with each beat of heart.

→ The number of beats per minute is the pulse rate.

→ A resting person usually has a pulse rate between 72 to 80 beats per minute.

Veins

→ Veins carry CO2-rich blood from various organs towards the heart.

→ They are thin-walled, non-elastic vessels that do not possess valves.

→ Pulmonary veins carry oxygen-rich blood from lungs to heart.

Capillaries

Capillaries are thin-walled blood vessels. They connect arteries with veins.

Excretory system

→ The organ system that performs the function of excretion is known as the excretory system.

Excretion

→ It is the process of removing harmful waste products produced in the cells of living organisms.

The excretory system in humans includes – a pair of kidneys, a pair of ureters, a urinary
bladder and a urethra.

Kidney

→ It is the main excretory organ of the human body.

→ It plays an important role in the formation of urine. Human kidney produces about 1 – 1.8L of urine in a day.

→ The urine consists of 95% water, 2.5% urea and 2.5% other waste products.

→ Nephrons are the basic filtering units of the kidneys.

→ The main components of a nephron are the glomerulus, Bowman’s capsule, and a long renal tube.

→ Ureter carries urine to the bladder.

→ Urinary bladder collects and stores urine.

→ Urethra carries urine out of the body.

Dialysis- The process of removing wastes using an artificial kidney is called dialysis.

Transport in plants

→ Plants have specialized vascular tissues called xylem and phloem for the transport of water, minerals and food respectively to all parts.

Transport of Water in Plants

→ Plant roots have hair that increase the surface area for absorption of water and minerals.

→ Root hair are deficient in water as they continuously supply the absorbed water to the
stems and leaves.

→ This creates a concentration gradient, which allows the active uptake of water by the root
xylem thereby creating a column of water, which steadily pushes upwards.

Transportation of food in Plants

→ Leaves prepare food for plant by the process called photosynthesis.

→ The prepared food is transported to remaining parts of the plants by a specialized vascular
tissue known as phloem.

→ The phloem forms a network of channels that transports food to the stem and to the roots of
the plant.

Excretion in plants

→ Plants get rid of the excess of water by transpiration.

→ In transpiration water evaporates into the atmosphere through stomata.

→ Stomata are the tiny openings or pores on the surface of leaves which help in the gaseous
exchange and transpiration.

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