Life processes class 10 notes part 3

Blood

Blood is red coloured fluid that circulates in our body. Its red colour due to red pigment haemoglobin. It constitutes the blood circulatory system that consists of heart and blood

Blood plasma is a pale coloured fluid that consists of about 90% water and 10% other substances as vitamins, urea, uric acid, enzymes and hormones.

Erythrocytes are also called red blood cells. It carries oxygen from lungs to tissues and CO₂ from tissues to lungs. RBC’s have life spen of about 120 days. Approx 2 – 10 million destroyed per seconds. It is about 5 – million per mm³ of blood.
Leucocytes are also called white blood cells. It is about 7000 per mm³ of blood. They are large sized nucleated cells and protect body from infections.
Platelets are non – nucleated and help in coagulation of blood. These are irregular in shape.

Function of Blood

It transports O₂ from lungs to all parts of body.
It carries hormones from endocrine gland to target site.
It transports excretory wastes from all part to kidney.
It helps in clotting of blood.
It protects body from infection.
Lymphatic system.

A system of lymph vessels and lymph nodes in human body which transports the liquids called lymph from the body tissues to the blood circulatory system is called lymphatic system. Lymph is another medium of circulation in human body and flow in one direction. It containing large protein molecules, digested fat, germs & fragments of dead cells from tissue fluid and seeps into lymph capillaries that have lymph nodes where it cleaned by white blood cells.

Lymph takes parts in nutritive process; it carries digested fat, large protein molecules from tissue into the blood stream.

Lymph protects the body by killing the germs and also make antibody.

Blood pressure

Blood pressure is measured by using an instrument called sphygmomanometer. It is the pressure at which blood is pumped around the body by the heart is called blood pressure. Blood Pressure always expressed in two values called systolic pressure and diastolic pressure.

Maximum pressure, at which blood leaves the heart through the main artery during the contraction phase, is called the systolic pressure.
The minimum pressure in the arteries during the relaxation phase of heart is called the diastolic pressure.

Normal blood pressure values are:

Systolic Pressure — 120 mm Hg
Diastolic Pressure — 80 mm Hg

It usually written as the 120/80

Human Circulatory System

Human circulatory consists of the heart, arteries, veins, Capillaries and blood. In circulatory system heart pumps to push out blood. Arteries veins and capillaries are pipes through which blood flows. These tubes are called blood vessels.

Arteries are thick walled blood vessels that carry blood from the heart to all parts of body. In arteries blood flows with the high pressure from heart to different organ. The valves remains absent in artery.
Veins are thin walled blood vessels that carry deoxygenated blood from different organ to heart. It has low pressure of blood and does not bear valves.
Capillaries are thin walled and extremely narrow tubes or blood vessels that the arteries to veins, Exchange of O₂, CO₂, food etc, b/w blood and body cells takes place through the capillaries.

Double Circulation

A circulation system in which the blood travels twice through the heart in one complete cycle of the body is called double circulation.

Pathway of blood movement

One complete contraction and relaxation of the heart is called a heartbeat. It is usually 72 times in a minute when we are in rest. It may become faster during the exercise. Heart beat nonstop all the time. It is due to the rhythmic contraction and the relaxation of heart muscles which make up atria and ventricles. There are two atria and two ventricles.

Mammals and birds have four chambered heart. The amphibian and reptiles have three chambered heart. Fish has chambered.

Transportation

Transportation is a life process in which a substance synthesized or absorbed in one part of the organism is carried to other parts of its body. Plants have specific tissue for the transportation of substances while animals have organs for transportation of materials.

Transportation of water and minerals

Transportation of water and minerals involve three distinct and interconnected processes:

Absorption of water and minerals

Water and minerals absorbed plants from soil, water molecules moves from higher water potential to lower water potential and then migrate from cell to cell passing from epidermis to cortex, to endodermis, to xylem vessel and tracheids. Mineral salts move from higher partial pressure to lower partial pressure along concentration gradient.

Ascent of sap

It refers the movement of water and mineral on the basis of cohesion-adhesive theory.

Transpiration

Loss of water in the form of vapours from the living tissues of aerial parts of the plant is termed as transpiration. It occurs by the process of diffusion through stomata. Stomata are the tiny pores present along the lower surface of leaf. Each stoma has two small, green-coloured, kidney-shaped guard cells which regulate opening and closing of stomata apertures.

In flowering plant both xylem and tracheid transport water and minerals.

In non- flowering plant only tracheids are water conducting tissues.

Transport of food

Transport of food from leaves to other parts of the plant is called translocation. Phloem translocate the food made in leaves to other parts of plant body. Phloem is made of many cells joined end to end to form long tubes sieve cells which forms phloem are living cells which contain cytoplasm but no nucleus and no lignin in their walls. Each sieve tube cell has a companion cell next to it that has nucleus and other organelles. Food made in mesophyll cells.

Part – 4