22-May-2020
Two types of blood vessels are arteries and veins which are connected to the heart for transporting blood.
- Arteries –
- Carry blood rich in oxygen from the heart to all the cells of the body.
- The pressure exerted by the arteries while blood leave heart is rapid and thus wall walls of arteries are thick.
- The arteries divide in to extremely small thin branches on reaching the tissues. These small branches are called as capillaries.
- Capillaries have walls and are one-cell thick through which the exchange of materials between the blood and surrounding cells take place across this thin wall.
Veins
- Veins carry blood rich in carbon di oxide from all the cells of the body to the heart.
- The pressure exerted by the walls of the veins is less and have thin walls.
- Valves present in the veins ensure that the blood flows only towards the heart.
HUMAN CIRCULATORY SYSTEM
* The human circulatory system consists of a network of arteries, veins, and capillaries, with the heart pumping blood through it.
* Its primary role is to provide essential nutrients, minerals, and hormones to various parts of the body. * Alternatively, the circulatory system is also responsible for collecting metabolic waste and toxins from the cells and tissues to be purified or expelled from the body.
FEATURES OF CIRCULATORY SYSTEM
The crucial features of human circulatory are as follows:
- The human circulatory system consists of blood, heart, blood vessels, and lymph.
- The human circulatory system circulates blood through two loops (double circulation) – One for oxygenated blood, another for deoxygenated blood.
- The human heart consists of four chambers – two ventricles and two auricles.
- The human circulatory system possesses a body-wide network of blood vessels. These comprise of arteries, veins, and capillaries.
- The primary function of blood vessels is to transport oxygenated blood and nutrients to all parts of the body. It is also tasked with collecting metabolic wastes to be expelled from the body.
- Most circulatory system diagrams do not visually represent is its sheer length. Theoretically, if the veins, arteries, and capillaries of a human were laid out, end to end, it would span a total distance of 1,00,000 kilometres (or roughly eight times the diameter of the Earth).
23-May-2020
TRANSPORTATION IN PLANTS
1. Transportation is a vital process in plants.
This process involves the transportation of water and necessary nutrients to all parts of the plant for its survival.
2. Food and water transportation takes place separately in plants.
3. Xylem transports water and phloem transports food.
PHLOEM
1. The phloem is responsible for translocation of nutrients and sugar like carbohydrates, produced by the leaves to areas of the plant that are metabolically active.
2. Sieve tubes, companion cells, phloem fibres, and phloem parenchyma cells are the components of this tissue.
3. The flow of material through phloem is bidirectional.
