Blood Vessels

1.  How is blood carried to all parts of the body?

Blood is the fluid connective tissue, which is carried to all body parts through tubes called blood vessels

2.  What are the different types of blood vessels?

There are three main types of blood vessels:

(i)  Arteries - Blood vessels that carry blood away from heart 
(ii)  Veins - Blood vessels that carry blood from body parts to heart.
(iii)  Capillaries - Blood vessels that joins arteries and veins.

3.  Differentiate between arteries, veins and capillaries.

Parameter	Arteries	Veins	Capillaries
Walls	Thick	Thin	Very thin
Flow of blood	Away from heart	Towards heart	From arteries to veins
Valves	Absent	Present	Absent
Function	Carries oxygenated blood( exception- pulmonary artery)	Carries deoxygenated blood (exception- pulmonary vein)	Exchange of material takes place through capillaries
Location in body	Generally deep seated inside the body	Generally superficial	Connects arteries and veins

4.  Why are the wall of arteries thicker than veins?

Arteries have thicker walls than veins because blood pumped from the heart flows through these arteries with high pressure. 

5.  Why do veins have valves in them?

Veins have valves in them to prevent backflow of blood.

6.  Actual exchange of material between blood and surrounding takes place in which of blood vessels.

Blood capillaries

7.  Why are the walls of capillaries only one cell thick?

The walls of capillaries are one celled thick to facilitate easy diffusion of gases and other materials across it.

                       Maomtemamce and repair of blood  

1.  Under what conditions can one suffer from blood loss?

One may suffer from blood loss during injury or during a surgery.

2.  What would happen if the bleeding is not minimised or stopped?

If the bleeding is not minimised there will be a drop in blood pressure.  This would reduce the efficiency of the pumping system and may cause death of the individual.

3.  Name the cells that help in plugging the leaks in the blood vessels. Where are they located?

Platelet cells helps in plugging the leaks in the blood vessels.  These are present in the blood plasma.

4.  How do platelet cells helps in minimising blood loss during injury?

Platelets circulate around the body in the blood vessels. Whenever there is an injury, platelets plug the leaks in the blood vessels by forming blood clots at the point of injury.                   

                                                Lymph

1.  Name one fluid other than blood that is also involved in the process of transportation

Lymph

2.  Why is lymph also referred to as tissue fluid?

As lymph is present between the intercellular spaces in the tissue, hence it is also called tissue fluid.

3.  How is lymph formed?

Some amount of plasma, proteins and blood cells (mainly WBC) escape from capillaries and spread into the intercellular spaces in the tissues.  This fluid forms the lymph.

4.  What are the components of lymphatic system?

Components of lymphatic system are- lymph, lymphatic capillaries, lymph vessels, lymph nodes and lymph glands.

5.  Differentiate betweens lymph and blood . 

Parameter	Blood	Lymph
Colour	Red (RBCs present)	Colourless (RBCs absent).
Components	RBC, WBC, platelets and plasma	Som e WBC and plasma
Moves through	Arteries, veins and capillaries	Lymphatic vessels and capillaries
Movement out of vessels	Only moves in vessels	Can come out of vessels and bathe the tissues as extra cellular fluid
Functions	Transportation of various  materials, defense, clotting, etc	Transportation of fats, fight against infection
Direction of flow	Circulates from heart to body parts and back	Only from body parts to heart

6.  What are the functions of lymph?

1. Lymph contains lymphocytes, which fight against infection and help in body's defense mechanism.
2. Lymph also carries digested fat.
3. Lymph returns proteins and fluid from circulation to tissues.