12.6.2 Blood Clotting

Question 1

Blood Clotting

Answer 1

• Blood consists of approximately 55% plasma and 45% cells. Blood plasma contains nutrients, wastes, hormones, and proteins in a water solution. The cellular elements of blood consist of red blood cells, or erythrocytes, white blood cells, and platelets.
• Blood clotting is a process that involves the plugging of broken blood vessels through the actions of chemicals that are present in the blood.

Question 2

blood

Answer 2

• Blood consists of about 55% plasma with the remaining 45% consisting of cells. Plasma consists of about 90% water. Dissolved in the water are inorganic salts, nutrients, wastes, hormones, and proteins.
• The cellular component of blood consists mostly of red blood cells, white blood cells, and platelets. Platelets are fragments of cells that originate from the bone marrow and are involved in blood clotting.
• Injury to a tissue stimulates a blood clotting response:
  platelets stick to the damaged connective tissue to form a plug on the injured vessel.
• The damaged tissues and platelets release chemicals called clotting factors that lead to clot formation in a multi-step process. First, clotting factors released from platelets, damaged tissues, and blood plasma convert the protein prothrombin to its active form, thrombin. Thrombin then converts the plasma protein fibrinogen to its active form fibrin. Fibrin forms a sticky, fibrous clot that traps red blood cells.
• The diagram to the left is an electron micrograph of a scab. Notice the meshwork of fibrin threads in which the red blood cells are trapped.

Question 3

Blood is a suspension of solids within a liquid. Which ratio represents that of plasma to the cellular component of blood?

Answer 3

• 11:9

Question 4

Damage to tissue and the platelet response result in the release of

Answer 4

• clotting factors.

Question 5

Which of the following is not considered part of plasma?

Answer 5

• erythrocytes

Question 6

Besides water, blood plasma also contains

Answer 6

• nutrients.
• wastes.
• hormones and proteins.

Question 7

Blood plasma consists primarily of

Answer 7

• water

Question 8

Fibrinogen is converted to fibrin by

Answer 8

• thrombin

Question 9

The blood components that have a specialized role in clot formation are

Answer 9

• platelets

Question 10

The cellular component of blood includes all of these except:

Answer 10

• endothelial cells