Question

Биологи помогите пожалуйста с заданием для 8 класса ._. Почему скорость движения крови в капиллярах низкая?

Answer 1

Ответ: Чем больше общая площадь сечения сосудов, тем меньше скорость движения крови, самая большая площадь сечения в капиллярах, поэтому скорость в них меньше.

Объяснение:

Answer 2

Why is the speed of blood flow in capillaries low?

The speed of blood flow in capillaries is low due to several factors:

1. Narrow Diameter: Capillaries are the smallest blood vessels in the body, with a diameter only slightly larger than that of red blood cells. This narrow diameter creates resistance to blood flow, resulting in slower movement of blood through the capillaries.

2. Large Total Cross-Sectional Area: Capillaries have a large total cross-sectional area, which means that the combined area of all the capillaries is much greater than that of larger blood vessels like arteries and veins. This large total cross-sectional area allows for efficient exchange of oxygen, nutrients, and waste products between the blood and surrounding tissues. However, it also slows down the speed of blood flow.

3. Regulation of Blood Flow: The speed of blood flow in capillaries is also regulated by the body to ensure optimal exchange of substances between the blood and tissues. The body can adjust the diameter of capillaries through a process called vasodilation (widening) or vasoconstriction (narrowing). This regulation helps maintain a balance between oxygen and nutrient delivery to tissues and the removal of waste products.

4. Permeability of Capillary Walls: Capillary walls are thin and highly permeable, allowing for the exchange of substances between the blood and surrounding tissues. This permeability slows down the speed of blood flow as the blood has to pass through the narrow gaps between the cells that make up the capillary walls.

In summary, the low speed of blood flow in capillaries is primarily due to their narrow diameter, large total cross-sectional area, regulation of blood flow, and the permeability of capillary walls.

I hope this helps! Let me know if you have any further questions.