Final answer:
Lymphatic capillaries are highly permeable and allow the entry of larger molecules and interstitial fluid, whereas blood capillaries primarily facilitate the exchange of gases and nutrients. Lymph is moved through the body via muscle movement and breathing, with the system using one-way valves to direct flow towards the heart, unlike blood which is pumped by the heart.
Step-by-step explanation:
Differences Between Lymphatic and Blood Capillaries
The lymphatic capillaries differ from blood capillaries in several ways. While both are involved in the transport of fluids within the body, the structure and function of these capillaries show distinct characteristics. Lymphatic capillaries are highly permeable vessels that are part of the lymphatic system, designed to collect excess tissue fluid and proteins from the interstitial spaces and transport them back to the bloodstream. They are composed of a one-cell thick layer of endothelial cells and have unique overlapping structures that act as one-way flaps—allowing interstitial fluid to enter but preventing it from flowing back into the tissue spaces. These capillaries are held in place by collagen fibers, which help in opening the flaps further when interstitial pressure rises.
On the other hand, blood capillaries are part of the cardiovascular system and are mainly involved in the exchange of gases, nutrients, and waste products between the blood and the body's cells. Unlike lymphatic capillaries, blood capillaries are not as permeable to large molecules or particles. The lymphatic system also lacks a central pump like the heart and relies on the motion of the body and muscles to propel the lymph fluid through a network of vessels equipped with one-way valves to ensure unidirectional flow towards the heart.
In summary, lymphatic capillaries serve as an auxiliary route for fluid that escapes from blood capillaries and cannot return directly so it is picked up and returned to the bloodstream separately through the lymphatic system. This fluid includes proteins and larger particles that the blood capillaries cannot easily absorb, and also the transport of fats from the digestive system to the blood.