Inside the deep tissues: nerves, arteries, veins, and lymph

Blood is circulated throughout the human body through a network of blood vessels called the circulatory system. This system includes arteries that transport blood from the heart to various body parts. These arterial pathways divide into smaller vessels until they reach the arterioles, which further split into capillaries. It is within these minuscule capillaries that the exchange of nutrients and waste products takes place. After this exchange, the blood is collected by venules, which fuse to...

Lymphatic vessels, known as lymphatics, are crucial in transporting lymph from peripheral tissues to our venous system. This process begins with lymph entering through tiny capillaries that branch through tissues. These capillaries have unique features such as larger diameters, thinner walls, and a distinctive one-way valve system formed by overlapping endothelial cells.
This one-way system allows fluids, solutes, and even pathogens to enter but prevents their return to the intercellular spaces.

Fascia, a thin layer of fibrous connective tissue, is distributed throughout the body. It demarcates and forms a supportive covering over skeletal muscles, bones, blood vessels, and organs. There are three main types of facia— superficial fascia, deep fascia, and subserous fascia. These are all present at different depths in the body. Fascia reduces the friction and permits muscles, joints, and organs to easily slide against each other, facilitating movement of the body and preventing tearing...

Lymph nodes are bean-shaped structures that cluster along the lymphatic vessels in the inguinal, axillary, and cervical regions. Each node is divided into compartments by a capsule that extends trabeculae inward.
From a histological perspective, lymph nodes can be split into two main areas: the superficial cortex and the deep medulla. The outer cortex is populated by dendritic cells, macrophages, and B lymphocytes, which are densely packed into follicles. When these B-lymphocytes are presented...

The vascular system comprises an extensive network of arteries, capillaries, and veins. The vascular system can be broadly divided into the blood and lymphatic systems. Typically, blood vessels can be categorized into three histological regions: tunica intima, tunica media, and tunica adventitia. The tunica intima consists of a single layer of endothelial cells attached to the basal lamina. Underlying the basal lamina is a connective tissue layer and an elastic lamina that gives stability and...

Blood and lymph are fluid connective tissues. They contain cells, also known as formed elements, circulating in a liquid extracellular matrix, the plasma. The formed elements are derived from hematopoietic stem cells in the bone marrow. Blood and lymph connect all vital parts and carry nutrients, oxygen, and other essential molecules like antibodies.
Blood
The blood flows through blood vessels— arteries, capillaries, and veins. Blood plasma is primarily made of proteins, solutes, and water.