They substances transported by blood.Gases,Nutrients,Water,Hormones,Urea,Ammonia,Other waste materials etc.
Molecules traveling within the bloodstream pass through the capillary cell wall via osmotic pressure and diffuse through the interstitial fluid before encountering the tissue cell wall.
Gases from the air, primarily oxygen, enter our cells through a process called diffusion. In the lungs, oxygen from inhaled air passes into the bloodstream, where it binds to hemoglobin in red blood cells. As blood circulates, oxygen is released from hemoglobin and diffuses through the capillary walls into surrounding tissues and cells. Once inside the cells, oxygen is utilized for cellular respiration to produce energy.
By the process of ultra-filtration. At the proximal end of the capillary, you have pressure of about 30 mm of mercury. So the fluid leaves the capillary and enter the interstitial compartment. At the distal end of the capillary the pressure is about 15 mm of Mercury. The fluid in drawn in due to oncotic pressure at that end.
the definition of the of tissue permeability is: - The absorption of substances within the body tissues. cell permeability, which allows nutrients and other substances to enter the cells more readily and allows the removal of waste products from the cells.
Perforin and granzymes are substances secreted by cytotoxic T cells to destroy target cells. Perforin creates pores in the target cell's membrane, allowing granzymes to enter and initiate cell death.
Capillaries, which are only one cell thick. The walls are semipermeable to the cell membranes in the body and are so narrow that red blood cells must pass through in a line, one behind the other. Oxygen and nutrients diffuse from the capillary to the body cells at the arterial end of the capillary while CO2 and other metabolic wastes enter the capillary at the venous end, because of diffusion gradients between the cell and the plasma and cells in the capillary.
Water and dissolved substances leave the arteriole end of the capillary due to hydrostatic pressure being higher than osmotic pressure and enter the venule of the capillary due to osmotic pressure being higher than hydrostatic pressure.
The pressure in the tissue surrounding the capillary, called interstitial fluid pressure, causes fluids to enter the venous side of the capillary due to the pressure gradient. This pressure helps to balance the forces of filtration and reabsorption in the capillary beds.
Diapedesis
Molecules traveling within the bloodstream pass through the capillary cell wall via osmotic pressure and diffuse through the interstitial fluid before encountering the tissue cell wall.
Capillaries with fenestrations and intercellular clefts allow for different diffusion of substances depending on structural characteristics (and permeability) of the capillary. Fenestrated capillaries are found where absorption are a priority, such as the intestines or endocrine glands, or where filtration occurs, such as the kidneys. A fenestra is an oval pore covered (usually) by a delicate membrane, and is much more permeable than a plain plasma membrane. Intercellular clefts are gaps in the plasma membrane, or areas not joined tightly, and are another way substances can enter the cell. Almost all capillaries have these. Substances can diffuse directly through the plasma membranes of cells only if the substances are lipid-soluble (like the respiratory gases), and certain lipid-insoluble substances can enter or leave the blood by passing through the plasma membranes of endothelial cells within vesicles, by endo or exocytosis.
Your white blood cells have that job.
Macrophages
Substances enter and leave cells through processes such as diffusion, facilitated diffusion, active transport, and endocytosis/exocytosis. Once inside the cell, substances can become distributed within cells through diffusion, cytoplasmic streaming, vesicular transport, and interactions with organelles.
Pores called stomata, which open and close by guard cells.
Proteins made on "bound" (attached) ribosomes leave through the cell membrane, and other proteins will enter the cell.
Capillaries. they have such thin walls that substances can easily diffuse through them.