Difference Between Blood Brain Barrier and Blood CSF Barrier

The key difference between blood brain barrier and blood CSF barrier is that blood brain barrier is the barrier which separates the blood tissue and the brain tissue while the blood CSF barrier is a functional barrier which separates the blood tissue and the cerebrospinal fluid.

Blood brain barrier and blood CSF barrier are two protective barriers in the brain. Also, they are important in transporting molecules across the brain and the peripheral blood tissues. Besides, both barriers have tight junctions facilitating the transfer of non-toxic compounds to the brain.

CONTENTS

1. Overview and Key Difference
2. What is Blood Brain Barrier
3. What is Blood CSF Barrier
4. Similarities Between Blood Brain Barrier and Blood CSF Barrier
5. Side by Side Comparison – Blood Brain Barrier vs Blood CSF Barrier in Tabular Form
6. Summary

What is Blood Brain Barrier?

The blood brain barrier is a structure which separates the brain tissue and the blood tissue. It has great morphological importance. There are three basic parts of the blood brain barrier. They are the layer of endothelial cells, basal membrane, and astrocytes. The endothelial cells interconnect the brain tissue and the blood tissue through a tight junction. The basal membrane helps to keep the astrocytes in contact. The astrocytes are the pedicles anneal to the basal membrane.

The blood brain barrier is a selectively permeable structure, allowing selected components to pass into the brain tissue. Therefore, it only allows the passage of non-toxic, harmless substances into the brain tissue. Moreover, the blood brain barrier passes molecules such as ions, ethanol and steroid hormones via diffusion as they are lipophilic. There are transporters present in the blood brain barrier which allow the uptake of glucose and amino acids. It takes place via active transport. In addition, pinocytosis also takes place in the blood brain barrier to pass some macromolecules into the brain tissue.

When transporting drugs across the blood brain barrier, a precursor molecule is required. It will allow the passage for the particular drugs into the brain tissue. In the absence of precursors, drugs and antibiotics will not cross the blood brain barrier.

What is Blood CSF Barrier?

Blood CSF barrier, as the name suggests, separates the cerebrospinal fluid and blood tissue. The cerebrospinal fluid is the protective fluid circulating around the brain. It protects the brain from external injury and shock. In addition, CSF also provides a metabolic function. It regulates the entry and exit of nutrients and waste products to the brain. Similar to the blood brain barrier, the blood CSF barrier also has three parts: choroid epithelial cells, basal membrane and endothelium of the pia mater capillaries. The choroid epithelial cells form a tight junction between the blood and the CSF, and it has microvilli lining.

The main function of the blood CSF barrier is the selective absorption and entry of nutrients to the brain liquor (CSF). Its permeability is greater than that of the blood brain barrier. The nutrients flow across a concentration gradient into the CSF. Most importantly, the transport taking place in the blood CSF barrier is bidirectional. Thus, the removal of toxic metabolic waste also takes place in the blood CSF barrier.

What are the Similarities Between Blood Brain Barrier and Blood CSF Barrier?

• Blood brain barrier and blood CSF barrier are two protective barriers of the brain.
• Both structures have three parts.
• Also, both possess a basement membrane.
• Besides, both structures are selectively permeable.
• Moreover, tight junctions are present in both barriers.

What is the Difference Between Blood Brain Barrier and Blood CSF Barrier?

The blood brain barrier is a physical barrier while the blood CSF barrier is a functional barrier. So, this is the key difference between blood brain barrier and blood CSF barrier. Additionally, there is a difference between blood brain barrier and blood CSF barrier in terms of structure. The endothelium in the blood brain barrier is made of cerebral capillary. In contrast, the blood CSF barrier is made of the choroid plexus of the brain.

Moreover, the permeability of blood brain barrier is high, while the permeability of blood CSF is low. It is because blood brain barrier has a larger surface area than the blood CSF barrier. Therefore, we can consider this also as a difference between blood brain barrier and blood CSF barrier.

Summary – Blood Brain Barrier vs Blood CSF Barrier

Blood brain barrier and blood CSF barrier are vital structures of the brain. The blood brain barrier is a physiological separation of the blood tissue and the brain tissue. In contrast, the blood CSF barrier is a functional barrier which carries out the absorption of the nutrients. Both barriers are selectively permeable and allow only non-toxic components to pass through them. However, blood brain barrier is more permeable than the blood CSF barrier. It also has a higher surface area. Thus, this summarizes the difference between blood brain barrier and blood CSF barrier.

Reference:

1. “11. Cerebrospinal Fluid, Blood-Brain Barrier and Blood-CSF Barrier.” Functions of Cells and Human Body, Available here.

Image Courtesy:

1. “Protective barriers of the brain” By Stolp HB, Liddelow SA, Sá-Pereira I, Dziegielewska KM and Saunders NR – Stolp HB, Liddelow SA, Sá-Pereira I, Dziegielewska KM and Saunders NR (2013) Immune responses at brain barriers and implications for brain development and neurological function in later life. Front. Integr. Neurosci. 7:61. (CC BY-SA 3.0) via Commons Wikimedia
2. “Blausen 0216 CerebrospinalSystem” By Blausen.com staff (2014). “Medical gallery of Blausen Medical 2014”. WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.010. ISSN 2002-4436. – Own work (CC BY 3.0) via Commons Wikimedia