Chapter 20, Problem 1TMW

Summary Introduction

To tell:

Why it is important that the cells forming the blood vessels of the spinal cord and brain should be tight against one another by forming a blood-brain barrier.

Introduction:

The blood vessels in the brain and spinal cord are lined on the inside with specialized endothelial cells. These endothelial cells are stuck together very tightly and forming 'tight junctions'.

Explanation of Solution

The spinal cord extends down from the brain to the lumbar region (lower back). Below lumbar region, a package of nerves called the cauda equina is seen. This bundle of nerves resembles the tail of a horse. The dura mater is a tough fibrous sheath which provides a flexible and strong covering for the delicate organs of the central nervous system (CNS). It acts as a barrier and prevents the spread of infections from the bones. The arachnoid mater is located deep to the dura mater is the arachnoid mater which contains many branching fibers, which gives the appearance of a spider web. The subarachnoid space is the cavities found in between the arachnoid mater fibers. Pia mater is the internal layer, which is pressed near to the spinal cord and brain. Blood vessels situated on the top of the pia mater supplies the central nervous system with blood. These blood vessel walls are composed of tightly packed cells that form the blood-brain barrier, thereby preventing the entry of microbes and other large molecules into the subarachnoid space. So the infections of blood do not spread easily to the CNS.

Conclusion

It is important that the cells that are involved in the formation of the blood vessels of the spinal cord and brain should be tight against with each other, forming a blood-brain barrier to prevent the entry of microbes from blood to subarachnoid space and spread the infection to the CNS.