Meninges, cerebrospinal fluid, arteries and veins LO8-10

Question 1

Dura mater – “tough mother”

Answer 1

• The outer dura mater is a strong, tough, leathery protective membrane.
• double-layered membrane;

Question 2

Meninges

Answer 2

Are three connective tissue membranes that cover the external surface of the brain (and spinal cord) to protect from mechanical forces.
- Dura mater
- arachnoid mater
- pia mater

Question 3

Arachnoid mater – “spider mother”

Answer 3

• A narrow cavity called the subdural space separates the arachnoid mater from the dura mater.
• This cavity contains a thin film of serous fluid and veins that drain deoxygenated blood into the dural sinuses.
• Beneath the arachnoid membrane is a larger cavity called the subarachnoid space and it contains major cerebral blood vessels and cerebrospinal fluid.

Question 4

Pia Mater –“gentle mother”

Answer 4

• very thin, delicate membrane that clings tightly to the surface of the brain. It contains a network of capillaries, and these capillaries pass through the membrane to nourish the underlying neural tissue.

Question 5

Cerebrospinal Fluid (CSF)

Answer 5

CSF protects the brain by forming a liquid cushion that:
- acts as a shock-absorbing medium - protects from mechanical forces that could cause the brain to hit the walls of the skull
- “floats” the brain - reduces the weight of the brain and prevents the lower parts of the brain from being crushed under its own weight
- acts as a diffusion medium: supplies neural tissue with nutrients and removes waste products

Question 6

The Blood-brain Barrier

Answer 6

• protects the neural tissue of the brain from harmful substances and pathogens (e.g. bacteria and viruses) circulating in the blood.
• mainly consists of the tight junctions that seal together the endothelial cells of brain capillaries, making them the least permeable capillaries in the body.

Question 7

The blood-brain barrier, therefore, is a selective barrier that is:

Answer 7

• permeable to lipid-soluble substances such as oxygen, carbon dioxide, lipids, alcohol, nicotine and anaesthetics
• permeable to nutrients such as glucose
• impermeable to metabolic wastes, proteins, toxins, potassium ions, most drugs and antibiotics