Lecture 8: CNS Protections and Cerebrum

Question 1

Protection of the CNS from superficial to deep.

Answer 1

1. Skin
2. Skull or vertebral column (bone)
3. The Meninges (connective tissue membranes)

Question 2

Where are the skull and vertebral column located?

Answer 2

Brain is contained within cavity of cranium.
Spinal cord travels down through the vertebral foramena of the vertebral column.

Question 3

What do the meninges consist of?

Answer 3

1. Dura mater
2. Arachnoid mater
3. Pia mater

Question 4

Explain the dura, arachnoid and pia mater.

Answer 4

Dura: Toughest membrane which anchors to the skull. Forms Falx cerebri (fold of tissues between the brain hemispheres).
Arachnoid: Weblike tissue with anchoring membrane.
Pia: Delicate thin tissue layer fitting contours of brain.

Question 5

What is the subarachnoid space?

Answer 5

Space between the arachnoid mater and the pia mater which is filled with cerebrospinal fluid.

Question 6

What is the cerebrospinal fluid?

Answer 6

Produced by specialized blood capillary beds called choroid plexuses. Fluid must pass through ependymal cells before entering ventricles of brain.

Question 7

How many ventricles are present in brain?

Answer 7

Four ventricles are present in brain with the 4th ventricle delivering CSF to central canal of spinal cord.

Question 8

Describe the circulation of CSF.

Answer 8

1. CSF is produced by choroid plexus of each ventricle.
2. CSF flows through ventricles and into subarachnoid space through median and lateral apertures. Some CSF pass through central canal of spinal cord.
3. CSF flows through subarachnoid space.
4. Fluid is returned to the blood stream in the superior sagittal sinus.

Question 9

What are the functions of CSF?

Answer 9

1. Absorb shock
2. Support weight of CNS
3. Provide oxygen, glucose, ions and other important nutrients to CNS.
4. Remove carbon dioxide and other wastes.

Question 10

What is meningitis?

Answer 10

Inflammation of the meninges caused by a bacterial, viral, fungal or parasitic infection in the cerebrospinal fluid.

Question 11

What is the blood brain barrier?

Answer 11

Epithelial cells that line in blood vessels in the brain are held together by tight junctions. These tight junctions prevent substances from passing out of blood stream between cells into the brain.

Question 12

What are the functions of the brain?

Answer 12

1. Process sensory information
2. Direct involuntary body functions to maintain homeostasis.
3. Directs our voluntary muscle movement.
4. Make you who you are (personality).

Question 13

What does the diencephalon consist of?

Answer 13

1. Thalamus
2. Hypothalamus
3. Epithalamus

Question 14

What divides the cerebrum into left and right hemispheres?

Answer 14

Longitudinal fissure

Question 15

What governs the right and left side of the body? How is communication between the two hemispheres possible?

Answer 15

Left hemisphere: Governs right side of the body.
Right hemisphere: Governs left side of the body.
Communication is possible through a bridge called corpus callosum.

Question 16

What are the ridges and grooves called in the cerebrum?

Answer 16

Ridges: Gyri (singular = gyrus)
Grooves: Sulci (singular=sulcus)

Question 17

What does the internal tissue of the cerebrum consist of?

Answer 17

1. Gray matter (cerebral cortex and basal nuclei)
2. White matter

Question 18

What is the difference between gray and white matter of the cerebrum?

Answer 18

Gray matter: Neuron cell bodies and short nonmyelinated neurons.
White matter: Mostly myelinated axons (with some nonmyelinated axons).