Central Nervous System: Protection of the Brain

Describe the composition of the CSF (cerebral spinal fluid): D--> Describe the function of CSF.

*Found in and around the brain and spinal cord. Forms a liquid cushion that gives vuoyancy to CNS structures. By floating the jellylike brain, the CSF effectively reduces brain weight by 97% and prevents the delicate brain from crushing under its own weight.. *Also protects the brain and spinal cord from blows and other trauma. *Additionaly, although the brain has a rich blood supply, CSF helps nourish the brain and there is some evidence that it carries chemical signals(such as hormones and sleep and appetite inducing molecules) from one part of the brain to another. -->protection and buoyancy -->chemical stability -->exchange of nutrients & wastes

List the four divisions of the brain

1. Frontal lobe 2. Parietal lobe 3. Occipital lobe 4. Temporal lobe

Describe the composition of the CSF (cerebral spinal fluid): C--> Where is CSF reabsorbed?

CSF is reabsorbed in the arachnoid villi

How is the blood brain bariier (BBB) formed?

Formed by the TIGHT JUNCTIONS between endothelial cells of capillaries and the "feet" of astrocytes

What blood vellels supply the brain with blood?

Internal carotid arteries & Vertebral arteries -these two branch at the base of the brain giving rise to a series of arteries that form the CIRCLE OF WILLIS!

What is the composition of the Cerebrospinal Fluid?

The composition of the CSF is similar to the blood plasma. -CSF has more Na+, Cl-, and H+ and proteins

The Blood Brain Barrier is not uniform throughout the brain, what happens?

Some areas are "leaky" -example: hypothalamus & Vomiting centers

What do the three layers of the meninges do?

-->Protective, fibrous membranes that cover the brain and spinal cord

What causes meningitis? What is the symptoms? What is performed?

-> A bacterial or viral infection that causes inflammation of the meninges -> Symptons: Fever, muscle stiffness, nauses, dizzy, fatigue, lathargic -> A spinal tap is performed between L3-4 or L4-5 to confirm diagnosis

Describe the composition of the CSF (cerebral spinal fluid): A --> Where does CSF circulate in the brain and spinal cord?

-CSF circulates thru the Ventricles and Central Canal and around the brain and spinal cord in the Subarachnoid space. *CSF flows through the entricles and into the subarachnoid space via the median ad lateral apertures.

Describe the composition of the CSF (cerebral spinal fluid): B--> Where is CSF produces?

-Each Choroid plexus(of each ventricle) consists of a knot of porous capillaries surounded by a single layer of ependymal cells joined by tight junctions and bearing long cilia. Fluid leaking from porous capillaries is processed b the ependmal cells to form the CSF in the Ventricles. **to sum up: the choroid plexus of each ventricle produces CSF --> in each ventricle the cells help make this up.

Which substances can pass thru the BBB

-Glucose, ions, water, oxygen, carbon dioxide. -Alcohol, caffeine, nicotine -Anesthetics

Describe the layers of the meninges: A. Dura Mater

-outer layer - Means (tough mother) - has periosteal & meningeal layers -dural septa( Falx cerebri, fal cerebeli, tentorium cerebelli)

Describe the layers of the meninges: B. Arachnoid mater

-subarachnoid space contains cerebrospinal fluid and large blood vessels -arachnoid villi reabsorb CSF

What are the 3 layers of the meninges layers?

A. Dura Mater B. Arachnoid Mater C. Pia Mater

What causes HYGROCEPHALUS? What is this?

Causes: -> Occurs when CSF accumulates in the Ventricles(usually in babies) ->Causes abnormal interventricular pressure that effects brain tissue. ->Abstruction, developmental abdormality -> CSF accumulate in the ventricles and start pushing on brain tissue. Brain tissue will be compressed, skull is not fused yet so it expands.