Ch12: Lecture 4_ Bones, Meninges, Csf, Blood Brain Barrier

Front 1

What protects the brain?

Back 1

1) Bone (skull)

2) Membranes (meninges)

3) Watery cushion (CSF - cerebrospinal fluid)

4) Blood brain barrier (astrocytes, and more?)

Front 2

What are the meninges composed of and what are their functions?

Back 2

Functions:

- Cover and protect CNS

- Protect blood vessels and enclose venous sinuses

- Contain CSF

- Form partitions in skull

Composition:

- connective tissue (dense irregular)

Front 3

What are the Three layers of the Meninges?

Back 3

1) Dura mater (outermost)

2) Arachnoid mater

3) Pia mater (innermost)

Front 4

Diagram of the layers of the meninges

Back 4

Front 5

General facts about the dura mater? (2)

Back 5

1) Strongest meninx

2) Two layers of fibrous connective tissue (around brain) separate to form dural venous sinuses

Front 6

What are the different Dural septa of the dural mater?

Also, what is the purpose of the dural septa?

Back 6

Purpose: limit excessive movement of brain

Dural Septa:

1) Falx cerebri - in longitudinal fissure; attached to crista galli

2) Falx cerebelli - along vermis of cerebellum

3) Tentorium cerebelli - horizontal dural fold over cerebellum and in transverse fissure

Front 7

Identify the indicated parts

Back 7

A - Superior sagittal sinus

B - Falx cerebri

C - Tentorium cerebelli

D - Falx cerebelli

E - Dura mater

F - Transverse sinus

Front 8

Diagram of dural septa and sinuses

Back 8

Front 9

What are some general facts about the Arachnoid Mater?

Back 9

1) Separated from dura mater by subdural space

2) Subarachnoid space contains CSF and largest blood vessels of brain

3) Arachnoid villi protrude into superior sagittal sinus and permit CSF reabsorption

Front 10

What type of tissue is the Pia Mater and where is it located?

Back 10

- Delicate vascularized connective tissue

- Innermost meninx; clings tightly to brain surface

Front 11

What is the composition of CSF?

Back 11

- Watery solution formed from blood plasma

- less protein and different ion concentrations than plasma

- Constant volume

Front 12

What are the functions of CSF?

Back 12

a) Gives bouyancy to CNS structures

b) Protects CNS from blows and other trauma

c) Nourishes brain and carries chemicals

Front 13

Diagram of the CSF - formation, location, and circulation

Back 13

Front 14

Where is CSF produced, and where does it circulate to?

Back 14

1) Produced: The choroid plexus of each ventricle

2)CSF flows through the ventricles and into the subarachnoid space via the median and lateral apertures

3) CSF flows through the subarachnoid space

4) CSF is absorbed into the dural venous sinuses via the arachnoid villi

Front 15

What are the Choroid Plexuses?

Back 15

1) Clusters of capillaries which hang from roof of each ventricle; produce CSF at constant rate 'k'

2) Ependymal cells use ion pumps to control composition of CSF and help cleanse CSF by removing wastes

3) Normal volume ~ 150 ml; replaced every 8 hours

Front 16

Diagram showing Choroid Plexuses and formation of CSF

Back 16

Front 17

What is the Blood Barrier?

Back 17

- A protective mechanism that helps maintain a stable environment for the brain

- Separates neurons from some blood borne substances (e.g. hormones, amino acids, ions)

Front 18

What creates the blood brain barrier?

Back 18

1) Continuous endothelium of capillary walls

2) Thick basal lamina around capillaries

3) Feet of astrocytes clinging to the capillaries

a) Provide signal to endothelium for formation of tight junctions

b) These tight junctions make the capillary endothelium the least permeable in the body

Front 19

What does it mean that the blood brain barrier is a SELECTIVE barrier?

Back 19

1) Allows nutrients to move by facilitated diffusion

2) DENIED access: Metabolic wastes, proteins, toxins, most drugs, small nonessential amino acids, K+

3) Ineffective at denying: fat-soluble substances including alcohol, nicotine, and anesthetics

Front 20

Where is the blood brain barrier absent?

Back 20

- vomiting center and hypothalamus for example

-> where necessary to monitor chemical composition of blood

Front 21

What are types of brain dysfunctions?

Back 21

1) Traumatic brain injuries

2) Cerebrovascular accidents

3) Degenerative brain disorders

Front 22

What are examples of traumatic brain injuries?

Back 22

a) Concussion

b) Contusion - bruise on the brain

c) Hemorrhage - subdural or subarachnoid

Front 23

What are examples of Cerebrovascular accidents?

Back 23

1) Ischemia (poor blood flow to brain => not enough O2)

2) Hemorrhage

Front 24

What are examples of degenerative brain disorders?

Back 24

a) Alzheimers disease - type of dementia (affects memory, behavior, and thinking)

b) Parkinson's disease - nervous system disease (rigidity, tremors, slow imprecise movement; degeneration of the basal ganglia, deficiency of dopamine)

c) Huntington's disease - hereditary disease (degeneration of the brain cells causing chorea and progressive dementia