Protection of the nervous tissue

Question 1

how is the cns protected

Answer 1

the skull encases the brain and the vertebrae shield the spinal cord
-connective tissue also sheathes the brain and spinal cord

Question 2

how is the pns protected

Answer 2

PNS axons are bundled into nerves covered by three layers of protective connective tissues. the endoneurium, perineurium, and epineurium

Question 3

endoneurium

Answer 3

a thin fibrous membrane that sheathes each axon in a nerve

Question 4

perineurium

Answer 4

a fibrous sheath that surrounds bundles of axons that are gathered into fascicles

Question 5

epineurium

Answer 5

a fibrous sheath that surrounds the nerve. the nerve is made up of multiple fascicles

Question 6

meninges

Answer 6

the collective term for the three membranes that surround the brain and spinal cord and act as a protective barrier , help anchor the brain, and prevent it from moving in the skull.

Question 7

Cerebrospinal fluid (CSF)

Answer 7

fills the space between two of the meninges, cushions the brain and spinal cord, and flows through the brain and spinal cord

Question 8

three meningeal membranes

Answer 8

dura mater, arachnoid mater, and pia mater

Question 9

dura mater

Answer 9

the outer most meningeal layer that is a strong, thick, fibrous membrane that extends from the brain to the most caudal region of the vertebral column

Question 10

venus/dural sinuses

Answer 10

blood vessels within the outer and inner layers of the dura mater

Question 11

outer layer of the dura mater

Answer 11

tightly applied to the interior wall of the skull

Question 12

the inner layer of the dura mater

Answer 12

has several folds that divide the cranial cavity , creating subdivisions of the brain that act to restrict movement of the brain

Question 13

epidural space

Answer 13

a thin space containing fat separates the vertebral dura and vertebral bone. vertebral dura is not attached to the bone

Question 14

subdural space

Answer 14

space beneath the dura mater that is filled with connective tissues, fat, and blood capillaries

Question 15

arachnoid mater

Answer 15

the middle meningeal layer

Question 16

subarachnoid mater

Answer 16

the space beneath the arachnoid mater that is filled with CSF and also contains the largest blood vessels that supply the brain. spider like extensions that extend from the arachnoid mater to the pia mater and hold them together

Question 17

arachnoid villi

Answer 17

small pockets of the arachnoid mater that protrude into the dural/venous sinuses. they allow CSF to exit the space beneath the arachnoid mater and enter the bloodstream

Question 18

pia mater

Answer 18

a thin membrane that is tightly fitted over every prominence and depression in the irregular surface of the brain and spinal cord

Question 19

Functions of the CSF

Answer 19

-protection: supports the weight of the brain and forms a cushion around it
-transport: supplies nutrients to the brain and bloodstream and removes waste

Question 20

choroid plexus

Answer 20

a network of blood vessels and ependymal cells that forms the CSF. it filters wastes and foreign substances out of the CSF

Question 21

CSF circulation

Answer 21

-from the choroid plexus through the ventricles of the brain
-the rest moves into the subarachnoid space, where it is absorbed into the bloodstream though arachnoid granulations that are one way valves.
-meaning CSF can move out of the subarachnoid space but blood cannot move in

Question 22

ventricles of the brain

Answer 22

consists of two lateral ventricles (right and left) the third ventricle, and the fourth ventricle. all interconnected by canals

Question 23

hydrocephalus

Answer 23

when the skull enlarges and fills with CSF

Question 24

Blood Brain Barrier

Answer 24

prevents harmful substances from entering the brain from the blood. protects from blood-borne infections and from the normal fluctuation of solutes in the extracellular environment. Not very protective against lipid-soluble substances

Question 25

structure of the BBB

Answer 25

endothelial cells of the brain joined together in tight junctions by astrocyte “feet” that prevent solutes from entering the brain.

Question 26

areas of the brain lacking a BBB

Answer 26

a few specialized areas in the brain lack a BBB. ex: chemoreceptor trigger zone that has free nerve endings that maintain direct contact with the blood and trigger vomiting when they pick up abnormalities in the blood