chapter 14

Question 1

is the brain encased in bone and has little room to swell or move?

Answer 1

yea, correct

Question 2

what is grey matter?

Answer 2

numerous cell bodies, relatively few myelinated axons

Question 3

what is white matter?

Answer 3

few cell bodies and chiefly made up of long-range myelinated axon tracts

Question 4

is every function of the body controlled by a specific site in the brain?

Answer 4

yes. this is when even microscopically benign brain tumors can cause death if in a central location
- every anatomic part of the brain fulfills a different function from every other part

Question 5

how many lymphatic channels does the brain have?

Answer 5

-very few, reabsorption of edema is difficult

Question 6

why does the brain need constant glucose supply?

Answer 6

because neurons are exquisitely sensitive to glucose deprivation. Cant store glucose- so the brain needs a constant glucose supply= affects the level of consciousness

Question 7

can large molecules diffuse easily into the brain from the blood?

Answer 7

no. they cannot diffuse easily

antibodies cant easily diffuse into brain because of BBB

Question 8

what are cerebral blood vessels frequently affected by?

Answer 8

atherosclerosis

Question 9

what is the circle of willis

Answer 9

The circle of Willis (also called Willis’ circle, loop of Willis, cerebral arterial circle, and Willis polygon) is a circulatory anastomosis that supplies blood to the brain and surrounding structures.
-there are relatively few interconnections elsewhere in the brain

Question 10

what are neurons exquisitely sensitive to?

Answer 10

O2 and glucose deprivation

-brain lacks fuel stores so needs a continuous supply of glucose

Question 11

why cant bloodborne substances cross capillaries?

Answer 11

cells in the capillary walls are essentially cemented together, compared to capillaries in the body

Question 12

what does the pia mater do?

Answer 12

helps keep some molecules from diffusing into the brain from CSF

Question 13

What can cross the BBB?

Answer 13

Small molecules (either fat or water soluble) such as caffeine, nicotine, glucose, amino acids.

Question 14

what does the BBB block?

Answer 14

the BBB blocks proteins such as antigens, antibodies, drugs (antibiotics), and bacteria

Question 15

where in the brain is there a lack of interconnections?

Answer 15

there is a lack of interconnections elsewhere in the cranium besides the circle of willis, this make the brain tissue at the far end of supply especially vulnerable to decreased blood flow because there is no alternative supply.
-this helps explain how pathological alterations to the nervous system can result in major changes in physiogically and psychologically, and how/why conditions like ischemia, cerebral edema, and increased ICP which occur secondarly to a primary disease can be even more devestating than the primary disease itself

Question 16

what is intracranial pressure dependent on the relationship between?

Answer 16

dependent on the relationship between brain tissue, cerebrospinal fluid, and blood

Question 17

what is the central nervous system surrounded with?

Answer 17

its surrounded with CSF, and amount produced must equal the amount drained

Question 18

how can the brain compensate (short term) with increased pressure?

Answer 18

• displacing CSF to the subarachnoid space
• blood volume can be shifted
• brain tissue can be compressed

Question 19

what is the most easily displaceable fluid in the brain?

Answer 19

CSF, from ventricles and subarachnoid space to spinal subarachoid space
it can be absorded or produce less

Question 20

what is the Manroe-Kellie hypothesis?

Answer 20

volume inside the cranium is a fixed volume

• blood, CSF, and brain tissue creare a state of equallibrium…
• any increase in volume of one of either blood, CSF, or brain tissue must be compensated by a decrease in volume of one of the other components
• AN INCREASE VOLUME OF ONE COMPONENT MUST BE OFFSET BY A DECREASE IN THE OTHERS

Question 21

how does increased intracranial pressure develop? Onset?

Answer 21

-increases gradually and may take hours or days

Question 22

for volume equilibrium in the brain, and to avoid ICP, what must occur?

Answer 22

aterial blood entering the brain requires a continous outflow on venous blood to make room. if something does not exit the cranial compartment to make room, the ICP increases,

Question 23

what are the volumes of the components of the skull in percentage?

Answer 23

brain tissue and extracellular fluid: 85%
blood: 10%
CSF: 5%

Question 24

what is the normal intracranial pressure inside the skull?

Answer 24

5-15 mmHg

Question 25

are compensatory mechanism effective in dealing with serious and sustained increased ICP and maintaining coronary perfusion pressure?

Answer 25

no. they are not effective and cannot maintain CPP

Question 26

true or false: | with an increase in intracranial pressure, a decreasing in cerebral perfusion results

Answer 26

true!

Question 27

what occurs once the brain can no longer compensate for increased intracranial pressure?

Answer 27

further injury to the brain occurs: - tissue edema - -decreased CPP - compression of arteries - death of brain cells - Co2 accumulates - vasodilation

Question 28

what can lead to ICP?

Answer 28

trauma, stroke, bleeding, embolus, fracture, abscess, excess CSF, brain injury, subarachnoid hemorrhage

Question 29

when the ICP is greater than cerebral perfusion pressure, what happens?

Answer 29

- decreased blood flow - ischemia - hypoxia - neural cell death - decompensation

Question 30

once ICP becomes greater than the mean arterial pressure, what happens?

Answer 30

cerebral blood flow stops all together | person will die

Question 31

what can happen if intracranial pressure is too high?

Answer 31

it can lead to deadly brain herniation, in which parts of the brain are squeezed past strucuture in the skull or into and around the spinal cord patient will die

Question 32

what are some manifestations of ICP?

Answer 32

- Altered level of conciousness (LOC) -confusion, restlessness - pupillary alternations (pupil sixe, shape, responce to light) - Changes in vital signs - Water imbalance (ADH) - from pressure on pituitary - seizures - headaches (more pressure= head hurts) - vomiting (vomiting center in the brain may be triggered, tends to be without warning, projectile) with no nausea - impaired brain stem and cranial nerve function - visual disturbances

Question 33

what is an indicator of secondary injury?

Answer 33

ICP

Question 34

what is the most critial index of nervous system function?

Answer 34

level of conciousness | -this is assessed by used the glasgow coma scale

Question 35

what are the terms for describing alterned LOC?

Answer 35

- confusion (impaired judgement, decison making, loss of ability to think rapidly and clearly - disorientation (to time, place, self) - lethargy (limited spontanious movement, easy arousal with speech or touch) - obtundation (mild-moderate decrease in awakeness with limited respones to enviroment. falls asleep unless stimulated. answered with minimal response) - stupor (deep sleep, may be aroused only by vigorous and repeated stimulation. response is usually withdrawl or localizing coma: no verbal response. cannot stimulate movement

Question 36

what does coniousness involve?

Answer 36

involves arousal (state of awakeness) and content of though (awareness)

Question 37

true are false: | are pupil changes on the same side of the skull as the injury?

Answer 37

yes. it injury and pupil abnormalites are ipsilateral | but as pressure builds, it will eventually affect the other pupil

Question 38

besides LOC, what other clinical manifestations can help determine the extent of brain dysfunction?

Answer 38

includes patterns of breathing, size and reactivilty of pupils, eye position, and reflexes

Question 39

what pupil abnormalities can occur?

Answer 39

-alterations in size includes pinpoint, larger, dilated -altered in response: sluggish or fixed -spontaneous eye opening, pupils equal in size and responsivness to light When eyes are fixed and dilated= overwhelming injury with damage to brain stem (very poor prognosis

Question 40

what will vital signs show with ICP?

Answer 40

temperature: (pressure on hypothalamus) respirations (medullar and pons) heart rate (medulla) blood pressure (medulla) -changes in vital signs can indicate deterioration in neurological status -watch for bradycardia, hypotension, inability to maintain body temp (possible brain stem damage)

Question 41

disruption of temp-regulating system in hypothalamus can manifest itself as what?

Answer 41

hypothermia or pyrexia (raised body temperature; fever)

Question 42

what is common with alterned LOC?

Answer 42

hypoventilation (not enough gas exchange)- can lead to respiratory acidosis

Question 43

what is cushings triad?

Answer 43

-indicative of impending herniation: - bradycardia -irregular respirations -widening pulse pressure (these are late findings)

Question 44

true or false | Clinical manifestations of neurological dysfunction are diverse depending on location and extent of neural tissue damage

Answer 44

true