1. Physiology Of CNS

Question 1

Nueroglia (astrocytes, olgliodendrocytes, ependymal, microglia)

Answer 1

Nerve glue, supports neurons

Astrocytes - metabolic buffers, neurons communication and metabolic support - acute cell injury cause cellular swelling

Oligodendrocytes - produce myelin which is wrapped around axons as insulation. Injury will result in demyelinating disorders

Ependymal cells - epithelial cell of brain and spinal cord, line Spinal cord and ventricles, produce CSF

Microglia - resident macrophages

Question 2

Sensory part of nervous system

Answer 2

Sensory receptors

Excite sensory receptors

Information enters CNS through peripheral nerves and travels to:
Spinal cord
Medulla, pons, mesenecphalon
Cerebellum
Thalamus
Cerebral cortex

Question 3

Motor part of nervous system

Answer 3

Effectors

Control various bodily activities by controlling:
Contraction of SK muscle
contraction of SM in organs
Secretion of substances from exocrine and endocrine glands

Question 4

Major levels of CNS functions and ARAS

Answer 4

Lower brain (subcortical level):
Subconscious activities - medulla, pons, hypothalamus, thalamus, cerebellum

Higher brain (cortical level):
Cerebral cortex - thinking, learning, remembering

Spinal cord level
Upper levels of nervous system send signals to control reflexes (GI/urinary excretion)

Ascending Reticular activating system (ARAS):
In brainstem
Relays stimulations from environment to thalamus then to cerebral cortex
Maintaining consciousness and alertness

Question 5

Cerebral cortex

Answer 5

Performs associated activities thinking, learning, remembering

Question 6

Thalamus and hypothalamus

Answer 6

Thalamus: interprets sensory messages (pain, temp, and pressure)

Hypothalamus: homeostatic functions (body temp, respiration, HR)

Question 7

Cerebellum,

Answer 7

Contributes to muscle tone, posture and balance (equilibrium)

Question 8

Brain stem

Answer 8

Regulates heart beat and breathing

Plays a role in consciousness

Question 9

CSF

Answer 9

Produced in choroid plexus

Functions:
shock absorber
Delivers nutrients to brain
Flow between cranium and compensate for changes in inter cranial blood volume

Balance between production and absorption critical

Question 10

Types of Barriers

Answer 10

BBB: tight junctions between endothelial cells ands astrocytes with processes on capillary walls

Blood-CSF barrier: tight junctions between choroid epithelial cells

Can produce cytokines

Question 11

Intercranial components

Answer 11

Brain parenchyma 80%
CSF 10%
Blood 10%

Normal pressure is less then or equal to 15mmHg

Question 12

Intracranial compliance /auto regulation

Answer 12

Displacement of CSF into thecal sac

CBF maintained at a constant level with mean arterial pressure - 60 to 150 mmHg

If auto regulation fails: vasodilation and cerebral edema -> inc ICP

Question 13

Two types of cerebral edema

Answer 13

Vasogenic: increase EXTRAcellular volume caused by BBB breakdown, inc vascular perm

Cytotoxic: potentially reversible inc in INTRAcellular fluid bc of neuronal, glial or endothelial cell membrane injury

Question 14

Clinical manifestationsof elevated ICP

Answer 14

Global: headache, dec consciousness, vomiting

Focal: herniation

Tonsillitis herniation: causes brainstem compression and compresses vital respiratory and cardiac centers in the medulla

Question 15

PVS vs Coma

Answer 15

PVS:brain injury due to lack of oxygen, progresses to state of wakefulness without arousal
Non traumatic : permanent in 3 months
Traumatic: after1 year is permanent

COma: unconsciousness caused by disruption of ARAS

3 outcomes of PVS:
Recover
Coma
Death

Question 16

Ischemic stroke vs TIA

Answer 16

TIA: transient episode of nuerologic abnormalities cause by focal brain or spinal cord without acute infarction

Stroke: infarction of brain or spinal cord due to ischemia - permanent injury

Question 17

Mechanisms of TIA

Answer 17

1. Embolic
2. Large artery, low flow - atherosclerotic lesions
   In carotid a, basilar a, vertebral a more then 50% closed
3. Lacunar or small penetrating vessel TIA - caused by stenosis

Question 18

Subarachnoid hematoma

Answer 18

Rupture of intracranial anyuerysm

Preventable risk factor: smoking

“Worst headache of my life”

Question 19

Sub dural hematoma

Answer 19

Head trauma - tearing of bridging veins

Question 20

Epidural hematoma

Answer 20

Trauma (skull fracture)

Expanding EDH - Increased ICP

Question 21

Primary vs secondary brain damage

Answer 21

Primary:
Parenchymal blood accumulation
Effect brain tissue
Elevated ICP -> damagedBBB -> edema

Secondary:
Thrombin activation
Lysis of RBCs by ROS causes release of hemoglobin -> heme and iron
Inflammatory relaxation

Commonality:
BBB breakdown
Edema
Neuronal necrosis

Question 22

Consequences of CNS trauma depend on:

Answer 22

Anatomical location of lesion

Injury to brain parenchyma may be:
Frontal lobe- clinically silent
Spinal cord - disabling
Brainstem - fatal

Shape of object
Force of impact
Whether head was in motion

Question 23

Concussion vs contusion

Answer 23

Both type of TBI

Contusions: areas of injury with localized ischemia, edema and mass effect

Concussion: wide reaching injury due to broad scale trauma, share symptoms, refers to symptoms of mild TBI

Brain contusions may delay recovery from concussion