Central nervous system

Central Nervous System

includes spinal cord and brain, contains 97% of all nervous tissue

peripheral nervous system

includes all other nervous tissue

neural cell body (CNS)

nuclei (grey matter)

neural cell bodies (PNS)

ganglia

Bundles of Axons (CNS)

Tracts or Fibers (White matter)

Bundle of Axons (PNS)

nerves

4 protections of the brain

skin, bone, cranial meninges, cerebrospinal fluid

cranial meninges

protective layers of tissue that surround the brain and spinal cord

function of cranial meninges

provide support, cushion the central nervous system, help circulate CSP

3 Cranial Meninges 

Dura Mater, arachnoid mater, pia mater 

dura mater (think fibrous)

tough, durable outer layer, just under the skull, strong protection

arachnoid mater(thin+ filamentous mesh)

middle web-like layer, subarachnoid layer that contains CSF

Pia mater (thin)

sticks tightly to the brain and spinal cord, wraps around CNS

3 functions of cerebrospinal fluid

homeostatic regulation, support, immune function 

Ventricles 

produces and stores CSF

Ventricle flow path

CSF flows through subarachnoid space, excess CSF drains through arachnoid villi into dural venous sinuses

CSF circulation production

made by ependymal cells in the choroid plexus

CSF circulation location

choroid plexus in the brain’s ventricles

Ependymal cells

a type of glial cell that lines the ventricles of the brain and the central canal of the spinal cord 

Ependymal cells function

produces CSF and helps circulate it through the CNS

Choroid Plexus

a network of ependymal cells and blood vessels found inside each ventricle of the brain

choroid plexus function

main site where CSF is produced 

Blood Brain barrier structure

endothelial cells of brain microvessels with tight junctions

BBB Functions

control molecular traffic, ion homeostasis, low protein environment

BBB purpose

separates the blood from the brain’s extracellular fluid, keeping harmful substances out while allowing essential nutrients in

Metabolic needs of the brain

oxygen, blood supply (15%), supports high energy demand for neuronal activity

Glucose Need of brain

main energy source (50%), mem. transporters move it from plasma into brain interstitial fluid

glucose importance

hypoglycemia- confusion, unconsciousness and death

internal carotid arteries

main arteries supplying the anterior and middle portions of the brain

vertebral arteries

travels up the spine and supply the posterior brain, including the brainstem and cerebellum 

circle of willis

circular arterial network at the base of the brain that provides backup in case of blockage

jugular veins

major veins that drain deoxygenated blood from the brain back to heart

cerebrum

higher brain function

diencephalon

controls homeostasis

Brainstem

automatic/ reflex center

cerebellum

coordinates movement and balance

Gyrus/Gyri

raised ridges

Sulcus/Sulci

shallow grooves 

longitudinal fissure

left and right cerebral

cerebral hemisphere

two halves of cerebrum

transverse fissure

separates cerebrum and cerebellum

lateral fissure

separates frontal and parietal

central sulcus

groove separating parietal and frontal

frontal lobe

motor control, speech, memory, emotion, personality

parietal lobe

somatosensory processing

occipital lobe

visual processing and visual memory

temporal lobe

hearing, speech, language, smell

contralateral control

each cerebral hemisphere controls the opposite side of the body