Unit 9: NERVOUS SYSTEM Flashcards
Myelin
insulating layer of lipid-rich schwann cells or oligodendrocytes wrapped around axon
nodes of ranvier
- areas of exposed axonal membrane between myelinated areas
- increase speed of action potentials
Demyelination
damage to sheath causes impulses to leak out and message cannot transmit further
Multiple Sclerosis
- autoimmune condition
- causes slow destruction of myelin
- ability of neurons to transmit impulses is impaired
Neuroglia
- supporting cells
- usually divide and can increase in number unlike neurons
Peripheral Nervous system cells
- Schwann cells = insulate axons
2. satellite cells = control effect of neurotransmitter
Central nervous system cells
- microglial cells = phagocytes, small, increase in number during infection
- Oligodendroglia cells = insulate (myelinate) cells
- Ependymal cell = line ventricles and central canal of spinal cord (produce, monitor and circulate CSF)
- Astrocytes = large and numerous, regulate ion and nutrient content in ICF
- make up most tumors of the brain
- maintain blood-brain barrier
nervous system development
neural plate -> neural crest -> neural tube
cephalization
anterior swelling and closing of neural tube
Spina bifida
failure of neural tube to close on posterior side = movement disorders
Anencephaly
failure of neural tube to close on anterior side = still born, no production of the brain
Hypothalamus
- hormone production
- regulates body temperature
- controls circadian cycles
- control of some reflexes
Thalamus
relay station of sensory information (except sense of smell)
Midbrain
info from eyes to ears
Medulla
autonomic functions -> HR, BP and breathing
Hindbrain
pons
medulla
cerebellum
Cerebellum
maintains balance and is influenced by alcohol consumption
Cerebral cortex
Frontal lobe = movement Parietal lobe = somatosensory Occipital lobe = vision Temporal lobe = hearing, memory limbic system = emotion
Meninges in brain
- Dura mater = outer layer, no space between dura anc cranium
- Arachnoid mater = spider-web filamentous middle layer
- Pia mater = thin layer contouring the brain
Epidural space
- space between dura and vertebra
- contains loose connective tissue, fatty tissue, lymphatics, spinal nerve roots and small blood vessels
Cerebrospinal fluid (CSF)
- formed in choroid plexus
- low protein content
- low glucose concentration
- similar to ECF
CSF function
- cushion and support brain, provides buoyency and reduces weight (1500g- 50g)
- transport nutrients, chemical messenger, and waste
- circulates via ventricles in brain
- produces 550ml/day, but approx volume 150ml
Spinal tap
- between L3-L4 vertebra
- sample CSF from subarachnoid space
Brain blood supply
- carotid arteries = supply side of brain
2. vertebral arteries = supply back of brain and branch into Circle of Willis
