Lec 5: The nervous system: structure and function

Afferent (input) Sensory

Efferent (outpout) Somatic (consious movement:s.motor neuron: skeletal muscle)/

Autonomic (no control: visceral motor neiron: cardiac muscle)

to spinal cord (some directly to brain-12nerves)

spinal nerves-nerve enter gaps: cervical, thoracic, lumbar, sacral

cranial nerves: olfactory, optic, oculomotor (eyes), trochlear, trigeminal (face sesnsory), abducens, facial, auditory vestibular, glossopharyngeal, vagus (πνευμονογαστρικο), spinal, accessory, hypoglossal

INPUT:

• touch&visceral -->> mechanoreceptors (movement), proprioreceptors (posture&balance), nocireceptors (noxus stimulus/pain receptors), chemoreceptors ( ↑A/B)
• sight, sound, smell, taste

unipolar: spinal cord, multipolar: every neuron in brain

Reflex: sth happens u don't have any control of!
Reflex Arc:
Receptor>------Afferent fibre---- Spinal cord----Efferent fibre---->Receptor responses


Dorsal back, ventral front
Dorsal root ganglion=> Αβ axon: AP comes in through dorsal root: mechanoreceptor/msg go str8 to brain


muscle stretch: tendon quadriceps (front): pulls on muscle, muscle spindle: sense muscle all of sudden been stretched, activation of muscle from motor neurone (α) causes contraction.

sensory neurones:
Aα, Αβ, Αδ, C
I, II, III, IV
←-------------
increasing diameter/speed
proprioreceptors(posture-balance) of skeletal muscles, skin mechanoreceptors, pain/T, pain/T/itch

Ascending vs Desceding pathways (e.g. control of pain)
1 up spinal cord->2 into brain medulla-> 3 thalamus-> 4 somatosensory cortex

dorsal column-medial (lemnisal pathway) spinothalamic pathway

evetyrhing right side of body sensed by left side of brain+ vice versa

visual neuroanatomy left->right

≠ brain through spinal cord to peripheral
PAG->midbrain-> Raphe nuclei (medulla)-> Dorsal horn (spinal horn)

Nervous system full of other cells-> Glial cells:

• provide myelin in brain cells, astrocytes*
• support, insulation buffering, guide developing neurones, scavenging (αφαιρω καταλοιπα), immune response, brain barrier

CereboSpinal Fluid (CSF):

• aqueous NaCl+glucose--> fuel/E
• surrounds cell neurones&brain+gives them food
• produced by choroid plexus, ~120ml, clear colourless solutn
• buoyancy&cushioning/compensation of changes in brain V/ diagnosis: lumbar puncture (needle test take fluid from sp.cord), drug delivery (inject pain relief--> delivery), hydrocephalus

Bl. supply to CNS&Bl. Brain Barrier:

separates bl. from CNS

stoping viruses&bac enter brain

also drugs getting in

antianxiety have pass bl.-brain Barrier

microglia act as white bl.cells