KIN 1Y03: Lecture 9 - Functional Organization of Nervous Tissue

integrative

analyze incoming sensory information, store some aspects, and make decisions
⤷ eg. putting on a fuzzy sweater in the morning but throughout the day, brain gets used to it, doesn't recognize the sensory anymore
⤷ eg. mental activities, thinking, memories, emotions

divisions of NS

CNS, PNS

central NS

brain and spinal cord

peripheral NS

sensory receptors and nerves (basically, everything thats not CNS)
⤷ nerves can be grouped depending on where they originate/terminate (eg. cranial nerves, spinal nerves)

sensory receptors

ending of neurons, that gather info internally/externally
⤷ specialized cells that detect things like temp, pain etc.

nerve

a bundle of axons and their sheaths that connects CNS to sensory receptors, muscles, and glands

cranial nerve

nerves that enter (envir → brain) and exit (brain → target) structures in the brain
⤷ 12 pairs ("pairs" are bilateral - left and right side)

spinal nerve

nerves that originate from spinal cord
⤷ 31 pairs

ganglion

collection of neuron cell bodies in PNS
⤷ when nerve is in a bundle of axons, the resulting neuron's cell body forms ganglion (if outside CNS)
↳ sensory info from spinal nerves will be in ganglion
↳ ganglion can also be the connection point between 2 neuron

plexus

extensive network of axon and sometimes neuron cell bodies

⤷ located in PNS

sensory

(afferent): transmit action potentials from receptors to CNS
⤷ gathers info from internal/external envir and bring info back to CNS
⤷ eg. light, touch, taste etc - detected by sensory receptors

dorsal root side of SC

if the electrical signal is sent to the dorsal root of the spinal nerve, then sensory info is carried - travelling from the stimulus → spine → CNS
^^ HAS THE GANGLION

action potential

gets created by sensory info/stimuli from envir → trigger receptors
⤷ become electrical signal

motor

(efferent) transmit action potentials from CNS to effectors (target tissues - muscles, glands)

ventral root side of SC

if electrical signal is sent to the ventral root of the spinal nerve, then motor info is carried - travelling from spinal cord to target muscle

somatic NS

allow for voluntary control from CNS to skeletal muscles (eg. moving your body, talking)
⤷ single neuron system (from neuron to target, NO MIDDLEMEN)
⤷ synapse with skeletal muscles @ neuromuscular junction:

autonomic NS

allows for involuntary control (eg. digestion, heartrate, pupil dilation)
⤷ from CNS to smooth muscle, cardiac muscle, and certain glands
⤷ two neuron system: first from CNS to ganglion, second from ganglion to effector
>> Divisions of ANS -- (sympathetic NS and parasympathetic)

sympathetic NS

prepares body for physical activity or a change from the regular "resting position"(fight or flight)
⤷ eg. seeing a bear: ↑ heart rate, ↑ breathing, pumps epinephrine

parasympathetic NS

regulars resting or vegetative functions (rest-and-digest)
⤷ active when youre not doing much physical activities
⤷ eg. digesting food: ↓ heart rate

enteric NS

series of plexuses within the walls of the digestive tracts
↳ controls the digestive tract independently of CNS, but still communicates with the CNS via the ANS (para and symp)
⤷ brain doesn't always need to know whats happening in the digestive system, in order for it to happen ⇒ ∴ the ENS allows for digestion to happen without the CMNS actively knowing

organization of nervous system