Nervous System

Allegedly the most feared unit. ALLEGEDLY

cells of the nervous tissue

• neuron

• glial cells

2 anatomical divisions of the nervous system and their components

• CNS (central nervous system) - consists of the brain, spinal cord, tracts, and neurons

• PNS (peripheral nervous system - cranial + spinal, ganglion nerves

2 main functional divisions of the nervous system and their components

• sensory - (receptors) PNS → CNS

  • somatic and visceral

• motor - (effectors) CNS → PNS

  • somatic and autonomic

    • sympathetic, parasympathetic

somatic

information we are aware of

ex: temperature, touch, smell, light, taste, vision, sound/equilibrium, proprioception

location: skin, nose, mouth, eyes, ears, joints & skeletal muscle

visceral

information we are not aware of

ex: internal body temperature, gas levels, hunger, water levels

location: internal organs

somatic

voluntary motor

ex: skeletal muscle

autonomic

involuntary motor

ex: smooth muscle, cardiac muscle, glands

• sympathetic - fight or flight, speed things up

  • ex: pupils dilating, heart rate going up, breathing goes up

• parasympathetic - rest and digest, slow things down

  • ex: constricted pupils, increase in digestive and urinary system

dendrite

short cytoplasmic extensions from soma

f: receives stimulus + info and sends to soma

soma

neuron cell body

f: receives and process information

axon

long cytoplasmic extension from soma

f: sends information/commands to effector

nissl body

rough er + fixed ribosomes

f: makes soma grey

axon hillock

where soma and axon meet

f: determine if an electrical impulse is sent down the axon

axon collaterals

a branch of main axon

f: send impulse to effectors

telodendrion

terminal branches of the axon

f: send the impulse from the axon to the synaptic knobs

synaptic knobs

enlarged end of telodendria

f: houses neurotransmitters

3 anatomical types of neurons

1. unipolar (sensory pns to cns)

• 1 cytoplasmic extension

1. bipolar (sensory pns to cns (nose and eyes))

• 2 cytoplasmic extension

1. multipolar (motor cns to pns)

interneuron

• between neurons

• between sensory + motor

characteristics of glial cells

• small

• numeric

• mitotic

• protects and nourishes neurons

• do not excite

glial cells of cns

1. astrocytes

2. ependymal cells

3. microglial cells

4. oligodendrocyte

astrocyte

• forms blood brain barrier

  • regulates what comes from the blood to the brain

a: astrocyte, basement membrane, tight junction, endothelium

• regulates fluid composition

• strengthen to organize tissue

• replaces damaged/dead cells

• guide neuron development

ependymal cells

f: creates cerebral spinal fluid (CSF)

• ependymal cells + blood vessels = choroid plexus

  • produces CSF

microglial cells

f: phagocytic, eats dead/damaged cells

• smallest in size + #

oligodendrocyte

a: filled with lipids = white

f: insulated axon to speed up impulse

• forms myelin sheath

l: many axons