the nervous system

nervous system

the body’s speedy, electrochemical communication system

peripheral (PNS)

the sensory + motor neurons that connect the CNS to the rest of the body

autonomic

controls involuntary functions or items that happen automatically within our body

don’t have to think these things

breathing, heartbeat, digestion, etc

somatic

includes the nerves that transmit signals from your brain to the skeletal muscles to allow voluntary movement

you control these things

sympathetic

• initiates “fight or flight” ; body’s emergency response system

• physically arouses the body, preparing it to act/react in successful situations, expending energy

• symptoms:

  • heart rate increases, attention becomes more focused, digestion slows, muscle tension increases, adrenaline is released into the bloodstream

parasympathetic

• default condition of the ANS

• initiates rest + digest

• symptoms:

  • calms body, reduces energy, expenditure, increases blood flow to digestion, etc

• returns body to homeostasis

central (CNS)

contains the brain and the spine; center of the body

coordinates the actions/interactions of the other systems of the body

brain

receives support + protection from other parts of the body

spinal cord

runs through center of our body; “backbone”

transmits messages from brain → muscles → glands throughout body

interneurons

cames outgoing info. from the CNS to the peripheral nervous system + muscles

sensory (afferent) neurons #2

carries incoming messages/info. from the sense receptors to the CNS

motor (efferent) neurons #2

the only neurons in the CNS, act as messengers between sensory + motor neurons

how do reflexes work?

a signal is sent from a sensory organ to the spinal cord, which processes and initiates a response without waiting for the info. to travel to the brain

sympathetic nervous system

• inhibited digestion

• stimulates the release of glucose by the liver

• stimulates release of epinephrine and norepinephrine by the adrenal gland

• dilates pupils

• increases breathing + heart rate to oxygenate blood

parasympathetic nervous system

• stimulates digestion

• contracts pupils

• slows breathing + heart rate