CNS + Chemical Messengers

The Nervous System

body’s communication network, consisting of a complete system of nerves, neurons, and specialized cells

Central Nervous System (CNS)

consists of brain and spinal chord:

command center of the body, responsible for processing info, coordinating responses, and regulating bodily functions

Peripheral Nervous System

consists of all nerves and ganglia outside the brain and spinal chord

• communication network, transmits info from body to CNS

Automatic Nervous System

division of peripheral nervous system:

regulates involuntary bodily functions. Operates automatically

• two branches: sympathetic and parasympathetic nervous system

Sympathetic Nervous System

responsible for activating body’s fight or flight response in times of stress or danger

Parasympathetic Nervous System

promoting relaxation and restoring body to calm state after experiencing stress or danger

• slows heart rate, allows body to conserve energy

ex: evacuating to safety

Somatic Nervous System

division of peripheral nervous system:

controls voluntary movements and relaying sensory info from body to CNS

ex: muscle movement and coordination - riding a bike

Neurons

specialized cell that serves as the building blocks of the nervous system

• transmits electrical and chemical signals throughout the body

  • motor neurons: carry outgoing info

  • sensory neurons: carry incoming info

  • interneurons: process info between sensory inputs and motor outputs

Glial Cells

“support cells” of the nervous system, provide structural support, insulation, and nourishment to neurons

• essential role in maintaining brain health and supporting neuron function

Reflex Arc

automatic response to stimulus. rapid and involuntary reaction designed to protect us from harm

ex: knee-jerk

Neurotransmitters

chemical messengers that transmit signals between neurons, allowing for communication within the nervous system

Glutamate

primary excitatory neurotransmitter in the CNS

• key role in synaptic transmission and neuronal communication

• involved in various brain functions including learning, memory, and neural plasticity

ex: study for test and engage in learning new information; brain releases glutamate in regions associated with memory formation, such as hippocampus

Inhibitory Neurotransmitters

chemicals released by neurons that decrease the likelihood of an action potential occurring in postsynaptic system

• like a pedal break - slows things down

GABA

neurotransmitter that acts as a primary inhibitory neurotransmitter in CNS

• promotes relaxation and reduces anxiety

Dopamine

regulates mood, reward, motivation, and movement

• experience of pleasure and reward

ex: hearing a phone notification - release of dopamine is triggered in brains reward pathway - makes you want to check your phone again

Serotonin

plays a vital role in regulating mood, sleep, appetite, and stress

• influence mood and emotional well-being

ex: spending a sunny day outside - brain releases serotonin which contributes to feelings of happiness

Endorphins

act as natural pain relievers

• released in response to stress, pain, or intense physical activity

Substance p

transmits pain signals to the nervous system

ex: accidently touching hot stove, substance p is released

Acetylcholine

involved in various functions like muscle contraction, memory, and learning

ex: playing basketball - acetylcholine enables coordination of muscle activity

Hormones

produced by glands in the endocrine system

• regulate various physiological processes and behaviors

ex: difference between men and women

Ghrelin

hormone produced by stomach - “hunger hormone”

• stimulates appetite and promotes hunger

Leptin

hormone produced primarily by fat cells

• regulates energy balance and appetite

• suppresses hunger

Melatonin

hormone that regulates sleep-awake cycle and circadian rhythm

• rise in melatonin - feel tired

Oxytocin

social bonding - “love hormone” or “bonding hormone”

Adrenaline

body’s stress response - often referred to as “fight or flight”

ex: playing piano at a recital; adrenaline kicks in causing heart rate to rise

Norepinephrine

helps the body stay alert and focused

• key role in fight or flight response

ex: big test coming up - feel more awake, alert, and ready to focus