HPS111 Lecture Notes - Lecture 5: Somatic Nervous System, Peripheral Nervous System, Autonomic Nervous System
WEEK 5
Types of neurotransmitters:
Norepinephrine – can have excitatory or inhibitory effects depending on which receptor sites they bind to.
Involved in neural circuits controlling learning, memory, wakefulness and eating. Undersupply causes
depression and oversupply causes stress and panic disorders.
Acetylcholine (ACh) – excitatory at synapses and involved in muscle activity and memory. Underproduction of
ACh is a factor in Alzheimer’s disease. Oversupply cause violent muscle contractions and convulsions. No
supply causes paralysis.
Serotonin – inhibitory or excitatory; involved in mood, sleep, eating and arousal. Undersupply causes
depression and sleeping and eating disorders, and oversupply results in OCD.
Dopamine – excitatory; involved in voluntary movement, emotional arousal, learning, memory and
experiencing pleasure or pain. Undersupply causes Parkinson’s disease and depression, and oversupply results
in schizophrenia.
Endorphin – inhibits transmission of pain impulses (neuromodulator).
Neuromodulator – these substances circulate around the brain and either increase or decrease the sensitivity of
neurons to their specific transmitters
Psychoactive drugs – chemicals that produce alterations in consciousness, emotion and behaviour.
Three major types of neurons carry out the system’s input, output and integration functions:
Sensory neurons – carries input messages from the sense organs to the spinal cord and brain.
Motor neurons – transmits output messages impulses from the brain and spinal cord to the body’s muscles
and organs.
Interneurons – outnumbering sensory and motor neurons, performs connective or associative functions
within the nervous system. E.g. link sensory input from the visual system with memory
The Nervous System is divided into two types; the peripheral and central nervous systems.
Peripheral nervous system (PNS) – contains all the neural structures that lie outside of the brain and spinal
cord. Its specialised neurons help carry out a) the input functions that enable us to sense what’s going on outside
our bodies and b) the output functions that enable us to respond with our muscles and glands. The PNS is further
divided into the Somatic nervous system (SNS) and Autonomic nervous system (ANS).
a) Somatic nervous system (SNS) – consists of sensory neurons that specialises in transmitting messages from
the sensory organs e.g. eyes and motor neurons, controlling voluntary movement. i.e. the SNS allows us to sense
and respond to the environment.
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Document Summary
Norepinephrine can have excitatory or inhibitory effects depending on which receptor sites they bind to. Involved in neural circuits controlling learning, memory, wakefulness and eating. Undersupply causes depression and oversupply causes stress and panic disorders. Acetylcholine (ach) excitatory at synapses and involved in muscle activity and memory. Serotonin inhibitory or excitatory; involved in mood, sleep, eating and arousal. Undersupply causes depression and sleeping and eating disorders, and oversupply results in ocd. Dopamine excitatory; involved in voluntary movement, emotional arousal, learning, memory and experiencing pleasure or pain. Undersupply causes parkinson"s disease and depression, and oversupply results in schizophrenia. Endorphin inhibits transmission of pain impulses (neuromodulator). Neuromodulator these substances circulate around the brain and either increase or decrease the sensitivity of neurons to their specific transmitters. Psychoactive drugs chemicals that produce alterations in consciousness, emotion and behaviour. Three major types of neurons carry out the system"s input, output and integration functions:
