Nervous system functioning Flashcards
Divisions of the CNS
- Brain
- Spinal cord
Divisions of the PNS
- Somatic NS
- Autonomic NS
- Sympathetic NS
- Parasympathetic NS
Role of the CNS
Main function is to process information received from the body’s internal and external environments in order to activate appropriate responses. It receives and transmits information from the PNS.
Role of the brain
Receives and analyses sensory information and controls all bodily actions and functions.
Role of spinal cord
Receives sensory information via the PNS and sends it to the brain via afferent tracts for processing.
Role of PNS (entire network of nerves)
Sends sensory information from the body to the CNS via sensory neurons in afferent tracts.
Sends motor information from the CNS to the body via motor neurons via efferent tracts.
Role of somatic NS
Controls voluntary movement through control of skeletal muscles.
Receives sensory information from receptor sites and transmits it to the spinal cord via sensory neurons in afferent tracts.
Receives motor information from the CNS and transports them to the skeletal muscles.
Role of autonomic NS
Processes under its control are self-regulating, meaning they occur involuntary.
Role of sympathetic NS
Prepares the body for action by activating visceral muscles, increasing physiological arousal.
Plays a role in the fight-flight-freeze response.
Fight-flight-freeze response
- increased heartrate
- increased breathing
- dilated pupils
- increased salivation
- decreased digestion
Role of parasympathetic NS
Reverses the effects of the sympathetic NS and returns the body to a normal state of functioning.
Plays a role in maintaining homeostasis.
Sensory information to CNS - process
- Sensory information from external environment is received by the somatic NS.
- Information is carried through PNS to the spinal cord in CNS.
- Spinal cord sends information to the brain via sensory neurons in the afferent tracts.
- Brain receives information and analyses/interprets it.
Motor information from CNS - process
- Motor information is sent from the brain to the spinal cord.
- Spinal cord sends motor information to skeletal muscles via motor neuron efferent tracts.
- Individual is able to control their body.
Conscious response
An intentional reaction to a sensory stimulus that involves awareness.
Unconscious response
An involuntary action to a sensory stimulus that does not involve awareness (spinal reflex).
Spinal reflex
An unconscious, involuntary response to certain stimuli, initiated within the spinal cord without any involvement of the brain.
Spinal reflex - process
- Receptor cells within skin detect stimulus.
- A neural message is sent to a singular sensory neuron.
- Sensory neuron carries message to spinal cord
- Interneuron relays message to a motor neuron
- Motor neuron carries message back to the appropriate muscles, causing them to contract and pull away from stimulus.
- Spinal cord also carries sensory information to the brain, however the individual would have already pulled away before the brain processes the perception of pain.
What is a neuron?
A neuron is an individual nerve cell that is specialised to receive, process and transmit information to other cells. They communicate with other neurons.
Dendrite
Detects and receives neurotransmitters from neighbouring neurons.
Axon
A tube-like extension that transmits neural information to other neurons.
Myelin sheath
Surrounds and insulates the axon. It enables for rapid transmission of neural information.
Axon terminals
Small branches at the end of an axon, with terminal buttons at the ends. Neurotransmitters are released from the terminal buttons.
Communication within a neuron - chemical or electrical?
Electrical
Communication between neurons - chemical or electrical?
Chemical
Sensory neurons - role
Transmits sensory information from sensory receptors in the PNS to the brain through afferent tracts.
Motor neurons - role
Transmits motor information from the brain to the muscles, organs and glands.
Interneurons - role
Create connections between sensory and motor neurons as they do not interact with one another.
How do neurons communicate with each other?
By sending neurotransmitters across the synaptic gap between neurons.
Neurotransmitter
A chemical substance manufactured by a neuron that carries a message to neighbouring neurons. It binds to receptor sites of post-synaptic neurons. They are mostly found in the brain.
Reuptake
When neurotransmitters that don’t bind to receptors in the post-synaptic neuron, so they are absorbed back into the the terminal buttons in the pre-synaptic neuron.
Types of neurotransmitters
GABA - inhibitory effect - makes post-synaptic neuron less likely to fire.
Glutamate - excitatory effect - makes post-synaptic neuron more likely to fire.
Lock-and-key process
- A neurotransmitters shape must precisely match the shape of the receptor site on the post-synaptic neuron in order to bind its receptors and communicate a message.
- The binding unlocks the neuron’s response, resulting in the inhibitory or excitatory effect.
Parkinson’s disease
a chronic and degenerative neurological condition that affects both motor and non-motor functions. It persists over a long period of time and symptoms get progressively worse.
Parkinson’s disease - cause
It is caused by the degeneration of dopamine-producing neurons in the substantia nigra.
Motor symptoms of Parkinson’s disease
- Tremor
- Bradykinesia
- Postural instability
Non-motor symptoms of Parkinson’s disease
- Impaired cognitive function (memory loss)
- Mental health problems
- Fatigue
