2 nervous system functioning Flashcards
nervous system
central nervous system (CNS): a major division of
the nervous system comprising the brain + spinal cord, which receives neural messages from & transmits neural msgs to the PNS
- process info recieved from body’s internal + external environments & activate appropriate responses
- made up of interneurons
peripheral nervous system (PNS): a major division of the nervous system comprising every neuron in the body outside the central nervous system
- carry info to CNS from body’s muscles, organs and glands (internal) & sensory organs (external)
- carry info from CNS to body’s muscles, organs and glands
- made up of motor and sensory neurons
central nervous system (CNS)
brain: coordinates mental processes, behaviour & regulates bodily activity
spinal cord: connects brain & PNS; initiates spinal reflexes
- recieve sensory info from body (via PNS) & sends these msgs to brain for processing
- recieve motor info from brain & sends to relvant parts of the body (via PNS) to control muscles, glands and internal organs so action can be taken
peripheral nervous system (PNS)
autonomic nervous system (ANS): a division of
the PNS that regulates visceral muscles, organs, and glands, and transmits neural messages to the CNS about their activity
- visceral muscles, organs & glands: muscles, organs, & glands not connected to the skeleton that are predominantly self-regulating & DON’T require conscious control
somatic nervous system (SNS): msgs from sensory receptors » sensory neural pathways made up of sensory neurons in the SNS » CNS » motor neural pathways made up of motor neurons in the CNS » skeletal muscles
- sensory neurons: afferent neurons arriving at the brain in CNS
- motor neurons: efferent neurons entering the brain in CNS
autonomic nervous system (ANS)
sympathetic nervous system (SNS): a division of
the ANS that activates visceral muscles, organs, and glands, preparing the body to respond to a threat or stressor
- increases activity of most visceral muscles, organs & glands in times of stress
parasympathetic nervous system (PNS): a division of the ANS that maintains the optimal and balanced functioning of visceral muscles, organs, and glands
- decreases activity of most visceral muscles, organs & glands + restores body functions to normal state
enteric nervous system (ENS): dedicated to the functioning of the gastrointestinal (digestive) tract & helps regulate digestion
activities of sympathetic (S) & parasympathetic (P) nervous systems
- pupils: dilate (S) | contract (P)
- salivary glands: decrease salivation (S) | increase (P)
- heart: accelerate heart rate (S) | slow (P)
- bronchioles of lungs: expand (S) | contract (P)
- stomach: decrease contractions (S) | increase (P)
- liver: increase release of glucose (S) | decrease (P)
- gall bladder: inhibit release of bile (S) | stimulate (P)
- adrenal glands: stimulate hormone secretion (S) | inhibit (P)
- bladder: relax (S) | increase contractions (P)
- intestines: relax (S) | increase contractions (P)
- genitals: excite (S) | relax (P)
- sweat glands: increase perspiration (S) | decrease (P)
structure of neuron
- nucleus (genetic material of neuron)
- stoma (cell body that contains the nucleus)
- dendrites (receive signals from other neurons)
- axon (conducts electrical impulses along the neuron)
- myelin sheath (insulates the axon to help protect the neuron & speed up transmission of electrical impulses)
- axon collaterals
- axon terminals (transmits electrical & chemical signals to other neurons)
- terminal buttons (release NT)
conscious and unconscious responses to sensory stimuli
conscious response: a deliberate and voluntary action that is initiated by the brain and performed intentionally by the body
unconscious response: an automatic and involuntary action that is performed by the body independently of the brain
- spinal reflex: an unconscious response to sensory stimuli that is initiated by interneurons in the spinal cord independently of the brain
sequence of spinal reflex involving withdrawal response (hot panhandle example)
- Sensory receptors respond to stimulation & initiate msg carried by sensory neuron to interneuron in spinal cord
- Interneuron acts as a link b/w sensory & motor neurons, relaying info from one to the other
- Interneuron sends msg to motor neuron that carries msg back to appropriate muscles, which stimulate + cause them to contract & pull away from stimulus
- Spinal cord also carries msg to brain, including info abt action taken
- Hot panhandle is released before brain processes conscious perception of pain
synaptic gap
the space between the presynaptic neuron and the postsynaptic neuron
neural synapse
the region that includes the terminal buttons of the presynaptic neuron, the synaptic gap, and the dendrites of the postsynaptic neuron
role of neurotransmitters
neurotransmitter: a chemical molecule that affects one or two postsynaptic neurons
- binds itself to receptor sites of postsynaptic neurons that are specialised to receive that specific NT
- reuptake: NT that DOESN’T bind to receptors in postsynaptic neurons is absorbed back into terminal buttons by presynaptic neuron
excitatory effect: when the neurotransmitter increases the likelihood of the postsynaptic neuron firing an action potential
inhibitory effect: when the neurotransmitter decreases the likelihood of the postsynaptic neuron firing an action potential
glutamate
type: excitatory NT
effect: increases the likelihood of the postsynaptic neuron firing an action potential
role: learning and memory
gamma-aminobutyric acid (GABA)
type: inhibitory NT
effect: decreases the likelihood of the postsynaptic neuron firing an action potential
role: regulates postsynaptic activation in neural pathways
glutamate & GABA
- inhibitory action of GABA counterbalances excitatory activity of glutamate & vice versa
- both are important in regulation of CNS arousal
role of neuromodulators
neuromodulator: a chemical molecule that affects multiple postsynaptic neurons
- NM can work together w another NT in synapse to make the other more or less potent
- NM influences the activity of multiple neurons at the same time
- NM’s effects take longer & last longer
dopamine
a NM primarily responsible for voluntary motor movement, the experience of pleasure, and reward-based learning
pathways:
- the substantia nigra (midbrain)
- the ventral tegmental area (midbrain)
effect: excitatory and inhibitory effects on the postsynaptic neuron
serotonin
a neuromodulator primarily responsible for the regulation of mood and sleep
pathways: raphe nuclei, which are masses of neurons in the brainstem that produce serotonin
effect: inhibitory effects on the postsynaptic neuron
role:
- mood regulation and stabilisation
- regulates sleep-wake cycle
- appetite, digestion & arousal
neural mechanisms of memory formation and learning
learning: the process of acquiring knowledge, skills, or behaviours through experience
memory: the process of encoding, storing, and retrieving information that has been previously encountered
synaptic plasticity and changes to connections between neurons
the ability of synaptic connections to change over time in response to activity or experience
experiences that cause synaptic connections to change:
- Ageing and maturation (developmental plasticity)
- Brain trauma or injury (adaptive plasticity)
sprouting, rerouting and pruning
sprouting: the ability of dendrites or axons to develop new extensions or branches
rerouting: the ability of a neuron that is connected to a damaged neuron to create an alternative synaptic connection with an undamaged neuron
pruning: the elimination of synaptic connections that are not adequately activated
long-term potentiation and long-term depression
long-term potentiation: the long-lasting and experience-dependent strengthening of synaptic connections that are regularly coactivated
long-term depression: the long-lasting and experience-dependent weakening of synaptic connections between neurons that are not regularly coactivated
why spinal cord damage can result in loss of brain-body control
when the spinal cord is injured, the brain loses both sensory input from & control over the body (but the severity of feeling loss and paralysis depends on
where the spinal cord is injured and the severity of the injury).
- neural pathways within the spinal cord transmit sensory & motor info required for control of voluntary movements from the brain to the body
neuron
a nerve cell that receives and transmits neural information
motor neuron (efferent neuron)
neurons that transmit neural messages about motor movement from the CNS to the peripheral nervous system
sensory neuron (afferent neuron)
neurons that transmit neural messages about bodily sensations from the peripheral nervous system to the CNS
interneurons
neurons that transfer neural messages between sensory neurons and motor neurons
process of synaptic transmission
- NT produced in the axon terminals (terminal button) of the presynaptic neuron
- NT released from terminal buttons of the presynaptic neuron into the synaptic gap
- NT binds to receptor sites on the dendrites of the postsynaptic neuron
- NT affects the postsynaptic neuron, either triggering or inhibiting a response
