unit 3 AOS 1 Flashcards
what are Neurons
Basic cell of the nervous system responsible for the reception and transmission of information throughout the nervous system
Neurons communicate with:
· Each other
· Glands
Muscles
types of neurons?
· Motor neurons take information form CNS to senses
· Sensory neurons take information from the senses to CNS · Interneurons (AKA relay/connector neuron) only in the CNS and allow neurons to communicate to each other e.g. motor and sensory neurons
The three main functions of the nervous system
- Receive info (what we sense and feel)
- Process info (what we think)
- Coordinate a response to info (what we should do)
what is the central nervous system?
- what does it do?
Compromises the brain and spinal cord
Main function: to process information received from the body’s internal and external environments and to activate appropriate responses
central nervous system: brain (what is it and what is it responsible for?)
The brain is an interactive network of cells that play a vital role in processing information received through neural pathways from the body and directing actions within the body.
- responsible for virtually everything we think, feel and do
central nervous system: spinal cord (what is it and what is it responsible for?)
The long, thin bundle of nerve tissue that extends from the base of the brain to the lower back; links the brain and the parts of the body below the neck.
- The spinal cord also initiates some simple motor reactions in the form of reflexes that occur extremely rapidly, independently of the brain. E.g. spinal reflexes
central nervous system: two main functionings of the spinal cord
- The spinal cord receives information from the body (via the peripheral nervous system) and sends those messages to the brain for processing.
- The spinal cord receives motor information from the brain and sends it to relevant parts of the body (via the peripheral nervous system) to control muscles, glands, and internal organs so that appropriate actions can be taken.
what is the Peripheral nervous system?
- what does it do?
Carries information to and from the central nervous system
· It is an entire network of nerves outside the CNS
Main function: carries information to the CNS from the body’s muscles, organs and glands (about the internal environment) and from the sensory organs (about the external environment)
what are the two sub-division of the peripheral nervous system?
Somatic nervous system (SNS)
Autonomic nervous system (ANS)
peripheral nervous system: what is the Somatic nervous system (SNS)
A sub-division of the peripheral nervous system that carries sensory information to the central nervous system and motor information from the central nervous system.
· Sensory information: afferent (incoming information) · Motor information: efferent (outgoing information)
- Involves in voluntary movement
peripheral nervous system: what is the Autonomic nervous system (ANS)?
A self-regulating sub-division of the peripheral nervous system that connects the central nervous system to the body’s internal organs and glands, providing feedback to the brain about their activities.
- Responsible for the automatic processes that keep your body alive (e.g. breathing, heart beat and digestion) and actively involved in reaction to extreme emotions, such as fear, anger or nervousness
Autonomic = automatic; keeps us alive automatically
The ANS involves automatic (involuntary) processes
peripheral nervous system: what are the three divisions of the autonomic nervous system
- Sympathetic NS
- Parasympathetic NS
- Enteric NS
autonomic nervous system: what is Sympathetic NS
A sub-division of the autonomic nervous system that arouses the body for vigorous activity or to deal with a stressful or threatening situation.
- controls/activates arousal, “fires us up” for action.
- Release of adrenaline, heart rate increases, breathing rate increases etc.
autonomic nervous system: what is Parasympathetic NS
A sub-division of the autonomic nervous system that helps to maintain the internal body environment in a steady, balanced state of normal functioning; calms or restores the body to its normal state of functioning after an extreme emotion subsides or a threat has passed.
- calms our internal functioning back down after the Sympathetic NS was dominant
Maintains a steady, stable & balanced level of normal functioning (dominates the Sympathetic NS most of the time).
what is a Conscious response?
a reaction to a sensory stimulus that involves awareness; usually voluntary, goal-directed and with some degree of control over it; compare with unconscious response
what is an Unconscious response?
a reaction to a sensory stimulus that does not involve awareness; involuntary, unintentional, automatic and we cannot ordinarily control its occurrence; compare with conscious response
Spinal reflex
an unconscious, involuntary response to certain stimuli, initiated within the spinal cord and controlled solely by neural circuits; also called reflex arc
autonomic nervous system: what is Enteric NS
The ENS has extensive, two-way connections with the CNS, and works together with the CNS to control the digestive system in the context of local and whole body physiological demands. For example, the ENS and brain interact in controlling stomach secretions and voluntary bowel movements.
Ens activity is influenced by:
- External factors (hunger, diet, mood..etc)
- Microbiota (the bacteria and trillions of other microscopic organisms that live in the gastrointestinal tract)
Unconscious response?: what is spinal reflex
an unconscious, involuntary response to certain stimuli, initiated within the spinal cord and controlled solely by neural circuits; also called reflex arc
Simple motor reactions in the form of reflexes that occur extremely rapidly, independently of the brain
Withdrawal reaction = adaptive response (aids survival)
The spinal reflex demonstrates that a response to a particular sensory stimulus can have both an unconscious and conscious component, one occurring before the other.
role of neurotransmitters
Neurons communicate with one another where they meet (but do not touch) at the synapse. The presynaptic neuron releases neurotransmitters from the terminal buttons into the synaptic gap. The neurotransmitters are then received by the dendrites in the postsynaptic neuron.
what is a neurotransmitter
a chemical substance produced by a neuron that carries a message to other neurons or cells in muscles, glands or other tissue
what is Neural synapse
the site where communication typically occurs between adjacent neurons
what is Synaptic gap
the tiny space between the axon terminal of a presynaptic neuron and the dendrite of a postsynaptic neuron
Excitatory effect of neurotransmitters
when a neurotransmitter stimulates or activates a postsynaptic neuron to perform its functions
Inhibitory effect of neurotransmitters
when a neurotransmitter blocks or prevents a postsynaptic neuron from firing and therefore performing its functions
what two effects do neurotransmitter typically have
Excitatory effect
Inhibitory effect
Excitatory neurotransmitter:
Glutamate (glu)
The primary excitatory neurotransmitter for information transmission throughout the brain
- plays crucial roles in the growth and strengthening of synaptic connections during learning an memory formation. - Glu is the second most abundant neurotransmitter in the brain and involved in most aspects of normal brain function, including perception, learning, memory, thinking and movement. ◊ Glu enhances information transmission by making postsynaptic neurons more likely to fire
Inhibitory neurotransmitter:
Gamma-amino butyric acid (GABA)
The primary inhibitory neurotransmitter in the CNS.
- Maintains neurotransmission at optimal levels my making postsynaptic ('receiving') neurons less likely to fire
(Calming neurotransmitter)
what does too much and not enough of glutamate do
Too much - too much glutamate in the brain can cause nerve cells to become overexcited
Not enough - can result in poor communication, mental health and physical development delays
what does too much and not enough of GABA do
Too much - can result in central nervous system depression
Not enough - anxiety and mood disorders
Role of neuromodulators
A neurotransmitter that can influence the effects of other neurotransmitters; also called modulator neurotransmitter
- Neuromodulators influence the activity of multiple neurons at the same time
Dopamine
A neurotransmitter or a neuromodulator that plays a key role in motivation, reward, pleasure, and movement. It helps regulate mood, attention, learning, and motor control. Imbalances in dopamine levels are linked to conditions such as Parkinson’s disease, schizophrenia, and addiction.
Serotonin
A neurotransmitter that plays a crucial role in regulating mood, emotions, sleep, appetite, and overall well-being. It is often associated with feelings of happiness and calmness. Low serotonin levels are linked to conditions such as depression and anxiety, while balanced levels contribute to emotional stability and relaxation.
Effects on brain activity (inhibitory and/or excitatory effects) - dopamine
although primarily an excitatory neurotransmitter, dopamine can have either an excitatory effect at one location or an inhibitory effect at another, depending on the type of receptors that are present.
Sends messages to the brain about voluntary movement
Effects on brain activity (inhibitory and/or excitatory effects) - serotonin
serotonin only has inhibitory effects, so it does not stimulate brain activity. Its inhibitory effects can help counterbalance excessive excitatory effects of other neurotransmitters, as GABA does with glutamate.
too much or too little of dopamine
Too little
If too little dopamine is produced then the brain will receive voluntary movements slower.
- can result in a condition of extreme muscle rigidity, or ‘stiffness’, that makes it difficult for a person to move
Too much
Hallucinations and delusions
Too much dopamine can lead to addicting behaviours, since dopamine provides rewards, too many rewards can lead to addiction. E.g. eating something unhealthy has an award - can lead to overeating
too much or too little of serotonin
Too little
Reduced levels of serotonin in the brain have also been associated with a number of anxiety disorders, particularly obsessive-compulsive disorder (OCD)
Too much
Impulse decisions, restlessness, high blood pressure, increased heart rate
the presence of an excessive amount of serotonin may cause serotonin syndrome, which can be life threatening in some people.
memory
the expression of what you have acquired
Learning
the acquisition of skill or knowledge
Synaptic plasticity
The ability of a synapse to change over time through use or disuse
- Synaptic plasticity enables a flexible, efficient and effectively functioning nervous system
It is also the biological basis of learning and memory
Hebbian learning
Donald Hebb is credited with the idea that learning involves the establishment and strengthening of neural connections at the synapse.
Hebb proposed that learning results in the creation of cell assemblies, or interconnected groups of neurons that form networks or pathways
Neurons that fire together, wire together
Changes in synaptic connections occur in 3 ways:
sprouting, rerouting and pruning
sprouting
new pathways form
Growth of nerve cells endings an axons or dendrites enables new links to be made
Rerouting
pathways go around
Entirely new neural pathways are formed
Pruning
use it or lose it
Synapse not frequently used to decay and disappear
Long term potentiation (LTP)
increased strength
The long lasting strengthening of synaptic connections, resulting in enhanced or more effective neurotransmission across the synapse
- Occurs after repeated strong stimulation - Enables postsynaptic neurons to be more easily activated · Increased transmission efficiency · Increased memory storage information · Decreased likelihood that learning will be forgotten · Rote memorisation works
Long term depression (LTD)
decreased strength
The long lasting decrease in the strength of synaptic connections and transmission and neuronal response
- Allows for the elimination of unused synapses through pruning unimportant or unwanted connections - Ability to adapt and correct problem solving strategies / physical skills etc.
