U3AOS1 Nervous System and Stress

Question 1

neurons definition

Answer 1

specialized cell within the nervous system that transmits chemical and electrical messages to and from the brain. They are the building blocks of the brain, spinal cord, and peripheral nerves.

Question 2

recall the three types of neurons

Answer 2

1. Motor/ efferent neuron
2. Sensory/ afferent neuron
3. Inter/ relay-neuron

Question 3

define motor neurons

Answer 3

transmit neural messages about motor movement from the central nervous system to the peripheral nervous system

Question 4

define sensory neurons

Answer 4

transmit neural messages about bodily sensations from the peripheral nervous system to the central nervous system

Question 5

define interneurons

Answer 5

transfer neural messages between sensory neurons and motor neurons. The central nervous system, including the brain and spinal cord, it made up of interneurons.

Question 6

recall the two types of responses

Answer 6

1. Conscious response
2. Unconscious response

Question 7

define conscious response

Answer 7

deliberate and voluntary actions that are intentionally initiated by the brain and performed by the body, involving the central and somatic nervous system.

Question 8

define unconscious response

Answer 8

automatic and involuntary actions that are performed by the body independently of the brain. They occur without conscious awareness in response to internal and external sensory stimuli. Include the autonomic nervous system and the spinal reflex.

Question 9

define the central nervous system

Answer 9

comprised of the brain and spinal cord, is a complex of nerve tissues that processes and coordinates responses to sensory stimuli received by the body.

Question 10

define the spinal cord

Answer 10

a dense bundle of nerve tissues that carries sensory information from the body to the brain and motor information from the brain to the body.

Question 11

define the brain

Answer 11

a complex structure that receives and processes sensory stimuli information, integrating it, organizing it, then coordinating a voluntary response in the skeletal muscles to respond to the stimuli.

Question 12

define ascending tracts

Answer 12

specific to the CNS, transmits sensory messages from the peripheral nervous system to the Brain.

Question 13

define descending tracts

Answer 13

specific to the CNS, transmits motor messages from the brain to the peripheral nervous system.

Question 14

define the peripheral nervous system

Answer 14

every neuron in the body outside the central nervous system that transmits neural messages between the central nervous system and the muscles, organs and glands throughout the body.

Question 15

recall the two subdivisions of the peripheral nervous system

Answer 15

1. Somatic nervous system
2. Autonomic nervous system

Question 16

somatic nervous system definition

Answer 16

a subdivision of the peripheral nervous system that transmits sensory neural messages to the central nervous system, and motor information to the body, related to voluntary movement

Question 17

define the autonomic nervous system

Answer 17

subdivision of the peripheral nervous system that regulates visceral muscles, organs, and glands not connected to the skeleton, and transmits neural messages to the central nervous system without requiring conscious control. Involved in self-regulated, unconscious responses.

Question 18

recall the five main pathways of neural messages through the somatic nervous system (steps)

Answer 18

1. the sensory stimulus comes into contact with sensory receptors, which are nerve endings that detect internal sensations in the body and external sensations from the environment.
2. their sensory neural message is transmitted via afferent pathways in the somatic nervous system, and the spinal cord, to the brain.
3. the brain processes this sensory information, coordinating and initiating a conscious motor response.
4. this motor neural message is transmitted via efferent pathways in the spinal cord, and then the somatic nervous system, to skeletal muscles.
5. the skeletal muscles carry out the conscious motor response to the sensory stimulus.

Question 19

recall the two subdivisions of the autonomic nervous system

Answer 19

1. sympathetic nervous system
2. parasympathetic nervous system

Question 20

define the sympathetic nervous system

Answer 20

a subdivision of the autonomic nervous system that initiates the physiological responses of increased arousal and energy, readying the body for a quick response when confronted with a threat of stressor.

Question 21

define the parasympathetic nervous system

Answer 21

a subdivision of the autonomic nervous system that controls the bodys internal environment, maintaining optimal, homeostasis, and balanced functioning during rest and physical inactivity.

Question 22

define spinal reflex

Answer 22

an involuntary and unconscious response to sensory stimuli that is initiated by interneurons in the spinal cord, independently of the brain.

Question 23

What is the purpose of the spinal reflex

Answer 23

an adaptive response to protect the body from injury/harm and increase chances of survival

Question 24

what neurons are involved in the spinal reflex reflex arc?

Answer 24

sensory/afferent neurons, motor/efferent neurons, and inter/relay neurons

Question 25

define the reflex arc of the spinal reflex

Answer 25

the path along which the neural signal is transmitted as part of the spinal reflex. The sensory neural message travels from sensory receptors to the spinal cord. It then loops around the spinal cord and now, as a motor neural message, travels from the spinal cord to the skeletal muscles.

Question 26

recall the four main pathways of neural messages through the spinal reflex arc (steps)

Answer 26

1. a dangerous or harmful sensory stimulus is detected by sensory receptors, which transmits this sensory message via sensory neurons in the somatic nervous system to the spinal cord.
2. an interneuron in the spinal cord immediately relays this sensory neural signal from a sensory neuron to a motor neuron as a motor neural signal, initiating an automatic and unconscious motor response.
3. the motor message is transmitted via motor neurons in the somatic nervous system to skeletal muscles, which carry out this unconscious motor response to the dangerous or harmful sensory stimulus.
4. the sensory message continues to travel via afferent tracts in the spinal cord to the brain. Then the brain independently registers the sensation that triggered the spinal reflex.

Question 27

explain the function of the presynaptic neuron

Answer 27

the neuron that releases neurochemicals into the neural synapse

Question 28

explain the function of the axon terminals

Answer 28

also known as terminal buttons, are the ends of a neuron that release neurochemicals into the neural synapse

Question 29

explain the function of the synaptic gap

Answer 29

the space between the presynaptic neuron and the postsynaptic neuron. In this way, despite being very close, neurons do not touch eachother

Question 30

explain the function of the postsynaptic neuron

Answer 30

the neuron that recieves neurochemicals from the neural synapse

Question 31

explain the function of the dendrites

Answer 31

branched extensions of a neuron on which receptor sites are located

Question 32

explain the function of receptor sites

Answer 32

are protein molecules on the dendrites of a neuron that recieve neurochemicals

Question 33

define neurochemicals

Answer 33

the chemical substance that transmits neural information within the nervous system by allowing for the communication between neurons

Question 34

define neurotransmitters

Answer 34

a subset of neurochemicals, a chemical substance produced and released by neurons to transmit signals across a synapse to another neuron, muscle cell, or gland cell.

Question 35

define neurotransmission

Answer 35

the process of communication between neurons using electrochemical energy

Question 36

recall the six steps of neurotransmission

Answer 36

1. A neural impulse (electrical energy) runs from the dendrite down the axon to the axon terminals.
2. neurochemicals are produced in the axon terminals of the presynaptic neuron.
3. neurochemicals are released from the axon terminals of the presynaptic neuron into the synaptic gap (released as chemical energy).
4. this chemical substance, known as a neurotransmitter, crosses the synapse.
5. neurochemicals bind to receptor sites on the dendrites of the postsynaptic neuron.
6. neurochemicals affect the postsynaptic neuron, either triggering or inhibiting a response (excitatory or inhibatory response)

Question 37

excitatory neurotransmitter definition

Answer 37

increasing the likelihood that the postsynaptic neuron will fire an action potential

Question 38

inhibitory neurotransmitter definition

Answer 38

decreasing the likelihood that the postsynaptic neuron will fire an action potential

Question 39

define glutamate

Answer 39

an excitatory neurotransmitter that increases the likelihood of the postsynaptic neuron firing an action potential.

Question 40

describe the roles of glutamate

Answer 40

glutamate has an important role in memory and learning. Specifically, the excitatory effects of glutamate form and strengthen synaptic connections between neurons as they are repeatedly activated during learning. These strong synaptic connections represent memories of what has been learnt. In this way, Glutamate enables synaptic plasticity. Also has an important role in though and movement.

Question 41

define GABA

Answer 41

gamma-amino butyric acid is an inhibitory neurotransmitter that decreases the likelihood of the postsynaptic neuron firing an action potential.

Question 42

describes the roles of GABA

Answer 42

GABA has an important role in regulating postsynaptic activation in neural pathways, preventing the overexcitement of neurons. In this way, GABA reduces anxiety by inhibiting excitatory neural signals that contribute to anxiety. Furthermore, by inhibiting the uncontrolled firing of action potentials, GABA has an important role in preventing seizures.

Question 43

describe the process of communication inside neurons via electrical energy

Answer 43

a neuron has a resting potential when not activated. Negatively charged ions are inside the axon, and positively charged ions are outside the neuron. An electrical impulse called action potential (or neural impulse) is initiated by the soma and travels along the axon towards the axon terminals. This turns the negatively charged internal ions to positive, and positively charged external ones to negative.

Question 44

describe the process of communication between neurons via chemical energy

Answer 44

neurotransmitters are stored in synaptic vesicles. When stimulated, the pre-synaptic neuron releases neurotransmitters across the synapse. The receptor site of the post-synaptic neuron receives the neurotransmitter.

Question 45

define neuromodulators

Answer 45

a subclass of neurotransmitters that alter the strength of neural transmission, by increasing or decreasing the responsiveness of neurons to neurotransmitter signals. Have widespread modulatory effects as the can influence large areas of the brain tissue via effecting multiple postsynaptic neurons.

Question 46

define dopamine

Answer 46

a multifunctional neurotransmitter and neuromodulator that has both inhibitory and excitatory effects that are involved in many central nervous system functions such as movement, pleasure, attention, cognition and motivation.

Question 47

define serotonin

Answer 47

an inhibitory neurotransmitter and neuromodulator that is involved in mood stabilisation, the sleep-wake cycle, appetite, digestion, and arousal.

Question 48

recall and explain the three roles of functioning of dopamine

Answer 48

• coordinates voluntary movement by transmitting neural information that enables smooth, coordinated muscle movements.
• dopamine is produced when rewarded for performing a behaviour in the ventral tegmental which is associated with experiences of pleasure.
• role in motivation given its role in reward based learning. Rewarding behaviours trigger the release of dopamine and have a pleasurable consequence and therefore are more likely to be repeated - thus motivating the person to engage in rewarding behaviours to experience pleasure once again.

Question 49

recall and explain the three roles of functioning of serotonin

Answer 49

• important role in mood regulation and stabilisation. Appropriate levels of serotonin in the brain enable a person to experience positive and stable moods, promoting wellbeing. Low levels of serotonin in the brain are associated with mental health disorders.
• regulates the sleep-wake cycle, influencing the quality and quantity of sleep at night, as well as feelings of alertness and wakefulness during the day.
• various roles depending on the receptor types it binds to and the brain area it acts upon including appetite, digestion and arousal.

Question 50

the reward system definition

Answer 50

a group of structures in the brain that are activated by rewarding or reinforcing stimuli

Question 51

define the serotonin pathway

Answer 51

serotonins neuromodulatory system which originates in the brain stem and extends to almost all areas of the cerebrum including the cerebral cortex.

Question 52

define synaptic plasticity

Answer 52

the ability of synaptic connections to physically change overtime through formation, strengthening, or weakening in response to activity or experience as the fundamental mechanism for memory formation that leads to learning.

Question 53

relate synaptic plasticity to memory

Answer 53

• changes to synaptic connections in the brain establish neural pathways that incorporate these memories and represent what has been learnt.
• these neural pathways that form during learning are referred to as memory traces, with each memory trace representing a different memory.

Question 54

define long-term potentiation

Answer 54

the long lasting and experience dependant strengthening of synaptic connections that are regularly activated at high intensity stimulation - making postsynaptic neurons more receptive to neural signals from presynaptic neurons and consequently more readily activated

Question 55

recall the changes as a result of increased release of neurotransmitters in long term potentiation

Answer 55

• increased number of receptor sites on the dendrites of the postsynaptic neuron
• bushier dendrites on the postsynaptic neuron due to sprouting
• increased number of synaptic connection between neurons due to sprouting

Question 56

define long-term depression

Answer 56

the long-lasting and experience dependant weakening of synaptic connections between neurons that are not regularly activated via the infrequent release of neurotransmitters - making the postsynaptic neuron less receptive to neural signals from the presynaptic neuron and consequently less readily activated.

Question 57

recall the structural changes that occur to the neural synapse through the decreased release of neurotransmitters via long-term depression

Answer 57

• decreased number of receptor sites on the dendrites of the postsynaptic neuron
• decreased number of dendrites on the postsynaptic neuron due to pruning
• decreased number of synaptic connections between neurons to pruning

Question 58

recall the three mechanisms of synaptic plasticity

Answer 58

1. Sprouting
2. Pruning
3. Rerouting

Question 59

define sprouting

Answer 59

the ability of dendrites or axons to develop new extensions or branches. This increases the reach of the neuron and enables the formation of new synaptic connections.

Question 60

define pruning

Answer 60

the elimination of synaptic connections that are not adequately activated. When neural synapses are not used, they are removed or ‘pruned’. This is necessary to accommodate stronger and more essential synaptic connections, consequently enhancing the efficiency of brain functioning.

Question 61

define rerouting

Answer 61

the ability of the neuron that is connected to a damaged neuron to create an alternative synaptic connection with an undamaged neuron. The neuron abandons its synaptic connection with an undamaged neuron. The synaptic connection is reestablished via an alternative route, restoring brain functioning.