Chapter 3 Burton: Neurons and the Brain

Question 1

Sensory Neurons

Answer 1

Carry sensory information from sensory receptors to the central nervous system.

Question 2

Motor Neurons

Answer 2

Transmit commands from the brain to the glands and muscles of the body.

Question 3

Interneurons

Answer 3

Connect neurons with one another

Question 4

Neurons

Answer 4

Generally have a cell body, dendrites (branch like extensions of the cell body) and an axon that carries information to other neurons

Question 5

Resting potential (Neuron)

Answer 5

When a neuron is at rest, it is polarised , with a negative charge inside the cell membrane and a positive charge outside

Question 6

Graded potentials

Answer 6

The spreading voltage changes along the cell membrane that occur as the neuron is excited by other neurons

Question 7

Action potential

Answer 7

Firing of the neuron or a nerve impulse

Question 8

Neurotransmitters

Answer 8

Transmit information from one neuron to another as they are released into the synapse. They bind with receptors in the membrane of the postsynaptic neuron, which produces graded potentials that can either excite or inhibit the postsynaptic neuron from firing.

Question 9

The endocrine system

Answer 9

A collection of glands that control various bodily functions through the secretion of hormones. Sends global messages through the bloodstream. Includes: Pituitary, thyroid, adrenals, pancreas, ovaries, testes.

Question 10

The peripheral nervous system

Answer 10

Neurons carry messages to and from the cns. Two subdivisions somatic and autonomic.

Question 11

PNS: Somatic nervous system

Answer 11

Carries sensory information to the brain and motor neurons that direct the action of skeletal muscles

Question 12

PNS: Autonomic nervous system

Answer 12

Controls basic life processes such as heartbeat, digestion and breathing. Consists of two parts, sympathetic and parasympathetic.

Question 13

PNS: Autonomic nervous system: Sympathetic

Answer 13

Activated in response to threats

Question 14

PNS: Autonomic nervous system: Parasympathetic

Answer 14

Involved in routine activities.

Question 15

Central nervous system

Answer 15

Consists of brain and the spinal cord

Question 16

CNS Spinal Cord

Answer 16

Carries out reflexes, transmits sensory info to brain and transits messages from brain to muscles and organs

Question 17

Sensory Neurons

Answer 17

Transmit information from sensory cells in the body called receptors (cells that receive sensory information) to the brain (either directly or by the way of the spinal cord). Thus sensory neurons might send information to the brain about the sensations perceived as a sunset or a sore throat.

Question 18

Interneurons

Answer 18

The output is received by interneurons, nerve cells that connect other neurons with one another. The vast majority of neurons in the brain and spinal cord are interneurons.

Question 19

Motorneurons

Answer 19

Transmit commands from interneurons to the glands and muscles of the body, most often through the spinal cord. Motor neurons carry out both voluntary actions, such as grabbing a glass of water, and vital bodily functions, such as digestion and heartbeat.

Question 20

Dendrites

Answer 20

Branch like extensions of the neuron receive inputs from other cells

Question 21

Cell body (neuron)

Answer 21

Includes a nucleus that contains the genetic material of the cell (the chromosomes).

Question 22

Nucleus

Answer 22

With its genetic blueprints, is the ‘brains’ of the operation, which determines how that particular neuron will manipulate the input from the dendrites.

Question 23

Axon

Answer 23

If a neuron recieves enough stimulation through its dendrites and cell body, it passes the manipulated input to the dendrites of the other neurons through its axon. Axon is a long extension from the cell body- sometimes as long as one metre- whose central function is to transmit information to other neurons. Axons often have two or more offshoots, or collateral branches

Question 24

Myelin Sheath

Answer 24

A tight coat of cells composed primarily of lipids (fats) that facilitates transmission of information to other neurons. Myelinated axons give some portions of the brain a white appearance (hence term ‘white matter’). The grey matter of the brain gets its colour from cell bodies, dendrites and unmyelinated axons.

• Insulates axon from chemical and physical stimuli that might interfere with transmission of nerve impulses
• Dramatically increases the speed of transmission of messages

Question 25

Terminal Buttons

Answer 25

At the end of the axon, they send signals from a neuron to adjacent cells. These signals are triggered by the electrical impulse that has travelled down the axon and then typically received by the dendrites or cell bodies of other neurons.

Question 26

Synapses.

Answer 26

Connections between neurons occur at synapses. Two cells do not actually touch at a synapse; instead, a space exists between the two neurons, called the synaptic cleft.
-Not all synapses work the same–> in the brain many located on parts of the cell other than the dendrite . Elsewhere in the nervous system, neurons may send their signals to glands or other muscles rather than to other neurons

Question 27

Firing of a neuron

Answer 27

Most neurons communicate at the synapse through a process that involves the conversion of the electrical charge in one neuron to a chemical ‘message’. When message is released into the synapse, it alters the electrical charge of the next neuron.

Question 28

Resting potential

Answer 28

When a neuron is at rest, its membrane is polarised, like two sides of a battery. Inside the membrane has a negative electrical charge, whereas the fluid outside the cell has a positive charge.

Question 29

The Soma

Answer 29

Contains mechanisms that control the metabolism and maintenance of the cell. It also collates ‘messages’ from other neurons

Question 30

Resting Potential (Chemicals)

Answer 30

It is the result of relative concentrations of potassium ions (K+), chloride ions (Cl-), negatively charged protein ions, and sodium ions (Na+).
The RMP is approximately equal to -70mV (-50 mV to -80mV).

Question 31

Action Potential

Answer 31

An action potential is a brief reversal in the resting charge of the neuron. It is triggered by an exchange of ions across the neuron membrane.
The action potential is created when the neuron membrane is sufficiently depolarised (i.e. the resting potential moves towards 0 mV). When the depolarisation reaches the threshold of about -55 mV, the neuron will fire an action potential. If the neuron does not reach this critical threshold level, then no action potential will fire.
The shift in polarity across membrane and subsequent restoration of the resting potential is called an action potential.

Question 32

Graded potentials

Answer 32

When a neuron is stimulated one of two things can happen. Stimulation can reduce the membrane’s polarisation, decreasing the voltage discrepancy between the inside and outside. E.g. resting potential may move from -70 to -60mv. This excites the neuron (renders it more likely to fire with further stimulation. Alternatively, stimulation from another neuron can increase polarisation. This inhibits the neuron (renders it less likely to fire).

Question 33

Transmission of information between cells

Answer 33

When nerve impulse travels down axon, sets in motion series of events that can lead to transmission of information to other cells.

Question 34

Synaptic Transmission

Answer 34

Neurons do not touch one another; they are separated by a small space known as the synaptic cleft (or synaptic gap… or synapse).
When an action potential reaches the terminal buttons it causes the release of specialised chemicals (neurotransmitters) that travel across the synaptic cleft and are received by the dendrites of other neurons.

Question 35

The release of neurotransmitters from a terminal button (Stage 1)

Answer 35

Before the action potential has arrived, the neurotransmitters are stored in vesicles within the terminal button

Question 36

The release of neurotransmitters from a terminal button (Stage 2)

Answer 36

The action potential triggers the release of the neurotransmitter into the synaptic cleft

Question 37

The release of neurotransmitters from a terminal button (Stage 3)

Answer 37

The neurotransmitters diffuse across the synaptic cleft. Some of them will attach to receptor molecules in the postsynaptic membrane and activate them, thus either inhibiting or enabling the postsynaptic neuron to generate an action potential.

Question 38

Presynaptic neuron

Answer 38

The neuron that is sending an impulse

Question 39

Postsynaptic neuron

Answer 39

The cell receiving the impulse

Question 40

Glutamate

Answer 40

(Glutamic acid) is a neurotransmitter that can excite nearly every neuron in the nervous system. Although glutamate is involved in many psychological processes, it appears to play a particularly important role in learning.

Question 41

GABA (Gamma-amniobutyric acid)

Answer 41

Opposite effect to glutamate. Neurotransmitter that plays an inhibitory role. Glycine another inhibitory neurotransmitter in the lower brain + spinal cord. One-third of all neurons in the brain use GABA for synaptic communication. Particularly important in regulating anxiety.

Question 42

Dopamine

Answer 42

Neurotransmitter that has wide-ranging effects in the nervous system. involving thought, feeling, motivation and behaviour. Some neural pathways that rely on dopamine are involved in emotional arousal, the experience of pleasure and learning to associate particular behaviours with reward. Abnormally high levels of dopamine in some parts of the brain have been linked to schizophrenia. Degeneration causes parkinsons.

Question 43

Serotonin

Answer 43

Neurotransmitter involved in regulation of mood, sleep, eating, arousal and panic. Decreased serotonin in brain common in severe depression. Antidepressants such as fluxoetine work by boosting serotonin levels. Serotonin usually plays inhibitory role, affecting neural circuits involved in aggression, antisocial behaviour and other forms of social behaviour.

Question 44

Acetylcholine

Answer 44

Neurotransmitter involved in learning and memory. Link to learning and memory through experiment that patients with alzheimer’s which destroys memory, show depleted ACh.

Question 45

Endorphins

Answer 45

Chemicals that elevate mood and reduce pain. They have range of effects, from the numbness people often feel immediately after tearing a muscle to the runners high some athletes sometimes report after a prolonged period of exercise. Essentially narcotics ‘pick the locks’ normally opened by endorphins.

Question 46

The endocrine system

Answer 46

Is a collection of glands that control various bodily functions through the secretion of hormones. The endocrine system complements the cell-to-cell communication of the nervous system by sending global messages through the bloodstream and can thus activate many cells simultaneously.

Question 47

The peripheral nervous system

Answer 47

Although endocrine system plays important role in psychological functioning, the centre of our psychological experience is the nervous system. The nervous system has two major divisions: the central nervous system and the peripheral nervous system.

Question 48

The central nervous system (CNS)

Answer 48

Consists of the brain and spinal cord.

Question 49

The peripheral nervous system (PNS)

Answer 49

The peripheral nervous system consists of neurons that convey messages to and from the central nervous system.

Question 50

(2 subdivisions of PNS) The somatic nervous system

Answer 50

Transmits sensory information to the central nervous system and carries out its motor commands. Sensory neurons receive information through receptors in the eyes, ears, tongue, skin, muscles and other parts of the body. Motor neurons direct action of skeletal muscles.
-SNS involved in shaking someones hand, standing up. Some involuntary or automatic reactions (adjustments in posture and balance)
VOLOUNTERY

Question 51

(2 subdivisions of PNS) The autonomic nervous system

Answer 51

Conveys information to and from internal bodily structures that carry out basic life processes such as digestion and respiration, beating of heart and responses to stress. Consists of two parts sympathetic and parasympathetic.

Question 52

Autonomic nervous system: Sympathetic nervous system

Answer 52

Typically activated in response to threats. Its job is to ready the body for fight or flight, does in several ways. It stops digestion, diverting blood away from the stomach and redirecting it to the muscles, which may need extra oxygen for an emergency response. It increases heart rate, dilates pupils, and causes hairs on body and head to stand erect. Also involved in other states of intense activation: ejaculation in males.
‘emergency system’

Question 53

Autonomic nervous system: Parasympathetic nervous system

Answer 53

Calms the body down; maintains energy
‘business as usual system’. Supports more mundane, or routine activities that maintain the body’s store of energy, such as regulating blood-sugar levels, secreting saliva and eliminate wastes. It also participates in functions such as regulating heart rate and pupil size.