psyc 11 mideterm 2

What are neurons?

Neurons are nervous-system cells that communicate to perform information-processing tasks; they receive and send electrochemical messages.

What are the three basic parts of a neuron?

Cell body (soma), dendrites, and axon.

What does the cell body (soma) do?

It coordinates information-processing tasks and keeps the neuron alive; protein synthesis, energy production, and metabolism occur there.

Which part of a neuron receives information from other neurons and relays it toward the cell body?

Dendrites.

What does an axon do?

It carries information away from the cell body to other neurons, muscles, or glands.

What is the myelin sheath?

An insulating layer of fatty material formed by glial cells that covers segments of many axons and speeds signal transmission.

What are glial cells?

Nervous-system support cells that provide physical and nutritional support, digest parts of dead neurons, and form myelin.

Which structure deteriorates in multiple sclerosis, slowing communication between neurons?

The myelin sheath

What is a synapse?

The junction or region between one neuron's axon and another neuron's dendrites or cell body; it includes the small gap across which signals pass.

What are the three major functional types of neurons?

Sensory neurons, motor neurons, and interneurons.

What do sensory neurons do?

They receive information from the external world and convey it to the brain via the spinal cord.

What do motor neurons do?

They carry signals from the spinal cord to muscles to produce movement.

What do interneurons do?

They connect sensory neurons, motor neurons, and/or other interneurons.

What are bipolar cells, and what do they do in the retina?

Bipolar cells are retinal neurons with one axon and one dendrite. They receive signals from rods and cones and pass them to retinal ganglion cells.

What are pyramidal cells?

Cerebral-cortex neurons with a triangular cell body and one long dendrite among many smaller dendrites.

Where are mirror neurons found, according to the notes?

In the frontal and parietal lobes of various animals.

What activates mirror neurons?

Performing a behaviour, such as grasping, and observing another individual perform the same behaviour.

Why are mirror neurons considered important?

They may help explain the brain's role in complex social behaviour and understanding others' actions.

What implications for social interaction did the notes associate with mirror neurons?

They suggest a possible inborn neural basis for empathy and may facilitate smooth social interaction.

What relationship between mirror-neuron function and ASD is mentioned in the notes?

Autism spectrum disorder (ASD) is associated with differential mirror-neuron function.

What are the two stages of neuronal communication?

Conduction and transmission

What is conduction?

The movement of an electrical signal within a neuron, from dendrites to cell body and along the axon.

What is synaptic transmission, and what is its basic sequence?

Synaptic transmission is chemical communication between neurons across a synapse.

What is resting potential?

The electrical difference across a neuron's membrane at rest

Potassium ions (K+) and negatively charged protein ions.

Which ions are more abundant inside a resting neuron?

Which ions are more abundant outside a resting neuron?

Positively charged sodium ions (Na+).

What is an action potential?

An electrical signal conducted along the length of a neuron's axon toward the synapse.

What triggers an action potential?

Depolarizing input brings the membrane charge to its threshold.

What does all-or-none mean for an action potential?

Below threshold, no action potential occurs; at or above threshold, an action potential occurs at full strength.

What happens to sodium channels when threshold is reached?

Voltage-gated sodium channels open, allowing positively charged Na+ ions to rush into the axon.

What happens to the neuron's internal charge as sodium enters during an action potential?

The inside becomes more positive relative to the outside.

What happens after an action potential reaches its peak?

Sodium channels inactivate and potassium channels open; K+ leaves the neuron, bringing the membrane back toward its negative resting level.

What is the refractory period?

The period after an action potential during which another action potential cannot be initiated.

How is the ion imbalance after an action potential reversed?

An active chemical pump moves sodium out of the axon and potassium back inside.

How does an action potential travel down an axon?

It spreads a short distance and triggers a new action potential in the nearby membrane

How does myelin help an action potential travel?

It insulates axon segments, allowing the electrical signal to travel more rapidly between exposed gaps.

What are the nodes of Ranvier?

The gaps between individual myelin-covered segments along an axon.

What is saltatory conduction?

Rapid conduction in a myelinated axon in which the signal appears to jump from one node of Ranvier to the next.

What are terminal buttons and vesicles?

Terminal buttons are knoblike structures at the end of an axon. They contain vesicles—small sacs that store neurotransmitters for release into the synapse.

neurotransmitters

Chemicals released by a sending neuron that transmit information across the synapse to a receiving neuron.

What are receptors on the postsynaptic neuron?

Parts of the receiving cell's membrane that bind neurotransmitters and can initiate or prevent a new electrical signal.

What is the presynaptic neuron?

The sending neuron that releases neurotransmitters into the synapse.

What is the postsynaptic neuron?

The receiving neuron whose receptors bind neurotransmitters.

How do neurotransmitters and receptors interact?

They operate like a lock-and-key system

What are autoreceptors?

Receptors that detect how much neurotransmitter has been released and can signal the sending neuron to stop releasing more.

What is reuptake?

Reabsorption of neurotransmitters by the presynaptic terminal buttons or nearby glial cells.

enzyme deactivation?

The breakdown of neurotransmitters by specific enzymes in the synapse.

Reuptake (reabsorption by the presynaptic terminal), enzyme deactivation (chemical breakdown), and diffusion (drifting away from the synapse).

What are the three ways neurotransmitters are cleared from the synapse?

What is acetylcholine (ACh) involved in?

Voluntary motor control, attention, learning, and memory.

What relationship between acetylcholine and Alzheimer's disease is in the notes?

Alzheimer's disease is associated with deterioration or low levels of ACh-producing neurons.

Which conditions are dopamine implicated in,?

Addiction, schizophrenia, and Parkinson's disease.

What is glutamate?

A major excitatory neurotransmitter involved in information transmission throughout the brain.

What is GABA?

Gamma-aminobutyric acid; the major inhibitory neurotransmitter in the brain.

What is norepinephrine (NE) involved in?

Mood, arousal, vigilance, and heightened awareness of danger; it also contributes to the body's fight-or-flight response.

What are beta blockers, and how can they reduce stage-fright symptoms?

Drugs that block beta-adrenergic receptors, reducing effects of norepinephrine and adrenaline such as a rapid heartbeat.

What is serotonin (5-HT) involved in?

Regulation of sleep and wakefulness, eating, and aggressive behaviour.

What are endorphins?

Chemicals that act in the brain's pain pathways and emotion centres.

What is the runner's high associated with?

A large release of endorphins.

What are agonists?

Drugs that increase or mimic the action of a neurotransmitter.

What are antagonists?

Drugs that block or diminish the function of a neurotransmitter.

What is L-Dopa(mine) used to treat?

Parkinson's disease.

How can the postsynaptic membrane adapt to chronically high dopamine?

It may manufacture new receptors.

How do opioids act on the neurotransmitter system, according to the notes?

They act in part as agonists for endorphins, producing powerful calm and euphoria.

What does naloxone do?

It acts as an opioid-receptor antagonist, blocking agonists

How does Prozac (fluoxetine) affect serotonin signalling?

It is an SSRI that blocks serotonin reuptake, increasing serotonin availability in the synapse.

What are the two major divisions of the nervous system?

The central nervous system (CNS) and peripheral nervous system (PNS).

Which structures make up the central nervous system (CNS)?

The brain and spinal cord.

The PNS carries information between the CNS and the rest of the body. somatic nervous and autonomic nervous system.

What is the peripheral nervous system (PNS), and what are its two divisions?

What does the somatic nervous system do?

It conveys information between the CNS and skeletal muscles and controls voluntary muscle movement.

The autonomic nervous system controls involuntary functions of organs, blood vessels, and glands. Its divisions are sympathetic (fight-or-flight) and parasympathetic (rest-and-digest).

What is the autonomic nervous system, and what are its two divisions?

What does the sympathetic nervous system do?

It triggers fight-or-flight: heart rate and pupil size increase, while digestion, salivation, and bowel activity decrease.

What does the parasympathetic nervous system do?

It helps the body return to its normal resting state; it is associated with rest and relaxation.

What are spinal reflexes?

Simple nervous-system pathways that rapidly generate muscle contractions, sometimes without input from the brain.

What is a reflex arc?

A neural pathway that controls a reflex; the patellar (knee-jerk) reflex is a familiar example.

Why can a person pull a hand away from a hot stove before consciously feeling pain?

A spinal reflex arc carries sensory input through the spinal cord to motor neurons, starting withdrawal before conscious pain perception.

What happens when the spinal cord is damaged?

Communication between the brain and sensory or motor neurons can be severed; damage higher in the cord generally causes greater impairment.

What are the three main sections of the brain?

Hindbrain, midbrain, and forebrain.

What is the general role of the hindbrain?

It coordinates information coming into and out of the spinal cord and supports basic life functions, alertness, and motor skills.

What does the medulla do?

It extends from the spinal cord into the skull and coordinates heart rate, circulation, and respiration.

What does the reticular formation do?

It helps regulate wakefulness, arousal, and sleep; reduced activity in arousal systems contributes to loss of consciousness under anaesthesia.

What does the pons do?

It relays information from the cerebellum to the rest of the brain.

the cerebellum

It coordinates fine motor skills and movement coordination.

What is the general role of the midbrain?

It helps orient an organism to its environment and supports movement and arousal.

What does the tectum do?

It orients an organism in the environment by receiving stimuli from the eyes, ears, and skin and coordinating movement toward stimuli.

What does the tegmentum do?

It is involved in movement and arousal.

What difficulties may result from tegmentum damage, according to the notes?

Difficulty with movement and staying alert.

What is the general role of the forebrain?

It coordinates higher-level cognitive, emotional, sensory, and motor functions.

What are the two components of the forebrains?

The cerebral cortex and subcortical structures.

Which three structures are identified in the notes as core parts of the limbic system?

The hypothalamus, hippocampus, and amygdala; these subcortical structures contribute to motivation and emotion.

What does the thalamus do?

It relays and filters sensory information and transmits it to the cerebral cortex.

Which major sense does not send its information through the thalamus first, according to the notes?

Smell.

How does the thalamus filter information?

It gives more weight to some inputs and less to others.

What is thalamic syndrome?

A condition associated in the notes with severe pain and extreme sensitivity to touch.

What does the hypothalamus regulate?

Body temperature, thirst, hunger, and sexual behaviour.

How can thoughts about sex lead to hormonal responses, according to the notes?

Messages from the cerebral cortex are sent to the hypothalamus, which triggers hormone release.

What can electrical stimulation of different hypothalamic areas produce?

Aggressive behaviour or intense pleasure.

What does the hippocampus do?

memory

What memory difficulty can follow hippocampal damage?

A person may acquire new information but retain it in awareness for only a few seconds.

What kinds of memory are especially associated with the hippocampus in the notes?

Memory for facts and events; motor skills may still be learned even when the person does not remember the learning events.

What does the amygdala do?

It plays a central role in emotional processes, especially forming emotional memories.