Neuroscience Fundamentals – Intro to the Brain

A comprehensive set of question-and-answer flashcards covering Module 1 introductory material on brain structure, cells, cerebrospinal fluid, the blood-brain barrier, action potentials, myelination, and synaptic transmission.

Where is grey matter located in the brain versus the spinal cord?

In the brain grey matter is on the outside (cortex); in the spinal cord it is on the inside.

What does white matter consist of?

Bundles of axons.

What structures make up grey matter?

Neuronal cell bodies (somas) and dendrites.

What is the major white-matter tract that connects the two cerebral hemispheres?

The corpus callosum.

Why does the cerebral cortex have gyri and sulci?

Folding (gyri and sulci) maximises cortical surface area within the limited skull volume.

Define sulci and gyri.

Sulci are the grooves/folds; gyri are the raised ridges between the sulci.

What is the primary function of the spinal cord?

It is the main pathway for ascending sensory and descending motor information.

Which cerebral hemisphere processes sensory inputs from the right side of the body?

The left cerebral hemisphere (crossed organisation).

Name the two major divisions of the nervous system.

Central nervous system (CNS) and Peripheral nervous system (PNS).

Which division carries information from the periphery to the CNS?

The afferent (sensory) division.

Which efferent subdivision of the PNS controls skeletal muscle?

The somatic nervous system.

What are the two branches of the autonomic nervous system?

Sympathetic and parasympathetic nervous systems.

Which three structures form the brainstem?

Midbrain, pons, and medulla oblongata.

List the four lobes of the cerebral cortex.

Frontal, parietal, temporal, and occipital lobes.

Which cortical area is responsible for voluntary movement?

The primary motor cortex.

Which cortical area is critical for speech formation?

Broca’s area.

Where is Wernicke’s area and what is its role?

Located at the parieto-temporal junction; responsible for speech understanding.

Which cortical region integrates somatosensory and visual input for complex movements?

Posterior parietal cortex.

What is the first principle of the neuronal doctrine?

The neuron is the structural and functional unit of the nervous system.

Who invented the “black reaction” staining technique for neurons?

Camillo Golgi.

Which scientist proved neurons are separate cells using Golgi’s stain?

Santiago Ramón y Cajal.

According to the neuronal doctrine, what are the three parts of a neuron?

Dendrites, soma (cell body), and axon.

In what direction does information flow within a neuron?

From dendrites → soma → axon terminals.

Name the four morphological types of neurons.

Unipolar, bipolar, multipolar, and pseudounipolar neurons.

What are the three functional classes of neurons?

Sensory, integrative (interneurons), and motor neurons.

Approximately how many glial cells are there relative to neurons?

Roughly 10 glial cells for every neuron (10 : 1).

Give four key functions of glial cells.

Produce/regulate CSF, maintain homeostasis (e.g., neurotransmitter uptake), form part of the blood-brain barrier, supply energy, provide immune defence, sculpt synapses, and form myelin.

Which glial cells form myelin in the CNS and PNS?

Oligodendrocytes (CNS) and Schwann cells (PNS).

What does CSF stand for and what is its steady-state volume?

Cerebrospinal fluid; about 150 mL is present at any given time.

Roughly how much CSF is produced each day?

About 500 mL per day.

List three roles of cerebrospinal fluid (CSF).

Supports the brain (buoyancy), supplies nutrients and removes waste, and enables chemical signalling.

What forms the blood-brain barrier (BBB)?

Tight junctions in brain capillary endothelial cells reinforced by astrocytes.

What is the primary purpose of the BBB?

To protect the brain from toxins and maintain a controlled chemical environment.

How long can cortical blood flow be interrupted before permanent damage occurs?

Several minutes (unconsciousness occurs after ~10 s).

Define an action potential.

An all-or-nothing depolarisation of the neuronal membrane triggered when membrane potential crosses threshold.

Which ion influx produces the depolarisation phase of an action potential?

Inward Na⁺ current through fast voltage-gated Na⁺ channels.

Which ion efflux causes repolarisation?

Outward K⁺ current via slow voltage-gated K⁺ channels.

At resting potential the membrane is most permeable to which ion?

Potassium (K⁺).

Which two electrical resistances influence passive spread of depolarisation along an axon?

Internal (axial) resistance (Rᵢ) and membrane resistance (Rₘ).

How does myelination increase conduction velocity?

By insulating the axon and restricting ion channels to nodes, enabling rapid saltatory conduction with lower metabolic cost.

What is saltatory conduction?

The action potential ‘jumps’ from one node of Ranvier to the next along a myelinated axon.

What is a synapse?

A specialised contact point where one neuron communicates with another, usually via chemical neurotransmitter release.

Give three key properties of chemical synapses.

Unidirectional, selective for specific target cells, and modifiable (strength can increase or decrease); signals can be excitatory or inhibitory.

What triggers neurotransmitter release at the presynaptic terminal?

Ca²⁺ influx through voltage-gated Ca²⁺ channels after an action potential arrives.

Name three ways neurotransmitter is cleared from the synaptic cleft.

Enzymatic breakdown, reuptake into presynaptic or glial cells, or diffusion away.

What determines whether a synapse is excitatory or inhibitory?

The combination of neurotransmitter released and the receptor/ion channel it activates, thus the resulting change in membrane potential.

Which ion movement typically produces an excitatory postsynaptic potential (EPSP)?

Opening of Na⁺ (cation) channels causing depolarisation (e.g., AMPA receptors).

Which ion movements can generate an inhibitory postsynaptic potential (IPSP)?

Opening of Cl⁻ channels (e.g., GABAᴀ) or K⁺ channels (e.g., GABAʙ) causing hyperpolarisation.

Which neurotransmitter is most common at modifiable (plastic) synapses?

Glutamate.

Why are modifiable synapses important?

Their ability to strengthen or weaken provides the cellular basis for learning and memory.