Oral Questions

Possible Questions

Motor output can be: somatic or autonomic. Somatic motor is about voluntary movements (i.e. skeletal muscles), while autonomic motor is about involuntary actions (for example: glands, cardiac or breathing).

The composition of the nervous system. The NS is composed by glial cells (90%) and neurons (10%). It's formed by brain and spinal cord (CNS) and nerves (PNS). We have 86 billion of neuron (80% in the cerebellum, 19% in the cerebral cortex and less than 1% in the rest of the brain).

Glial cells. Glial cells play different roles: structural, nutritional and preventive. There are 6 types of glial cells, 4 in the CNS and 2 in the PNS. In the CNS there are astrocytes, oligodendrocytes, ependymal and microglia. In the PNS there are Schwann cells and satellites. Astrocytes prevent the entering of undesirable substances via blood vessels, that they constrain. Furthermore, they help oligodendrocytes to perform better and are also important for the nutrition and structure of the NS.

Oligodendrocytes make myelin sheets around the axon (in CNS, while Schwann cells play the same role in PNS). Ependymal cells regulate the exchange of several substances between the cerebrospinal fluid and the cerebral cortex, so they are important for structure of the NS. Microglia are phagocytes, so they engulf bacteria to defend the NS. The last one, satellites (PNS), support cell bodies (structural function).

5. Structure of neurons. Neurons are formed by a soma, one or more dendrites and an axon. The soma contains the nucleus of the cell and keeps the cell alive. The dendrites are tree-like fibers that collect info and send it to the soma. The axon transmits the info to the axon terminal, so to the subsequent cell neurons, muscles or glands.

6. Structural classification of neurons. Neurons are characterized by the number of processes (dendrites and axons) extending from the soma. They can be unipolar, bipolar or multipolar. Unipolar neurons have a single process which divides into two.

branches: one to the CNS and the other one to the PNS; they generally are sensory neurons. Bipolar neurons have two processes: a dendrite and an axon; they generally are sensory neurons and can be found in sensory areas (ears, eyes or nose). Multipolar neurons have an axon and many dendrites; the 99% of them are in the CNS and the mostly part of them are motor neurons.

7. Functional classification of neurons. Neurons can play three main roles: sensory, motor or can be interneurons. Sensory neurons collect info from internal (soft organs) or external environment, then they send info to CNS. Motor neurons transmit messages away from CNS to effector organs, employing peripheral neurons. Interneurons are in the CNS, they are generally multipolar and transmit info from one part of CNS to another one, so they process, store and receive info and make decisions in response.

8. Directional classification. Neurons can be afferent (mainly sensory neurons) or efferent (mainly motor neurons). Afferent neurons

transmit info from PNS to CNS, efferent from CNS toPNS. Sensory Afferent Uni/Bipolar Somatic, special, visceral DorsalMotor Efferent Multipolar Somatic, autonomic Ventral9. Resting membrane potential. Since neuron is a living cell, it has a plasma membraneimpermeable to ions, but in the membrane the are Sodium (Na) and Potassium (K) channels.The resting membrane potential is between -60 and -70 mV and it’s reached when electricalgradient (ions charge) is balanced by diffusion gradient (Fick’s law). In these particularconditions Sodium channels are closed and there’s no net movement of K ions.

10. Action potential. It represents an injection of energy capable to open Sodium channels. Aninjection of current pushes the membrane voltage toward more positive (depolarization) ornegative (hyperpolarization) voltages, in a proportionality way. If the membrane potentialreaches the threshold (around -40 mV), the action potential is generated. Action potential is anall-or-none event,

That means if different stimuli can generate it, the amplitude of the action potential is not proportional to the stimulus, but it's always the same. The action potential can be divided into 6 phases: resting (-60 mV, K channels opened); rising (-60 mV ÷ -40 mV, Na channels are opening); overshoot (positive membrane voltage, Na channels start to close); falling (membrane potential returns to resting value); undershoot (voltage is less than resting voltage because some K channels are still opened); recovery (-60 mV, delayed closing of K channels). Action potential time is 1 millisecond.

11. Conduction of action potential. Action potential is conducted along the axon, where two different blocks alternate themselves: myelin sheets and nodes of Ranvier. Node of Ranvier has Sodium and Potassium channels, so in this segment there's a continuous generation of action potentials (thanks to all-or-none principle) that's a sort of exchange of information that requires a certain time.

Along the myelin sheets segment, instead, there’s no exchange of info and the signal speed up.

12. Synapse. Synapses are the junction point of two different neurons, so it’s the point where the exchange of info takes place. There are electrical and chemical synapses. Electrical synapses have direct physical contact and enable the bidirectional passage of currents: the presynaptic action potential propagates to the postsynaptic cell, while the membrane resting potential of postsynaptic cell simultaneously propagates to the presynaptic cell. Chemical synapses involve neurotransmitters: the energy coming from action potential opens Calcium channels, so Ca ions come through synapses and release information. Some Ca ions are re-absorbed by presynaptic cell, but it’s necessary that at least one ion reaches the postsynaptic to transmit the info, because when it attaches a receptor, the receptor opens Sodium channels. Postsynaptic potentials duration is between 10 and hundreds of milliseconds.

Presynaptic potential duration is 2 ms and it's biphasic, while postsynaptic potential duration is more than 10 ms and it's monophasic (only depolarization).

13. Summation of postsynaptic potential. Summation of postsynaptic potential can be temporal or spatial. Temporal summation means that some closed (in time) impulses are able to generate an action potential because the potential has no time to decrease. Spatial summation means that some impulses that takes place in different positions at the same time are able to generate an action potential. Impulses can be excitatory (EPSP, depolarizing) or inhibitory (IPSP, hyperpolarizing), and the number of useful impulses is the difference between these two types (#EPSP - #IPSP).

14. Hindbrain. Hindbrain is composed by pons, medulla, decussation and cerebellum. The pons bridges the signal from the forebrain to the medulla or to the cerebellum. The medulla stimulates the most involuntary action of the body. The decussation is the point where

1. The nerves cross from one side of the brain to the other one, and it's why the left hemisphere controls the right arm movements, for example.
2. The cerebellum contains 80% of the neurons and it controls every task about movement: maintaining balance, refining moves, spatial processing, processing the trajectory of an object in space, and allowing for the recognition of objects from different angles.
3. The midbrain enables the brain to integrate sensory information coming from ears, eyes, nose, muscle moves, thereby enabling the body to make fine adjustments to moves. The midbrain and the hindbrain compose the brainstem.
4. The forebrain is the most external part of the brain and it's composed of the thalamus, hypothalamus, and cerebrum.
5. The thalamus is a relay between subcortical areas and the cerebral cortex. In fact, every sensory system includes a thalamic center that receives and sends sensory info to the associated primary cortical area.
6. The hypothalamus controls the...

1. Metabolic processes and the autonomic nervous system, in fact it controls temperature, hunger, fatigue and sleep, it also secretes neurohormones.
2. The cerebrum controls thinking, skeletal movements (somatic motor), language, logic and emotions.
3. From external to internal of the brain there are different layers: gyrus, sulcus, grey matter (cerebral cortex) and white matter.
4. The cerebral cortex is a part of cerebrum, it has a large surface that convolutes in order to fit in skull, forming sulci and gyri; it can be divided into two hemispheres left and right, by the longitudinal fissure) and into two gyri: precentral and postcentral by the central fissure.
5. Functions of the brain. The precentral gyrus has mainly motor functions, while the postcentral has mainly sensory functions.
6. The lateralization phenomenon establishes that the left hemisphere has logic, computation, thinking in words, sequencing, mathematics, analysis and language functions while the right one has creativity, artistic, time of songs.

rhythm, non-verbal, daydreaming, visualization and feelings functions. The cerebral cortex can be divided also in four lobes: frontal, parietal, temporal and occipital. Frontal lobe is the association area (thinking), the parietal lobe is the somatosensory area, the temporal lobe is the audition area and the occipital lobe is the visualization area. Cerebral cortex is also divided by 52 Broadman or brain areas (BA), according cytoarchitectonic or functional features.

Action: execution - 6 / 1,2,3,4,7,8,40
Imagination - 6,40 / 7,9,10,46
Inhibition - 6 / 7,9,10,37,40,46
Observation - 6 / 7,10,19,21,37,40,44,45

Language: Language - 19 / 9,18,37,39,47
Orthography - 6,7,9,40 / 7,8,19,37,39
Phonology - 6,9 / 7,37,40,46
Semantic - 6,9,18,37 / 19,40,47
Syntactical - 9,10,46 / 18,19,22,38
Execution of speech - 6 / 1,2,3,4

Working memory - 6,9 / 7,10,40
Cognitive reasoning - 6,7,9,40 / 8,10,1918.

The spinal cord. The CNS