Sistema Nervoso

Question 1

What are the main parts of the nervous system?

Answer 1

The nervous system has two main parts:

• The central nervous system is made up of the brain and spinal cord.
• The peripheral nervous system is made up of nerves that branch off from the spinal cord and extend to all parts of the body.

Question 2

What are the nerve cells of the nervous system?

Answer 2

neuron, and glia (non-neuron cells)

Question 3

Describe the structure of a neuron?

Answer 3

A neuron has a cell body (soma), short receiving branches called dendrites that receive chemical signals, a long conducting branch called an axon. The axon ends in short sending branches called terminal branches that send messages to other neurons.

Question 4

What is the difference between motor neurons and sensory neurons?

Answer 4

motor neurons transmit messages from the brain to the muscles to generate movement. Meanwhile, Sensory neurons detect light, sound, odor, taste, pressure, and heat and send messages about those things to the brain.

Question 5

Describe the neural process?

Answer 5

When a neuron sends a message to another neuron, it sends an electrical signal down the length of its axon. At the end of the axon, the electrical signal changes to a chemical signal. At the terminal axons the chemical signal is released with chemical messengers called neurotransmitters into the synaps.

The neurotransmitters move the signal through the synapse to the neighboring dendrite, which converts the chemical signal back into an electrical signal. The electrical signal then travels through the neuron and goes through the same conversion processes as it moves to neighboring neurons.

Question 6

What is synapse?

Answer 6

synapse is a small gap between two neurons, where neurotransmitters are released from one neuron to pass the signal to the next neuron.

Question 7

What are the sheaths covering the axon?

Answer 7

Myelin sheath (internal) and Schwann sheath (external)

Question 8

What are the nodes of Ranvier and where are the found?

Answer 8

Nodes of Ranvier are periodic gaps in the myelin sheath on the axon of certain neurons that serves to facilitate the rapid conduction of nerve impulses.

Question 9

How do neurons communicate?

Answer 9

Neurons communicate via both electrical signals and chemical signals. The electrical signals are action potentials, which transmit the information from one of a neuron to the other; the chemical signals are neurotransmitters, which transmit the information from one neuron to the next.

Question 10

What is action potential?

Answer 10

An action potential is a rapid, temporary change in membrane potential (electrical charge), and it is caused by sodium rushing to a neuron and potassium rushing out.

Question 11

What are glial cells?

Answer 11

Glial cells, or neuroglia, are cells that surround the neurones of the central nervous system embedded between them, providing both structural and physiological support.

Question 12

What are the four main classes of neuroglia cells?

Answer 12

Astrocyte
Oligodendrocyte
Ependymal cells
Microglia cell
Schwann cells

Question 13

Do neurons touch each other to communicate?

Answer 13

Neurons do not touch each other, instead they are separated by a tiny gap called synapse

Question 14

What are neurotransmitters?

Answer 14

Neurotransmitters are chemical messengers which are released from one neuron as a result of an action potential; they cause a rapid, temporary change in the membrane potential of the adjacent neuron to initiate an action potential in that neuron.

Question 15

Describe an axon?

Answer 15

An axon is a tube-like structure that propagates the integrated signal to specialized endings called axon terminals. The axon carries the action potential to the next neuron. Neurons usually have one or two axons. Some axons are covered with myelin, which acts as an insulator to minimize dissipation of the electrical signal as it travels down the axon, greatly increasing the speed on conduction. This insulation is important as the axon from a human motor neuron can be as long as a meter, from the base of the spine to the toes. The myelin sheath is not actually part of the neuron, and is produced by glial cells. Along the axon there are periodic gaps in the myelin sheath called nodes of Ranvier, which are sites where the signal is “re-charged” as it travels along the axon.

Question 16

What is the function of astrocytes?

Answer 16

Astrocytes: provide nutrients and other substances to neurons, regulate the concentrations of ions and chemicals in the extracellular fluid, and provide structural support for synapses; also form the blood-brain barrier, which blocks entrance of toxic substances into the brain.

Question 17

What role does satellite glia play?

Answer 17

Satellite glia: nutrients and structural support for neurons in the peripheral nervous system (PNS).

Question 18

What’s the function of microglia?

Answer 18

Microglia: immune cells of the central nervous system (CNS); scavenge and degrade dead cells and protect the brain from invading microorganisms.

Question 19

What do the Oligodendrocyte do?

Answer 19

Oligodendrocytes: form myelin sheaths around axons in the CNS; one axon can be myelinated by several oligodendrocytes, and one oligodendrocyte can provide myelin for multiple neurons.

Question 20

Function of the Schwann cells?

Answer 20

Schwann cells: form myelin sheaths around axons in the PNS; unlike oligodendrocytes, a single Schwann cell provides myelin for only one axon as the entire Schwann cell surrounds the axon.

Question 21

Function of ependymal cells?

Answer 21

Ependymal cells: line fluid-filled ventricles of the brain and the central canal of the spinal cord; help circulate cerebrospinal fluid, which serves as a cushion for the brain.

Question 22

What is the membrane potential?

Answer 22

The difference in total charge between the inside and outside of the cell is called the membrane potential.

The lipid bilayer membrane that surrounds a neuron is impermeable to charged molecules or ions. To enter or exit the neuron, ions must pass through special proteins called ion channels that span the membrane and regulate the relative concentrations of different ions inside and outside the cell. Cells can use energy to preferentially move certain ions either inside or outside of the membrane, setting up a difference in ion charge across the membrane, where one side is relatively more negative and the other side is relatively more positive.

Question 23

What is the resting membrane potential

Answer 23

The resting membrane potential goes from -50mV to -70mV. The resting potential is established and maintained by two main processes: an ATP-powered ion channel called the sodium-potassium pump, and a passive ion channel called the potassium leak channel.

Question 24

How does the sodium-potassium pump function?

Answer 24

The sodium-potassium pump, which is also called Na+/K+ ATPase, transports sodium out of a cell while moving potassium into the cell. The Na+/K+ pump is an important ion pump found in the membranes of many types of cells. These pumps are particularly abundant in nerve cells, which are constantly pumping out sodium ions and pulling in potassium ions to maintain an electrical gradient across their cell membranes

Question 25

Role of Myelin?

Answer 25

Myelin acts as an insulator that prevents current from leaving the axon; this increases the speed of action potential conduction.

Question 26

What are the nodes of Ranvier?

Answer 26

The nodes of Ranvier are gaps in the myelin sheath along the axon. These unmyelinated spaces are about one micrometer long and contain voltage gated Na+ and K+ channels. Flow of ions through these channels, particularly the Na+ channels, regenerates the action potential over and over again along the axon. This “jumping” of the action potential from one node to the next is called saltatory conduction.

Question 27

What are the main components of the central nervous system?

Answer 27

Brain and spinal cord

Question 28

Function of the central nervous system?

Answer 28

The central nervous system’s responsibilities include receiving, processing, and responding to sensory information.

Question 29

Describe the brain?

Answer 29

The brain is an organ of nervous tissue that is responsible for responses, sensation, movement, emotions, communication, thought processing, and memory. Protection for the human brain comes from the skull, meninges, and cerebrospinal fluids.

Question 30

Describe the cerebral cortex?

Answer 30

The cerebral cortex is the outermost layer that surrounds the brain. It is composed of gray matter and filled with billions of neurons used to conduct high-level executive functions. The cortex divides into four lobes; frontal, parietal, occipital, and temporal by different sulci.

Question 31

What is the thalamus and it’s function

Answer 31

The thalamus is the relay center of the brain. It receives afferent impulses from sensory receptors located throughout the body and processes the information for distribution to the appropriate cortical area. It is also responsible for regulating consciousness and sleep.

Question 32

Describe the action of the hypothalamus

Answer 32

While the hypothalamus is one of the smallest parts of the brain, it is vital to maintaining homeostasis. The hypothalamus connects the central nervous system to the endocrine system. It is responsible for heart rate, blood pressure, appetite, thirst, temperature, and the release of various hormones. The hypothalamus also communicates with the pituitary gland to release or inhibit antidiuretic hormone, corticotropin-releasing hormone, gonadotropin-releasing hormone, growth hormone-releasing hormone, prolactin inhibiting hormone, thyroid releasing hormone, and oxytocin.[3]

Question 33

Describe the function of the medulla oblongata

Answer 33

Medulla oblongata: The medulla oblongata is at the bottom of the brain stem, where the spinal cord meets the foramen magnum of the skull. It is responsible for autonomic functions, some of which are crucial for survival. The medulla oblongata monitors the bodies respiratory system using chemoreceptors. These receptors are able to detect changes in blood chemistry. For example, if the blood is too acidic, the medulla oblongata will increase the respiratory rate allowing for more oxygen to reach the blood.[4] It is also a cardiovascular and vasomotor center. The medulla oblongata can regulate the body’s blood pressure, pulse, and cardiac contractions based on the body’s needs. Lastly, it controls reflexes like vomiting, swallowing, coughing, and sneezing.

Question 34

What is the spinal cord and it’s main function?

Answer 34

The spinal cord is part of the central nervous system and consists of a tightly packed column of nerve tissue that extends downwards from the brainstem through the central column of the spine.

The spinal cord carries nerve signals from the brain to other parts of the body (importantly the muscles we use to move) and receives sensory input from the body, partially processes it, and then transmits that information to the brain.

Along with its role in relaying motor and sensory signals between the brain and periphery, the spinal cord also provides separate neural circuits for many of our reflexes.

The spinal cord is the major conduit and reflex centre between the peripheral nerves and the brain and transmits motor information from the brain to the muscles, tissues and organs, and sensory information from these areas back to the brain

Question 35

How many vertebrae does the spinal cord have?

Answer 35

Externally, the spinal cord is protected by 33 vertebrae, which sit between a semi-rigid intervertebral disc, which provide a level of flexibility to the vertebral column. Its flexibility is greatest in the cervical region and lowest in the thoracic region.

Question 36

What is the the protective layer of the spinal cord ?

Answer 36

The spinal cord is protected by 3 layers of meninges membranes: pia mater, arachnoid mater and dura mater

Question 37

Where does the spinal cord starts and ends?

Answer 37

The spinal cord extends from the foramen magnum, C1 to the lowest border of the first lumbar vertebra L1

Question 38

What are the 5 regions of the spinal cord?

Answer 38

Cervical (7 vertebrae)
Thoracic spine (12 vertebrae)
Lumbar spine (5 vertebrae)
Sacrum ( 5 vertebrae)
Coccygeal (4 vertebrae)

Question 39

Inside the spinal cord what can you find?

Answer 39

Inside, the spinal cord consists of grey matter and white matter.

1. The grey matter takes on the shape of a butterfly, with four ‘wings’ called horns: The horns in the front contain motor neurons; the horns in the back contain sensory neurons which carry sensory information.
2. The spinal cord grey matter is surrounded by a column of white matter, containing axons that allow different parts of the spinal cord to communicate smoothly, with signals passing upwards and downwards conveying eg sensation and motor signals.

Question 40

What enters and exits the spinal cord?

Answer 40

Sensory Nerve Fibres enter the Spinal Cord via the Posterior (Dorsal) Root. The cell bodies for these neurons are situated in the Dorsal Root Ganglia.
Motor and Preganglionic Autonomic Fibres exit via the Anterior (Ventral) Root.

Question 41

What is the cauda equina

Answer 41

A bundle of nerves extends down from the bottom of the spinal cord through the bones of the lower back (vertebrae) or onto the bone at the base of the spine (sacrum)
The cauda equina may be compressed by a ruptured or herniated disc, tumor, or abscess. It can become damaged by an injury or swell up because it becomes inflamed (as in ankylosing spondylitis). The resulting symptoms are called cauda equina syndrome.

Un fascio di nervi si estende verso il basso dal fondo del midollo spinale attraverso le ossa della regione lombare (vertebre) o sull’osso alla base della colonna vertebrale (sacro). Questo fascio è chiamato cauda equina, che significa coda di cavallo in latino, perché assomiglia a una coda di cavallo.

La cauda equina può venire compressa da una rottura o un’ernia del disco, un tumore o un ascesso. Può venire danneggiata da una lesione o gonfiarsi perché si infiamma (come nella spondilite anchilosante). I sintomi che ne risultano sono detti sindrome della cauda equina.

Question 42

What are the two roots emerging from the spinal cord?

Answer 42

The spinal nerves are relatively large nerves that are formed by the merging of two nerve roots: a sensory nerve root and a motor nerve root. Sensory nerve roots emerge from the back of the spinal cord and the motor nerve roots from the front of the spinal cord. As they join, they form the spinal nerves on the sides of the spinal cord.

Question 43

What is the ventricular system?

Answer 43

The ventricular system of the brain is an interconnected series of cavities filled with cerebrospinal fluid (CSF) that cushions the brain, but it is also responsible for removing waste and delivering nutrients to your brain

Question 44

What are the parts of the ventricular system?

Answer 44

The ventricular system is composed of
- 2 lateral ventricles —> The left and right lateral ventricles are located within their respective hemispheres of the cerebrum.
- the third ventricle —> The lateral ventricles are connected to the third ventricle by the foramen of Monro. The third ventricle is situated in between the right and the left thalamus.
- the fourth ventricle —> it receives CSF from the third ventricle via the cerebral aqueduct. It lies within the brainstem, at the junction between the pons and medulla oblongata. From the 4th ventricle, the fluid drains into two places:
Central spinal canal – bathes the spinal cord;
Subarachnoid cisterns – bathes the brain, between arachnoid mater and pia mater. Here the CSF is reabsorbed back into the circulation.

Question 45

Describe the Brain stem?

Answer 45

The brainstem is divided into: the medulla (oblongata) situated caudally, the midbrain (mesencefalo) and the pons (bridge) located between them.

Question 46

Where is the cerebellum?

Answer 46

The cerebellum is located at the base of the brain, with the large mass of the cerebral cortex above it and the portion of the brainstem called the pons in front of it. It is separated from the overlying cerebrum by a layer of tough dura mater; all of its connections with other parts of the brain travel through the pons.

Question 47

What are the cerebellum functions?

Answer 47

The cerebellum controls voluntary movements such as:
walking.
posture.
balance.
coordination.
eye movements.
speech.

Question 48

What is the diencephalon?

Answer 48

The diencephalon is the central portion of the brain located around the third ventricle, superior to the brainstem (medulla, pons and midbrain), and inferior to the corpus callosum and cerebral cortex. It is divided into four main parts including the epithalamus, thalamus, subthalamus, and hypothalamus.

Question 49

What is the function of epithalamus

Answer 49

The epithalamus is a posterior or dorsal segment of the diencephalon.

The function of the epithalamus is to connect the limbic system to other parts of the brain. Some functions of its components include the secretion of melatonin by the pineal gland (involved in circadian rhythms), and regulation of motor pathways and emotions.

Question 50

Thalamus functions

Answer 50

The thalamus is a paired gray matter structure of the diencephalon.
Your thalamus has many functions, including:
- Relaying sensory information
- Relaying motor (movement) information
- Prioritizing attention
- Role in consciousness
- Role in thinking (cognition) and memory.

Question 51

Hypothalamus functions?

Answer 51

The hypothalamus is a structure deep within your brain. It’s the main link between your endocrine system and your nervous system. Your hypothalamus keeps your body balanced in a stable state called homeostasis.

While it’s very small, the hypothalamus plays a crucial role in many important functions, including:
- releasing hormones.
- maintaining daily physiological cycles
- controlling appetite
- managing sexual behavior
- regulating emotional responses
- regulating body temperature

Question 52

Where is the telencephalon?

Answer 52

The telencephalon is more commonly known as the cerebrum. It is located in the forebrain and makes up the largest part of the brain.

Question 53

What are the 5 lobes of the telencephalon?

Answer 53

Each cerebral hemisphere is organized into five lobes: frontal, parietal, occipital, temporal and insula.

Lateral sulcus : it is the sulcus that separates the frontal lobe from the temporal lobe

Central sulcus : separates the parietal from the frontal lobe.
Parieto-occipital sulcus separates the parietal from the occipital lobe.

Question 54

What are the four components of telencephalon?

Answer 54

The telencephalon has four major components: the cerebral cortex, the limbic forebrain structures, the basal ganglia, and the olfactory system.

Question 55

What is the peripheral nervous system?

Answer 55

The peripheral nervous system consists of the nerves that branch out from the brain and spinal cord. These nerves form the communication network between the CNS and the body parts.

Question 56

What are the 3 main organs of peripheral nervous system?

Answer 56

The organs of the peripheral nervous system are the nerves and ganglia. Nerves are bundles of nerve fibers. Ganglia are collections, or small knots, of nerve cell bodies outside the CN

Question 57

Describe the various divisions that make up the peripheral nervous system?

Answer 57

The peripheral nervous system is subdivided into an afferent (sensory) division and an efferent (motor) division. The afferent or sensory division transmits impulses from peripheral organs to the CNS. The efferent or motor division transmits impulses from the CNS out to the peripheral organs to cause an effect or action.
The efferent or motor division is again subdivided into the somatic nervous system and the autonomic nervous system. The somatic nervous system, supplies motor impulses to the skeletal muscles. Because these nerves permit conscious control of the skeletal muscles, it is sometimes called the voluntary nervous system. The autonomic nervous system, also called the visceral efferent nervous system, supplies motor impulses to cardiac muscle, to smooth muscle, and to glandular epithelium.
The autonomous nervous system is further subdivided into sympathetic and parasympathetic divisions. Because the autonomic nervous system regulates involuntary or automatic functions, it is called the involuntary nervous system.

Question 58

What kind of nerves are spinal nerves?

Answer 58

Mixed, half afferent and half efferent

Question 59

Describe the structure of a spinal nerve?

Answer 59

Each spinal nerve is a mixed nerve, formed from the combination of nerve fibers from its dorsal and ventral roots. The dorsal root is the afferent sensory root and carries sensory information to the brain. The ventral root is the efferent motor root and carries motor information from the brain. The spinal nerve emerges from the spinal column through an opening (intervertebral foramen) between adjacent vertebrae. This is true for all spinal nerves except for the first spinal nerve pair (C1), which emerges between the occipital bone and the atlas (the first vertebra).

Question 60

What us the difference between dermatome and myomere?

Answer 60

A dermatome is an area of skin that is mainly supplied by afferent nerve fibres from the dorsal root of any given spinal nerve.
Meanwhile a myomere is a muscle that is mainly supplied by efferent nerve fibers from the ventral root of any given spinal nerve