T.2 Neuroscience Applied to Orthoprothesis

Question 1

Eukaryotic cell

Answer 1

is a type of cell characterized by having a distinct nucleus enclosed within a membrane, along with other specialized organelles that are also membrane-bound. Eukaryotic cells are more complex than prokaryotic cells (like bacteria), and they form the basis for most of the organisms we are familiar with, including animals, plants, fungi, and protists

Question 2

Nucleus

Answer 2

houses the cell’s genetic material (DNA). nuclear envelope, a double membrane, separates the nucleus from the rest of the cell

Question 3

Cell membrane

Answer 3

The cell is enclosed by a lipid bilayer known as the plasma membrane, which controls the movement of substances in and out of the cell

Question 4

Cytoplasm

Answer 4

gel-like substance inside a cell that fills the space between the cell membrane and the nucleus. Everything within the cell except for the nucleus, including the cytosol (the fluid part), organelles (like mitochondria and ribosomes), and other structures. The cytoplasm plays a central role in maintaining cell function and structure, and it’s where many critical biochemical processes occur

Question 5

Organelles (7)

Answer 5

Mitochondria: Energy
Ribosomes: protein synthesis
Rough endoplasmatic reticulum (RER): Site of protein synthesis
Smooth ER: synthesis and storage of lipids
Golgi apparatus: Involved in modifying, packaging, and distributing proteins and lipids.
Lysosomes: Contain digestive enzymes that break down waste materials and cellular debris.
Cytoskeleton: made of microtubules, microfilaments, and intermediate filaments, which help maintain the cell’s shape, support intracellular transport, and facilitate movement

Question 6

Neuron (general)

Answer 6

The neuron is a specialized cell in the nervous system that transmits information through electrical and chemical signals. Neurons are the fundamental building blocks of the brain, spinal cord, and peripheral nerves, and they play a key role in processing and transmitting information throughout the body.

Question 7

3 types of neurons

Answer 7

Sensory, motor and interneurons

Question 8

Sensory neurons

Answer 8

These neurons carry signals from sensory receptors (e.g., in the skin, eyes, ears) to the central nervous system (CNS). Sensory neurons are responsible for transmitting information about the external and internal environments, such as touch, light, sound, and body position.

Question 9

Motor neurons

Answer 9

Motor neurons transmit signals from the CNS to muscles or glands, enabling movements or triggering the release of substances like hormones. A motor neuron in the anterior horn of the human spinal cord may be more than 1 meter long

Question 10

Interneurons

Answer 10

Found only in the CNS (brain and spinal cord), interneurons connect sensory and motor neurons and play a critical role in processing and interpreting information. They are the most abundant type of neuron and are responsible for higher cognitive functions like learning, memory, and decision-making.

Question 11

structure of a neuron (cell body, soma)

Answer 11

nucleus and most of the cell’s organelles, including the endoplasmic reticulum and mitochondria. It is the metabolic center of the neuron.

The nucleus contains the genetic material (DNA), which directs protein synthesis necessary for neuron function.

Question 12

structure of a neuron (dendrites)

Answer 12

branch-like extensions that receive signals from other neurons or sensory stimuli and transmit these signals to the cell body.
Dendrites are covered in synapses, where they make contact with the axon terminals of other neurons. This allows the neuron to integrate input from multiple sources.

Question 13

Dendrites (structure)

Answer 13

Branch-like extensions: Dendrites typically appear as multiple, tree-like extensions radiating from the cell body (soma) of a neuron.

Dendritic spines: Many dendrites have small protrusions called dendritic spines, which increase the surface area available for synaptic connections with other neurons.

Cytoplasm: Like the rest of the neuron, dendrites contain cytoplasm, including various organelles such as ribosomes and cytoskeletal elements like microtubules, which help maintain their structure.

Question 14

Dendrites (function)

Answer 14

Receiving signals: Dendrites are specialized to receive neurotransmitters (chemical signals) released by the axons of other neurons at synapses. These signals are converted into electrical impulses.

Integrating information: The dendrites integrate incoming signals from multiple neurons and convey this information to the cell body of the neuron. If the signal is strong enough, it can trigger an action potential in the neuron’s axon.

Signal modulation: The shape and size of dendritic spines, which change inresponse to activity, are thought to be involved in learning and memory, as they affect the strength of the synaptic connections.

Question 15

Axon

Answer 15

long, thin projection that carries electrical impulses (action potentials) away from the cell body to other neurons or target cells->muscles or glands.

Question 16

Axon hillock

Answer 16

is the region where the cell body connects to the axon and is the site where action potentials are generated.

Question 17

Myelin sheath

Answer 17

Many axons are covered with a myelin sheath, which is made up of Schwann cells in the peripheral nervous system (PNS) or oligodendrocytes in the central nervous system (CNS).

The myelin sheath acts as insulation, allowing the electrical signal to travel faster along the axon.

Question 18

Nodes of Ranvier

Answer 18

These are gaps in the myelin sheath where ion channels are concentrated, enabling the electrical signal to jump between nodes, a process known as saltatory conduction, which speeds up signal transmission.

Question 19

Axon terminals

Answer 19

These are the ends of the axon, where neurotransmitters are released to communicate with the next neuron or target cell across a synapse.

Question 20

Anterograde transport

Answer 20

movement of molecules, vesicles, from the soma to the axon-synapse

Question 21

Retrograde transport

Answer 21

Axon to the soma

Question 22

Information flow (neurons)

Answer 22

Pyramidal neuron are a type of multipolar neuron found in areas of the brain including the cerebral cortex, the hippocampus, and the amygdala.

Question 23

Cytoskeleton in neurons

Answer 23

The cytoskeleton in neurons plays a crucial role in maintaining the cell’s structure, enabling communication, and facilitating intracellular transport. It consists of three main types of protein filaments: microtubules, neurofilaments, and actin filaments (also called microfilaments). These structures support the complex and extended shape of neurons and are essential for their function, particularly in processes such as signal transmission and axonal transport.

Question 24

Cytoskeleton in neurons

Answer 24

The cytoskeleton in neurons plays a crucial role in maintaining the cell’s structure, enabling communication, and facilitating intracellular transport. It consists of three main types of protein filaments: microtubules, neurofilaments, and actin filaments (also called microfilaments). These structures support the complex and extended shape of neurons and are essential for their function, particularly in processes such as signal transmission and axonal transport.

Question 25

3 types of protein filaments (neuron cytoskeleton)

Answer 25

Actin: next to the cellular membrane, Abundant in the growing axons and synapsis.
Microtubules: shape of the cell, intracellular transport.
Intermediate filaments: structural function, neurofilament, specialized intermediate filament of the neurons. structural support and axonal.

Question 26

neurons & glia (neuron)

Answer 26

Neurons:
From Greek: neûron sinew, cord, nerve
Limited regeneration (olfactory)
Hundreds (maybe more) of types
The “neuron doctrine”: the single neuron constitutes the structural and functional unit of the CNS (Golgi, 1906)

Question 27

glia or glial cells

Answer 27

From latin: “glue”
Unlike neurons, they are proliferative (glial scars), only a few types
Called the “support cells,” but do much more!
Major types: astrocytes, myelinating glia (oligodendrites, Schwann cells)

Question 28

neuron classification (axon-dendrites)

Answer 28

• unipolar
• bipolar
• multipolar

Question 29

neuron classification (shape)

Answer 29

• pyramidal
• purkinje

Question 30

neuron classification (function)

Answer 30

• sensory
• motor
• interneuron

Question 31

Astrocytes (def)

Answer 31

Astrocytes are a type of glial cell found in the central nervous system (CNS) that play critical roles in maintaining the health and functionality of neurons. They are named for their star -like shape, with numerous long processes extending from the cell body, resembling a star or “astro. “

Question 32

Astrocyte (structural support)

Answer 32

provide structural support to neurons by filling the spaces between them and other elements in the CNS. This helps maintain the proper architecture of brain tissue

Question 33

Astrocyte (connect with the BBB)

Answer 33

maintain the blood -brain barrier, a protective layer that regulates the passage of substances from the bloodstream into the brain. Astrocytes release signals that help the endothelial cells of blood vessels form tight junctions, ensuring that harmful substances are kept out of the brain.

Question 34

Astrocyte (nutrient and metabolic support)

Answer 34

supply neurons with essential nutrients, such as glucose and lactate, and remove metabolic waste products. Glucose storage and release, helping to regulate energy metabolism in the brain.

Question 35

Astrocyte (synapse formation and function)

Answer 35

formation and maintenance of synapses (the connections between neurons). They release signaling molecules that influence synaptic development and function, contributing to the plasticity of neural networks

Question 36

Astrocyte (repair snd scarring)

Answer 36

After injury to the CNS, astrocytes become reactive, a state called reactive gliosis. In this state, they proliferate and migrate to the site of injury, where they form a “glial scar” to prevent further damage.

Question 37

Astrocyte (immune response)

Answer 37

Astrocytes contribute to the immune response in the brain by producing and releasing cytokines and other inflammatory mediators in response to infection or injury. They also help regulate the activity of microglia, the primary immune cells of the CNS.

Question 38

Microglial cells (def)

Answer 38

Microglial cell Glial Cells Axons Blood vessels Supporting cells: Microglial cells are a type of glial cells in the central nervous system (CNS) that act as the primary immune cells of the brain and spinal cord.

In adulthood, microglia continue to help maintain healthy synaptic connections by regulating synaptic plasticity, which is important for learning and memory. Response to Injury (Reactive Microglia): After CNS injury (such as trauma, stroke, or neurodegeneration), microglia become reactive. In this state, they move toward the injury site, remove dead or damaged cells and release factors that promote tissue repair.
However, prolonged activation of microglia in response to chronic injury or disease can lead to sustained inflammation, contributing to further neuronal damage

Question 39

Microglial cells (immune defense)

Answer 39

first line of defense in the CNS. detect pathogens, damaged cells, or abnormal proteins, they become activated and shift from a resting state to a more mobile and aggressive form. In this activated state, microglia can phagocytose (engulf and digest) cellular debris, dead neurons, pathogens, and misfolded proteins, clearing away harmful substances and preventing further damage

Question 40

Microglial cells (monitoring and surveillance)

Answer 40

In their resting state, microglia have highly branched processes that extend throughout the CNS, constantly scanning the environment for threats or abnormalities. This constant surveillance is essential for maintaining brain homeostasis.

Question 41

Microglial cells (regulation of inflammation)

Answer 41

Microglia release cytokines, chemokines, and other inflammatory molecules in response to injury or infection, initiating an immune response. While this inflammatory reaction helps fight off pathogens or repair damaged tissue, chronic or excessive microglial activation can contribute to neuroinflammation, which is harmful to neurons. Microglia can also help resolve inflammation by releasing anti-inflammatory signals after the threat is neutralized, ensuring that inflammation doesn’t persist longer than necessary.

Question 42

Microglial cells (synaptic prunning)

Answer 42

synaptic pruning during brain development, where they help remove excess or weak synapses. This process is essential for the proper development of neural circuits and optimizing brain function.

Question 43

OLIGODENDROCYTES AND SCHWANN CELLS

Answer 43

Types of glial cells responsible for producing and maintaining the myelin sheath that insulates nerve fibers
The myelin sheath is essential for speeding up the transmission of electrical signals (action potentials) along the axons of neurons.
Both cell types perform a similar function, they are found in different parts of the nervous system and have some key differences in their structure and operation

Question 44

Oligodendrocytes (location + function)

Answer 44

Oligodendrocytes

Location: found in the central nervous system (CNS), which includes the brain and spinal cord.

Function:
Oligodendrocytes are responsible for myelinating multiple axons
A single oligodendrocyte can extend its processes and wrap around the axons of several neurons, creating segments of the myelin sheath for each one.
Myelination increases the speed of electrical impulses (via saltatory conduction), allowing for efficient communication between neurons in the brain and spinal cord.

Question 45

Oligodendrocytes (structure + injury and disease)

Answer 45

Structure: Oligodendrocytes have a star-like shape with several long, thin extensions. Each extension wraps around a different section of multiple axons, forming multiple layers of myelin.
Injury and Disease: In diseases like multiple sclerosis (MS), the immune system attacks the myelin in the CNS, damaging oligodendrocytes. This leads to demyelination, which disrupts nerve signaling and causes the symptoms of MS, such as muscle weakness, coordination issues, and cognitive impairments.

Question 46

Schwann cells (location and function)

Answer 46

Location: Schwann cells are found in the peripheral nervous system (PNS), which includes all nerves outside the brain and spinal cord (e.g., sensory and motor nerves).

Function: Schwann cells myelinate axons in the PNS. Unlike oligodendrocytes, a single Schwann cell wraps around a single axon segment, creating a myelin sheath for just one axon section. Schwann cells also play a role in nerve regeneration in the PNS. If a peripheral nerve is damaged, Schwann cells can help guide the regrowth of axons and promote repair.

Question 47

Schwann cells (structure + disease)

Answer 47

Structure: Schwann cells have a more elongated, cylindrical structure and form individual myelin sheaths by wrapping around one section of an axon. This wrapping creates multiple layers of myelin, insulating the axon.
Disease: Schwann cells can aid in the recovery of peripheral nerve injuries by guiding regrowth, unlike oligodendrocytes in the CNS, where repair is more limited.

Question 48

Myelin sheet

Answer 48

Myelin sheet: Composed by several layers of oligodendrocytes (or Schwann cell ) membranes that form these layers Provide electrical insulation, increasing the speed of the transmission of the information

Nodes of Ranvier: Small exposed segments of the axon Restrict action potentials to short unmyelinated axonal segments (saltatory action potential propagation)

Question 49

Examples of demyelinating diseases

Answer 49

Multiple Sclerosis:
Loss of myelin in sensory and motor pathways
Weakness
Loss of balance
Double visión

Optic Neuritis:
Demyelinating inflammation of the optic nerve
Loss of vision
Pain in eye movements