Hoja de repaso: Nervous System Fundamentals

📋 Course Outline

1. Nervous system components
2. Sensory and motor message pathway
3. Cerebral cortex and sensory areas
4. Neuron structure
5. Neural networks and synapses
6. Nervous system disorders and damage
7. Diagram reading and message tracing

📖 1. Nervous system components

🔑 Key Concepts & Definitions

• Brain : The brain is a central organ of the nervous system that receives messages and creates responses.
• Spinal cord : The spinal cord is a central nervous system structure that relays messages between the brain and nerves.
• Nerve : A nerve is a nervous system structure that carries messages between parts of the body and the central nervous system.

📝 Essential Points

• The nervous system is made of the brain, the spinal cord, and nerves.
• Sensory receptors detect a signal and create a sensory nerve message.
• A sensory nerve message travels to the brain through the sensory nerve path.
• The brain creates a motor nerve message that goes via the spinal cord and a motor nerve to a muscle.
• When the message reaches the muscle, it contracts and movement occurs.

💡 Memory Hook

Sensory input → brain analysis → motor output → muscle contraction.

📖 2. Sensory and motor message pathway

🔑 Key Concepts & Definitions

• Sensory message pathway : The sensory pathway is the route a sensory nerve message follows from sensory receptors to the brain.
• Motor message pathway : The motor pathway is the route a motor nerve message follows from the brain to a muscle for action.
• Sensory receptors : Sensory receptors are located in sensory organs and detect signals such as sound or images to start a sensory message.

📝 Essential Points

• A sensory nerve message is created after sensory receptors detect a signal like sound or an image.
• The motor nerve message is created by the brain and then passes through the spinal cord before reaching a motor nerve.
• At the start of a run example, the sensory direction is hearing and the signal is the whistle sound.
• At the start of the soccer example, the sensory direction is seeing and the signal is the incoming ball.
• The path tracing activity requires writing both the sensory and motor trajectories in the body images.

💡 Memory Hook

One route to the brain (sensory), one route back to muscles (motor).

📖 3. Cerebral cortex and sensory areas

🔑 Key Concepts & Definitions

• Cortex : The cortex is the superficial part of the brain divided into several zones.
• Visual area : The visual area is a cortex zone located at the back of the brain and active when looking at something.
• Brain hemispheres : The brain is organized into right and left hemispheres, with cortical organization across them.

📝 Essential Points

• The superficial part of the brain is called the cortex.
• The cortex is divided into several zones with different roles.
• The visual area is located at the back of the brain and works when you look at something.
• The cortex is associated with right and left hemispheres in brain organization.
• The diagram distinguishes cortical and subcortical regions as well as grey matter nuclei.

💡 Memory Hook

Back-of-brain cortex zone = visual area when you look.

📖 4. Neuron structure

🔑 Key Concepts & Definitions

• Neuron : A neuron is a nervous cell that has a membrane, a nucleus, and cytoplasm.
• Cell body : The cell body is the part of the neuron that includes the main components on the neuron diagram.
• Axon : The axon is the neuron part along which an electrical message travels toward synapses.
• Nerve endings : Nerve endings are the endings of a neuron that participate in communication at synapses.

📝 Essential Points

• The brain, the spinal cord, and all nerves are made of neurons.
• Neurons are the nerve cells.
• A neuron diagram labels the cell body, nucleus, axon, and nerve endings.
• The brain contains about 100 billion neurons.
• The membrane has a special shape, and the axon and nerve endings are separate parts of the cell.

💡 Memory Hook

Diagram parts: cell body + nucleus + axon + nerve endings.

📖 5. Neural networks and synapses

🔑 Key Concepts & Definitions

• Neural network : A neural network is an organization of interconnected neurons that communicate to process messages.
• Synapse : A synapse is the very thin gap between two neurons.
• Neurotransmitters : Neurotransmitters are chemical substances released at synapses to pass the message to the next neuron.

📝 Essential Points

• Neurons are organized in networks and send messages from neuron to neuron very rapidly.
• An electrical nerve message travels along the axon until it reaches the synapse.
• Because there is an space at the synapse, the electrical message cannot cross directly.
• At the synapse, the message is transmitted chemically via neurotransmitters.
• Fixation of neurotransmitters on the next neuron triggers a new electrical message that continues along its axon.

💡 Memory Hook

Synapse gap blocks electricity → neurotransmitters bridge it → new electricity starts.

📖 6. Nervous system disorders and damage

🔑 Key Concepts & Definitions

• Sensory receptor damage : Sensory receptor damage happens when sensory organs are harmed, which can disrupt nervous system functioning.
• Message transmission disturbance : Message transmission disturbance is when the passage of the nerve message is slowed or altered.
• Spinal cord lesion : A spinal cord lesion is an injury to the spinal cord that can lead to major movement problems.

📝 Essential Points

• Very strong noise or too strong light can damage ears or eyes at the sensory receptor level.
• Fatigue, alcohol, and drugs can slow or perturb the transmission of nerve messages.
• An accident that creates a lesion of the spinal cord can cause paralysis.

💡 Memory Hook

Damage levels: receptors → transmission → spinal cord injury.

📖 7. Diagram reading and message tracing

🔑 Key Concepts & Definitions

• Labelling a diagram : Labelling a diagram means matching the correct names to the parts shown in a nervous system or neuron image.
• Message tracing : Message tracing means following the sensory and motor trajectories through the body to movement.
• Sensory vs motor arrows : Sensory vs motor arrows are the two directions shown to distinguish input travel and output travel.

📝 Essential Points

• You must be able to label the required parts on a neuron diagram and nervous system diagrams.
• For a run example, trace both sensory message path (hearing) and motor message path to muscles during movement.
• In the run example, the message sensory signal is the whistle sound.
• In the soccer example, the sensory signal is the ball arriving and you trace both sensory and motor paths.
• When images are jumbled, reorder them to match the progression electrical vs chemical messages.

💡 Memory Hook

Check arrows: sensory trip toward brain, motor trip toward muscles, then apply the electrical→chemical synapse step.

⚠️ Common Pitfalls & Confusions

1. Mixing up the two routes can lead to swapping sensory travel to the brain and motor travel to the muscles.
2. Saying the electrical message crosses the synapse directly is wrong because the synapse is a gap that requires neurotransmitters.
3. Confusing sensory receptors with neurons can cause errors: receptors detect signals, while neurons transmit messages.
4. Placing the visual area anywhere else than the back of the brain leads to incorrect cortex mapping.
5. Thinking that every brain part is responsible for vision rather than the specific visual area can blur cortex zone roles.
6. Interpreting “message faster” without conditions can be misleading because fatigue, alcohol, and drugs can slow or disturb transmission.

✅ Exam Checklist

1. Know the three components of the nervous system: brain, spinal cord, and nerves.
2. Identify what sensory receptors do: detect a signal and start a sensory nerve message.
3. State the sensory pathway idea: sensory message goes to the brain through a sensory nerve path.
4. State the motor pathway idea: the brain creates a motor message that goes via the spinal cord and a motor nerve to a muscle.
5. Explain the end of the chain: the muscle contracts when the message arrives, producing movement.
6. Recognize that the cortex is the superficial part of the brain and is divided into zones.
7. Locate the visual area at the back of the brain and link it to looking at something.
8. List neuron structures to label: cell body, nucleus, axon, and nerve endings.
9. Recall the brain neuron count level: about 100 billion neurons.
10. Describe neuron communication through a synapse: electrical along axon then chemical at the synapse via neurotransmitters, then electrical continues.
11. Define the synapse as the very thin space between two neurons.
12. Recall transmission perturbations: fatigue, alcohol, and drugs can slow or disturb messages.
13. Use damage examples: strong noise/light can harm sensory organs, and a spinal cord lesion from an accident can cause paralysis.
14. Read and trace message pathways on provided diagrams, distinguishing sensory and motor directions and placing electrical vs chemical message steps in order.