Sistema nervoso (seconda parte).

Summary

The video explores the neural pathways involved in voluntary movements, focusing on the pyramidal and extrapyramidal systems. It explains how motor impulses travel from the motor cortex through the brainstem, spinal cord, and peripheral nervous system to reach skeletal muscles, resulting in voluntary movement. The pyramidal pathway is responsible for conscious, voluntary actions, while the extrapyramidal system regulates automatic movements. The video also covers the role of the cerebellum in coordination and posture, the autonomic nervous system’s regulation of involuntary functions, and the functioning of neuromuscular junctions in muscle contraction.

Takeaways

• 😀 The pyramidal tract is responsible for sending voluntary motor impulses to skeletal muscles, starting from the motor cortex.
• 😀 Motor impulses cross over (decussate) at the brainstem to control muscles on the opposite side of the body.
• 😀 The motor cortex is divided into regions controlling different parts of the body, such as the hands, face, and lower limbs.
• 😀 The extrapyramidal tract helps regulate the intensity of motor impulses and controls automatic movements that no longer require conscious thought.
• 😀 The cerebellum plays a key role in coordinating automatic movements and maintaining posture and balance.
• 😀 The spinal cord is a key pathway for communication between the central nervous system and peripheral nervous system.
• 😀 The spinal cord's gray matter houses motor neurons in the anterior horn and sensory neurons in the posterior horn.
• 😀 The autonomic nervous system, consisting of sympathetic and parasympathetic divisions, regulates involuntary functions such as heart rate, digestion, and breathing.
• 😀 The sympathetic nervous system stimulates activity in the body, while the parasympathetic system works to slow down or inhibit certain functions.
• 😀 The neuromuscular junction is where motor impulses trigger muscle contraction through the release of the neurotransmitter acetylcholine.

Q & A

What is the function of the pyramidal pathway in the nervous system?

The pyramidal pathway is responsible for transmitting voluntary motor impulses from the motor cortex to the skeletal muscles, allowing conscious and controlled movements.

What happens at the decussation of motor neurons in the brainstem?

At the decussation point in the brainstem (medulla oblongata), the motor neurons cross from the left side of the brain to the right side of the body, and vice versa, ensuring that the left motor cortex controls the right side of the body and vice versa.

What is the role of the extrapyramidal system in movement control?

The extrapyramidal system regulates the intensity and coordination of motor impulses, particularly for automatic movements such as walking, that no longer require conscious thought due to repeated practice.

How does the motor cortex control different parts of the body?

The motor cortex is organized into a 'motor homunculus,' where different areas of the motor cortex correspond to specific body parts. For example, one area controls the legs, another controls the hands, and another controls facial muscles.

What is the relationship between the motor cortex and the spinal cord?

The motor cortex sends signals through the brainstem to the spinal cord, where they synapse with motor neurons that then carry the impulses to the muscles, causing muscle contraction and voluntary movement.

What is the function of sensory neurons in the nervous system?

Sensory neurons transmit information from external stimuli or from within the body to the brain, allowing us to perceive sensations like touch, pain, temperature, and other stimuli.

How are the motor neurons of the central and peripheral nervous systems different?

Motor neurons in the central nervous system originate in the brain and spinal cord, while motor neurons in the peripheral nervous system extend from the spinal cord to muscles and other organs, facilitating movement and responses.

What is the autonomic nervous system and how does it function?

The autonomic nervous system regulates involuntary functions like breathing, heart rate, and digestion. It is divided into the sympathetic system, which stimulates activity, and the parasympathetic system, which inhibits or slows down activities.

What is the role of acetylcholine at the neuromuscular junction?

Acetylcholine is the neurotransmitter that is released at the neuromuscular junction, allowing the nerve impulse to be transferred from the motoneuron to the muscle fiber, which triggers muscle contraction.

What is an 'unità motoria' (motor unit) in the nervous system?

A motor unit consists of a single motoneuron and the group of muscle fibers it innervates. The motoneuron activates the muscle fibers, causing them to contract in response to nervous stimulation.