Videoaula 10 Sistema somatomotor (PARTE 1) - COMO MOVEMOS O NOSSO CORPO?

Summary

This lesson explores the somatomotor system, explaining how it coordinates bodily movements in response to sensory stimuli. The motor system is divided into the autonomic and somatomotor systems, with the latter controlling voluntary and involuntary movements. The process involves motor neurons, neuromuscular junctions, and muscle fibers. Reflexes, such as stretch and withdrawal reflexes, are discussed in relation to sensory receptors and interneurons. The hierarchical structure of the motor system is also outlined, from the spinal cord to the brainstem and cortex, highlighting their roles in controlling reflexes, posture, balance, and voluntary movements.

Takeaways

• 😀 The sensory system monitors everything happening in the body and the environment, but responding appropriately to stimuli is just as important. This is the role of the motor system.
• 😀 The motor system is divided into the autonomic motor system, which controls vital functions like organ function, and the somatomotor system, which coordinates body movements.
• 😀 The somatomotor system generates appropriate responses based on sensory information to ensure survival. It controls skeletal muscles through motor neurons originating in the spinal cord or brainstem.
• 😀 Muscles are controlled by somatomotor system neurons, and each muscle fiber is innervated by a motor neuron. The neuromuscular junction facilitates muscle contraction through acetylcholine.
• 😀 The motor neurons receive excitatory or inhibitory signals, some of which come from sensory system synapses, such as when you touch a hot surface, triggering a reflex.
• 😀 Reflexes can be involuntary (like pulling your hand away from a hot pan) or voluntary (like consciously lifting your arm).
• 😀 The motor system is hierarchically organized, with reflexes coordinated at the spinal cord level, while more complex voluntary movements are controlled by the brain's motor cortex.
• 😀 Reflex movements at the spinal cord level are either monosynaptic (one synapse) or involve interneurons and multiple synapses.
• 😀 The muscle spindle detects muscle stretch, sending signals to the central nervous system to maintain muscle tone and awareness of body position (proprioception).
• 😀 The Golgi tendon organ detects muscle tension during contraction, protecting muscles from injury by inhibiting excessive contraction through reflex pathways.
• 😀 Spinal reflexes like the stretch reflex, inverse stretch reflex, and withdrawal reflex all play a vital role in body movement, some being protective (like the withdrawal reflex) and others maintaining muscle tone and balance.

Q & A

What is the role of the sensory system in the body?

The sensory system monitors everything happening in the body and around it, providing the necessary information for proper responses to stimuli. It helps in perceiving various stimuli and coordinating the body’s reaction through the motor system.

What is the motor system and how does it respond to sensory input?

The motor system is responsible for generating appropriate responses to sensory input to ensure the survival of the organism. It has two subdivisions: the autonomic motor system, which controls vital organ functions, and the somatic motor system, which coordinates voluntary movements.

What is the somatic motor system responsible for?

The somatic motor system is responsible for coordinating all body movements. It controls skeletal muscles by transmitting signals from the brain and spinal cord, which leads to voluntary and involuntary movements.

How do skeletal muscles produce movement?

Skeletal muscles are responsible for movement, and they are controlled by motor neurons originating from the spinal cord or brainstem. These motor neurons transmit signals to muscle fibers, causing them to contract and produce movement.

What is the neuromuscular junction and how does it function?

The neuromuscular junction is the synapse between a motor neuron and a skeletal muscle fiber. It releases acetylcholine, which binds to receptors on the muscle fibers, increasing permeability to sodium ions, leading to depolarization and muscle contraction.

What is the role of sensory neurons in motor response?

Sensory neurons detect stimuli (such as heat from touching a hot object) and transmit signals to the spinal cord, where interneurons interact with motor neurons. This initiates reflexive muscle contractions to respond to the stimulus, like pulling the hand away from the hot object.

What is a reflex and how is it related to the spinal cord?

A reflex is an involuntary, automatic response to a stimulus. Reflexes are processed by the spinal cord, and these movements do not require conscious thought, such as when the body quickly withdraws from a painful stimulus.

How does the brain contribute to voluntary movements?

Voluntary movements are initiated by the brain, specifically the motor cortex, which sends signals to the spinal cord to activate or inhibit motor neurons. These movements are conscious and purposeful, like lifting your arm.

What are the three types of spinal reflexes mentioned in the script?

The three types of spinal reflexes discussed are: 1) The stretch reflex, which causes muscle contraction when a muscle is stretched. 2) The inverse stretch reflex, which triggers muscle relaxation in response to high tension. 3) The withdrawal reflex, which helps remove the body from harmful stimuli.

What is the function of the Golgi tendon organ and how does it protect muscles?

The Golgi tendon organ detects the tension or force generated during muscle contraction. It helps protect muscles from injury by initiating a reflex that inhibits further contraction when excessive tension is detected.