Sistema nervoso periférico - Brasil Escola

Summary

In this educational video, Professor Fred introduces the Peripheral Nervous System (PNS), explaining its structure and functions. The PNS consists of cranial and spinal nerves that connect the central nervous system to the rest of the body. It plays a crucial role in both voluntary movements and reflex actions. The video explores different types of nerves, including sensory, motor, and mixed nerves, and also covers the two divisions of the PNS: somatic and autonomic. Understanding the PNS helps clarify how our body responds to stimuli and maintains vital functions.

Takeaways

• 😀 The Peripheral Nervous System (PNS) consists of 12 pairs of cranial nerves and 31 pairs of spinal nerves.
• 😀 Cranial nerves directly connect to the brain and control functions like sight, taste, and facial movements.
• 😀 Spinal nerves connect the spinal cord to limbs and organs, playing a vital role in body function.
• 😀 Nerves in the PNS can be classified as sensory, motor, or mixed, depending on their function.
• 😀 Sensory nerves carry information from sensory receptors to the central nervous system (CNS).
• 😀 Motor nerves transmit signals from the CNS to muscles or glands to trigger action.
• 😀 Mixed nerves contain both sensory and motor functions, linking the CNS to various organs.
• 😀 Ganglia are clusters of neuron cell bodies, often found in the PNS, and they aid in processing nerve signals.
• 😀 The spinal nerves consist of two roots: the dorsal root (sensory) and the ventral root (motor).
• 😀 Reflex actions are involuntary and occur quickly, often without the brain’s involvement, to protect the body from harm.
• 😀 The PNS is divided into the somatic nervous system, which controls voluntary movements, and the autonomic nervous system, which controls involuntary actions like heartbeat and digestion.

Q & A

What is the peripheral nervous system (PNS) composed of?

The peripheral nervous system is composed of 12 pairs of cranial nerves directly linked to the brain and 31 pairs of spinal nerves connected to the spinal cord.

Why are the nerves in the peripheral nervous system described as being in pairs?

Nerves in the peripheral nervous system are in pairs because humans are bilateral, meaning each side of the body has corresponding nerves. This results in symmetric pairs of nerves on each side.

What are the three types of nerves found in the peripheral nervous system?

The three types of nerves in the peripheral nervous system are sensory nerves, motor nerves, and mixed nerves. Sensory nerves carry information to the central nervous system, motor nerves carry signals from the central nervous system to muscles or organs, and mixed nerves can perform both functions.

What is a ganglion, and where is it found in the peripheral nervous system?

A ganglion is a cluster of neuron cell bodies and can be found both within and outside the central nervous system. In the peripheral nervous system, they are often located outside the brain and spinal cord.

Can you name and describe the function of some cranial nerves mentioned in the video?

Some cranial nerves mentioned are: the olfactory nerve (sensory, responsible for smell), the optic nerve (sensory, responsible for vision), the oculomotor nerve (motor, controls eye movement), and the facial nerve (motor, controls facial muscles).

What is the function of the spinal nerves?

Spinal nerves, of which there are 31 pairs, are responsible for connecting the spinal cord to the rest of the body, allowing for both sensory and motor signals to be transmitted to and from various body parts.

What is the difference between a voluntary action and a reflex action?

A voluntary action is a conscious, controlled movement initiated by the brain, such as moving your hand to grab something. A reflex action is an involuntary, automatic response that is processed by the spinal cord and occurs without conscious thought, like pulling your hand away from a hot surface.

How does the spinal cord contribute to reflex actions?

The spinal cord plays a key role in reflex actions by processing simple stimuli and generating immediate responses, often without involving the brain. For example, touching something hot triggers a reflex to withdraw your hand before the brain processes the sensation.

What is the difference between the somatic and autonomic divisions of the peripheral nervous system?

The somatic nervous system controls voluntary movements and connects the central nervous system to skeletal muscles, while the autonomic nervous system controls involuntary actions, such as those of smooth and cardiac muscles, regulating functions like heart rate and digestion.

What are the two main types of nervous systems within the autonomic system?

The two main types of nervous systems within the autonomic system are the sympathetic and parasympathetic nervous systems. The sympathetic system prepares the body for 'fight or flight,' while the parasympathetic system helps the body rest and digest.