Problem 6 - Biology Today and Tomorrow with Physiology

Question

Skeletal muscles are controlled by __________ nerves. a. sympathetic b. parasympathetic c. somatic d. both a and b

Step-by-Step Solution

Answer

c. somatic

Step 1: Understand the question

We need to identify which type of nerves control skeletal muscles. Skeletal muscles are those that are attached to bones and aid in movement through voluntary control.

Step 2: Analyze the options

The options provided are: a. Sympathetic - part of the autonomic nervous system involved in 'fight or flight' responses. b. Parasympathetic - part of the autonomic nervous system involved in 'rest and digest' processes. c. Somatic - part of the peripheral nervous system responsible for voluntary movements. d. Both a and b - implying both sympathetic and parasympathetic control.

Step 3: Recall relevant information

Skeletal muscles are controlled voluntarily, which means they are controlled by nerves that are conscious and direct actions. These refer to the somatic nervous system rather than the autonomic nervous system.

Step 4: Choose the answer

Based on the involvement of the somatic nervous system in voluntary control and movement, the correct choice would be c. somatic.

Key Concepts

Skeletal Muscles

Skeletal muscles play a crucial role in our daily activities. These muscles are attached to bones, allowing us to perform a myriad of movements. They enable us to walk, jump, write, and even smile. Skeletal muscles are unique because they are striated, meaning they have a distinct banding pattern when looked at under a microscope.
Skeletal muscles work through contraction and relaxation. When a muscle contracts, it pulls on the bone, creating movement. These contractions are typically under our control, which means we decide when and how to move our bodies. Because of this, skeletal muscles are said to be under voluntary control.

Somatic Nerves

Somatic nerves are a key component of the peripheral nervous system. These nerves are responsible for carrying information from the brain and spinal cord to skeletal muscles. This enables us to perform voluntary actions like lifting a glass or scribbling notes during a lecture.

• The somatic nervous system consists of motor neurons. These neurons transmit signals from the central nervous system directly to the skeletal muscles.
• It ensures precise control over muscle movements as needed for both simple and intricate tasks.

Without somatic nerves, our ability to initiate voluntary movement would be compromised.

Voluntary Control

Voluntary control refers to the ability to consciously command our muscles to perform specific tasks. It is a defining characteristic of how skeletal muscles function. Unlike the involuntary control seen in muscles like those of the heart, skeletal muscle contractions are initiated according to our desires.
This control involves planning and executing movements:

• Planning begins in the brain where a decision to move is made.
• Signals are then sent through the somatic nerves to the targeted muscles.
• The muscles contract in response, resulting in the intended movement.

This system of voluntary control is what enables us to engage dynamically with our environment.

Peripheral Nervous System

The peripheral nervous system (PNS) is a vast network of nerves that lie outside the central nervous system, extending throughout the body. It plays a crucial role in connecting the brain and spinal cord to limbs and organs.
The PNS is divided into two main parts:

• The somatic nervous system, responsible for voluntary movements and relaying information back and forth from the brain to muscles.
• The autonomic nervous system, which controls involuntary functions like heart rate and digestion.

Thanks to the peripheral nervous system, our bodies can react and adapt to the constantly changing world around us.