Anatomy & Physiology Exam 3 Study Guide – Step-by-Step Guidance

Q1. What is the somatic nervous system? Compare and contrast it with the autonomic nervous system.

Background

Topic: Nervous System Divisions

This question tests your understanding of the organization and function of the somatic and autonomic nervous systems, which are subdivisions of the peripheral nervous system.

Key Terms:

• Somatic Nervous System (SNS): Controls voluntary movements via skeletal muscles.

• Autonomic Nervous System (ANS): Regulates involuntary functions (e.g., heart rate, digestion).

Step-by-Step Guidance

1. Start by defining the somatic nervous system, focusing on its main function and the type of effectors it controls.

2. Define the autonomic nervous system, noting its primary functions and the effectors it targets.

3. List at least two similarities between the SNS and ANS (e.g., both are part of the peripheral nervous system).

4. Identify at least two key differences, such as voluntary vs. involuntary control, and the types of muscles or glands each system innervates.

5. Consider how the pathways differ (e.g., number of neurons from CNS to effector).

Try solving on your own before revealing the answer!

Final Answer:

The somatic nervous system is the part of the peripheral nervous system that controls voluntary movements by innervating skeletal muscles. In contrast, the autonomic nervous system regulates involuntary functions by controlling smooth muscle, cardiac muscle, and glands.

• Similarities: Both are subdivisions of the peripheral nervous system and involve motor pathways.

• Differences: The SNS uses a single motor neuron to connect the CNS to skeletal muscle (voluntary), while the ANS uses a two-neuron chain (preganglionic and postganglionic) to reach involuntary effectors (smooth/cardiac muscle, glands).

The SNS is responsible for conscious movement, while the ANS manages automatic body functions.

Q2. Describe three features of a somatic motor pathway.

Background

Topic: Motor Pathways

This question focuses on the anatomical and functional characteristics of the pathway that carries signals from the CNS to skeletal muscles.

Key Terms:

• Somatic Motor Neuron: The neuron that directly innervates skeletal muscle fibers.

• Neuromuscular Junction: The synapse between a motor neuron and a muscle fiber.

Step-by-Step Guidance

1. Identify the number of neurons involved in the somatic motor pathway from the CNS to the effector.

2. Describe the neurotransmitter released at the neuromuscular junction and its effect.

3. Explain the specificity of the target (i.e., which tissue is innervated).

4. Consider the nature of the response (excitatory or inhibitory).

Try solving on your own before revealing the answer!

Final Answer:

• The somatic motor pathway uses a single, myelinated motor neuron to connect the CNS to skeletal muscle.

• Acetylcholine is released at the neuromuscular junction, always causing excitation of the muscle fiber.

• The pathway is highly specific, targeting only skeletal muscle fibers for voluntary movement.

These features ensure rapid, precise, and voluntary control of skeletal muscles.

Q3. What are the three types of muscles? Compare and contrast their basic appearance and control.

Background

Topic: Muscle Tissue Types

This question tests your knowledge of the structural and functional differences among skeletal, cardiac, and smooth muscle tissues.

Key Terms:

• Skeletal Muscle: Striated, voluntary control.

• Cardiac Muscle: Striated, involuntary control, found in the heart.

• Smooth Muscle: Non-striated, involuntary control, found in walls of hollow organs.

Step-by-Step Guidance

1. List the three types of muscle tissue.

2. For each type, describe its appearance under the microscope (striated or not).

3. State whether each type is under voluntary or involuntary control.

4. Identify the main locations where each muscle type is found.

5. Note any unique features (e.g., intercalated discs in cardiac muscle).

Try solving on your own before revealing the answer!

Final Answer:

• Skeletal muscle: Striated, voluntary, attached to bones.

• Cardiac muscle: Striated, involuntary, found only in the heart, contains intercalated discs.

• Smooth muscle: Non-striated, involuntary, found in walls of hollow organs (e.g., intestines, blood vessels).

Striations are due to the arrangement of actin and myosin; only skeletal muscle is under conscious control.

Q4. Describe flexor-extensor pairs (antagonistic muscle groups).

Background

Topic: Muscle Actions

This question examines your understanding of how muscles work in pairs to produce movement at joints.

Key Terms:

• Flexor: A muscle that decreases the angle at a joint.

• Extensor: A muscle that increases the angle at a joint.

• Antagonistic Pair: Muscles that produce opposite actions at a joint.

Step-by-Step Guidance

1. Define what is meant by a flexor and an extensor muscle.

2. Explain how these muscles are arranged around a joint.

3. Describe how contraction of one muscle leads to relaxation of its antagonist.

4. Give a common example (e.g., biceps and triceps at the elbow).

Try solving on your own before revealing the answer!

Final Answer:

Flexor-extensor pairs are antagonistic muscle groups that produce opposite movements at a joint. For example, the biceps (flexor) bends the elbow, while the triceps (extensor) straightens it. When one contracts, the other relaxes, allowing smooth and controlled movement.

Q5. Understand skeletal muscle terminology and basic organization (Table 12.1).

Background

Topic: Skeletal Muscle Structure

This question is about the hierarchical organization and terminology used to describe skeletal muscle anatomy.

Key Terms:

• Muscle fiber: A single muscle cell.

• Myofibril: Bundles of contractile proteins within a muscle fiber.

• Sarcomere: The functional contractile unit of a myofibril.

• Fascicle: A bundle of muscle fibers.

Step-by-Step Guidance

1. Start by listing the levels of organization from largest to smallest (muscle, fascicle, fiber, myofibril, sarcomere).

2. Define each term and its role in muscle structure.

3. Identify the connective tissue layers (epimysium, perimysium, endomysium) and which structures they surround.

4. Relate these terms to the function of skeletal muscle contraction.

Try solving on your own before revealing the answer!

Final Answer:

Skeletal muscle is organized as follows: the whole muscle is made of bundles called fascicles, each fascicle contains muscle fibers (cells), each fiber contains myofibrils, and myofibrils are made up of repeating sarcomeres. Connective tissue layers (epimysium, perimysium, endomysium) provide support and organization.