BIOL 2111A Final Lab Study Guide: Muscular and Nervous Systems

Muscular System

Overview of Major Muscles and Functions

The muscular system consists of specialized tissues responsible for movement, posture, and heat production. Key muscles and their functions are essential for understanding human anatomy.

• Sartorius: The longest muscle in the human body; involved in hip and knee flexion.

• Biceps Brachii: Anterior upper arm muscle; flexes elbow and supinates forearm.

• Pectoralis Major: Large chest muscle; adducts and medially rotates the humerus.

• Gastrocnemius: Calf muscle; plantar flexes the foot.

• Adductor Tendon: Connects adductor muscles to the skeleton; provides strong tension for movement.

Example: The biceps brachii is commonly used when lifting objects, as it flexes the elbow joint.

Muscle Group Classification

• Muscles are grouped based on their anatomical location and function (e.g., flexors, extensors).

• Muscle tissue types include skeletal, cardiac, and smooth muscle.

Additional info: Skeletal muscles are voluntary and striated, while cardiac muscle is involuntary and striated, and smooth muscle is involuntary and non-striated.

Nervous System & Neuron Structures

Neuron Anatomy

Neurons are the basic functional units of the nervous system, responsible for transmitting electrical signals throughout the body.

• Olfactory Nerve: Cranial nerve I; responsible for the sense of smell.

• Optic Nerve: Cranial nerve II; transmits visual information from the retina to the brain.

• Other Cranial Nerves: Include facial, vestibulocochlear, and accessory nerves, each with specific sensory or motor functions.

Example: Damage to the optic nerve can result in loss of vision.

Brain Anatomy Overview

The brain is divided into several regions, each with distinct functions:

• Cerebral Cortex: Responsible for higher cognitive functions, sensory perception, and voluntary motor actions.

• Medulla Oblongata: Controls breathing, heart rate, and autonomic functions.

• Frontal Lobe: Involved in motor control, decision making, and personality.

• Reflex Pathways: Automatic responses to stimuli, such as the withdrawal reflex.

Additional info: The cerebellum coordinates voluntary movements and maintains posture and balance.

Spinal Cord Anatomy

Structural Features

The spinal cord is a major conduit for information between the brain and peripheral nervous system.

• Dorsal Horn: Contains sensory neurons.

• Ventral Horn: Contains motor neurons.

• Gray Commissure: Connects the two sides of the spinal cord.

• Central Canal: Contains cerebrospinal fluid.

Ascending and Descending Tracts: Ascending tracts carry sensory information to the brain; descending tracts carry motor commands from the brain to the body.

Special Senses

Eye Anatomy

The eye is a complex organ responsible for vision, consisting of several key structures:

• Cornea: Transparent front part of the eye; refracts light.

• Optic Nerve: Transmits visual information to the brain.

• Retina: Contains photoreceptor cells (rods and cones) that detect light.

• Aqueous Humor: Fluid in the anterior chamber; maintains intraocular pressure.

Example: The retina converts light into neural signals for visual perception.

Auditory System & Reflexes

The auditory system detects sound and maintains balance.

• Tuning Fork: Used in Weber and Rinne tests to assess hearing function.

• Auditory Reflexes: Involuntary responses to sound stimuli, such as the startle reflex.

Autonomic Nervous System (ANS)

Sympathetic and Parasympathetic Divisions

The ANS regulates involuntary body functions, including heart rate, digestion, and respiratory rate.

• Sympathetic Division: Prepares the body for 'fight or flight' responses; increases heart rate, dilates pupils.

• Parasympathetic Division: Promotes 'rest and digest' activities; slows heart rate, stimulates digestion.

Example: The sympathetic division is activated during stressful situations, while the parasympathetic division is active during relaxation.

ANS Pathways

• Preganglionic neurons originate in the CNS and synapse with postganglionic neurons in peripheral ganglia.

• Postganglionic neurons transmit signals to target organs.

Additional info: Neurotransmitters such as acetylcholine and norepinephrine mediate ANS responses.

HTML Table: Major Muscles and Their Functions

Muscle	Location	Primary Function
Sartorius	Anterior thigh	Hip and knee flexion
Biceps Brachii	Upper arm	Elbow flexion, forearm supination
Pectoralis Major	Chest	Arm adduction, medial rotation
Gastrocnemius	Calf	Plantar flexion of foot

Key Equations and Concepts

• Nerve Impulse Transmission:

$V = IR$

Where V is voltage, I is current, and R is resistance. This equation describes the relationship between electrical potential and current in neurons.

• Muscle Contraction:

$F = m imes a$

Where F is force, m is mass, and a is acceleration. This equation is relevant for understanding the mechanics of muscle movement.