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Introduction to Anatomy & Physiology

Study Guide — Introduction to Anatomy & Physiology

1.1 Compare and Contrast Anatomy and Physiology

Anatomy

  • Definition: The study of the structure of body parts and their relationships to one another.

  • Examples:

    • Studying the shape of the femur.

    • Identifying the chambers of the heart.

Physiology

  • Definition: The study of the function of body parts—how they work and carry out life-sustaining activities.

  • Examples:

    • How muscles contract.

    • How the kidneys filter blood.

Comparison

  • Aspect

    • Anatomy: Structure

    • Physiology: Function

  • Example Question:

    • Anatomy: What does it look like?

    • Physiology: How does it work?

  • Relationship:

    • Structure determines function.

    • Function reflects structure.

1.2 Structural Organization of the Body (Smallest → Largest)

  1. Chemical Level:

    • Components: Atoms & molecules (e.g., water, DNA)

  2. Cellular Level:

    • Components: Cells (e.g., muscle cell, neuron)

  3. Tissue Level:

    • Components: Groups of similar cells (e.g., muscle tissue)

  4. Organ Level:

    • Components: Two or more tissue types working together (e.g., heart, stomach)

  5. Organ System Level:

    • Components: Group of organs that perform a common function (e.g., digestive system)

  6. Organism Level:

    • Components: All systems working together as one living being (the human body)

Key Idea

  • Each level builds upon the previous one to form a functioning organism.

1.3 Body Systems — Major Components & Functions

System

Major Organs

Main Functions

Integumentary

Skin, hair, nails

Protection, temperature regulation, vitamin D synthesis

Skeletal

Bones, joints

Support, protection, blood cell formation, mineral storage

Muscular

Skeletal muscles, tendons

Movement, posture, heat generation

Nervous

Brain, spinal cord, nerves

Fast control, coordination, response to stimuli

Endocrine

Glands (pituitary, thyroid, adrenals, pancreas)

Hormone production, slower control of body functions

Cardiovascular

Heart, blood, blood vessels

Transport of gases, nutrients, wastes

Lymphatic/Immune

Lymph nodes, lymph vessels, spleen

Defense against infection, fluid return

Respiratory

Lungs, trachea, bronchi

Gas exchange (O₂ in, CO₂ out)

Digestive

Mouth, esophagus, stomach, intestines

Breakdown and absorption of nutrients

Urinary

Kidneys, bladder, urethra

Waste removal, water and electrolyte balance

Reproductive

Ovaries/testes, uterus/penis

Production of offspring, hormones

1.4 Homeostasis & Negative Feedback

Homeostasis

  • Definition: The body’s ability to maintain a stable internal environment despite external changes.

  • Normal Values = Set Points:

    • Example: Body temperature ≈ 37°C or 98.6°F

    • Example: Blood glucose ≈ 90 mg/dL

Components of a Homeostatic System

  1. Receptor (Sensor): Detects change (stimulus).

  2. Control Center: Processes information and determines response (usually the brain).

  3. Effector: Carries out response (muscle, gland).

Negative Feedback Loop

  • Definition: Mechanism that reverses a deviation from the set point to maintain balance.

  • Examples:

    • Body Temperature: If too hot → sweat → cool down.

    • Blood Sugar: If too high → insulin lowers it.

  • Characteristics:

    • Negative = Stabilizing effect; helps maintain homeostasis.

Positive Feedback (for comparison)

  • Definition: Mechanism that enhances or amplifies a change.

  • Example: Labor contractions (oxytocin release).

1.5 Hyponatremia — A Case of Homeostasis Disruption

Definition

  • Hyponatremia: Low sodium (Na⁺) concentration in the blood, excess of total body water.

  • Normal Sodium Range: 135–145 mEq/L

  • Threshold for Hyponatremia: <135 mEq/L

Causes

  • Excessive Water Intake: (dilutional hyponatremia).

  • Loss of Sodium: Via sweat, vomiting, diarrhea.

  • Certain Medications: (e.g., diuretics).

  • Kidney Dysfunction or Hormonal Imbalance: (e.g., SIADH).

Symptoms

  • Headache, nausea, confusion, muscle cramps.

  • Severe Symptoms: Seizures, coma, death.

Connection to Homeostasis

  • Sodium's Role: Crucial for maintaining fluid balance, nerve function, and muscle contraction.

  • Effects of Low Sodium Levels: When sodium levels drop, osmotic balance is disturbed → cells swell with water → dangerous effects on brain and body.

  • Feedback Mechanisms: Negative feedback may fail or be overwhelmed, disrupting homeostasis.

Quick Summary

  • Anatomy = Structure; Physiology = Function.

  • 6 Levels of Organization: Atom → Molecule → Cells → Tissue → Organ → System → Organism.

  • 11 Body Systems: Each with unique functions that work together.

  • Homeostasis: Keeps internal conditions stable via negative feedback.

  • Hyponatremia: Low sodium → disrupted fluid homeostasis → serious symptoms.