Study Guide: Lymphatic, Immune, Respiratory, and Digestive Systems

Chapter 20: The Lymphatic System

Structures and Functions of the Lymphatic System

The lymphatic system is a network of vessels, nodes, and organs that helps maintain fluid balance, protects the body from infection, and absorbs fats from the digestive tract.

• Main Structures: Lymphatic vessels, lymph nodes, spleen, thymus, tonsils, and Peyer's patches.

• Functions:

  • Returns interstitial fluid and leaked plasma proteins to the blood.

  • Transports dietary fats from the gastrointestinal tract to the blood.

  • Provides sites for immune surveillance and lymphocyte activation.

• Direction of Flow: Lymph flows in one direction—toward the heart—via lymphatic capillaries, vessels, trunks, and ducts.

Example: Lymph nodes filter lymph, trapping pathogens and foreign particles.

Chapter 21: The Immune System

Basic Components and Functions

The immune system defends the body against pathogens through innate (nonspecific) and adaptive (specific) mechanisms.

• Innate Immunity: Physical barriers (skin, mucous membranes), phagocytes, natural killer cells, inflammation, fever, and antimicrobial proteins.

• Adaptive Immunity: Involves lymphocytes (B cells and T cells) and the production of antibodies.

B Cells and T Cells

• B Cells: Lymphocytes that mature in the bone marrow; responsible for humoral immunity by producing antibodies.

• T Cells: Lymphocytes that mature in the thymus; responsible for cell-mediated immunity by directly attacking infected or abnormal cells.

Example: Upon encountering an antigen, B cells differentiate into plasma cells that secrete antibodies, while T cells may become cytotoxic T cells that destroy infected cells.

Chapter 22: The Respiratory System

Gas Transport and Exchange

The respiratory system facilitates the exchange of oxygen and carbon dioxide between the atmosphere and the blood.

• Gas Exchange: Occurs in the alveoli by diffusion across the respiratory membrane.

• Oxygen Transport: Most oxygen is carried by hemoglobin in red blood cells; a small amount is dissolved in plasma.

• Carbon Dioxide Transport: Transported as bicarbonate ions, bound to hemoglobin, or dissolved in plasma.

Equation for Bicarbonate Formation:

$\mathrm{CO_2 + H_2O \rightarrow H_2CO_3 \rightarrow H^+ + HCO_3^-}$

Lung Structure and Location

• Lungs: Paired organs in the thoracic cavity, separated by the mediastinum.

• Lobes: Right lung has three lobes; left lung has two lobes and a cardiac notch.

Parts of the Respiratory System and Pathway

• Pathway of Air: Nasal cavity → Pharynx → Larynx → Trachea → Bronchi → Bronchioles → Alveoli

Innervation, Blood Flow, and Mechanism

• Innervation: Autonomic nervous system regulates airway diameter and respiratory rate.

• Blood Flow: Pulmonary arteries carry deoxygenated blood to the lungs; pulmonary veins return oxygenated blood to the heart.

• Mechanism: Breathing involves diaphragm and intercostal muscles; inspiration is active, expiration is usually passive.

Palate and Sinuses

• Palate: Separates the nasal and oral cavities; consists of hard and soft palate.

• Sinuses: Air-filled spaces in the skull that lighten the head and warm/moisten air.

Larynx and Trachea

• Larynx: Voice box; contains vocal cords and is involved in sound production and airway protection.

• Trachea: Windpipe; reinforced with C-shaped cartilage rings to maintain airway patency.

Bronchi, Alveoli Tissue, Bronchioles, Blood Oxygenation

• Bronchi: Main passageways into the lungs; branch into smaller bronchioles.

• Alveoli: Tiny air sacs composed of simple squamous epithelium for efficient gas exchange.

• Bronchioles: Smallest airways lacking cartilage; control airflow resistance.

• Blood Oxygenation: Occurs as blood passes through pulmonary capillaries surrounding alveoli.

Oxygen Circulation

• Oxygen enters alveoli, diffuses into capillaries, binds to hemoglobin, and is transported to tissues.

Zones, Gross and Fine Anatomy

• Conducting Zone: Includes all respiratory passages that carry air to the sites of gas exchange (nose to terminal bronchioles).

• Respiratory Zone: Site of gas exchange (respiratory bronchioles, alveolar ducts, alveoli).

Pleura and Ventilation, Mechanism, Muscles

• Pleura: Double-layered serous membrane (parietal and visceral) surrounding each lung.

• Ventilation Mechanism: Involves changes in thoracic volume and pressure; diaphragm and external intercostals are primary muscles.

Equation for Boyle's Law (Ventilation):

$P_1V_1 = P_2V_2$

Basic Gas Exchange and Oxygen Transport

• Oxygen diffuses from alveoli to blood; carbon dioxide diffuses from blood to alveoli.

• Hemoglobin saturation depends on partial pressure of oxygen ($P_{O_2}$).

Chapter 23: The Digestive System

Major Structures and Layers

The digestive system breaks down food, absorbs nutrients, and expels waste. It consists of the alimentary canal and accessory organs.

• Major Structures: Mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, anus.

• Accessory Organs: Teeth, tongue, salivary glands, liver, gallbladder, pancreas.

• Layers of GI Tract (from inner to outer):

  • Mucosa

  • Submucosa

  • Muscularis externa

  • Serosa (or adventitia)

Tooth Basics

• Types of Teeth: Incisors, canines, premolars, molars.

• Functions: Cutting, tearing, and grinding food.

• Structure: Crown (exposed), root (embedded in jaw), enamel (hardest substance), dentin, pulp cavity.

Process of Digestion: Esophagus to Expulsion

• Esophagus: Muscular tube transporting food from pharynx to stomach via peristalsis.

• Stomach: Mixes and churns food with gastric juices to form chyme.

• Small Intestine: Main site of digestion and absorption; consists of duodenum, jejunum, ileum.

• Large Intestine: Absorbs water and electrolytes; forms and expels feces.

• Expulsion: Defecation reflex eliminates waste through the anus.

Nerve, Blood, and Nutrient Supply

• Nerve Supply: Enteric nervous system regulates GI motility; autonomic nervous system modulates activity.

• Blood Supply: Splanchnic circulation delivers blood to digestive organs; hepatic portal system carries nutrient-rich blood to the liver.

• Nutrient Absorption: Occurs mainly in the small intestine via villi and microvilli.

Digestive System Figures (Lab Study)

• Teeth and Digestive Organs: Identification of structures in the head and abdominal cavity (referenced figures: 23.1, 23.5, 23.6, 23.8, 23.9, 23.10, 23.11, 23.12).

• Esophagus: Structure and histology (referenced figures: 23.13, 23.14, 23.15, 23.16, 23.18).

Additional info: For detailed identification, refer to labeled diagrams in your textbook or lab manual as indicated by the figure numbers.