Respiratory, Digestive, Immune & Lymphatic Systems – Exam 2 Study Guide

Vocabulary flashcards covering key respiratory, digestive, immune, and lymphatic concepts for Exam 2 preparation.

Forced Vital Capacity (FVC)

Maximum amount of air forcibly exhaled after the deepest possible inhalation.

Forced Expiratory Volume (FEV)

Volume of air that can be forcibly exhaled during a specified interval of an FVC test (e.g., 1 s, 2 s).

FEV1

Volume of air exhaled in the first second of a forced breath; used to detect airway obstruction.

Tidal Volume (TV)

Air inhaled or exhaled during a normal quiet breath (~500 mL in adults).

Inspiratory Reserve Volume (IRV)

Additional air that can be inhaled after a normal inspiration.

Expiratory Reserve Volume (ERV)

Additional air that can be forcibly exhaled after a normal expiration.

Residual Volume (RV)

Air remaining in lungs after maximal exhalation; prevents alveolar collapse.

Inspiratory Capacity (IC)

Total air inhaled after a normal exhalation (IC = TV + IRV).

Functional Residual Capacity (FRC)

Air remaining in lungs after a normal exhalation (FRC = ERV + RV).

Vital Capacity (VC)

Maximum amount of air exhaled after a maximal inhalation (VC = TV + IRV + ERV).

Total Lung Capacity (TLC)

Total lung volume after maximal inspiration (TLC = VC + RV).

Cooperative Binding

Phenomenon where binding of one O₂ to hemoglobin increases affinity for additional O₂ molecules.

Inspiration (Quiet)

Diaphragm contracts and external intercostals lift ribs, increasing thoracic volume and lowering intrapulmonary pressure.

Expiration (Quiet)

Passive relaxation of diaphragm and intercostals; thoracic volume decreases and air flows out.

Forced Expiration

Active process using internal intercostals and abdominal muscles to expel air forcefully.

Diaphragm

Primary muscle of inspiration innervated by the phrenic nerve.

External Intercostal Muscles

Muscles that elevate ribs during quiet inspiration.

Sternocleidomastoid

Accessory muscle that elevates sternum during forced inspiration.

Scalene Muscles

Accessory neck muscles that elevate first two ribs during forced inspiration.

Internal Intercostal Muscles

Muscles that depress ribs during forced expiration.

Abdominal Muscles (Expiration)

Muscles that increase intra-abdominal pressure to push diaphragm upward during forced expiration.

Central Chemoreceptors

Receptors in medulla sensitive to CO₂-induced pH changes in cerebrospinal fluid.

Peripheral Chemoreceptors

Receptors in carotid and aortic bodies sensitive to ↓O₂, ↑CO₂, and ↓pH.

Secondary Bronchi (Right)

Three branches serving the three lobes of the right lung.

Secondary Bronchi (Left)

Two branches serving the two lobes of the left lung.

Ventral Respiratory Group (VRG)

Medullary center that sets basic respiratory rhythm and drives forced breathing.

Dorsal Respiratory Group (DRG)

Medullary center that integrates sensory input and modifies VRG output.

Pneumotaxic Center

Pontine center that inhibits inspiration, helping switch to expiration.

Apneustic Center

Pontine center that promotes prolonged deep inspiration by stimulating DRG.

Mucociliary Escalator

Coordinated movement of cilia transporting mucus and trapped debris toward the pharynx.

Goblet Cells (Respiratory)

Mucus-secreting cells that trap dust and microbes in conducting airways.

Alveolar Pores

Openings between alveoli that equalize air pressure and provide alternate air routes.

Respiratory Membrane

Barrier for gas exchange consisting of alveolar epithelium, fused basement membrane, and capillary endothelium.

External Respiration

Gas exchange between alveoli and pulmonary capillary blood.

Internal Respiration

Gas exchange between systemic capillaries and body tissues.

Cellular Respiration

Metabolic use of O₂ by cells to produce ATP, generating CO₂.

Carbonic Anhydrase

Enzyme in RBCs that converts CO₂ + H₂O ↔ H₂CO₃, enabling bicarbonate transport.

Chloride Shift

Exchange of HCO₃⁻ out of and Cl⁻ into RBCs to maintain charge balance during CO₂ transport.

Bohr Effect

Right shift of hemoglobin dissociation curve promoting O₂ unloading at tissues due to ↑CO₂ or ↓pH.

Type I Alveolar Cells

Thin epithelial cells forming most of alveolar wall; primary site of gas exchange.

Type II Alveolar Cells

Cuboidal cells secreting surfactant to reduce surface tension.

Anatomical Dead Space

Air in conducting zones where no gas exchange occurs (~150 mL).

Alveolar Dead Space

Air in non-functional or poorly perfused alveoli.

Physiological Dead Space

Sum of anatomical and alveolar dead space; increases in lung disease.

Ventilation-Perfusion Matching

Physiological adjustment of blood flow and airflow to optimize gas exchange.

Hering–Breuer Inflation Reflex

Stretch receptor reflex that inhibits inspiration to prevent lung over-inflation.

Tracheal Cartilage Rings

C-shaped hyaline cartilages that keep trachea open while allowing esophageal expansion posteriorly.

Pyloric Sphincter

Valve controlling passage of chyme from stomach to duodenum.

Duodenal Bicarbonate

Alkaline secretion (primarily pancreatic) that neutralizes acidic chyme for optimal enzyme activity.

SGLT-1

Sodium-glucose symporter on intestinal apical membrane that actively transports glucose and Na⁺ into enterocytes.

GLUT2

Facilitated diffusion transporter moving glucose across basolateral membrane into blood.

Chylomicron

Lipoprotein particle transporting triglycerides from intestinal cells into lymph.

Pepsin

Stomach endopeptidase activated from pepsinogen by HCl; begins protein digestion.

Trypsin

Pancreatic endopeptidase activated from trypsinogen by enteropeptidase; activates other zymogens.

Chymotrypsin

Pancreatic endopeptidase activated by trypsin; digests proteins in small intestine.

Carboxypeptidase

Pancreatic exopeptidase activated by trypsin; removes amino acids from peptide ends.

Zymogen

Inactive enzyme precursor stored to prevent autodigestion (e.g., trypsinogen).

Peristalsis

Propulsive wave-like contractions moving food along the GI tract.

Segmentation

Mixing contractions in small intestine that churn chyme and enhance absorption.

Upper Esophageal Sphincter

Muscular ring preventing air entry into esophagus during breathing.

Lower Esophageal Sphincter

Ring at gastroesophageal junction preventing acid reflux into esophagus.

Visceral Pleura

Serous membrane covering lung surfaces.

Parietal Pleura

Serous membrane lining thoracic cavity walls.

Pleural Fluid

Thin fluid layer creating surface tension that links visceral and parietal pleurae together.

Chief Cells

Stomach cells that secrete pepsinogen.

Parietal Cells

Stomach cells that secrete hydrochloric acid and intrinsic factor.

G Cells

Endocrine stomach cells that release gastrin to stimulate gastric secretion.

Mucosa (GI)

Innermost alimentary canal layer; secretes mucus, enzymes, and absorbs nutrients.

Submucosa

Connective tissue layer housing blood vessels, lymphatics, and the submucosal nerve plexus.

Muscularis Externa

Circular and longitudinal smooth muscle layers responsible for GI motility.

Serosa

Protective outer visceral peritoneum of the alimentary canal.

Lacteals

Lymphatic capillaries in intestinal villi that absorb chylomicrons (dietary fats).

Cell-Mediated Immunity

Adaptive response employing T cells to destroy infected or abnormal cells; no antibody secretion.

Humoral Immunity

Adaptive response where B cells produce antibodies that neutralize pathogens in body fluids.

Plasma Cell

Differentiated B cell that secretes large quantities of specific antibodies.

Antigen Receptor

Specific membrane-bound protein on B or T cells that binds a particular antigen.

Epitope

Discrete antigenic determinant recognized by an antibody or lymphocyte receptor.

Helper T Cell (CD4+)

Lymphocyte that releases cytokines to activate B cells, cytotoxic T cells, and macrophages.

Cytotoxic T Cell (CD8+)

T cell that kills virus-infected or abnormal cells via perforin and granzymes.

Classical Complement Pathway

Complement activation triggered by antigen-antibody complexes leading to opsonization, inflammation, and MAC formation.

Natural Acquired Active Immunity

Immunity from natural infection that produces memory cells (e.g., after chickenpox).

Artificially Acquired Active Immunity

Immunity from vaccination stimulating memory cell formation.

Natural Acquired Passive Immunity

Temporary immunity from maternal antibodies via placenta or breast milk.

Artificially Acquired Passive Immunity

Temporary immunity from injected antibodies such as antivenom or monoclonals.

Variable Region (Antibody)

Antibody portion that binds specific antigen epitopes; differs among antibodies.

Constant Region (Antibody)

Identical region within an antibody class that determines effector function and isotype.

Perforin

Protein released by cytotoxic T and NK cells that forms pores in target cell membranes.

Granzymes

Serine proteases entering target cells via perforin pores to trigger apoptosis.

Primary Immune Response

Initial adaptive response to first antigen exposure; slow, low antibody titer.

Secondary Immune Response

Rapid, strong antibody response upon re-exposure due to memory cells.

Natural Killer (NK) Cell

Innate lymphocyte that kills virus-infected or tumorous cells without prior sensitization.

Inflammation

Innate response characterized by redness, heat, swelling, pain, and loss of function to limit injury and recruit defenses.

IgG

Most abundant antibody; crosses placenta to confer fetal immunity.

IgA

Antibody in mucosal secretions such as breast milk, saliva, and tears.

IgM

First antibody produced in primary response; pentameric structure effective at agglutination.

IgE

Antibody involved in allergic reactions and defense against parasites.

IgD

Surface antibody on naïve B cells; exact function unclear.

Lymphedema

Chronic swelling caused by impaired lymphatic drainage due to blockage or removal of vessels/nodes.

Afferent Lymphatic Vessel

Vessel that delivers lymph into a lymph node.

Efferent Lymphatic Vessel

Vessel that carries filtered lymph away from a lymph node.