Respiratory, Digestive, and Urinary Systems – Exam 3 Study Guide

Vocabulary flashcards covering major terms and definitions in the respiratory, digestive, and urinary systems for Exam 3 preparation.

Nasal Cavity

Filters, warms, and humidifies incoming air as the first part of the respiratory tract.

Pharynx

Muscular tube that serves as a common passageway for air and food; subdivided into naso-, oro-, and laryngopharynx.

Larynx

Voice box that routes air and food and houses the vocal cords.

Trachea

Windpipe reinforced by C-shaped hyaline cartilage rings to keep the airway patent.

Primary Bronchi

First branches of the trachea that conduct air into each lung.

Bronchioles

Small airway passages lacking cartilage that lead to the alveolar ducts.

Alveoli

Microscopic air sacs where gas exchange occurs with pulmonary capillaries.

Diaphragm

Primary skeletal muscle of inspiration that increases thoracic volume when it contracts.

Boyle’s Law

Pressure of a gas is inversely proportional to its volume (P ∝ 1/V).

Henry’s Law

Amount of gas dissolved in a liquid is proportional to its partial pressure and solubility.

Dalton’s Law

Total pressure of a mixture equals the sum of the partial pressures of each gas.

Atmospheric Pressure

Force exerted by the weight of air at sea level (~760 mm Hg).

Alveolar Pressure

Air pressure within the alveoli that drives ventilation when it differs from atmospheric pressure.

Intrapleural Pressure

Pressure within the pleural cavity; always negative to keep lungs expanded.

Lung Compliance

Measure of the lung’s distensibility; ease with which lungs expand.

Surfactant

Detergent-like secretion of type II alveolar cells that reduces surface tension and prevents alveolar collapse.

Ventilation–Perfusion Coupling

Physiologic matching of air flow to blood flow in the lungs for efficient gas exchange.

Chloride Shift

Exchange of chloride ions for bicarbonate across RBC membranes to maintain ionic balance during CO₂ transport.

Respiratory Minute Volume

Total air moved per minute; calculated as tidal volume × respiratory rate.

Medullary Respiratory Centers

Clusters of neurons in the medulla oblongata (VRG & DRG) that set basic breathing rhythm.

Pontine Respiratory Centers

Neurons in the pons that smooth the transition between inspiration and expiration.

External Respiration

Gas exchange between alveolar air and pulmonary blood.

Internal Respiration

Gas exchange between systemic capillaries and tissue cells.

Respiratory Membrane

Thin barrier consisting of alveolar epithelium, fused basement membranes, and capillary endothelium.

Altitude Sickness

Hypoxia-related condition caused by lower atmospheric pressure at high elevations.

Hemoglobin

Oxygen-binding pigment in red blood cells that also carries some CO₂.

Tidal Volume (TV)

Amount of air inhaled or exhaled during normal quiet breathing (~500 mL).

Inspiratory Reserve Volume (IRV)

Extra air that can be inhaled after a normal inspiration.

Expiratory Reserve Volume (ERV)

Extra air that can be exhaled after a normal expiration.

Residual Volume (RV)

Air remaining in lungs after maximal exhalation.

Vital Capacity (VC)

Total exchangeable air; TV + IRV + ERV.

Total Lung Capacity (TLC)

Sum of all lung volumes; VC + RV.

surface tension

is the force created by the thin layer of fluid lining the inside of the alveoli that causes the alveoli to want to shrink or collapse

The force create by the thin layer of fluid lining the inside of the alveoli that causes the alveoli to want to shrink or collapse

Digestive System

Organs that ingest, digest, absorb nutrients, and expel waste.

Mucosa

Innermost lining of the alimentary canal involved in secretion and absorption.

Submucosa

Connective tissue layer containing blood vessels, nerves, and glands in the GI tract.

Muscularis Externa

Smooth muscle layer responsible for peristalsis and segmentation.

Serosa

Outer visceral peritoneum covering most digestive organs.

Hepatic Portal Circulation

Vascular system that directs nutrient-rich blood from GI tract to the liver for processing.

Circular Folds

Permanent folds of the small intestine that increase surface area for absorption.

Villi

Finger-like projections of mucosa in the small intestine that contain blood and lymph capillaries.

Microvilli

Cytoplasmic extensions of enterocytes forming the brush border to maximize absorption.

Parotid Gland

Largest salivary gland located anterior to the ear; secretes enzyme-rich saliva.

Submandibular Gland

Salivary gland beneath the mandible producing mixed (serous & mucous) saliva.

Sublingual Gland

Smallest major salivary gland under the tongue; secretes mostly mucous saliva.

Saliva

Digestive fluid that moistens food and contains amylase, mucus, and antimicrobial agents.

Intrinsic Factor

Gastric glycoprotein essential for vitamin B₁₂ absorption in the ileum.

Amylase

Enzyme that breaks down starch into sugars; produced by salivary glands and pancreas.

Lipase

Enzyme that hydrolyzes triglycerides into fatty acids and monoglycerides.

Bile

Liver secretion stored in the gallbladder that emulsifies fats for digestion.

Parietal Cell

Gastric gland cell that secretes HCl and intrinsic factor.

Chief Cell

Gastric gland cell that secretes pepsinogen and gastric lipase.

Mucous Neck Cell

Gastric cell that produces acidic mucus to protect the stomach lining.

Enteroendocrine Cell

Gastrointestinal cell releasing hormones (e.g., gastrin) that regulate digestion.

Goblet Cell

Mucus-secreting epithelial cell found throughout the GI tract.

Haustra

Pouches of the large intestine created by teniae coli contraction.

Which type of muscle moves food through the digestive tract?

Smooth muscle

Peristalsis

Wave-like contractions that move food along the digestive tract.

Segmentation

rhythmic contractions that mix and churn the food in the intestines, breaking it into smaller pieces and mixing it with digestive juices without pushing it forward much.

Cephalic Phase

Triggered by the sight, smell, taste, or thought of food; the brain signals the stomach to prepare for digestion by increasing secretion of gastric juices. First stage of digestion

Gastric Phase

Begins when food enters the stomach; stomach distension and presence of proteins stimulate the release of gastric juices, including acid and enzymes.

Intestinal Phase

Starts when chyme enters the small intestine; it regulates gastric secretion through hormones and nervous reflexes to slow stomach emptying and digestion.

Rugae

folds in the mucosa and submucosa layers of the stomach lining that allow the stomach to expand when it fills with food.

The liver is composed of cells called

Hepatocyte

Hepatic Portal Triad

Group of three vessels—hepatic artery, portal vein, and bile duct—at the liver lobule corners.

Cystic Duct

Duct through which bile leaves the gallbladder to join the common bile duct.

Common Bile Duct

Duct carrying bile from liver and gallbladder to the duodenum.

Carbohydrate Digestion

Breakdown of polysaccharides by amylases into simple sugars (glucose) for absorption.

Protein Digestion

Hydrolysis of proteins by pepsin and pancreatic proteases into amino acids.

Lipid Digestion

Emulsification by bile and hydrolysis by lipase into fatty acids and monoglycerides.

Nucleic Acid Digestion

Breakdown by pancreatic nucleases into nucleotides and nitrogenous bases.

Kidney

Organ that filters blood, forms urine, and regulates fluid, electrolyte, and acid-base balance.

Ureter

Muscular tube that transports urine from the kidney to the bladder using peristalsis

Urinary Bladder

Distensible organ that stores urine; lined by transitional epithelium.

Transitional Epithelium

Stretchy epithelium lining the urinary bladder and ureters.

Glomerulus

Fenestrated capillary knot in the nephron where filtration occurs.

Glomerular (Bowman’s) Capsule

Cup-shaped structure that encases the glomerulus and captures filtered fluid (filtrate.)

Nephron

Structural and functional unit of the kidney because they filter the liquid waste products out of the blood.

What triggers the initiation of Micturition?

stretch receptors in the bladder wall detecting when the bladder is full. This sends nerve signals to the spinal cord and brain, prompting the urge to urinate and causing the bladder muscles to contract.

Aquaporin

A membrane protein that forms channels in the cell membrane to facilitate the transport of water molecules in and out of the cell.

Macula Densa

Chemoreceptor cells in the juxtaglomerular apparatus that monitor NaCl in filtrate.

Diuretic

Substance that increases urine output by inhibiting water reabsorption; alcohol blocks ADH and acts as one.

Angiotensin II

Hormone that raises blood pressure via vasoconstriction; constricts blood vessels and stimulates aldosterone release.

Aldosterone

Adrenal cortex hormone promoting Na⁺ (sodium) reabsorption and water retention in the kidneys.

Atrial Natriuretic Peptide (ANP)

Decreases blood pressure by promoting sodium and water excretion.

Antidiuretic Hormone (ADH)

Increases water reabsorption in kidneys to concentrate urine and conserve water.

Fenestrated Capillary

Capillary with pores that allow high filtration; typifies glomerular capillaries.

Podocyte

A kidney cell with foot-like extensions that help filter blood in the glomerulus.

Net Filtration

The pressure responsible for moving fluid out of the capillaries and into the surrounding space, such as from the glomerulus into the nephron. It is the balance between forces that promote and oppose filtration.

Urology

Medical study of the urinary system.

Polyuria

Excessive urine output (>2.5 L/day).

Oliguria

Abnormally low urine output (<500 mL/day).

Anuria

Virtually no urine output (<50 mL/day).

Cortical Nephron

Located mostly in the renal cortex with a short nephron loop that barely dips into the medulla. They primarily handle filtration and reabsorption and make up about 85% of all nephrons.

Juxtamedullary Nephron

Located near the cortex-medulla junction with a long nephron loop that extends deep into the medulla. They are important for producing concentrated urine and maintaining the body’s water balance.

Glomerular Filtration

First step of urine formation where plasma is filtered into Bowman’s capsule.

Tubular Reabsorption

Process of reclaiming water and solutes from filtrate back into the blood.

Tubular Secretion

Addition of substances from blood into the filtrate for excretion.

Explain the pressure changes that occur to bring air into our lungs.

Breathing in (inhalation) is driven by pressure changes based on Boyle’s Law. As volume increases, pressure decreases.

Explain the pressure changes that occur to push air out of our lungs

as volume decreases, pressure increases