Human Anatomy Exam 3 Study Guide: Digestion, Respiration, Circulation, and Lymphatics

Comprehensive vocabulary flashcards covering the digestive system, respiratory anatomy, cardiovascular circulation and vessels, as well as the lymphatic and portal systems for Human Anatomy Exam 3.

Alimentary Canal (GI Tract)

The continuous muscular digestive tube extending from the mouth to the anus, through which food passes and is processed; includes the oral cavity, pharynx, esophagus, stomach, small intestine, and large intestine.

Accessory Digestive Organs

Organs that aid in mechanical or chemical digestion but do not form part of the continuous digestive tract; includes teeth, tongue, salivary glands, liver, gallbladder, and pancreas.

Salivary Amylase

An enzyme produced by the salivary glands that initiates the chemical breakdown of carbohydrates and starches in the oral cavity.

Lysozyme

An antibacterial enzyme present in saliva and other secretions that inhibits bacterial growth to protect the mouth from infection.

Bolus

A lubricated mass of chewed food mixed with saliva that is formed in the mouth and swallowed down the esophagus.

GI Tract Wall Layers

The four concentric structural tissue tunics comprising the alimentary canal wall: the inner mucosa with crypts, submucosa (containing the submucosal plexus), muscularis propria (circular and longitudinal smooth muscle separated by the myenteric plexus), and outer serosa or adventitia.

Myenteric Plexus (Auerbach's Plexus)

A major nerve supply located between the circular and longitudinal smooth muscle layers of the muscularis propria that regulates GI tract motility and peristalsis.

Submucosal Plexus (Meissner's Plexus)

A network of intrinsic autonomic nerve fibers located in the submucosa that regulates glandular secretions and localized blood flow.

Stomach Anatomy

A J-shaped digestive organ comprising the cardia, fundus, body, and pylorus, anchored by the lesser and greater omenta, and characterized internally by temporary folds called rugae.

Rugae

Large, longitudinal folds of mucosa and submucosa in an empty stomach that allow it to expand and flatten when filled with food.

Parietal Cells

Secretory cells located within gastric glands that produce hydrochloric acid ($\text{HCl}$) and intrinsic factor.

Chief Cells

Secretory cells found in the basal regions of gastric glands that synthesize and secrete the inactive enzyme precursor pepsinogen.

Chyme

The acidic, semifluid paste of partially digested food and gastric juices formed in the stomach and passed into the duodenum.

Plicae Circulares

Permanent, deep circular folds of the mucosa and submucosa in the small intestine that increase surface area and slow the passage of chyme for maximum absorption.

Lacteals

Specialized lymphatic capillaries located in the core of intestinal villi that absorb dietary lipids and fat-soluble vitamins.

Mesentery Proper

A fan-shaped fold of peritoneal membrane that suspends the jejunum and ileum from the posterior abdominal wall and carries blood vessels, nerves, and lymphatic vessels.

Greater Omentum

A large, apron-like fold of visceral peritoneum extending from the greater curvature of the stomach and draping over the intestines, storing adipose tissue and cushioning abdominal organs.

Retroperitoneal Structures

Organs positioned behind or posterior to the parietal peritoneum of the abdominal cavity, such as the kidneys, pancreas, and parts of the duodenum and ascending/descending colon.

Pancreatic Acinar Cells

Exocrine cells of the pancreas arranged in clusters that produce and secrete digestive enzymes (amylases, proteases, and lipases) into pancreatic ducts.

Conducting Zone

Respiratory structures (from the nasal cavity to the terminal bronchioles) that filter, warm, and humidify air, providing a conduit to and from the gas-exchange sites.

Respiratory Zone

The terminal site of gas exchange within the lungs, consisting of microscopic structures including respiratory bronchioles, alveolar ducts, and alveoli.

Epiglottis

An elastic cartilage flap situated at the superior opening of the larynx that folds down to close off the trachea during swallowing, preventing food or liquids from entering the airways.

Trachealis Muscle

A band of smooth muscle spanning the posterior open ends of the C-shaped tracheal cartilages, allowing tracheal constriction during coughing and accommodating esophageal expansion.

Type I Alveolar Cells

Simple squamous epithelial cells that form the predominant structural lining of the alveolar wall, optimized for rapid gas diffusion across the respiratory membrane.

Type II Alveolar Cells

Cuboidal epithelial cells scattered among the alveolar wall that secrete surfactant, reducing surface tension to prevent alveolar collapse.

Alveolar Macrophages

Phagocytic cells within the alveoli that engulf and remove inhaled dust, pathogens, and debris from the inner lung surfaces.

Eupnea

Normal, quiet, unlabored breathing at rest, primarily driven by the rhythmic contraction and relaxation of the diaphragm and external intercostal muscles.

Chemoreceptors (Respiratory)

Sensory receptors that monitor concentrations of oxygen, carbon dioxide, and hydrogen ions; categorized into central chemoreceptors in the brainstem and peripheral chemoreceptors in the carotid and aortic bodies.

Pericardium

The double-walled fibroserous sac enclosing the heart, consisting of an outer tough fibrous pericardium and an inner serous pericardium (divided into parietal and visceral layers).

Endocardium

The glistening, simple squamous epithelial inner lining of the heart chambers and valves, continuous with the endothelial lining of the major blood vessels.

Chordae Tendineae

Collagenous 'heart strings' extending from the papillary muscles to the cusps of the atrioventricular (AV) valves to prevent them from everting into the atria during ventricular contraction.

Papillary Muscles

Cone-shaped muscular projections from the ventricular walls that attach to chordae tendineae and contract during ventricular systole to anchor the AV valve leaflets.

Fossa Ovalis

An oval depression on the interatrial septum representing the closed remnant of the fetal foramen ovale.

Ductus Arteriosus

A fetal vascular shunt connecting the pulmonary trunk directly to the aorta, bypassing the non-functioning fetal lungs; closes after birth to become the ligamentum arteriosum.

Ductus Venosus

A fetal blood vessel that shunts oxygenated blood from the umbilical vein directly into the inferior vena cava, bypassing the immature liver; forms the ligamentum venosum after birth.

Heart Murmur

An abnormal heart sound generated by turbulent blood flow, typically resulting from defective, stenotic, or incompetent/regurgitant heart valves.

Tunica Media

The intermediate layer of a blood vessel wall composed primarily of circularly arranged smooth muscle cells and elastin fibers, responsible for vasoconstriction and vasodilation.

Arterioles

Small, resistance-regulating branches of arteries leading directly to capillary beds, possessing thick circular smooth muscle to adjust systemic blood pressure and local perfusion.

Continuous Capillaries

The most abundant type of capillary, featuring an uninterrupted endothelial lining with narrow intercellular clefts that permit limited passage of fluids and small solutes.

Fenestrated Capillaries

Capillaries with pores (fenestrations) in the endothelial cells that allow high-volume filtration and absorption, found in the kidneys, endocrine glands, and small intestine.

Sinusoidal Capillaries (Sinusoids)

Highly permeable, wide-bore capillaries with large fenestrations and gaps between endothelial cells, allowing large molecules and cells to pass; found in the liver, spleen, and bone marrow.

Atherosclerosis

A progressive vascular condition characterized by lipid plaque accumulation and subsequent inflammatory hardening within the tunica intima of elastic and muscular arteries.

Celiac Trunk

A major unpaired anterior visceral branch arising from the abdominal aorta just below the diaphragm ($\text{T}_{12}$) that divides to supply the stomach, liver, gallbladder, spleen, and duodenum.

Portal System

A specialized circulatory arrangement in which blood travels from one capillary bed directly through a vein into a second capillary bed before returning to the heart.

Hepatic Portal System

A venous portal system that drains nutrient-rich, deoxygenated blood from the capillary beds of the GI tract and spleen into the liver capillary sinusoids for processing.

Hypothalamic-Hypophyseal Portal System

A vascular network connecting the capillary bed of the hypothalamus to the capillary bed of the anterior pituitary gland to quickly transport regulatory releasing and inhibiting hormones.

Glymphatic System

A waste clearance pathway in the central nervous system that utilizes cerebrospinal fluid (CSF) flow along perivascular channels to eliminate metabolic wastes.

Lymphedema

Localized tissue swelling caused by the obstruction or surgical removal of lymphatic drainage pathways, resulting in the abnormal accumulation of interstitial fluid.

Thymus

A primary bilobed lymphoid organ situated in the superior mediastinum that provides an essential environment for the maturation and immunocompetence of T lymphocytes.

Spleen (White vs. Red Pulp)

A secondary lymphoid organ containing white pulp (lymphoid tissue clustered around central arteries for immune surveillance) and red pulp (splenic sinusoids and cords that destroy aged erythrocytes).

Mucosa-Associated Lymphoid Tissue (MALT)

Diffuse follicular clusters of lymphoid tissue located throughout the mucous membranes of the respiratory, digestive, and urogenital tracts to defend against foreign antigens.

Peyer's Patches

Aggregated lymphoid nodules embedded specifically within the wall of the ileum that monitor and prevent pathogenic bacteria from invading intestinal tissue.

Buboes

Grossly enlarged, tender, and inflamed lymph nodes characteristically associated with systemic infectious diseases such as the bubonic plague.