IB 131 MID 3 LEC 6

Placenta (Fetal Function)

Site of fetal gas exchange where carbon dioxide is exchanged for oxygen as fetal lungs are non-functional for respiration.

Umbilical Vein

Carries oxygenated blood from the placenta to merge with the inferior vena cava in the fetus.

Fetal Inferior Vena Cava (IVC)

Carries oxygenated or partially oxygenated blood past the liver after receiving blood from the umbilical vein.

Foramen Ovale

Interatrial shunt allowing oxygenated blood from the right atrium directly into the left atrium to bypass fetal lungs.

Fossa Ovalis

Adult structural remnant of the fetal foramen ovale that closes at birth due to thoracic pressure changes during the first breath.

Cyanosis ("Blue Babies")

Clinical condition occurring when congenital heart defects prevent proper oxygenation.

Ductus Arteriosus

Shunt transferring blood from the pulmonary trunk or right ventricle directly into the systemic aorta bypassing fetal lungs.

Ligamentum Arteriosum

Adult fibrous remnant of the fetal ductus arteriosus.

Hepatic Portal Vein

Shunts nutrient-rich blood from the small intestine directly to the liver so glucose can be stored as glycogen.

Epithelial Tissue Functions

Provides physical protection; controls permeability; provides sensory innervation; forms glands for secretion.

Epithelial Polarity (Apical vs. Basal)

Apical side faces the external environment or lumen; Basal side attaches to the basement membrane facing internal tissues.

Epithelial Vascularity & Innervation

Epithelial tissues are avascular (no direct blood vessels) but innervated (contain nerve endings).

Cilia vs. Microvilli

Microvilli increase cell surface area for absorption or secretion; Cilia move substances across the cell surface.

Basement Membrane Components

Composed of the basal lamina and reticular fibers anchoring epithelial cells to underlying connective tissue.

Simple vs. Stratified Epithelium

Simple epithelium consists of a single layer of cells; Stratified epithelium consists of multiple stacked layers.

Pseudostratified Epithelium

Single layer of columnar cells that appears multi-layered because nuclei are positioned at different heights.

Naming Stratified Epithelia

Always classified and named based on the shape of cells at the most apical (top) layer.

Simple Squamous Epithelium

Single layer of flat cells suited for rapid diffusion and filtration; lines alveoli renal glomeruli serous membranes and blood vessels.

Endothelium

Specialized simple squamous epithelium lining the interior of blood vessels.

Simple Cuboidal Epithelium

Single layer of cube-shaped cells active in secretion and absorption; lines thyroid follicles and kidney tubules.

Simple Columnar Epithelium

Single layer of tall cells functioning in absorption and secretion; lines GI tract fallopian tubes and small bronchi.

Goblet Cells

Single-cell exocrine glands embedded in columnar epithelium; 60% of cell volume contains vesicles secreting mucus.

Cystic Fibrosis

Obstructive respiratory condition caused by abnormally thick dense mucus secretions from goblet cells.

Pseudostratified Ciliated Columnar Epithelium

Lines the respiratory tract; functions in mucus secretion and sweeping debris via the mucus escalator.

Stratified Squamous Epithelium

Multiple layers of flat cells specialized for protection against abrasives; regenerates from the basal layer upward.

Keratinized vs. Non-Keratinized Stratified Squamous

Keratinized forms the outer layer of skin (epidermis); Non-keratinized lines moist friction areas like oral pharynx and esophagus.

Stratified Cuboidal Epithelium

Multiple layers of cube cells offering protection and secretion in ducts of salivary sweat and mammary glands.

Transitional Epithelium

Stratified cells capable of distension or stretching; lines the ureters urinary bladder and urethra.

Conducting vs. Respiratory Zones

Conducting zone conducts filters warms and humidifies air; Respiratory zone performs actual gas exchange.

Acid-Base Balance Role

Respiratory system disposes of carbon dioxide (CO2) to maintain blood pH balance via bicarbonate.

Nasal Conchae & Meatus

Shelves and recesses in the nasal cavity that create air turbulence to filter particulates and warm or humidify incoming air.

Nasal Cavity Epithelial Transition

Anterior nose is lined by stratified squamous epithelium; deeper nasal cavity is lined by pseudostratified ciliated columnar epithelium.

Trigeminal Nerve (CN V) in Nasal Cavity

Provides sensory innervation to nasal mucosa and triggers the sneeze reflex.

Auditory (Eustachian) Tube

Connects the nasopharynx to the middle ear to equilibrate atmospheric pressure with middle ear pressure.

Three Pharyngeal Regions

Nasopharynx (posterior to nasal cavity) Oropharynx (posterior to oral cavity) and Laryngopharynx (posterior to larynx).

Pharyngeal Constrictor Muscles

Skeletal muscles surrounding the pharynx responsible for swallowing.

Epiglottis & Glottis

Glottis is the opening into the larynx; Epiglottis is an elastic cartilage flap that swings down over the glottis during swallowing.

True Vocal Cords (Vocal Folds)

Pearly white connective tissue bands anchored to arytenoid cartilage that vibrate during exhalation to produce sound.

Vocal Pitch vs. Volume

Pitch is determined by vocal cord length or tension; Volume is determined by the force of airflow across the cords.

False Vocal Cords (Vestibular Folds)

Superior protective tissue folds in the larynx that play no role in sound production.

Trachea Structure

Supported by 16 to 20 C-shaped hyaline cartilage rings anteriorly to maintain an open airway.

Trachealis Muscle

Smooth muscle on the posterior trachea separating it from the esophagus; contracts during coughing to reduce tracheal diameter.

Carina

Internal cartilaginous ridge at the base of the trachea where it branches into primary bronchi.

Right vs. Left Lung Anatomy

Right lung has 3 lobes and horizontal or oblique fissures; Left lung has 2 lobes cardiac notch and oblique fissure.