BIOL 236 Lab Exam 5 Study Guide Flashcards

Dental Anatomy and Hepatobiliary Function

• Anatomy of the Human Tooth:     

• * Crown: The visible portion of the tooth located above the gum line (gingiva).     

• * Enamel: The outermost layer of the crown; it is the hardest substance in the human body and protects the tooth from wear and tear.     

• * Dentin: The calcified tissue located beneath the enamel, making up the bulk of the tooth's structure.     

• * Pulp Cavity: The central chamber containing pulp, which consists of connective tissue, blood vessels, and nerves.    

•  * Root: The portion of the tooth embedded within the alveolar bone of the jaw.     

• * Root Canal: The narrow extension of the pulp cavity that runs through the root to the base of the tooth.     

• * Cementum: A bone-like substance covering the root that helps attach the tooth to the periodontal ligament.     

• * Periodontal Ligament: The fibrous connective tissue that anchors the tooth root into the bony socket.

• Bile Production and Storage:    

•  * Synthesis: Bile is synthesized by hepatocytes in the Liver.     

• * Function: It acts as an emulsifier to break down large fat globules into smaller micelles to aid in lipid digestion.    

•  * Storage: Bile is transported via the hepatic and cystic ducts to the Gallbladder, where it is stored and concentrated until needed in the small intestine.

Respiratory System: Volumes and Capacities

• Respiratory Volumes:     

• * Tidal Volume ($TV$): The amount of air inhaled or exhaled during a single normal, resting breath (approximately $500\,mL$).     

• * Inspiratory Reserve Volume ($IRV$): The maximum volume of additional air that can be forcibly inhaled after a normal tidal inspiration (approximately $3100\,mL$).     

• * Expiratory Reserve Volume ($ERV$): The maximum volume of additional air that can be forcibly exhaled after a normal tidal expiration (approximately $1200\,mL$).     

• * Residual Volume ($RV$): The volume of air that remains trapped in the lungs even after the most forceful expiration; this prevents lung collapse (approximately $1200\,mL$).

• Respiratory Capacities:     

• * Vital Capacity ($VC$): The total amount of exchangeable air. Formula: $VC = TV + IRV + ERV$.     * Total Lung Capacity ($TLC$): The sum of all lung volumes. Formula: $TLC = TV + IRV + ERV + RV$.

The Urinary System: Nephron Structure and Function

• The Nephron: The functional unit of the kidney responsible for urine formation.     

• * Renal Corpuscle:         

• * Glomerulus: A tuft of high-pressure capillaries where blood filtration occurs.         

• * Bowman’s (Glomerular) Capsule: The cup-shaped structure surrounding the glomerulus that collects the filtrate.     

• * Renal Tubule Segments:         

• * Proximal Convoluted Tubule ($PCT$): Primary site for the reabsorption of water, ions (like $Na^+$), and organic nutrients (like glucose and amino acids).         

• * Nephron Loop (Loop of Henle): Consists of the descending limb (permeable to water) and the ascending limb (permeable to solutes); creates an osmotic gradient in the renal medulla.   

• * Distal Convoluted Tubule ($DCT$): Site for regulated secretion of ions and acids; also involved in selective reabsorption under hormonal control.         

• * Collecting Duct: Receives filtrate from many nephrons and performs final adjustments to urine concentration based on the presence of Antidiuretic Hormone ($ADH$).

Urinalysis: Pathological Indicators and Diseases

• Urinalysis Components and Clinical Significance:     

• * Glucose (Glycosuria): Its presence typically indicates Diabetes Mellitus, where blood glucose levels exceed the renal threshold for reabsorption.     

• * Proteins (Proteinuria/Albuminuria): Indicates damage to the glomerular filtration membrane; commonly associated with Kidney Failure or chronic hypertension.     

• * Ketones (Ketonuria): Products of fat metabolism; their presence suggests starvation, low-carb diets, or untreated Diabetes Mellitus (Diabetic Ketoacidosis).     

• * Erythrocytes (Hematuria): The presence of red blood cells indicates trauma, kidney stones, or infection along the urinary tract.     

• * Leukocytes (Pyuria): The presence of white blood cells indicates an active inflammation or infection, such as a Urinary Tract Infection (UTI).     

• * Bilirubin (Bilirubinuria): May indicate liver pathology or bile duct obstruction.

Urinary Tract Infections (UTI): Pathophysiology and Demographics

• Risk Factors:     

• * Demographic Prevalence: Females are significantly more likely to contract a UTI than males.     

• * Anatomical Reasoning:         

• * Urethral Length: The female urethra is much shorter (approximately $3-4\,cm$) compared to the male urethra (approximately $20\,cm$), allowing bacteria to reach the bladder more easily.

• * Proximity: The female urethral opening is located closer to the anal opening, increasing the risk of fecal bacteria (such as E. coli) entering the urinary system.

The Renin-Angiotensin-Aldosterone System (RAAS)

• The RAAS Pathway: This is a critical hormonal cascade used to regulate long-term blood pressure and extracellular fluid volume.     

• 1. Trigger: A drop in blood pressure, a decrease in blood volume, or a decrease in $Na^+$ concentration is detected by the juxtaglomerular ($JG$) cells of the kidney.    

•  2. Renin Release: The kidneys secrete the enzyme Renin into the bloodstream.     

• 3. Angiotensinogen Conversion: Renin acts on Angiotensinogen (a plasma protein produced by the Liver) to convert it into Angiotensin I.     

• 4. ACE Conversion: Angiotensin-Converting Enzyme (ACE), produced primarily in the capillaries of the Lungs, converts Angiotensin I into the active hormone Angiotensin II.

• Functions of Angiotensin II:     

• * Systemic Vasoconstriction: Increases peripheral resistance, leading to an immediate rise in blood pressure.     

• * Adrenal Stimulation: Stimulates the adrenal cortex to release Aldosterone.     

• * Aldosterone Effect: Causes the kidneys ($DCT$ and collecting ducts) to reabsorb more $Na^+$ and water, increasing blood volume.     

• * ADH Release: Stimulates the posterior pituitary to release Antidiuretic Hormone ($ADH$) to increase water retention.    

• * Thirst: Stimulates the hypothalamus to trigger the thirst mechanism.

• Pharmacological Interventions (Drugs affecting the pathway):     

• * ACE Inhibitors: (e.g., Lisinopril) Block the conversion of Angiotensin I to Angiotensin II; used to treat hypertension and heart failure.     

• * Angiotensin II Receptor Blockers (ARBs): (e.g., Losartan) Block the action of Angiotensin II at the cellular receptors to prevent vasoconstriction.     

• * Renin Inhibitors: (e.g., Aliskiren) Directly inhibit the initial enzymatic step of the cascade.     * Aldosterone Antagonists: (e.g., Spironolactone) Block the effect of aldosterone on the kidneys, promoting the excretion of sodium and water (diuretic effect).