The Digestive System Lecture Review

Chapter 24 - Gastrointestinal Tract

  • Accessory Organs and Their Functions:

    • Salivary Glands: Produce saliva to aid in digestion.

    • Pancreas: Produces digestive enzymes and bicarbonate.

    • Liver: Produces bile for fat emulsification.

    • Gallbladder: Stores bile until needed.

  • Major Organs and Their Functions:

    • Mouth: Begins digestion mechanically and chemically.

    • Esophagus: Transports food to the stomach.

    • Stomach: Mixes food and begins protein digestion.

    • Small Intestine: Main site for digestion and absorption.

    • Large Intestine: Absorbs water and forms feces.

  • Structure of the Tooth:

    • Enamel: Hard outer layer.

    • Dentin: Layer beneath enamel, makes up bulk.

    • Pulp: Contains nerves and blood vessels.

    • Cementum: Covers the root of the tooth.

  • Stages of Deglutition (Swallowing):

    1. Voluntary Stage: Tongue pushes bolus to the back of the mouth.

    2. Pharyngeal Stage (Involuntary): Bolus moves through the pharynx; epiglottis covers larynx.

    3. Esophageal Stage (Involuntary): Peristalsis moves bolus to the stomach.

  • Different Cells of the GI Tract and Their Functions:

    • Mucous Cells: Produce mucus for lubrication.

    • Parietal Cells: Secrete hydrochloric acid and intrinsic factor.

    • Chief Cells: Produce pepsinogen and gastric lipase.

    • G Cells: Secrete gastrin.

  • Major Pancreatic Enzymes and Functions:

    • Amylase: Digests carbohydrates.

    • Lipase: Digests fats.

    • Proteases: Break down proteins (e.g., trypsin).

    • Nucleases: Digest nucleic acids.

  • Major Hormones of GI Tract and Functions:

    • Gastrin: Stimulates gastric acid secretion.

    • Secretin: Stimulates bicarbonate secretion from pancreas.

    • Cholecystokinin (CCK): Stimulates bile release and pancreatic enzyme secretion.

  • Diseases of the GI Tract:

    • GERD: Gastroesophageal reflux disease.

    • Ulcers: Erosions in the stomach lining.

    • IBD: Inflammatory bowel disease.

    • Celiac Disease: Gluten intolerance.

  • Layers of the Tissues of the GI Tract:

    • Mucosa: Innermost layer for absorption and secretion.

    • Submucosa: Connective tissue with blood vessels and nerves.

    • Muscularis: Smooth muscle for peristalsis.

    • Serosa: Outermost layer (visceral peritoneum).

  • Aging in the GI Tract:

    • Decreased motility and secretion.

    • Increased risk for digestive disorders.

Chapter 26 - Urinary Tract

  • Major Organs and Their Functions:

    • Kidneys: Filter blood, produce urine.

    • Ureters: Transport urine from kidneys to bladder.

    • Urinary Bladder: Stores urine.

    • Urethra: Transmits urine from bladder to exterior.

  • Parts of the Kidney:

    • Cortex: Outer portion, contains nephrons.

    • Medulla: Inner region containing renal pyramids.

    • Renal Pelvis: Collects urine before entering the ureters.

  • Parts of the Nephron:

    • Glomerulus: Network of capillaries for filtration.

    • Bowman's Capsule: Surrounds glomerulus, collects filtrate.

    • Proximal Convoluted Tubule (PCT): Reabsorbs nutrients and water.

    • Loop of Henle: Concentrates urine.

    • Distal Convoluted Tubule (DCT): Further adjusts urine composition.

  • Pathway of Blood Flow Through the Kidney:

    • Renal artery → Afferent arterioles → Glomerulus → Efferent arterioles → Peritubular capillaries → Renal vein.

  • Parts of the Renal Corpuscle:

    • Glomerulus: For filtration.

    • Bowman's Capsule: Collects filtrate.

  • Differences Between Cortical Nephrons and Juxtamedullary Nephrons:

    • Cortical Nephrons: Mainly in the cortex; shorter loops of Henle.

    • Juxtamedullary Nephrons: Extend deep into the medulla; longer loops important for concentration of urine.

  • Summary of Events at the Nephron:

    1. Filtration: Blood is filtered at glomerulus.

    2. Reabsorption: Nutrients and water are reabsorbed in tubules.

    3. Secretion: Toxins and excess ions are secreted into tubules.

  • Hormones Involved in Urinary Tract:

    • Antidiuretic Hormone (ADH): Increases water reabsorption in kidneys.

    • Aldosterone: Increases sodium reabsorption.

    • Natriuretic Peptide: Decreases sodium and water reabsorption.

  • Characteristics of Normal Urine:

    • Light yellow in color, clear, and specific gravity of 1.005 to 1.030.

  • Characteristics of Abnormal Urine and Diseases Associated:

    • Cloudy or Dark Urine: Possible infection or dehydration.

    • Presence of Blood: Indicates possible kidney stones or infection.

    • High Glucose: Suggests diabetes.

  • What Does a Urinalysis Test for?:

    • Presence of glucose, proteins, ketones, blood, and specific gravity.

  • Aging in the Urinary System:

    • Decreased kidney function and blood flow.

    • Increased risk of urinary incontinence and infections.