P4

Comparison of Digestion of the Three Macronutrients

• Carbohydrates

  • Digestion Process: Begins in the mouth with salivary amylase, continues in the small intestine with pancreatic amylase.

  • Enzymes:

  • Salivary amylase (mouth)

  • Pancreatic amylase (small intestine)

  • End products: Monosaccharides (glucose, fructose, galactose).

• Proteins

  • Digestion Process: Begins in the stomach with pepsin, continues in small intestine with pancreatic proteases (e.g., trypsin, chymotrypsin).

  • Enzymes:

  • Pepsin (stomach)

  • Pancreatic proteases (small intestine)

  • End products: Amino acids and small peptides.

• Fats

  • Digestion Process: Begins in the small intestine, emulsified by bile salts, digested by pancreatic lipase.

  • Enzymes:

  • Bile salts (small intestine)

  • Pancreatic lipase (small intestine)

  • End products: Fatty acids and monoglycerides.

Urinary System Composition of Urine

• Main Components:

  • Water (95%)

  • Urea: Byproduct of protein metabolism.

  • Creatinine: Byproduct of muscle metabolism.

  • Uric Acid: Byproduct of nucleic acid metabolism.

  • Electrolytes: Sodium, potassium, chloride, etc.

Labeling Structures of the Urinary System

• Kidneys: Filters blood and produces urine.

• Ureters: Transport urine from kidneys to the bladder.

• Bladder: Store urine until excretion.

• Urethra: Conducts urine out of the body.

Roles of Parts of the Urinary System

• Kidneys: Blood filtration, urine formation, regulation of electrolytes, acid-base balance.

• Ureters: Active transport of urine via peristalsis.

• Bladder: Stores urine, contracts for excretion.

• Urethra: Serves as a conduit for urine excretion and differs between sexes (longer in males).

Macroscopic and Microscopic Structures of the Kidney

• Macroscopic Structures:

  • Renal cortex, renal medulla, renal pelvis, nephron.

• Microscopic Structures:

  • Nephron components: Glomerulus, Bowman's capsule, loop of Henle, distal convoluted tubule, collecting duct.

Blood Flow Through the Kidney

• Pathway:

  1. Renal artery

  2. Afferent arterioles

  3. Glomerulus

  4. Efferent arterioles

  5. Peritubular capillaries

  6. Renal vein

Blood Filtration in the Kidney Nephron

• Filtration Process:

  • Occurs in the glomerulus where blood pressure forces water and solutes into Bowman's capsule.

  • Selectivity of filtration based on size and charge (positive ions filtered more readily).

Symptoms of Kidney Failure

• Symptoms Include:

  • Fatigue, weakness, loss of appetite.

  • Swelling (edema) due to fluid retention.

  • Changes in urination patterns: less urine output or presence of blood in urine.

  • High blood pressure.

Solutes Filtered, Secreted, and Reabsorbed in the Kidney

• Filtered:

  • Water, glucose, sodium, potassium, urea.

• Secreted:

  • Hydrogen ions, potassium ions, certain drugs.

• Reabsorbed:

  • Water, glucose, sodium, bicarbonate (HCO₃).

Role of Portal System in the Kidney

• Portal System Function:

  • The renal portal system assists in the regulation of blood flow and filtration in the nephron, connecting the glomeruli to the peritubular capillaries.

Hormonal Regulation of Urine Osmolarity

• Hormones Involved:

  • Antidiuretic Hormone (ADH): Increases water reabsorption in the kidneys, leading to more concentrated urine.

  • Aldosterone: Regulates sodium and potassium balance, affecting water retention.

Regulation of Major Ions by the Kidney

• Major Ions:

  • Sodium (Na+): Reabsorbed through the proximal convoluted tubule and regulated by aldosterone.

  • Potassium (K+): Secreted mainly in the distal convoluted tubule.

  • Calcium (Ca2+): Reabsorption influenced by parathyroid hormone (PTH).

Role of Kidneys in Maintaining Acid-Base Balance

• Acid-Base Regulation:

  • Kidneys regulate the excretion of H+ ions and reabsorption of bicarbonate (HCO₃), maintaining a stable pH in blood (around 7.4).

  • Buffers in urine assist in maintaining acid-base homeostasis.