Urinary Physiology
What is the functional unit of the kidney?
Nephron
Define tubular secretion and reabsorption.
Secretion - substances move from blood to filtrate
Reabsorption - substances move from filtrate to blood
Where does carbohydrate digestion begin and which enzyme is involved?
Mouth, salivary amylase
What are the four regions of the stomach?
Fundus, body, cardia, pylorus
A patient has anemia due to vitamin B12 deficiency. What is the cause?
Lack of parietal cells --> lack of intrinsic factor
List the correct order of urine passage:
Ureters --> Urethra --> Kidneys --> Bladder
Kidneys --> Ureters --> Bladder --> Urethra
What is the order of filtrate through the nephron?
Glomerular capsule --> PCT --> loop of Henle --> DCT --> collecting duct
Which hormones respond to dehydration?
ADH, aldosterone
What produces bile and where is it stored? What is its function?
Liver; Gallbladder; Emulsification of lipids to increase surface area for lipase (fat digestion)
A 45-year-old patient has proteinuria (protein in the urine). What is the cause?
Damage to the glomerular filtration barrier
What is the macula densa and its function?
A group of epithelial cells in the DCT; senses NaCl concentration
What are the components of the glomerular filtration barrier and their functions in filtration?
Fenestrated endothelium - pores that filter large molecules
Basement membrane - repels proteins due to its negative charge
Podocytes - slit diaphragms prevent large molecules from entering filtrate
What is the function of CCK in digestion?
Stimulates gallbladder to contract to release bile and the pancreas to secrete digestive enzymes
What is the function of the large intestine in digestion?
Absorption of water, electrolytes, vitamins B & K, and folic acid
A patient is lactose intolerant. Which enzyme is deficient?
Lactase
How does the myogenic mechanism of renal autoregulation maintain GFR?
Constricts the afferent arterioles when bp rises; dilates it when bp falls
What are the differences between cortical and juxtamedullary nephrons?
Cortical- more common, short loops of Henle, mostly in cortex
Juxtamedullary- less common, long loops of Henle, extends deep into medulla
What is the role of brush border enzymes in digestion?
Complete the final digestion of carbs and proteins into absorbable monosaccharides and amino acids
What is the function of the duodenum and jejunum in digestion?
Duodenum: chemical digestion
Jejunum: nutrient absorption
A patient has high PTH levels due to osteoporosis. What is the effect?
Increased calcium reabsorption, hypercalcemia
Describe the process of micturition (urination). Which muscles are involved, and what kind of muscle are they?
2. Internal sphincter relaxes (involuntary smooth muscle)
3. External sphincter relaxes (voluntary skeletal muscle)
Explain how the Loop of Henle establishes the countercurrent multiplier.
Descending limb: permeable to water, not solutes --> water leaves, filtrate becomes concentrated
Ascending limb: impermeable to water, pumps out Na+/Cl- --> decreases filtrate osmolarity
Describe the effects of ADH, ANP, PTH, and aldosterone.
ADH - increases H2O reabsorption by inserting aquaporins in collecting duct, responds to high plasma osmolarity or low blood volume
ANP - decreases Na reabsorption, increases GFR, increases urine output
PTH - increases Ca2+ reabsorption
Aldosterone - increase Na reabsorption and K secretion in distal tubule/collecting duct when blood pressure is low
List the functions of chief cells, parietal cells, mucous cells, regenerative cells, and enteroendocrine cells.
Chief cells- secrete pepsinogen for protein digestion
Parietal cells- secrete HCl for stomach acid and intrinsic factor for B12 absorption
Mucous cells- secrete mucus for stomach protection and lubrication
Regenerative cells- maintain epithelium
Enteroendocrine cells- regulate gut motility
A patient presents with fatty stools due to poor emulsification of fats. This occurs after gallbladder removal. Explain why this happens.
Bile is no longer being stored and concentrated