BIOL40C Ch.26 Urinary System

• 1) kidney (2)
• 2) ureter (2)
• 3) bladder (1)
• 4) urethra (1)

study of the anatomy/physiology/pathology of kidneys

study of the anatomy/physiology/pathology of male/female urinary systems, and male reproductive system

• 1) blood ionic composition regulation
• 2) blood pH regulation
• 3) blood volume regulation
• 4) blood pressure regulation
• 5) blood osmolarity maintenance (300 mOsm/L)
• 6) hormone production (calcitriol, erythropoietin)
• 7) blood glucose level regulation
• 8) excretion on wastes/foreign substances

unit of osmotic pressure equivalent to amount of solute substances dissociated in solution to form 1mol of particles

concentration of a solution in terms of osmoles of solutes per liter of solution

between T10 and L3

partially protected by 11th & 12th (floating) ribs

left, bc of larger size of right liver lobe

4-5in long, 2-3in wide

• 1) renal capsule (dense irregular CT)
• 2) adipose capsule
• 3) renal fascia (dense irregular CT, anchors kidney to peritoneum)

• 1) renal cortex (outer portion)
• 2) renal medulla (inner portion)

• 1) cortical zone
• 2) juxtamedullary zone
• 3) renal columns (extend into medulla)

narrower end of renal pyramids facing hilum

renal arteries

afferent arterioles

efferent arterioles

• - formed from divided efferent arterioles
• - surround tubular parts of nephron in cortex

~1M

• - renal corpuscles lie in outer portion of renal cortex
• - short loops of Henle (mostly in cortex)
• - receive blood from peritubular capillaries

• - renal corpuscles deep in cortex, close to medulla
• - long loop of Henle (extends into medulla)
• - receive blood from peritubular capillaries and vasa recta

attached to glomerular capsule

further away from glomerular capsule

tightly coiled

• 1) proximal convoluted tubule
• 2) loop of Henle
• 3) distal convoluted tubule

• 1) glomerular (Bowman's) capsule
• 2) glomerulus

• -modified squamous epithelial cells (podocytes)
• -foot-like projections of podocytes wrap around endothelium of glomerular capillaries forming inner wall of capsule

simple squamous epithelium

microvilla for increased absorption

simple squamous for easy exchange

cuboidal then columnar

crowded epithelial cells in thick ascending loop making contact with afferent arterioles of renal corpuscle

macula densa in contact with modified smooth muscle fibers of the arteriole wall

• 1) principal cells
• 2) intercalated cells

have receptors for ADH and aldosterone

role in homeostatic control of blood pH

water and solutes in blood -> glomerular capillaries into glomerular capsule -> renal tubule

• - return of substances to blood
• - 99% of water reabsorbed

kidney removes substances that are not wanted for disposal in urine

150-180L

• - net filtration pressure
• - total pressure that promotes filtration

• - glomerular blood hydrostatic pressure
• - amount of fluid formed in all the renal corpuscles of both kidneys each minute

capsular hydrostatic pressure

blood colloid osmotic pressure

NFP = GBHP - CHP - BCOP

• 125mL/min (males)
• 105mL/min (females)

needed substances may pass out of body too quickly

everything may be reabsorbed, including some waste products

• 1) adjusting blood flow into/out of glomerulus
• 2) altering glomerular surface area available for filtration

• 1) myogenic mechanisms
• 2) tubuloglomerular feedback

stretch in walls of afferent arterioles causes smooth muscle to respond by contracting or relaxing

macula densa provides feedback to glomerulus

leads to decreased NO secretion (stops vasodilation) if there is an increase in blood flow

between adjacent tubules

through an individual tubular cell

substance has 2 membranes to cross

side in contact with tubular fluid

side in contact with interstitial fluid

• 1) angiotensin II
• 2) atrial natriuretic hormone (inhibits reabsorption)

antidiuretic hormone

• 1) collecting duct
• 2) papillary duct in renal pyramid
• 3) minor calyx
• 4) major calyx
• 5) renal pelvis
• 6) ureter
• 7) urinary bladder
• 8) urethra

simple squamous

modified simple squamous epithelial cells - podocytes

glomerular filtrate

fraction of blood plasma in the afferent arterioles of the kidneys that becomes glomerular filtrate

16-20%

• 1) endothelial cells of glomerular capillaries
• 2) podocytes

• leaky
• have fenestrations that measure .07-.1um in diameter

• contractile cells that help regulate glomerular filtration
• located amound glomerular capillaries and in the cleft between afferent and efferent arterioles

prevents filtration of larger plasma proteins

• collagen and proteoglycans in a glycoprotein matrix
• acellular

• footlike processes of podocytes
• wrap around glomerular capillaries

• spaces between pedicels
• permits passage of molecules smaller than .006-.007 (water, glucose, vitamins, amino acids, very small plasma proteins, ammonia, urea, ions)

they regulate how much of the glomerular capillary surface area is available for filtration by contraction/relaxation

permits all solutes in blood plasma to exit glomerular capillaries, but prevents filtration of blood cells and platelets

50x

the efferent arteriole is smaller in diameter than the afferent arteriole, so resistance to the outflow of blood from the glomerulus is high

• decreases
• vasoconstriction of the afferent arterioles predominates -> blood flow into glomerular capillaries is decreased

norepinephrine

• ₁ receptors
• plentiful in smooth muscle fibers of afferent arterioles

• atrial natriuretic peptide
• secreted by cells in the atria of the heart

blood volume increases -> atria stretch -> secrete ANP -> relaxation of glomerular mesangial cells -> increase capillary surface area available for filtration -> GFR rises

• vasoconstrictor that narrows both afferent and efferent arterioles
• reduces renal blood flow
• decreases GFR when blood volume and blood pressure decrease
• enhances reabsorption of Na+, Cl-, and water in PCT

• enters cell by Na+/glucose symporter (2 Na+, 1 glucose)
• leaves cell by facilitated diffusion

• enters cell by Na+ symporters
• leaves cell by active transport

evaluation of the volume and physical, chemical, and microscopic properties of urine

ratio of the weight of a substance to the weight of an equal volume of water

bile breakdown products (urochrome)

4.5-8.0

more acidic

more alkaline

• blood urea nitrogen test
• measures blood nitrogen that is part of urea

• urine test
• creatinine occurs in plasma from breakdown of creatine phosphate in skeletal muscle
• high values indicate poor renal function

volume of blood that is cleared of a particular substance each minute in mL/min

• 1) glomerular filtration
• 2) tubular reabsorption
• 3) tubular secretion

artificial cleansing of blood when kidneys fail

• directly filters the blood and then returns cleansed blood
• uses an artificial membrane in a machine (hemodialyzer)

uses the peritoneal membrane of the abdominal cavity as the dialysis membrane

any infection of part of the urinary system resulting in microbes in the urine

• inflammation of the kidneys that involves the glomerulus
• glomeruli become swollen and fail as a filtration membrane
• often caused by allergy to toxins produced by streptococcal bacteria

• glomerular filtration abruptly stops working
• common in major trauma/blood loss
• may be reversible

• progressive decrease/cessation of glomerular filtration
• irreversible

• kidney tubules become full of cysts
• non-cystic tubules die by apoptosis
• inherited disorder

• diabetics often suffer glomerular damage
• proteins leak into urine

presence of urea/other nitrogen-containing substances in blood

painful urination

excessive urination

toxic levels of urea in blood

failure to urinate