Urinary System Part 1 Flashcards
External Structures of the Kidney:
-Kidneys
Retroperitoneal- location
Renal capsule- surrounds each
- Imbedded in mass of fat
Renal fascia- fibrous tissue surrounding the capsule and fat layer that attaches the kidney to posterior abdominal wall
- Hilum- medial indentation for entry/exit blood vessels, nerves, lymph vessels, ureter
Structures of the Kidney
- Renal cortex
- Renal medulla
- Renal pyramids
- Renal columns
- Minor calyx
- Major calyx
- Renal pelvis
Nephron
Nephron 1.2 million nephrons per kidney Functional unit of the kidney 3 kinds Superficial cortical nephrons Extend partially into medulla Midcortical nephrons Juxtamedullary nephrons Extend deep into medulla- urine concentration
Nephron- Tubular structure with subunits that contribute to urine formation
- Renal corpuscle
- Proximal convoluted tubule
- Loop of Henle
- Distal convoluted tubule
- Collecting duct
Nephron- Tubular structure with subunits that contribute to urine formation:
-Renal corpuscle
Glomerulus- “tuft of capillaries”
Bowman capsule
Mesangial cells-support, contractile, phagocytic, produce vasoactive substances, control flow
Bowman space- Space inside Bowman’s capsule
Nephron
- Glomerular filtration membrane (wall of glomerular capillary for filtration)
- Glomerular endothelium
- Basement membrane
–Capillary epithelium
Also referred to as podocytes or visceral epithelium
Filtration slits
Nephron
Juxtaglomerular apparatus
- Juxtaglomerular cells- around the afferent arteriole where it enters renal corpuscle
- Macula densa- portion of distal convoluted tubule with specialized sodium and chloride sensing cells.
Nephron
- Renal tubules Proximal tubule Loop of Henle Distal tubule Collecting duct --- Principal cells-resorb Na and H2O, secrete K --- Intercalated cells- secrete H, bicarbonate, resorb K
Structures of the kidney: Blood Vessels
- Renal arteries
- Interlobar arteries
- Arcuate arteries
- Interlobular arteries
- Afferent arterioles
- Glomerular capillaries
- Efferent arterioles
- Peritubular capillaries and vasa recta
Ureters
- 30 cm long
- Long, intertwining muscle bundles
- Pass obliquely though posterior aspect of bladder
- Peristaltic activity
- Micturition compresses the lower end of the ureter to avoid urine reflux
Bladder
- Detrusor muscle
- Transitional epithelium-barrier to prevent water and solutes moving between urine and blood
- Trigone- between openings ureters and urethra
- Micturition reflex
Urethra:
- internal and external sphincters (muscles)
- 3 to 4 cm in females
- 18 to 20 cm in males
Renal Blood flow:
Receive 1000 to -1200 mL of blood per minute
-Glomerular filtration rate (GFR)
1) Plasma vol per unit
time
2) Directly related to
perfusion pressure
in glomerular
capillaries
3)Directly related to
renal blood flow
(RBF)
Regulation of Renal Blood Flow:
- Autoregulation
- Try to keep RBF and GFR constant
- Myogenic mechanism
1) ↓Arterial pressure → ↓ stretch afferent arteriolar SM → arteriole relaxes → increase RBF
2) ↑ Arterial pressure → ↑ stretch afferent arteriolar SM → arteriole contracts → decrease RBF
-Tubuloglomerular feedback
–Macula densa cells sense flow and sodium and triggers compensatory changes in arteriolar resistance and GFR
Regulation of Renal Blood Flow:
Neural regulation
-Baroreceptor reflex response to Systemic BP
- Sympathetic ANS- NE stimulates
vasoconstriction when systemic BP decreases
Hormones
- Renin- angiotensin systems
- Natriuretic peptides- atrial natriuretic peptide (ANP) from right atrium