Anatomy of the Kidney Flashcards
The Kidneys functions
Filter the blood to maintain the intra and extracellular environments Regulating ions concentration Regulating body fluid Removal of cellular wastes pH regulation Erythrocyte formation
Position of Kidneys
- retroperitoneal organs
- Kidneys lie on the psoas muscle beside the vertebral bodies.
- left kidney is higher
- left renal vein is longer
- The diaphragm and 11th and 12th ribs lie behind the upper half of each kidney.
- renal vein is most anterior –> renal artery –> pelvis/ureter
- LEFT RENAL VEIN receives the left gonadal vein
Retroperitoneal organs
Pancreas Majority of duodenum Ascending colon Descending colon Kidneys
Position & Size of the kidneys
upper side between T11 and T12 Hilum at L1/2 Lower poles at L3 Width is about 5 - 6cm Length is about 10 -11cm
Kidney is located in the
right/left lumbar (flank)
Anterior Relations of the RIGHT kidney
Right Kidney
Top to bottom: suprarenal hepatic duodenal right colic flexure
The liver and jejunum is separated from the kidney by __________
peritoneum
Anterior Relations of the LEFT kidney
spleen
left suprarenal gland
The splenic artery runs across the kidney immediately above the pancreas
pancreas
jejunum
left colic flexure
stomach
Posterior Relations of the Kidneys
The kidney rests on the ff:
Diaphragm - Separates the upper part of the kidney from the pleura and the 12th rib (11th rib for left kidney)
Psoas major muscle
Quadratus lumborum
Origin of the transversus abdominis muscle
Medial and lateral lumbocostal arches (origin of the fibres of the diaphragm)
Ureter length and constrictions
Approximately 25 cm – 30cm long
The upper half of this length lies on the posterior abdominal wall and the lower half in the true pelvis.
Position:
Posteriorly, rests on the psoas major muscle
Anteriorly, covered by peritoneum
At the brim of the pelvis, it crosses the upper end of the external iliac artery and vein.
Comes to lie on the lateral wall of the pelvis.
Constrictions:
Hilum
Pelvic brim
Bladder entrance
Male Ureter
- Superior vesical artery
- Obturator nerve
- Inferior vesical artery
- ductus deferens.
Female Ureter
- Superior vesical artery
- Obturator nerve, artery and vein
- Vaginal artery
- Uterine artery
- Ovary
- Cervix
- Vagina
Urinary Bladder
Lies in the pelvis but when distended, part extends above the level of the pubic symphysis and comes in contact with the abdominal wall. The urge to urinate comes at 300 ml. The total capacity is about 500 ml. Has 4 surfaces 2 inferolaterals Superior surface Base of posterior surface
Wall of bladder layers
- Adventitia
- Detrusor muscle
- Submucosa
- Lamina propia
- Transitional epithelium
Male Urethra
Around 20 cm
Average diameter in both sexes is 6 mm
Divided into 3 parts
- Prostatic (3 cm)
- Membranous (1.5 cm)
- Penile/spongiosa (15 cm)
Female Urethra
Very short
About 4 cm long
Corresponds to both the prostatic and membranous parts of the male urethra
Closely related to the anterior wall of the vagina
Clinical significance
Renal radiology = two types:
- descending pyelography = intravenous
- ascending pyelography = retrogate
Foley catheter insertion
Kidney blood supply
Aorta Renal artery Segmental artery Interlobar artery Arcuate artery Interlobular artery Afferent arteriole Glomerulus Efferent arteriole Peritubular capillary/Vasa recta Interlobular vein Arcuate vein Interlobar vein Renal vein
Blood Flow to the kidneys
in 24 hours - 1750 L blood passes
170-175 L is absorbed/filtered
1-3 million nephrons per kidney
Nephron
AA PCT Thick LoH Thin LoH DCT Collecting tubule Collecting ducts EA
Nephron
Bowman’s capsule= Collects filtrate, ultrafiltration
Proximal convoluted/straight tubules= Reabsorption
Loop of Henle= Hypertonic gradient
Distal straight/convoluted tubules= Acid base balance; Water balance; Absorption; Secretion
Collecting tubule and ducts= Reabsorption of water
Nephron’s Epithelium
Bowmans capsule: parietal layer - capsular squamous epithelium
visceral layer - podocyte, basement membrane, fenestrated endothelium
Glomerulus
PCT cells: with microvilli, infolded PM, mitochondria
DCT cells: fewer mitochondria, fewer microvilli
LoH: thin segment cells
Collecting duct cells: principal cell, intercalated cell
Types of Nephrons
Cortical
Has short nephron loop and glomerulus further from the corticomedullary junction
Efferent arteriole supplies peritubular capillaries
Juxtamedullary
Has long nephron loop and glomerulus closer to the corticomedullary junction
Efferent arteriole supplies vasa recta
Filtration Membrane
podocytes: cell body; pedicels; filtration slits
slit membrane between pedicels
basal lamina
fenestrations of glomerular endothelial cells
Juxtaglomerular complex
consists of:
- juxtaglomerular cells/granular cells
- macula densa cells
- extraglomerular mesangial cells
It is where the most distal portion of the ascending loop of Henle or part of the distal convoluted tubule (DCT) lies between the afferent arteriole (feeding the glomerulus) and efferent arteriole (draining the glomerulus).
These structures are modified at the point of contact
State the functions of the different cells in the JGA
- Granular or JG cells
Enlarged smmu cells with prominent secretory granules called RENIN.
Act as mechanoreceptors that sense the blood pressure in the afferent arteriole. - Macula Densa
Closely packed specialized cells lining the wall of the cortical thick ascending limb
Sensitive to the concentration of sodium chloride in the late thick ascending limb.
These are chemoreceptors that respond to changes in the NaCl content of the filtrate.
The JG cells and macula densa are important in the regulation of the rate of filtration and systemic pressure.
- Extraglomerular mesangial cells
The function remains unclear
Tubuloglomerular Feedback
MAP increase:
increase RBF, GFR, Na+ to Macula dense => (NOS inhibition = decrease NO and adenosine release) Constriction if AA
MAP decrease:
decrease RBF, GFR, Na+ to macula densa => (NOS promotion = increase NO) DILATION of AA
