Phase 1 - Week 10 (Kidneys, Prostatic Hyperplasia, Screening Programmes) Flashcards
Describe the location of the kidneys
- Posterior abdominal walls
- Level T12-L3
- Right slightly lower than left (due to right lobe of liver)
- Held to posterior abdominal wall, behind parietal peritoneum (retroperitoneal)
- Partially protected by lower ribs
List the layers of the external anatomy of the kidneys
From inside to outside:
- Renal capsule
- Adipose tissue
- Renal fascia
Renal capsule
Thin, fibrous sac, dense irregular connective tissue. Adheres closely to kidney. Maintains shape and protects from trauma and infection.
Adipose capsule of kidneys
Layer of fat - surrounds renal capsule. Protects and supports the kidney.
Renal fascia
Layer of tissue, passes in front of and behind both kidneys to anchor them to the peritoneum and posterior abdominal wall. Dense, irregular connective tissue, attaches to renal capsule by strings of fibres. Provides anchorage of kidneys to surrounding tissues.
List the sections of the internal anatomy of the kidneys
From outside to inside:
- Renal cortex
- Renal columns
- Renal medulla
Renal cortex
Dark outer 1cm of kidney, contains arcuate + interlobar arteries + veins + cortical nephrons (except parts of loop of Henle + collecting ducts - in medulla). Where ultrafiltration takes place.
Renal columns
Extensions of cortex - project in between the pyramids of the medulla - anchor the cortex.
Renal medulla
Inner section of kidney, contains renal pyramids. Appears striated - contains tubular systems of the juxtamedullary nephrons, parts of loop of Henle + collecting ducts of cortical nephrons
Describe the route which urine takes after production
- Renal pyramids
- Renal papilla
- Minor calyces
- Major calyces
- Renal pelvis
- Ureters
Renal pyramids
- Contain tubules of juxtamedullary nephrons, parts of loop of Henle + collecting ducts of cortical nephrons
- Cone-shaped
- Terminate medially, protrude into minor calyces
- Appear striated - bundles of nephron loops and collecting ducts and associated capillaries
Renal papilla
- Tips of pyramids, protrude into minor calyces
- Where all urine from collecting ducts drains into minor calyces
Minor calyces
- Cup-like projections
- Surround the papilla of each pyramid in renal medulla
- Several converge to from a minor calyx
- Collect and convey urine produced by kidneys to major calyces
Major calyces
- 2/3 per kidney
- Formed by fusion of minor calyces
- Unite to form renal pelvis
- Collect urine from minor calyces, drain it to renal pelvis then into ureter
Renal pelvis
- Single, funnel-shaped structure
- Located centrally at hilum of kidney
- Forms from union of major calyces
- Drains urine out of kidney to ureter
Describe the passage of blood through the kidneys
- Renal artery
- Segmental artery
- Interlobar artery
- Arcuate arteries
- Interlobar arteries
- Capillary network
- Interlobar vein
- Arcuate vein
- Renal vein
Renal arteries
- Pass laterally from abdominal aorta to hilum of kidney
- Branch into segmental arteries
Segmental arteries
- Branch from renal artery
- Split into interlobar arteries
- No venous equivalent
Interlobar arteries
- Branch from segmental arteries
- Pass through renal column
Arcuate arteries
Leave interlobar arteries at right angles, branch over outer surface of pyramids, forming arterial anastomosis.
Interlobular arteries
- Also called cortical radiate arteries
- Branch from arcuate arteries
- Supply cortex
Capillary network of the kidneys
- Interlobular arteries enter renal cortex - divide into branches called afferent arterioles
- Each nephron receives one arteriole - divides to plexus of capillaries around nephron
- Network of vessels is highly specialised - location of filtration of blood flowing through kidney
- Capillaries leave nephron as efferent arteriole - carry blood out of glomerulus
- Efferent arterioles divide into peritubular capillaries - eventually reunite to from interlobular veins
Interlobular veins
- Also called cortical radiate veins
- Drain cortex into arcuate veins
Arcuate veins
- Travel along outer surface of pyramid
- Travel down renal columns as interlobular veins - forming a venous anastomosis
Renal vein
- Formed by union of the arcuate veins at the hilum of the kidney
- Passes medially to drain into inferior vena cava
Describe the innervation of the kidneys
- Origins at renal ganglion
- Travel along renal arteries - inter-renal plexus
- Renal nerves regulate volume of blood through kindeys by affecting vasoconstriction/vasodilation of the aterioles
- Part of the autonomic nervous system
List the functions of the kidneys/urinary system
- Excretion of waste/toxins - products of metabolism
- Regulation of blood ionic composition
- Maintenance of blood osmolarity
- Regulation of BP
- Hormone production
- Regulation of blood glucose
List the waste products excreted in urine
Products of metabolism - mostly urea from breakdown of amino acids, also bilirubin, ammonia and uric acid
Which ionic components of blood are regulated by the kidneys?
Sodium ions, potassium ions, chloride ions, phosphate ions
What is the normal osmolarity of blood?
300 mOsm/L
How do the kidneys contribute to the regulation of blood pressure?
Through secretion and activity of renin - renin production increases BP
List the hormones secreted by the kidneys
- Renin - BP
- Erythropoietin - RBC production
- Calcitriol - active Vit. D, absorption of calcium and phosphorus
How do the kidneys contribute to the regulation of blood glucose?
Decrease in blood glucose, kidneys metabolise glutamine to glucose via gluconeogenesis - blood glucose increases
Nephrons
Functional units of urinary system
List the types of nephrons
- Cortical
2. Juxtamedullary
Cortical nephrons
Short loops of Henle, barely penetrate the renal medulla
Juxtamedullary nephrons
Within the cortex, long loops of Henle - penetrate deep into the medulla
Renal corpuscle
- Compact network of capillaries - glomerulus, surrounded by glomerular capsule (Bowman’s capsule)
- Surface between glomerulus and capsule is highly specialised to facilitate filtration of blood to produce the glomerular filtrate - enters renal tubules for further processing before it becomes urine
Describe the structure of the Bowman’s capsule
2 layers
1. Visceral layer
2. Parietal layer
+ basal lamina