What is the flow of urine through the urinary system?
- Kidneys
- Ureters
- Urinary bladder
- Urethra
Describe the kidneys
Paired bean shaped organs located retroperitoneally on the posterior wall
Explain the location of the kidneys
Retropeeritoneal, specifically in the paravertebra gutters on either side of the aorta and inferior vena cava
Left kidney is approximately located at the level of the transverse processes of T12-L3 vertebra
What are superiorly related to the kidneys?
Suprarenal glands
What structures are anteriorly related to the right kidney?
Liver, duodenum, ascending colon, hepatic flexure, jejunum
What structures are anteriorly related to the left kidney?
Spleen, splenic flexure, stomach, pancreas, descending colon and jejunum
What structures are posteriorly related to the kidney?
12th rib, diaphragm, psoas major, quadratus lumborum, transversus abdominals muscle, iliohypogastric and ilioinguinal nerves
Left kidney is associated with the 11th rib also
What are the functions of the kidney?
- Excretion of metabolic waste from the body (urea, creatinine)
- Regulation of water and electrolyte balance in the body
- Regulation of blood pressure(Renin-angiotensinog-aldosterone system)
- regulation of the body’s acid-base balance
- synthesis of the hormone erythropoietin
- Production of active vitamin D-1,25 dihydroxyl-cholecalciferol
What is the renal hilum?
A concave cavity located on the medial border of each kidney where structures enter and leave
What are the 3 main structures contained in the renal hilum?
Renal vein
Renal artery
Pelvis of the ureter
What are the 3 layers of connective tissue that surround the kidney?
- renal fascia
- Perirenal fat
- Renal capsule
Describe the renal fascia
A layer of connective tissue encapsulating the kidneys and suprarenal glands
Divides the fat surrounding the kidney into 2 layers
Describe the 2 layers of fat that the renal fascia divides
Perirenal fat- located between the renal fascia and The renal capsule
Pararenal fat- located outside the renal fascia
What is the function of the renal fascia?
Anchors the kidney to surrounding structures
What structures do the renal fascia fuse with posteriorly and anteriorly?
Posteriorly it fuses with deep fascia surrounding the muscles of the body wall
Anteriorly, the renal fascia forms a thick layer that fuses with the peritoneum
How does the function of the renal fascia help us in day to day function?
These attachments holds the kidney in a firm position thus preventing the jolts and shocks of day-to-day activity from interfering with the kidney
What can result from weakness or degradation of the renal fascia?
Can result in the kidney dropping down into the pelvis when in a standing position, a condition known as Nephroptosis(floating kidney)
Describe perinephric and paranephric fat
Perinephric fat(adipose capsule)- surrounds kidneys and suprarenal glands and is continuous with the fat in the renal sinus
Renal fascia- a membranous layer that surrounds the perinephric fat, kidneys and suprarenal gland
Paranephric fat- external to the renal fascia
Describe the renal capsule
A tough fibrous capsule surrounding the kidney and directly covers the renal cortex
What are the functions of the renal capsule?
- The renal capsule protects the kidney from trauma and damage
- Also penetrates the renal parenchyma to form trabeculae that lobulate kidneys
Give the pathway of urine through the kidneys
- Collecting duct
- Papillary duct
- Minor calyx
- Major calyx
- Renal pelvis
- Renal pelvis
- Ureter
- Urinary bladder
Describe the renal medulla
Darker in color with striated appearance
Composed of 8-16 renal pyramids
Apex of pyramid is directed into the sinus as renal papilla
Describe the surface of the papilla
Surface of the papilla is perforated by the ducts of Bellini
Describe the renal pelvis
Is the expanded upper end of the ureter
Lies within the renal sinus
Gives the 3-4 major calyces
Describe the minor calyces
Is associated with a single renal pyramid
Is cup shaped and surrounds a renal papilla
What is the purpose of minor calyces?
Receives urine from the renal papilla for passage into the ureter and bladder
Give the order of blood supply for kidneys
Renal artery ->Segmental artery ->Interlobar arteries -> Arcuate arteries-> cortical radiate arteries -> Afferent arterioles -> glomerular capillaries-> efferent arterioles -> peritubular capillaries -> peritubular venules -> cortical radiate veins -> arcuate veins -> interlobar veins -> renal vein
Describe the veinous drainage of the left renal vein
- Is longer than the right
- Passes anterior to the aorta
- Receives the left suprarenal vein and left gonadal vein
Describe the veinous drainage of the right renal vein
Passes posterior to the second part of the duodenum and head of the pancreas
Explain nerve supply of the kidneys
- The kidneys are innervates by the renal plexus
- renal plexus comprises of sympathetic, parasympathetic and visceral Afferent nerve fibers
- Nerve fibers from this plexus accompany the renal arteries into the kidney
How long is the ureter?
10 inches long
Describe the ureter
A muscular tube extending from renal pelvis to the posterior surface of the urinary bladder
Retroperitoneal, descends on the anterior surface of the psoas major muscle
What are the 3 constrictions of the ureter?
- Uteropelvic junction
- Where it crosses the pelvic brim
- Where it pierces the bladder wall
Describe the pathway of the ureter
Descends on the anterior surface of the psoas major muscle
Passes anterior to the bifurcation of the common iliac artery before descending into the pelvis
What is the capacity of the urinary bladder?
200-300ml
