1. Renal Anatomy and Histology Flashcards
What are the main functions of the kidneys? 2
Filter metabolic waste products and toxins from the bloodstream and convert the filtrate into urine.
BP regulation
What makes up the urinary tract which store and transport urine out of the body?
ureters, urinary bladder and urethra
The kidneys are ‘retroperitoneal lying’ meaning they are behind the peritoneal cavity at around T12-L3 levels. What is above the kidneys and which kidney lies lower?
The suprarenal gland lies above both kidneys and the right kidney is lower than the left kidney
The transpyloric plane is transverse through T12 and the superior pole of the right kidney. What else can be found near the transpyloric plane?
the left hilum of the kidney
The inferior pole of the right kidney is an index fingers breath superior to?
iliac crest
**right kidney is less covered by the 11th and 12th ribs, so more easily damaged
What fat is adjacent to the kidney capsule and extends into the renal hilum and pelvis, helping support and protect the kidney?
perinephric fat
What fascia covers fat enveloping kidney and suprarenal gland (perinephric fat). It also sheaths renal vessels and superiorly is continuous with the inferior diaphragmatic fascia?
renal fascia
The normal renal mobility is 3cm. What fat is external to the renal fascia?
paranephric fat
Where are biopsies commonly done of the kidney?
Towards the posterior lateral flank to avoid going through the peritoneal cavity
The renal capsule is dense irregular CT on the surface with a thin layer of myofibroblasts. What is the difference between renal cortex and medulla?
The cortex is the outer portion containing renal corpuscles while the medulla is towards the middle and consists of renal pyramids and columns
Renal columns lie between renal pyramids, both of which project into the?
major and minor calyxes
The renal lobes consist of a single pyramid plus the surrounding cortex. Where can renal pelvis and papillae be found?
Renal pelvis is the collecting funnel for urine
Renal papillae are projections of medullary pyramids apices into the calyxes
How does blood supply get to the kidneys? (3)
abdominal aorta to renal arteries (left and right) to segmental arteries
What are the main supplies to the ureter? (6)
renal branches gonadal branches from aorta abdominal aorta branches iliac branches superior vesicular branches pelvic branches (rectal, uterine, vaginal, inferior vesicular)
What is the blood supply to the kidneys after it reaches segmental arteries?
interlobar to arcuate to cortical radiate artery to afferent arteriole to glomerulus (capillaries) to efferent arteriole
How is the blood returned to the heart from the efferent arteriole?
peritubular capillaries and vasa recta to cortical radiate and arcuate vein to interlobar vein to renal vein to inferior vena cava
What is the main sympathetic innervation of the kidneys? (3)
- lesser splanchnic nerve (t10-11)
- least splanchnic nerve T12
both of these synapse in aorticorenal ganglia - Lumbar splanchnic nerves L1-L2
What is the parasympathetic innervation to the kidneys?
the vagus nerve
A nephron is a urine forming unit which consists of?
renal corpuscle and renal tubules
The second part of the urine carrying unit is made of cortical and medullary collecting ducts which houses what?
final concentration of urine
List the tubular structures starting from the bowmans capsule to the papillary duct. (11 structures total)
- Bowmans Capsule
- Proximal Convoluted Tubule
- Proximal straight tubule
- Thin loop of Henle
- Thick ascending loop of henle
- Macula densa location
- Distal convoluted tubule
- Collecting tubule
- Cortical Collecting duct
- Medullary collecting duct
- papillary duct
The cortex of the medulla contains renal corpuscles and consists of which tubular structures?
Proximal and distal convoluted tubules, straight tubules and cortical collecting ducts and collecting tubules
What are aggregations of collecting ducts and straight tubules running between the renal corpuscles and convoluted tubules within the cortex?
Cortical (medullary) rays
What has tufts of fenestrated capillaries with open pores, along with afferent and efferent arterioles?
glomerulus
The glomerular capsule (Bowman’s Capsule) consists of a parietal layer with simple squamous eptihelium, a visceral layer with podocytes and glomerular space which contains?
primary filtrate/urine
the visceral layer with podocytes will be on the capillary with podocytes
The glomerulus and the glomerular capsule together are called the ________ which are only located in the cortex of the kidney?
Renal Corpuscle
In the renal corpuscle there is a vascular pole where the afferent and efferent arterioles are and there is a urinary pole where what can be found?
the origin of the proximal convolute tubule
The glomerular endothelium has open fenestrations with few diaphragms. It has a thick luminal glycocalyx (which repels negeatively charged cells) and it has a large number of aquaporin water channels. What can the endothelium generate with the help of angiotensin 2?
NO and Prostaglandin E2- vasodilators
Podocytes on the visceral layer of the glomerular capillary are single cells which have foot like pedicles that interdigitate to make filtration like slits, so they are able to do what?
have diaphragms made with extracellular proteins which allow it to regulate size, patency and selectivity of the filtration
The filtration membrane is made up of fenestrated capillary endothelium, basement membrane of both the endothelium and podocytes, and smaller slits from podocytes which restricts what from passing? (3)
blood cells, Igs, and large proteins
allows water, ions, glucose, AA and urea to pass
The glomerular basement membrane is made up of type 4 and 18 collagen, laminin, entactin, and proteoglycans. Why does a high albumin in urine indicate GBM damage?
Albumin is large and normally cannot pass to be filtrated out. So when there is a membrane damage, then larger proteins will be able to filter through
Mesangial cells support glomerular loops and podocytes, are phagocytic, control filtration, prevents glomerular distention due to high BP via contraction, secretes GF and cytokines in response to injury and can proliferate in certain?
kidney diseases
The proximal convoluted tubule is the most abundant tubule, most active in resorption and secretion. Has simple cuboidal to columnar epithelium with abundant _______. Also has abundant mitochondria with highly folded cell membranes to increase surface area. This is hwere what can be found?
abudant microvilli
Na/K ATPase pump, aquaporins, glucose tranporters (sGLT2) and AA transporters can be found in the folds of the proximal convoluted tubule
What has thin permeable simple squamous epithelial wall lacking brush border with some nuclei bulging into the lumen?
Thin limb loop of henle
What has simple cuboidal epithelium with numerous microvilli but no visible brush border?
Thick limb loop of henle
What has simple cuboidal epithelium with sparse microvilli. Its luminal surface is smoother than PCT and fewer in number. It cells are taller than ascending LoH and angiotensin II influences Na+ resorption here
Distal convoluted Tubule
Parathyroid hormone regulates _____ uptake/absorption in the DCT
calcium (Ca2+)
What receive primitive urine from nephrons, are lined with simple cuboidal but are columnar at the ends. Their primary function is water reabsorption and run straight through the cortex into the medulla?
collecting ducts
multiple form together to form a papillary duct which drains to the minor calyx
There are two different cell types in the collecting tubules/ducts. Light and dark cells… how are the differentiated?
Light cells (principle cells) are the target of aldosterone, which have white cilia Dark cells (intercalated cells) involved in H+ and bicarbonate transport- look speckled?
The hallmark of the collecting ducts is what? What is the target of both ADH and aldosterone here?
Hallmark is seeing all boreders of each individual cell
The target of both is increasing Na reabsorption and water retention
Efferent arterioles go to __________ which surround convoluted tubules and are lined with fenestrated epithelium to allow reuptake of H20 and salts
peritubular capillaries
Efferent arterioles of juxtamedullary glomeruli give rise to _______ which are thin walled vessels, descending with continuous endothelium but fenestrated when ascending. Along loop of henle to help concentrate urine.
vasa recta
Juxtaglomerular cells are mechanosensory which secrete renin in response to low renal BP, which increase sodium retention, blood volume and BP. Macula densa are what?
Macula densa are at the distal end of thick ascending LoH, and act as chemoreceptors by monitoring salt levels, signaling release of renin if sodium is too low!
The urethra, ureter and urinary bladder are all lined with transitional epithelium. Which does what?
When it is relaxed it is more bubbly and larger but when it is stretched it shrinks and gets pulled, can be binucleated cells
There are three layers to the transitional epithelium which is also known as urothelium. They are?
Superificial: streched and relaxed
Intermediate: sliding layer
Basal: contains stem cells to reproduce epithelium
What is in the transitional epithelium in most of the urinary tract system that fuses with plasma membranes when the cell is distended and endocytosed when the cell is non-distended?
Fusiform vesicles (FV)
urothelial plaques form an impermeable barrier with uroplakin proteins
Ureters are long fibromuscular tubes which carry urine from kidneys to bladder. Exits via renal pelvis and enters bladder obliquely to prevent backflow. Has transitional epithelium along with a muscularis with 3 layers. they are?
Inner longitudinal layer (parallel with ureter)
Outer circular layer (perpendicular to ureter)
Outer longitudinal layer
(Above is middle layer)
also has adventitial layer (outermost) and urothelium (innermost)
The bladder usually contains 4-600 ml of urine but can hold up to 1L. Expands into abdomin when full and lies on the pelvis when empty. What are the three layers in the bladder wall?
Transitional epithelium (urothelium)
3 layers of thick smooth muscle (called detrusor muscle)
Fibrous adventitia
What is the trigone of the bladder?
A triangle on the floor of the bladder-inferior posterior wall where ureters and urethra open
The urethra is made of 3 different epitheliums. Transitional epithelium more towards the bladder, psuedostratified columnar in most of the urethra and _____ at the distal end
stratified squamous epithelium
The female urethra is short and opens at the external urethral orifice right past the sphincter. it only consists of which type of urethra?
membranous
The internal urethral sphincter is involuntary smooth muscle while the external urethral sphincter is composed of ________ which allows?
skeletal muscle which allows the female to have some control over the release of urine
The male urethra is 20cm in length and tranports both semen and urine. There are three named regions which include?
Prostatic urethra Membranous urethra (through urogenital membrane like females) Spongy (penile) urethra- goes thru penis
Polycystic kidney disease is autosomal dominant. They are asymptomatic at first until 30-40 years of age. Only option is dialysis and kidney transplant. What is commonly seen in someone with the disease?
Cysts form that crush tissue and impede drainage. Eventually leading to kidney failure, blood pressure misregulation and many kidney infections
