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91 Cards in this Set

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  • Back
What are the three main filtration functions of the kidney?
Removal and excretion of metabolic waste (ie: nitrogen), balancing bodily fluids and electrolyte concentration, and reabsorption of molecules, ions, and fluids to maintain homeostasis.
What four functions does the kidney participate in (via secretions and excretions)?
Regulating BP by secretion of renin, producing erythropoietin for RBC formation, helping regulate calcium levels, and vitamin D sythesis.
How does the kidney help regulate calcium levels in the body?
Excess calcium ions are excreted through the kidney.
What function of the kidney is an endocrine function?
Producing erythropoietin for RBC formation.
What is the general shape of the kidney?
Kidney bean-shaped with a hilum entering the medulla
What are the renal columns of Bertin?
Boundries of the renal lobes, cortical material found between medullary pyramids.
Human kidneys are ____lobar.
What is a renal lobe?
A medullary pyramid and its associated cortical covering
What is the general structure of a medullary pyramid?
The corticomedullary junction is at the base of the pyramid, and the papilla is at the apex.
Where does urine first come out of the kidney?
Through the papilla in a medullary pyramid.
What is a minor calyx?
A "bowl"-like structure that surrounds the papilla and collects the urine.
What is a major calyx?
Where minor calyxes converge, leads to the renal pelvis
Where is the renal pelvis?
Forms from the major calyx leaving the renal medulla
Where are medullary rays located?
In the renal cortex, extending from the renal medulla
How often does 100% of the body's blood pass through the kidneys?
Every five minutes
How much of the blood entering the kidney actually reaches the medulla?
About 10% of the blood; the rest goes into the cortex and back out the renal vein, never going through the medulla
How many liters of fluid per day are reabsorbed into the tubules of the kidney?
180 liters/day
How many liters of fluid are excreted from the kidney per day?
1.5 to 2 liters/day
Through what vascular element does oxygenated blood enter the kidney?
Through the renal artery (branching from the descending aorta)
From the renal artery, how does blood get to Bowman's capsule?
Blood enters through the renal artery, goes to the interlobar artery, then to the arcuate arteries (at corticomedullary junction), then to interlobar arteries, which become afferent glomerular arteries, turn into glomerular capillaries, then the blood goes through Bowman's capsule
Where does blood go once it exits the renal corpuscle?
It leaves via efferent glomerular arterioles and either becomes peritubular capillaries that eventually lead back to the renal vein (most common route), or become vasa recta and enter the medulla.
What problems can arise as a result of the absence of arterial anastomoses in the renal cortex?
If there is a blockage of a vessel, blood can't get around it, and that part of the kidney is irreversibly damaged.
What is the "normal" route of venous drainage from the renal corpuscle?
Efferent arterioles carry the blood out of the corpuscle, then they become peritubular capillaries, which enter the interlobar vein, leading to the arcuate vein, which finally leads to interlobar veins that are continuous with the renal vein.
What is the difference between the vasa recta and the vena recta?
The vasa recta is the arteriole portion; it forms a capillary bed around medullary structures. The vena recta brings blood back to the cortex and rejoins arcuate veins, through which blood eventually arrives at the renal vein.
Are vasa recta arterioles or veins?
They include both.
What are the four parts of the nephron?
What are the two layers of Bowman's capsule?
The visceral (inner) layer and the parietal (outer) layer
What is the visceral layer of Bowman's capsule?
The inner layer, attached to the glomerulus
What is the parietal layer of Bowman's capsule?
The outer layer, associated with the C.T. stroma
How many loops of capillaries are there in the glomerulus?
50 loops
What are the two types of nephrons?
Cortical nephrons and juxtamedullary nephrons
Where are juxtamedullary nephrons located?
In the cortex in the region adjacent to the medulla; their loops of Henle almost reach the papilla (via vasa recta)
The ______ the concentration of urine, the more juxtamedullary nephrons that are needed.
What is included in the structure of the renal corpuscle?
Bowman's capsule surrounding the glomerulus, a urinary space between the two layers of Bowman's capsule, vascular and urinary poles, and the juxtaglomular apparatus
Where are the vascular and urinary poles located on a renal corpuscle?
The vascular pole is "north," where afferent and efferent arterioles enter and leave; the urinary pole is "south," where urine exits the corpuscle.
Where does the filtrate go after leaving the urinary pole?
Into the proximal convoluted tubule
What type of epithelium lines the proximal convoluted tubule?
Low columnar epithelium with microvilli, basal striations, and many mitochondria
What is the main function of the proximal convoluted tubule?
Reabsorption and ion transport; it reabsorbs 70% of the water, all glucose, sodium, potassium and other substances
Why do people with diabetes have glucose in their urine?
Because they cannot reabsorb all the glucose in the proximal convoluted tubule and end up with excess glucose in their urine.
What are the four portions of the loop of Henle (starting where filtrate enters)?
The thick descending portion, the thin descending portion, the thin ascending portion, and the thick ascending portion
In what portion of the loop on Henle can water be absorbed?
The descending portion (especially thin descending)
What part of the loop of Henle is lined by simple squamous cells that do not allow water to pass through?
The thin ascending portion
What lines the thick ascending portion of Henle's loop?
Cuboidal cells with basal striations, mitochondria, and short microvilli
Where is the macula dense located?
In the distal convoluted tubule
What portion of the loop of Henle is sensitive to aldosterone?
The thick ascending portion-aldosterone stimulates the resorption of NaCl
Overall, what does the loop of Henle absorb?
About 15% of the water and 25% of the NaCl
What effect does ADH have on the distal convoluted tubule?
ADH makes the cells permeable to water so it can be absorbed.
What hormones have an effect on the distal convoluted tubule?
Aldosterone (especially) and ADH
What lines the distal convoluted tubule?
Identical to the thick descending loop of Henle: cuboidal cells with mitochondria, basal striations, and short microvilli
What are the linings of the thick ascending loop of Henle and the distal convoluted tubule best suited for?
Ion transport
What is the difference between collecting tubules and collecting ducts?
Collecting tubules are smaller and have cuboidal epithelium. Collecting ducts are larger and have columnar epithelium.
How much of the volume of urine is lost in the collecting tubules and ducts?
About 90%
What two types of cells are found in the collecting tubules and ducts?
Principle cells and intercalated cells
What do principle cells in the collecting tubules and ducts do?
Absorb water and Na+ and secrete K+ ions
What do intercalated cells in the collecting ducts and tubules do?
They have abundant mitochondria and secrete H+ or HCO3- (therefore helping regulate the acid-base balance); they also resorb K+ ions.
What are the ducts of Bellini?
The largest collecting ducts in the kidney
Where do ducts of Bellini empty into?
They empty the final urine product at the papilla and into the minor calyx.
What hormones effect the collecting ducts and tubules?
Aldosterone (somewhat) and ADH (predominantly)
What do ADH levels have to do with dilute urine?
Low ADH levels cause dilute urine because the collecting system doesn't absorb enough water in the urine.
What makes up the renal corpuscle?
Bowman's capsule and glomerular capillaries
What composes the parietal layer of Bowman's capsule?
Simple squamous epithelium
What composes the visceral layer of Bowman's capsule?
Podocytes, nephrin, and basal lamina (of epithelial podocyte cells)
What is a podocyte?
Epithelial cells found in the visceral layer of Bowman's capsule; they have primary and secondary processes that wrap around fenestrated glomerular capillaries, leaving small gaps bridged with nephrin.
Why is the basement membrane doubled between the glomerular capillaries and the visceral layer of Bowman's capsule?
The podocytes (of the visceral layer) have a basal lamina, which is on top of the basal lamina of the endothelial cells lining the glomerular capillaries.
What makes up the "filter" in the renal corpuscle?
Fenestrations in the capillaries, the double basal lamina (from podocytes and endothelial cells), the electronically charged basement membrane, the filtration slits formed between secondary podocyte processes and finally, the nephrin diaphragms connecting podocyte processes.
Where is the juxtaglomerular apparatus located?
At the vascular pole of the renal corpuscle
What are the three components of the juxtaglomerular apparatus?
Juxtaglomerular cells (renin-secreting), the macula densa portion of the distal convoluted tubule, and the extraglomerular mesangial cells.
Where are juxtaglomerular cells located?
In the smooth muscle in the tunica media of the afferent and efferent arterioles.
What do juxtaglomerular cells secrete?
When is renin secreted?
When BP or NaCl concentration falls
Is the juxtaglomerular apparatus parasympathetically or sympathetically innervated?
What are the main functions of the mesangial cells?
(1)Regulating blood flow by expanding or contracting and changing the diameter of the fenestrated capillaries, (2)providing mechanical support for the glomerular capillaries, holding them apart, (3) varies the amount of filtrate and rate of filtration by contracting and expanding, (4) engage in phagocytic activity that cleans the filtration slits and controls turnover of the basal lamina, and (5) secretes prostaglandins and endothelins
What is the macula densa?
A physical concentration of cells attached to the afferent and efferent arterioles
How do the extraglomerular mesangial cells communicate with other mesangial cells and juxtaglomerular cells?
Via gap junctions
What is the function of extraglomerular mesangial cells?
To act as transducers, taking signals from the macula densa to the tunica media (and therefore, the juxtaglomerular cells, which secrete renin)
What is the overall function of the juxtaglomerular apparatus?
To help control BP and rate of urine formation
Is the interstitium more prominant in the renal cortex or the renal medulla?
In the renal medulla; tubules and capillaries take up so much of the renal cortex that the interstitium is negligible.
What are the functions of cells found in the interstitium of the renal medulla?
Secreting a non-fibrillar material called interstitial substance, secreting erythropoietin; the cells and their secretions participate in creating the medulla's osmotic gradients.
How many cell types have been found in the renal medulla?
Three types
Where does transitional epithelium first appear in the excretory passages?
In the minor calyx
What are the three layers in the wall of the ureter?
Mucosa (consisting of transitional epithelium and C.T.), muscularis (2 or 3 layers) and adventitia
What is the adventitia of the ureter composed of?
Fibroelastic C.T. with nerves and blood vessels
What are rugae (in the bladder)?
Folds in the walls
What is the difference between the lining of the bladder and that of the ureter?
The bladder's muscularis has three distinct layers, with a middle circular layer
What is micturition?
How long is the urethra in females (and in males)?
Four cm in females, 15 to 20 cm in males
What lines the urethra?
Mixed epithelium; begins as transitional and becomes stratified squamous
How many layers of smooth muscle are in the wall of the urethra?
Two layers
What type of muscle composes the external sphincter of the urethra?
Skeletal muscle
What are the three parts of the male urethra?
Prostatic (lined by transitional epithelium), membranous (by external sphincter), and penile (both this and membranous portion lined by pseudostratified to stratified columnar epithelium)
What are the glands of Littre?
Glands in the lamina propia of the urethra whose secretions raise the pH of the urethra to counteract the acidity of urine and protect the cells