Urinary System(A&P) Flashcards
Urinary-Excretory System(Function)
- excretion of wastes(nitrogenous waste=protein metabolism)
- fluid and electrolyte balance
- acid base balance(ph balance)
- normal range: 4.8-6(acidic)
- regulation of Bp
- aldosterone: cause kidney to reabsorb sodium; water allows kidney to get rid of potassium
- posterior pituitary: ADH all kidney to get rid of water
- stimulated erythropoiesis
- kidney activates vitamin D in fortified milk, helps calcium absorption
Organs of the urinary system
1) Kidney
2) Ureters
3) Urinary Bladder
4) Urethra
Kidney(Location)
- retropentoneal in the upper portion of the abdominal cavity at about the level of T12/L1
- r. kidney is usually lower than the L kidney
Kidney(Description)
- reddish brown bean shaped organs
- 4inch long, 2inch wide, 1inch thick
- medial structure has an indentation called the hilus which is the point at which blood vessels enter and exit from the kidney. it also has a point where the uterers exit the kidney
- covered with renal capsule(fibrous membrane) embedded in adipose tissue and the renal fascia which also anchors the kidney to the peritoneum and the abdominal wall
Renal Cortex:
Kidney internal structure
-outer layer made up of renal corpuscles and convoluted tubules
Renal Medulla:
Kidney internal structure
- inner layer of tissure made up of Loop of henle and collecting tubules
- tubules form cone shaped structures called renal pyramids
- the tips(apex/papilla) of the renal pyramid points toward the renal the renal pelvis
Renal Pelvis
- funnel shaped cavity that forms the upper part of the ureter
- collects urine made by the kidney and directs it towards the ureter
- edges of the renal pelvis are cup/funnel shapes called calyces.
- urine flows from the renal pyramid to the calyces to the renal pelvis to the ureter
Blood Supply
- kidney is perfused by the renal artery
- kidney recieves 20-25% of cardiac output
- in the kidney the renal artery branches into a number of arteries which branch into a number of arterioles
- arterioles came in contact with the nephrons
- venules in the kidney unite to form veins
- veins in the kidney merge to form the renal vein which leaves the kidney and joins the inferior vena cava
Nephron(Microscopic structures)
- structural and functional unit of the kidney
- each kidney contains about 1 million nephrons
- each nephron makes urine
nephron
made up of two parts
1) tubular structure(a tube w/ capsule at one end)
2) vascular structure(network of blood vessels
- function of the nephrons depends on the way in which the tubular component and the vascular component are arranged in relationship to each other
Filtration(Function of nephron)
-movement of water and solutes from the glomerulus to bowmen’s(glomerular capsule)
Secretion(Function of nephron)
-additional waste products and unneeded electrolytes are moved from the bloodstream into the forming urine
reabsorption(function of nephron)
-water,electrolytes, and additional needed materials are moved from the forming urine into the bloodstream.
Renal Corpuscle
2 parts
- glomerulus=vascular/capillary
- glomerular(bowmans) capsul=tubular
glomerulus(renal corpuscle)
- cluster of capillaries
- afferent-arteriole brings blood to the renal corpuscle and branch into large number of capillaries; the afferent arteriole has a wider diameter which takes blood away from the renal corpuscle
- capillaries merge to form the efferent arteriole which take blood away from the renal corpuscle
bowmans/glomerular capsule(renal corpuscle)
- part of the tubular structure
- surrounds the glomerulus and receives the filtrate
- renal corpuscle is the site of filtration
renal tubules
-long tubular structure that is surrounded by the peritublar capillaries
-renal tubules are the site for:
SECRETION: waste products and unneeded electrolytes are moved from the bloodstream into the forming urine
REABSORPTION: water, electrolytes and additional needed materials are moved from the forming urine into the bloodstream
proximal convoluted tubule
- first part of renal tubules after the glomerular capsule
- site of most reabsorption
- normally 100% of the filtered glucose, amino acids and other useful metabolizes are absorbed
loop of henle
- hair pin, u shaped structure
- has a descending limb and an ascending limb
- reabsorption of K,NA,Cl and the beginning of H20 reabsorption occurs in the loop of henle
distal concoluted tubule
- extension of the ascending limb of the loop of henle
- reabsorption of NACL and h2o continues
- DCT is the site for the action of aldosterone
- DCT is the site of tubular secretion
- site of most secretion
collecting tubule
- formed by the union of the dct from seceral nephrons
- collecting tubules empty into the calyces of the renal pelvis
physiology of urine production
- urine is formed as water and solutes
- more btw the vascular and the tubular structure of the nephron
- urine formation involves 3 process:
- glomerular formation
- tubular reabsorption
- tubular secretion
glomerular filtration
- occur b/c the pressure in the glomerulus is higher than the pressure in the glomerular capsule
- recall that afferent arteriole is wider in diameter than the efferent arteriole
- glomerular filtration is dependent on Bp
- glomerular filtration involves movement of water and solutes from the bloodstream into the bowmans capsule
- what passes into the filtrate is dependent on the size of the pores of the filter
- normally electrolytes,urea,creatine,and glucose pass easily into the filtrate
- normally rbc and large proteins do not pass into the filtrate
- glomerular filtration depends on Bp and the amount of blood that reaches the kidneys
- normal urine production is 1-2Liters a day
glomerular filtration is
125ML/min or 180L/day
- normal urine production is 1-2Liters a day
- approx. 99% of the filtrate gets reabsorbed
Tubular reabsorption
- as filtrate passes through the tubules water and other useful substances move from the tubules to the peritubular capillaries(99% of the filtrate is reabsorbed)
- most tubular reabsorption takes place in the proximal convoluted tubule(PCT)
- the kidneys regulate both the substances and the quantity of these substances that gets reabsorbed
reabsorption takes place by
- diffusion: movement of solute from high to low concentration
- active transport: movement of solute from low to high(need atp and pump)(against diffusion gradient)
- osmosis: diffusion of water from high to low across semipermeable membrane(from dilute solution to concentrated solution)
- na is reabsorped by active transport
- cl by diffusion
- water by osmosis follows the sodium
- na is the single most important electrolyte that is involved in fluid balance and fluid distribution in the body
- all of the glucose in the filtrate gets reabsorbed by active transport
- all the amino acids and small proteins in the filtrate get reabsorbed by active transport
- PTH promotes the reabsorption of calcium(PTH dissolves bone)
- waste do not get reabsorbed comes back by osmosis
- for many of the substances that are reabsorped by the renal tubules there is a threshold level limit for reabsorption
Tubular secretion
- actively moves material from the blood stream to the tubules
- H+(ph balance), K+, ammonium ion, urea, uric acid, creatine, drugs and metabolites
concentration of urine volume
-additional fluid balance and bp regulation
-concentration of urine depends on:
Osmosis
ADH secreted by the posterior pituitary
Aldosterone(secreted by the cortex of the adrenal gland)
ADH makes
