Renal System (Final Exam) Flashcards
What does glomerular filtration mean?
filtration of plasma from glomerular capillaries into Bowman’s space
What does tubular secretion mean?
direction of movement is from medulla interstitial fluid into tubule lumen
What does tubular reabsorption mean?
direction of movement is from tubule lumen into medulla interstitial fluid
What is normally filtered?
plasma
What is not normally filtered?
blood cells and negatively charged proteins
What is the function of vasopressin/antidiuretic hormones in the formation of urine?
increase the permeability of the distal tubules and collecting ducts to water
What is the Vasa Recta?
capillary blood vessels that form loops parallel to the loop of Henle in the renal medulla that minimizes the washout of the hyperosomotic medulla
Function of the kidneys?
filter the plasma and form urine
Function of the ureters?
transport urine from kidneys to bladder
Function of the bladder?
stores urine
Function of the urethra?
excretes urine from bladder to outside of the body
What is the glomerulus?
the capillary network for filtration plasma
What is the Bowman’s capsule?
receives filtered plasma for entry into renal tubules
What are nephrons?
subunits of the kidney consisting of renal corpuscle and tubules
What is the glomerular filtration rate?
volume of plasma filtered from the glomeruli into the Bowman’s space per unit time (ie: mL/min)
What is the efferent arteriole?
renal vessel that brings blood from glomerulus to vasa recta
What is filtrate?
ultrafiltrate of plasma produced in the glomerulus from the renal arteries that is usually free of cells and large proteins
What effect would increasing the arterial pressure have on glomerular capillary hydrostatic pressure (P-GC) and GFR?
the P-GC and GFR will increase
How is the secretion of ADH affected when there is excess water in the body?
decreases the production of ADH so that there is little water being reabsorbed into the distal tubule and collecting ducts
What is the afferent arteriole?
vessels in kidney that carries blood from artery to glomerulus
What is the renal corpuscle?
combination of glomerulus and Bowman’s capsule
Where is the vasa recta placed in relation to the nephron?
very close to the juxtamedullary nephrons
What does juxtamedullary mean?
in between the cortical (outer) and medulla (inner) side of the kidney
What is the countercurrent multiplier?
mechanism that uses energy to create a concentration gradient
Purpose of countercurrent multiplier?
make medullary interstitial fluid hyperosmotic in order to create urine
What is the proximal tubule do?
drains the Bowman’s capsule
What does the proximal convoluted tube do?
right after the renal corpuscle and takes part in the reabsorption/secretion of ions and molecules – reabsorbs ions and molecules like glucose our body needs from the tubules
What does the descending loop of Henle do?
ONLY permeable to water – reabsorbs water due to high-salt concentration gradient of medulla
What does the ascending loop of Henle do?
permeable to salts to pump it out into interstitial space of medulla tissues – reabsorbs salt
What is the function of the distal convoluted tube?
reabsorbs more salt and secretes ammonia, some water and potassium
What is the function of the collecting duct?
runs back into the medulla to filter out more water and salts to keep in the body, sometimes urea is also reabsorbed into the medulla
What is the medulla connected to in the kidney?
the renal pelvis
What is the renal pelvis?
funnel-shaped tubes composed of smooth muscle where the collecting ducts all connect for urine to flow into the bladder via ureters
Purpose of the loop of Henle
drive reabsorption of water by creating a salt concentration gradient in the tissues of the medulla
How does the loop of Henle create a salt concentration gradient to drive the reabsorption of water?
actively pumps out salts in the ascending limb in order to create a salty interstitial fluid in the medulla so that water from the next filtrate can be pumped into the interstitial fluid in the descending limb
What are the cortical nephrons?
same as juxtamedullar nephrons but have a mini version of loop of Henle which does not penetrate deep into medulla
How are cortical nephrons different than juxtamedullar nephrons?
does not contribute to the hypertonic medullary interstitium but still involved in reabsorption/secretion
What does osmotic pressure mean?
-
How is water moved around?
-
How is the glomerular filtration rate (GFR) affected if the smooth muscle on the afferent arteriole contracts (constricted) and the efferent arteriole is dilated? How does this affect the glomerular capillary hydrostatic pressure (P-GC)?
the GFR decreases as well as the P-GC
How is the glomerular filtration rate (GFR) affected if the smooth muscle on the afferent arteriole dilates and the efferent arteriole contracts (constricted)? How does this affect the glomerular capillary hydrostatic pressure (P-GC)?
the GFR increases as well as the P-GC
What kinds of controls exist for regulating the GFR?
myogenic (intrinsic), tubuloglomerular feedback (intrinsic), mesangial cell contraction (intrinsic), sympathetic nerves (extrinsic)
What are the two keys to form a concentrated urine?
high level of ADH to increase water reabsorption and a high osmolarity of the medullary interstitial fluid
What does osmolarity mean?
concentration of solutes in the solution (salts in water basically)
What is myogenic regulation of the GFR?
increase of mean arterial pressure causes smooth muscle of afferent arterioles contract in response to stretch
What is tubuloglomerular feedback regulation of the GFR?
paracrine secretion from distal tube cells into mesangial cells of renal corpuscle due to an increase of flow through glomerulus = causes afferent arterioles to contract
What are the mesangial cells?
modified smooth muscle cells
What is mesangial cell contraction regulation of the GFR?
reduces surface area of glomerular capillaries = decrease in GFR
How will a hemorrhage affect glomerular filtration pressure?
hemorrhage decreases mean arterial pressure = decreases glomerular filtration pressure
How will the efferent and afferent arterioles be affected when there is an increase in sympathetic nervous activity?
efferent and afferent arterioles will constrict = renal blood flow decreases = GFR decreases
What are aquaporins?
water channels on a membrane
How will an increase in vasopressin/ADH increase water permeability of collecting duct cells?
vasopressin/ADH catalyze a cascade that leads to an increase of presence of aquaporins on the membrane surface of the tubular lumen = water from lumen to medullar interstitial fluid
How does the renal respond to acidosis?
urine is highly acidic – more new HCO3- added into blood = increases plasma bicarbonate
