Unit 7: Urinary System Flashcards
Name the 5 functions of the kidneys
Excretion
Filter blood plasma
Regulate blood volume, pressure, and osmolarity
Secrete hormones
Regulate acid/base balance of blood
What wastes are filtered by the kidneys
Excess minerals
Nitrogenous wastes
What are 3 nitrogenous wastes
Urea
Uric acid
Creatinine
What is urea produced from
Protein metabolism
What is uric acid produced from
Nucleic acid metabolism
What is creatinine produced from
phosphagen energy system
Describe the flow of blood INTO the kidneys
- renal artery
- segmental arteries
- interlobar arteries
- arcuate arteries
- cortical radiate arteries
- afferent arteriole
- Glomerulus
Where do segmental arteries branch from
renal artery
Where would you find interlobar arteries in the kidney
running between pyramids in the renal columns
Where would you find arcuate arteries
Running OVER renal pyramids
Where do cortical radiate arteries lead to
renal cortex
Define Glomerulus
capillary network which is the filtration center of the nephron
Describe the flow of blood OUT of the kidney
- Glomerulus
- efferent arteriole
- peritubular capillary
- cortical radiate veins
- arcuate veins
- interlobar veins
- renal vein
What is the function of a nephron
Filter blood to produce urine
What are the 2 types of nephrons
Cortical nephrons
Juxtamedullary nephrons
Describe cortical nephrons
80% of nephrons
Short loop which produces most of the urine
Describe juxtamedullary nephrons
20% of nephrons
Long loop which extends deep into the renal medulla
Maintains Na+ levels and water balance
What are the 2 major parts of the nephron
renal corpuscle
renal tubule
Describe a renal corpuscle and its function
Site of filtration where the glomular capsule surrounds the glomerulus
What are the renal tubules
Proximal convoluted tubule (PCT)
Nephron Loop
Distal convoluted tubule (DCT)
end at the collecting duct
Describe the form and function of proximal convoluted tubules (PCTs)
Longest tube (microvilli lined) with many coils (mitochondria lined)
Receives filtrate from the glomerulus
Performs majority of reabsorption of filtrate
Describe the form and function of the nephron loop
U-shaped with a thin (descending) limb and thick (ascending) limb
Ascending limb does active transport of salts
Descending limb balances water
WATER CONSERVATION
REGULATE BLOOD pH
What is the function of mitochondria in the proximal convoluted tubule
active transport of filtrates (glucose and amino acids)
What is the function of microvilli in the proximal convoluted tubule
increased surface area for more reabsorption
What are the 2 routes of reabsorption in the proximal convoluted tubule
Transcellular (across cell)
Paracellular (between cells)
Renal tubules are surrounded by
peritubular capillaries
The collecting duct receives ____ from _____
urine from nephrons
Describe flow of urine out of kidney
glomerular capsule
proximal convoluted tubule
nephron loop
distal convoluted tubule
collecting duct
papillary duct
minor calyx
major calyx
renal pelvis
ureter
urinary bladder
urethra
What are the 4 parts of urine formation
Filtration
Reabsorption
Secretion
Water conservation
Urinary excretion =
glomerular filtration + tubule filtration - tubular reabsorption
Filtrate is made of
water and solutes
(like glucose, amino acids, urea, uric acid, creatinine, creatine, salts)
Describe the filtration membrane of glomerulus
Has fenestrations, basement membrane, and filtration/glomerular slits
Describe the function of fenestrations in the glomerulus
increases permeability of capillaries but excludes large particles like RBCs
Describe the function of basement membrane in the glomerulus
excludes large particles like proteins
Describe function of glomerular sites in glomerulus
has podocytes (cells)
has slits which exclude very small particles, too
What does it mean if there is protein in filtrate
Kidney failure
Define Glomerular Filtration Rate (GFR)
Amount of filtrate formed per minute
______ of filtrate is reabsorbed
99%
GFR =
NFP x Kp
(pressure x surface area)
Net filtration pressure is determined by
glomerular capillary pressure (BP), colloid osmotic pressure (albumin), and pressure in glom. capsule
Kf (filtration coefficient) is determined by
surface area and permeability of filtration membrane
An increased GFR leads to
increase urine output
dehydration
decreased electrolytes
A decreased GFR leads to
waste retention
GFR maintains homeostasis through what 3 methods
Autoregulation
Sympathetic Nervous System
Hormonal control
Describe autoregulation of GFR
Myogenic mechanism
an increased BP causes afferent arteriole to stretch, causing ion channels to open, depolarize, and contract
BP kept constant by vasoconstriction
Describe how the sympathetic nervous system controls GFR
increased exercise or stress causes afferent arterioles to contract, which decreases GFR and urine output, while redirecting blood to heart, brain, and muscles
Describe hormonal control of GFR
Angiotensin - Renin system
Describe the Angiotensin - Renin system
Angiotensinogen converted to Angiotensin I by Renin enzyme
Angiotensin I converted to Angiotensin II by ACE
Angiotensin II stimulates production of aldosterone which causes water retention in kidneys
Distal Convoluted Tubule and collecting duct has which hormone receptors
Renin
Aldosterone
Antidiuretic hormone (ADH)
Atrial natriuretic peptide (ANP)
Parathyroid hormone (PTH)
Which hormones decrease urine output to increase water retention
Renin
Aldosterone
ADH
PTH
What does aldosterone promote
Salt and water reabsorption
(decrease urine, increase BP)
What does antidiuretic hormone (ADH) promote
Water reabsorption in collecting ducts in response to dehydration
What does atrial natriuretic peptide (ANP) promote
Water and salt excretion in response to high BP
(increase urine, decrease BP)
What does parathyroid hormone (PTH) promote
Kidney reabsorption of calcium and osteoclast activity to increase blood calcium levels
More salt means
MORE WATER RETAINED!
What is the purpose of the countercurrent mechanism in nephron
Retain water to avoid dehydration
What does the descending limb of the countercurrent mechanism do
Reabsorb water from tubule
Concentrates tubular fluid
What does the ascending limb of the countercurrent mechanism do
Reabsorb Na+, K+, Cl-
Maintain osmolarity of renal medulla
Dilute tubular fluid
Describe Vasa Recta
Blood vessels by juxtamedullary nephrons which maintain salt and water concentration
Receives salt and water from countercurrent mechanism
The countercurrent multiplier is a ________ feedback loop
positive
What does the collecting duct do
Concentrate urine
Releases water in response to high medulla osmolarity
Describe Kidney Stones
Cause?
Symptoms?
Risk Group?
Kidneys collected stones made of calcium with oxalate, phosphate, or carbonate OR stones made of other substances (e.g. struvite, uric acid, or cystine)
Back pain, blood in urine, cloudy urine, burning urination, fever, vomiting
Dehydrated, women with UTIs (struvite), men with gout (uric acid), hereditary (cystine)
Describe Urinary Tract Infections
Cause?
Symptoms?
Risk Group?
Bacterial infection of urinary tract, usually in bladder but can travel to kidneys
Painful urination, cloudy urine, blood in urine, persistent urge to urinate
women (especially if sexually active), diabetics, people with difficulty fully emptying bladder
Describe Bladder Cancer
Cause?
Symptoms?
Risk Group?
Cancerous tissue in bladder lining
Blood in urine, frequent urge to urinate, painful urination, low back pain
Caucasians, men, smokers, elderly, hereditary
