Urinary System Flashcards
What are the functions of the kidney?
Filters 200L of blood daily
Regulate volume and makeup of blood
Maintain proper balance between water & salts AND acids & base
What are the other functions of the kidney?
Gluconeogenesis during prolonged fasting
Activation of vitamin D
Production of erythropoietin and renin
What is the function of renin?
To regulate blood pressure
What is the function of erythropoietin?
To regulate red blood cell production
What are the parts of the urinary system?
Paired ureters
Urinary bladder
Urethra
What is the function of the urinary bladder?
Provides a temporary storage reservoir for urine
What is the function of urethra?
Transports urine from the bladder out of the body
What is the function of the paired ureters?
Transport urine from the kidneys to the bladder
Where is the kidney located?
In a retroperitoneal position in the superior lumbar region
It extends approximately from T12 to L3 vertebrae
Why is the right kidney lower than the left kidney?
Because it is crowded by the liver
What is the shape of the lateral and medial side of the kidney?
Lateral surface is convex
Medial surface is concave
Where does the ureters, renal blood vessels, lymphatics, and nerves enter and exit?
Hilus
What are the three layers of tissue in the kidney?
renal fascia
perirenal fat capsule (adipose capsule)
fibrous capsule
What is the function of the renal capsule?
Fibrous capsule that prevents kidney infection
What is the function of adipose capsule?
Fatty mass that cushions the kidney and helps attach it to the body wall
What is the function of renal fascia?
outer layer of dense fibrous connective tissue that anchors the kidney
What are the three internal parts of the kidney?
Cortex
Medulla
(Renal) Pelvis
What are calyses?
large branches of the renal pelvis
What are the function of calyses?
Collect urine draining the papillae
Empty urine into the pelvis
What is the nerve supply in the kidney?
Renal plexus
How much systemic cardiac output flows through the kidney each minute?
Approximately one fourth (1200 mL) per minute
What are nephrons?
Structural and functional unit of the kidneys that form urine
What is nephrons consists of:
Glomerulus
Glomerular (Bowman’s) capsule
Renal corpuscle
Glomerular endothelium
What is the function of proximal convoluted tubule (PCT)?
Reabsorbs water and solutes from filtrate and secretes substances into it
What is proximal convoluted tubule (PCT)?
Composed of cuboidal cells with numerous microvilli and mitochondria
Part of the renal tubule
What is the Loop of Henle?
a hairpin-shaped loop of the renal tubule
What is distal convoluted tubule (DCT)?
Cuboidal cells without microvilli that function more in secretion than reabsorption
What are the two type of cells that can be found in connecting tubules?
intercalated cells
principal cells
What is the function of the intercalated cells?
Functions in maintaining the acid-base balance of the body
What is the function of the principal cells?
Help maintain the body’s water and salt balance
What is the function of juxtamedullary nephrons?
Production of concentrated urine
What are the two capillary bed of every nephron?
Glomerulus
Peritubular capillaries
What are the mechanisms of urine formation?
- Glomerular filtration
- Tubular reabsorption
- Tubular secretion
What is glomerular filtration?
“dumping into the waste container”
takes place in the renal corpuscle and produces a cell- and protein-free filtrate
What is tubular reabsorption?
“reclaiming what the body needs to keep”
is the process of selectively moving substances from the filtrate back into the blood
Where does tubular reabsorption and tubular secretion takes place?
Renal tubules and collecting ducts
What happens to the things that are not reabsorbed in the tubular reabsorption?
It becomes urine
What is tubular secretion?
“selectively adding to the waste container”
is the process of selectively moving substances from the blood into the filtrate.
Net filtration pressure equation
NFP = HPg - (OPg + HPc)
HPg = glomerular hydrostatic pressure OPg = oncotic pressure of glomerular blood HPc = capsular hydrostatic pressure
If the GFR is too high
Needed substance cannot be reabsorbed quickly enough and are lost in the urine
If the GFR is too low
Everything is reabsorbed, including wastes that are normally disposed of
Three mechanisms control the GFR
Renal autoregulation
Neural controls
Hormonal mechanism
When the sympathetic nervous system is at rest:
Renal blood vessels are maximally dilated
Autoregulation mechanisms prevail
How does adenosine affects glomerular filtration?
Vasoconstrictor of renal vasculature
Substances are not reabsorbed if they:
Lack carriers
Are not lipid soluble
Are too large to pass through membrane pores
Loop of Henle reabsorbs ______ in the descending limb
Water, sodium, chlorine, potassium
Loop of Henle reabsorbs ____ in the ascending limb
Calcium, Magnesium, Sodium
Substances reabsorbed in the PCT include:
Sodium, all nutrients, cations, anions, water
Urea and lipid-soluble solutes
Small proteins
Distal convoluted tubule (DCT) absorbs:
Calcium, sodium, hydrogen, potassium, water, bicarbonate, chlorine
Collecting ducts absorbs:
Water and urea
Atrial Natriuretic Peptide (ANP) does what?
Reduces blood sodium
What does ANP does to the blood?
Decreases blood volume
Lowers blood pressure
How does ANP lower blood sodium?
Acts directly on medullary ducts to inhibit sodium reabsorption
Counters the effect of angiotensin II
Tubular secretion is important for:
Disposing substances not filtrated
Eliminates undesirable substances such as urea & uric acid
Ridding the body of excess potassium ions
Controlling blood pH
What is osmolality?
The number of solute particles dissolved in 1L of water
Reflects the solutions’s ability to cause osmosis
Chemicals that enhance the urinary output include:
Any substance not reabsorbed
Substances that exceed the ability of the renal tubules to reabsorb it
Substances that inhibit sodium reabsorption
Examples of diuretics
High glucose levels
Alcohol
Caffeine & most diuretic drugs
Lasix and diuril
Renal clearance equation
RC = UV/P RC= renal clearance rate U = concentration (mg/ml) of a substance in urine V = flow rate of urine formation (ml/min) P = concentration of the same substance in plasma
What does cloudy urine indicate?
Cloudy urine might indicate infection of the urinary tract
What can affect the color of the urine?
Urochrome
Drugs, vitamin supplements, and diet
pH range of urine
Slightly acidic (pH 6) with a range of 4.5 to 8.0
Specific gravity of urine?
Ranges from 1.001 to 1.035
Is dependent on solute concentration
Chemical composition of urine
95% water and 5% solutes
Nitrogenous wastes include urea, uric acid, and creatinine
