Urinary system Flashcards
Identify the following structures of the nephron: Bowman’s capsule, glomerulus, afferent arteriole, efferent arteriole, proximal convoluted tubule, loop of Henle, distal convoluted tubule and collecting tubule (collecting duct).
A = Renal Vein (Carries oxygenated depleted blood)
B = Renal Artery (Carries oxygenated blood)
C = Proximal Convoluted Tubule (PCT)
D = Afferent Arteriole
E = Glomerulus
F = Efferent Arteriole
G = Bowman’s Capsule
H = Distal Convoluted Tubule (DCT)
I = Collecting Tubule
J = Descending Limb of Loop of Henle
K = Ascending Limb of Loop of Henle
L = Loop of Henle
Identify the contents of urine.
95% water and 5% solutes
Explain the role of the kidney in the elimination of nitrogenous waste.
The kidneys remove nitrogenous wastes, urea, and ammonia. Urea is the main excretory product filtered and excreted from the blood by the kidneys. Ammonia is mostly converted into urea in the liver and excreted in the urine.
Discuss the role of the kidney in the regulation of pH.
· Acid-base regulation is one of the most important roles of the kidneys.
· pH is normally maintained using HCO3- buffer:
- The kidney maintains HCO3- concentrations in a normal range to regulate pH.
- The kidney can raise or lower HCO3- concentration to adapt to other changes in the body.
In the case of renal failure, patients become increasingly acidic, which causes a whole host of problems.
What is the structure and function of the kidneys?
Structure:
The kidneys lie against the back muscles in the upper abdomen. They have a layer of fat that’s called the adipose capsule. An outer layer of fascia anchors the kidneys.
They have an outer layer called the cortex, a middle layer called the medulla, and an inner layer called the pelvis.
Function:
To filter the blood, remove waste and produce urine.
Describe the function of the renal pelvis.
A large cavity that collects the urine as it is produced.
Describe the ureters. Explain how urine travels through them.
The ureters are 2 long and slender muscular tubes that use peristalsis and gravity to move urine along. They extend from the kidneys.
Describe the function of the urinary bladder.
The urinary bladder is a temporary reservoir for urine and has many layers. It’s lined with mucous membrane and transitional epithelium. When it’s empty, the bladder has rugae.
Describe the structure and function of the urethra.
The urethra is the tube that extends from the bladder, leading to the outside of the body, allowing urine to pass out.
Why does low BP affect the kidneys?
It’s blood pressure that drives that filtration process.
Describe the internal anatomy of the kidney.
A = Nephron
B = Renal Cortex
C = Renal Medulla
D = Renal Column
E = Renal pyramid in renal medulla
F = Renal sinus
G = Renal papilla
H = Fat in the renal sinus
I = Renal capsule
J = Papillary duct in renal pyramid
K = Minor Calyx
L = Renal pelvis
M = Ureter
N = urinary bladder
O = Renal artery
P = Renal vein
Filtration Process in the Nephron:
Describe the physiological processes of filtration with reference to the nephron. (blood flow to glomerulus)
Filtration Process in the Nephron:
Blood Flow to Glomerulus:
- Blood enters the glomerulus through the afferent arteriole.
- Hydrostatic Pressure: Blood pressure forces water and solutes into Bowman’s capsule through the glomerular capillary walls.
- Bowman’s Capsule: Collects the filtrate, which includes water, glucose, electrolytes, amino acids, urea, and other small molecules. Blood cells and large proteins are excluded from the filtrate.
Blood Exit from Glomerulus: - Efferent Arteriole: Takes filtered blood away from the glomerulus.
Describe the physiological processes of reabsorption with reference to the nephron.
Reabsorption Process in the Nephron:
- Proximal Convoluted Tubule (PCT):
Water, Sodium, Glucose and Amino Acids
Bicarbonate (HCO₃⁻), Chloride, and Potassium are reabsorbed.
- Descending Limb of Loop of Henle:
Water: Reabsorbed due to high osmolarity of the medulla (impermeable to solutes).
- Ascending Limb of Loop of Henle:
Sodium (Na⁺), Chloride (Cl⁻), and Potassium (K⁺): Reabsorbed (impermeable to water).
- Distal Convoluted Tubule (DCT):
Sodium (Na⁺): Reabsorbed, regulated by aldosterone.
Calcium (Ca²⁺): Reabsorbed, regulated by parathyroid hormone (PTH).
- Collecting Duct:
Water: Reabsorbed, regulated by antidiuretic hormone (ADH).
Sodium (Na⁺): Further reabsorbed, regulated by aldosterone.
Urea: Partially reabsorbed to maintain osmotic gradient in the medulla.
Describe the physiological processes of secretion with reference to the nephron.
Secretion in the Nephron:
- Proximal Convoluted Tubule (PCT):
Secretion of metabolic waste products, drugs, toxins, Hydrogen Ions and Ammonium.
- Loop of Henle:
Minimal Secretion: Most of the secretion processes occur in other parts of the nephron.
- Distal Convoluted Tubule (DCT):
Hydrogen Ions, Potassium Ions, Urea.
- Collecting Duct:
Hydrogen Ions, Potassium Ions and Ammonium
What is the main parts of the urinary system?
2 kidneys
2 Ureters
1 Urinary bladder
1 Urethra
What is a nephron?
A nephron is the functional unit of the kidneys. It does the kidneys work.
How many nephrons are contained in each kidney?
1 million
Describe how kidneys maintain blood pressure.
The juxtaglomerular apparatus controls the pressure of filtration.
When stimulated by low sodium volume in the blood, receptor cells secrete the enzyme renin, which initiates the process that activates angiotensin, a protein which elevates blood pressure.
Describe the pathway of urine elimination, beginning with the kidney.
Kidneys—>ureters—>bladder—>urethra—»outside of the body
List the major electrolytes needed by the body and their functions.
Sodium- maintains osmotic balance and body fluid volume. Required for nerve impulse conduction.
Potassium- helps transmit nerve impulses. Major cation of ICF.
Calcium- bone formation, muscle contraction, nerve impulse transmission, blood clotting.
Magnesium- muscle contraction
Bicarbonate- body fluid buffer
Chloride- formation of HCI in the stomach. It helps regulate fluid balance and pH. Major anion in ECF.
Phosphate- Carbohydrate metabolism, bone formation, pH. Found in nucleic acids (DNA, RNA) and ATP.
What are plasma proteins?
Plasma proteins are found in the plasma and never leave the plasma unless in diseased conditions.
What is the organic composition of urine?
urea, creatinine, uric acid, hippuric acid, other substances
What is the inorganic composition of urine?
sodium chloride, potassium, sulfate, phosphate, ammonium, magnesium, calcium
What is the normal pH of blood?
7.35-7.45 pH
What is Glomerular filtration?
-Water, ions, glucose, and small proteins are pushed out of glomerular capillaries into the glomerular capsules, forming filtrate.
What is Tubular Reabsorption?
-Moves substances from filtrate back into the blood in peritubular capillaries via active transport.
What is Tubular secretion?
-Moves substance from blood in peritubular capillaries back into the filtrate.
-Occurs in parts of renal tubule and collecting duct.
-Remainder (urine) is excreted
The glomerular capsule has two layers:
1.) What is the Parietal layer?
- Consists of simple squamous epithelium and forms the outer wall of the capsule
The glomerular capsule has two layers:
2.) What is the visceral layer?
- Consists of epithelial cells called podocytes that have footlike processes called pedicels
Where are Pedicels?
They wrap around the glomerular capillaries.
What are Filtration slits?
-Spaces between pedicels.
-Substances passing out of the blood at the glomerulus must be small enough to fit through.
-Substances are forced from the blood through the filtration membrane based on size
What is the filtration membrane?
-Allows blood plasma and its components to pass through.
-Water, amino acids, glucose, ions, and small proteins, like albumin, enter the capsular space as filtrate.
Blood cells and most plasma proteins
- Remain in glomerular capillaries and are taken out of the glomerulus via the efferent arteriole.
What is the Path of filtrate?
-Glomerular capsule
-Proximal convoluted tubule
-Loop of Henle
-distal convoluted tubule
-collecting duct
-papillary duct-> minor calyx -> major calyx-> renal pelvis -> ureter-> urinary bladder
What are some factors that assist Filtration?
-Glomerular capillaries are long and extensive -> large surface area for filtration.
-Filtration membrane is thin and porous.
-Glomerular capillaries have large fenestrations, and are 50x leakier than capillaries in most tissue.
-BP in glomerular capillaries is high.
What are the Factors Opposing Filtration
Capsular hydrostatic pressure
-Pressure exerted against the filtration membrane by fluid already in the capsule.
-Back pressure opposes glomerular blood hydrostatic pressure.
A base gives off what ions?
Gives off hydroxide ions
An acid gives off what ions?
Gives off Hydrogen ions,
How do the kidneys Regulate Electrolyte Balance?
Filtration: Electrolytes are filtered from the blood in the glomerulus.
Reabsorption: Necessary electrolytes like sodium, potassium, calcium, and chloride are reabsorbed in the renal tubules.
Secretion: Excess electrolytes are secreted into the urine.
How does Hormones Regulate Electrolyte Balance?
Aldosterone: Secreted by the adrenal cortex, it increases sodium reabsorption and potassium excretion in the kidneys.
Antidiuretic Hormone (ADH): Released by the pituitary gland, it promotes water reabsorption, indirectly affecting electrolyte balance.
Describe the changes in fluid balance that may occur with ageing.
Decreased Total Body Water: Reduction in muscle mass and increase in fat.
Diminished Thirst Response: Increased risk of dehydration.
Reduced Kidney Function: Lower glomerular filtration rate (GFR), affecting fluid excretion.
Describe the changes in electrolyte balance that may occur with ageing.
Sodium: Risk of hypernatremia due to impaired renal concentrating ability and reduced water intake.
Potassium: Risk of hyperkalemia due to decreased renal excretion and use of certain medications (e.g., ACE inhibitors).
Calcium: Risk of hypercalcemia due to decreased renal function and altered vitamin D metabolism.
Describe the changes in acid-base balance that may occur with ageing.
Reduced Renal Buffering Capacity: Less efficient hydrogen ions excretion and bicarbonate reabsorption.
Respiratory Changes: Decreased lung function may impair CO₂ elimination, affecting acid-base balance.
