Renal Function: Reabsorption and Secretion Processes

What is tubular reabsorption?

The process of moving substances from the renal tubules back into the blood of peritubular capillaries.

What substances are commonly reabsorbed in the renal tubules?

Sugar, amino acids, lactic acid, citric acid, phosphates, sulfates, calcium, potassium, sodium, and water.

What is the transport maximum (Tm)?

The maximum amount of a specific molecule that can be reabsorbed in a given time.

What is tubular secretion?

The process of moving wastes and large molecules that were not filtered by the glomeruli into the renal tubules.

What substances are typically secreted during tubular secretion?

Drugs, potassium, and hydrogen ions.

What role does ADH play in the distal tubule and collecting duct?

ADH makes these cells permeable to water, allowing for water reabsorption by osmosis.

What is the function of the renal corpuscle?

Filtration of water and dissolved substances from plasma, receiving glomerular filtrate.

What occurs in the proximal tubule?

Reabsorption of glucose, amino acids, various acids, phosphate, sulfate, calcium, potassium, sodium, and water, along with active secretion of substances like penicillin and hydrogen ions.

What happens in the ascending limb of the nephron loop?

Reabsorption of sodium, chloride, and potassium ions by active transport.

What is the composition of normal urine?

Generally 95% water, with urea, uric acid, creatinine, small amounts of amino acids, and electrolytes.

What is renal clearance?

The rate at which a chemical is removed from plasma by the kidneys, used to calculate GFR.

What are kidney stones made of?

Uric acid, calcium oxalate, calcium phosphate, and magnesium phosphate.

What are the layers of the bladder?

1) Mucosa (transitional epithelium), 2) Submucosa, 3) Muscularis (detrusor muscle), 4) Serosa (visceral peritoneum).

What is the function of the urethra?

To convey urine from the bladder to the outside of the body.

What are the two types of urethral sphincters?

Internal urethral sphincter (smooth muscle, involuntary) and external urethral sphincter (skeletal muscle, voluntary).

How long is the female urethra?

Approximately 4 cm.

How long is the male urethra?

Approximately 19.5 cm.

What are some common urinary issues?

Incontinence (lack of control over urination) and nocturnal enuresis (bedwetting).

What is the trigone in the bladder?

A triangular area containing two openings for ureters and one for the urethra.

What is the main cause of gout?

Excess uric acid that precipitates in blood and forms crystals in joints.

What is the normal urine volume range per day?

0.6 to 2.5 liters, depending on fluid intake and other factors.

What is the significance of the renal plasma threshold?

It indicates when there is too much of a specific molecule to be reabsorbed completely.

What is the role of the detrusor muscle?

To contract during micturition, facilitating the expulsion of urine.