Urinary System Overview

The process of controlling water intake based on ion concentration in blood.

Sodium ions are the major extracellular ions; their concentration influences osmotic pressure.

Potassium ions are crucial for the proper function of excitable tissues like muscles and nerves.

Calcium ion concentration affects excitable tissues; regulated by hormones and vitamin D3.

Increases extracellular calcium concentration.

Lowers extracellular calcium concentration.

Increases intestinal calcium absorption.

Reabsorbed actively in the kidneys.

The fluid inside all the cells of the body.

The fluid outside the cells.

High K+, Mg2+, PO43-, and SO42-; low Na+, Ca2+, Cl-, and HCO3-.

High Na+, Ca2+, Cl-, and HCO3-; low K+, Mg2+, PO43-, and SO42-.

Cell membranes allow water to pass but not ions readily.

Water movement is mainly controlled by hydrostatic pressure differences and osmotic differences between compartments.

Osmosis controls the movement of water between intracellular and extracellular spaces.

Maintaining specific ion concentrations, like Na+, K+, and Ca2+, is critical for action potentials, muscle contractions, and cell function.

The body maintains a stable pH level through a combination of buffers, respiratory, and kidney mechanisms.

Chemicals that resist changes in pH of a solution by binding to H+ ions. They contain salts of weak acids or bases.

The respiratory system quickly adjusts blood pH by altering carbon dioxide elimination. Increased breathing raises pH; decreased breathing lowers pH.

Blood pH rises due to increased carbon dioxide elimination (e.g., hyperventilation).

Blood pH falls due to reduced carbon dioxide elimination (e.g., hypoventilation).

Kidneys secrete H+ ions into urine to directly regulate blood pH. H+ secretion is increased in acidosis and decreased in alkalosis.

Blood pH falls below 7.35. It leads to a lower than normal pH.

Blood pH rises above 7.35. It leads to a higher than normal pH.

The urinary system's main job is to remove waste products from the blood. It's like a filter for your body. This includes getting rid of unwanted byproducts of your cells' activities.

The urinary system controls the amount of fluid in your body, which directly affects your blood pressure. By adjusting how much water and ions are eliminated in urine, it keeps your blood pressure in check.

The kidneys are the powerful workhorses of the urinary system; they filter your blood, removing waste products and excess substances.

The ureters act like pipes, carrying urine away from the kidneys to the bladder.

The bladder is a storage tank for urine. It collects the urine until it's ready to be released from your body.

The urethra is the final tube that allows urine to exit the body.

Erythropoietin is a hormone produced by the kidneys that helps your body make red blood cells. Red blood cells are crucial for carrying oxygen throughout your body.

The kidneys play a crucial role in activating vitamin D, a vitamin that helps your body absorb calcium from food. Calcium is essential for strong bones and other functions.

A thin layer of connective tissue that surrounds each kidney, protecting it and providing structural support.

The medial indentation of the kidney where blood vessels, nerves, and the ureter enter and exit.

A cavity within the kidney, located at the hilum, that houses the renal pelvis, calyces, blood vessels, and other connective tissues.

Cone-shaped structures within the kidney's medulla, extending from the cortex to the renal sinus.

Cup-shaped structures in the kidney that surround the tips of renal pyramids and collect urine.

A funnel-shaped structure in the kidney that collects urine from the calyces and funnels it into the ureter.

Urine is formed in the cortex and medulla, then flows through the tips of the renal pyramids, calyces, renal pelvis, ureter, urinary bladder, and finally exits through the urethra.

The functional unit of the kidney, responsible for filtering blood and producing urine.

A specialized type of epithelium that lines the ureters and urinary bladder, allowing for stretching and contraction as the organs fill and empty.

Contractions of smooth muscle in the ureters propel urine from the kidneys to the bladder.

A ring of smooth muscle located at the junction of the bladder and urethra, preventing involuntary leakage of urine.

A ring of skeletal muscle surrounding the urethra, allowing voluntary control over urination.

A non-selective process where blood is filtered based on size and charge, removing waste products.

The process of recovering valuable substances from the filtered fluid and returning them to the blood.

Adding substances from the blood into the filtered fluid, primarily for waste removal or pH regulation.

Urine production involves three key steps: filtration, reabsorption, and secretion, each contributing to removing waste and regulating blood composition.

Filtrate is the fluid that passes from the blood in the glomerular capillaries through the filtration membrane into the Bowman's capsule.

Urine is composed of substances that were directly filtered from blood and those secreted into the renal tubules, minus the substances that were reabsorbed.

The filtration membrane acts as a sieve, allowing smaller molecules like glucose and amino acids to pass through, but preventing larger molecules like antibodies.

No, filtrate is not completely protein-free because some small proteins, like albumins, can pass through the filtration membrane.

Filtration pressure is the pressure gradient that forces fluid from the glomerular capillaries into the Bowman's capsule.

Filtration pressure is regulated by the dilation or constriction of the afferent and efferent arterioles, which control the blood flow through the glomerular capillaries.

Sympathetic stimulation causes constriction of the kidney arteries, which decreases filtrate formation and urine volume.

Tubular reabsorption is the movement of water and solutes from the filtrate back into the blood.

A hormone released from the posterior pituitary gland in response to increased blood solute concentration. ADH increases water reabsorption by making the kidneys' distal tubules and collecting ducts more permeable to water, resulting in concentrated urine.

A hormone released from the heart's right atrium when blood pressure increases. ANH promotes sodium excretion in urine, reducing blood volume and consequently blood pressure.

A reflex that triggers urination when the urinary bladder is stretched by urine. It involves involuntary muscle contractions that expel urine from the bladder.

The ability to consciously control urination by inhibiting or facilitating the micturition reflex, primarily through signals from the brain.

Specialized cells in the bladder wall that detect the stretching caused by increasing urine volume, initiating the micturition reflex.

The autonomic nervous system influences bladder muscle contractions and the external urethral sphincter, contributing to the micturition reflex.

The ability to consciously control urination develops over time, typically around the ages of 2-3 years.

The cells lining the thick segment of the nephron are simple cuboidal epithelium. They are impermeable to water, but contain active transport proteins for reabsorbing solutes like Na+, K+, and Cl-. This reabsorption is a key mechanism for water conservation by the kidneys.

The movement of solutes like Na+, K+, and Cl- across the membrane of the thick segment of the nephron is driven by active transport. This requires energy, usually supplied by ATP-powered pumps and carrier molecules. This active transport is essential for the kidneys' ability to reabsorb water.

Reabsorption of solutes in these segments is primarily regulated by hormones, ensuring the body retains water and essential ions as needed. Under hormonal control, these sections can also become permeable to water, allowing for further reabsorption.

The movement of substances from the blood into the filtrate within the renal tubules is called tubular secretion. This process helps remove waste products like toxins, drugs, and molecules not normally produced by the body. Tubular secretion can be active or passive.

Ammonia, a toxic by-product of protein metabolism, is secreted into the renal tubules by epithelial cells. This process involves removing amine groups from amino acids, which then diffuse into the lumen of the tubule.

H+, K+, and penicillin are actively secreted into the renal tubules using active transport or counter transport mechanisms. This helps regulate body fluid pH and eliminate these substances from the blood.

One example of the kidneys using counter transport to regulate pH is the secretion of H+ ions into the renal tubules. This process is important for maintaining a stable pH balance in the body's fluids.