Excretion in Humans - Vocabulary Flashcards

Vocabulary flashcards covering key terms related to the human excretory system, its structure, functions, and associated diseases.

Excretion

The removal of metabolic wastes from the body to maintain normal cell function.

Waste products

Substances produced by metabolism that must be removed to prevent harm (e.g., CO2, urea, salts, excess water).

Lungs

Organs that excrete carbon dioxide and water vapour during respiration.

Alimentary canal

Excretes faeces and undigested waste from digestion.

Skin

Excretes water and salts through sweat.

Liver

Produces urea and bile pigments for excretion.

Kidneys

Major excretory organs; regulate water/salt balance and remove nitrogenous wastes.

Ureter

Tube that transports urine from the kidneys to the bladder.

Bladder

Muscular sac that stores urine until it is released.

Urethra

Tube that conducts urine from the bladder to the outside of the body.

Nephron

Structural and functional unit of the kidney; about 1 million per kidney; consists of Malpighian body and renal tubules.

Malpighian body

Bowman’s capsule plus glomerulus; site of glomerular filtration.

Bowman's capsule

Cup-shaped structure surrounding the glomerulus; part of the Malpighian body.

Glomerulus

Capillary tuft where blood filtration occurs under high pressure.

Glomerular filtration

Process by which blood is filtered into Bowman's capsule to form glomerular filtrate; blood cells and large proteins stay in blood.

Glomerular filtrate

Fluid that passes into Bowman's capsule; contains water, glucose, amino acids, salts, urea, uric acid, creatinine.

Proximal convoluted tubule

Segment where most useful substances are reabsorbed into the blood.

Loop of Henle

Part of the nephron that creates an osmotic gradient to concentrate urine; has descending and ascending limbs.

Distal convoluted tubule

Site of selective reabsorption and secretion; regulated by hormones like aldosterone.

Collecting duct

Final site for water reabsorption under ADH; urine is collected here and moves toward the renal pelvis.

Podocytes

Specialised cells with filtration slits lining Bowman's capsule, part of the filtration barrier.

Peritubular capillaries

Capillary network around tubules where reabsorption and secretion occur.

Afferent arteriole

Wider vessel bringing blood to the glomerulus; helps create high pressure for filtration.

Efferent arteriole

Narrow vessel carrying blood away from the glomerulus; contributes to filtration pressure.

Osmoregulation

Maintenance of proper water and salt balance in blood and tissues.

ADH (antidiuretic hormone)

Hormone that increases water reabsorption by making collecting ducts more permeable to water.

Hypothalamus

Brain region that produces ADH and regulates its release.

Pituitary gland

Gland that secretes ADH into the bloodstream.

Aldosterone

Hormone from the adrenal cortex that increases sodium (and thus water) reabsorption in the kidney.

Adrenal gland

Gland that secretes aldosterone, influencing salt and water balance.

Kidney stones

Crystals formed from salts (e.g., calcium, uric acid) that can block urine flow and cause pain.

Cystitis

Bladder infection; a type of urinary tract infection.

Pyelonephritis

Kidney infection, often arising from a UTI.

Kidney failure

Loss of kidney function; can be acute or chronic and may require dialysis or transplant.

Dialysis

Treatment using a semipermeable membrane to remove waste from blood when kidneys fail.

Dialysate

Fluid used in dialysis that helps remove waste and regulate ions.

Semipermeable membrane

Membrane that allows some substances to pass while restricting others; used in dialysis.

Renal pelvis

Central funnel where urine collects before entering the ureter.

Calyx

Small (minor) and large (major) chambers that drain urine from renal pyramids into the renal pelvis.

Renal capsule

Protective outer membrane surrounding the kidney.

Renal cortex

Outer layer of the kidney containing many nephrons and glomeruli.

Renal medulla

Inner kidney region that contains renal pyramids.

Renal pyramids

Cone-shaped tissue in the medulla that drain urine into calyces.