Anatomy and Physiology of the Kidney, Nephron, and Neuron

Comprehensive vocabulary flashcards covering the anatomical structures, physiological functions, and key characteristics of the human kidney, nephron, and neuron.

Kidney

An organ that filters waste products, maintains water and electrolyte balance, regulates blood pressure, and keeps the body healthy.

Renal cortex

The outer layer of the kidney containing glomeruli and convoluted tubules.

Renal medulla

The inner layer of the kidney containing renal pyramids and collecting ducts.

Renal pyramids

Cone-shaped structures located within the renal medulla that contain collecting ducts.

Minor calyx

A cup-like structure in the kidney that receives urine directly from a renal pyramid.

Major calyx

A urine-collecting structure in the kidney formed by the convergence of $2\text{--}3$ minor calyces.

Renal pelvis

A funnel-shaped cavity that collects urine from the major calyces and leads into the ureter.

Ureter

A duct that carries formed urine from the renal pelvis to the urinary bladder.

Renal artery

A major blood vessel that brings oxygenated blood and metabolic waste from the body into the kidney.

Renal vein

A blood vessel that carries filtered blood away from the kidney back to the circulatory system.

Erythropoietin

A hormone produced by the kidney that stimulates the production of red blood cells.

Renin

An enzyme/hormone produced by the kidney that regulates blood pressure.

Nephron

The functional unit of the kidney, measuring roughly $4\text{--}6\,\text{cm}$ in length, that filters blood and forms urine.

Afferent arteriole

The arteriole that brings blood into the glomerulus for filtration.

Efferent arteriole

The arteriole that carries blood out of the glomerulus after filtration.

Glomerulus

A high-pressure capillary bed in the nephron that serves as the primary site of blood filtration.

Bowman's capsule

A cup-like sac enclosing the glomerulus that collects the filtered fluid (filtrate).

Peritubular capillaries

A network of capillaries surrounding the nephron tubules that participates in reabsorption and secretion.

Proximal convoluted tubule (PCT)

Nephron segment responsible for reabsorbing $\sim 65\%$ of water, $\text{Na}^+$, glucose, and amino acids, while secreting $\text{H}^+$, $\text{K}^+$, drugs, and toxins.

Loop of Henle

A U-shaped tubule segment that creates an osmotic concentration gradient via a counter-current mechanism.

Descending limb of Loop of Henle

The section of the Loop of Henle that is highly permeable to water.

Ascending limb of Loop of Henle

The section of the Loop of Henle that is impermeable to water and actively reabsorbs $\text{Na}^+$, $\text{K}^+$, and $\text{Cl}^-$.

Distal convoluted tubule (DCT)

Nephron segment that regulates electrolytes ($\text{Na}^+$, $\text{K}^+$, $\text{Ca}^{2+}$) and controls pH via $\text{H}^+$ secretion and $\text{HCO}_3^-$ reabsorption.

Collecting duct

Tubular system that concentrates urine and reabsorbs water and urea under the influence of ADH and aldosterone.

Neuron

An excitable specialized cell that receives, processes, and sends electrical signals (nerve impulses).

Dendrites

Branched extensions of a neuron that receive signals from other neurons, sensory receptors, or the environment.

Cell body (soma)

The core part of a neuron that integrates incoming signals and contains the nucleus and organelles such as mitochondria and Nissl bodies.

Axon

A long, slender projection of a neuron that conducts electrical impulses away from the cell body at speeds of $1\text{--}120\,\text{m/s}$.

Myelin sheath

An insulating fatty layer surrounding the axon that increases the conduction speed of nerve impulses.

Node of Ranvier

Periodic gaps in the myelin sheath along the axon that enable rapid saltatory conduction.

Axon terminals

Distal endings of an axon that release neurotransmitters to communicate with target cells such as other neurons, muscles, or glands.