Kidney #1

Vocabulary flashcards covering key concepts of the urinary system and nephron structure and function.

Urinary System

Primary means of waste removal from the body.

Waste

toxins that are removed from the body by various systems which include

• respiratory, digestive, sweat glands, and urinary system

Urinary and reproductive

closely associated, share embryonic development, share adult anatomical relationship

Urologists

Doctors that treat both urinary and reproductive disorders.

Anatomy of urinary

consists of 2 kidneys, 2 ureters, urinary bladder and urethra

What is the primary function of the kidneys related to blood plasma?

The kidneys filter blood plasma by removing toxins and waste products, which are excreted in urine, while returning useful chemicals to the blood.

How do the kidneys regulate blood volume and blood pressure?

The kidneys regulate urine volume by conserving or eliminating water based on salt movement, thereby affecting overall blood volume and pressure.

What role do the kidneys play in regulating osmolarity?

The kidneys control the osmolarity of body fluids by adjusting the amount of water and salt excreted; since water follows salt, changes in salt elimination affect water balance.

How do kidneys influence erythrocyte count?

The kidneys produce erythropoiet

What is a nephron?

Found within renal pyramids that form a network of tubes that are responsible for filtering blood, regulating blood volume and pressure via salt movement and water movement, and produces urine by removing wastes

Renin

An enzyme secreted when blood pressure is low, activating hormonal mechanisms to control blood pressure and electrolyte balance.

Erythropoietin

A hormone produced by the kidneys to stimulate red blood cell production.

What are the three tubes going into/out of the kidney?

Renal artery, renal vein, and ureter

What is the function of the ureter?

Waste exits kidney via the ureter to enter the urinary bladder

What is the function of the renal vein?

Materials that we want to keep return to the systemic circuit via this artery

What is the function of the renal artery?

Brings oxygenated blood into kidney which branches into segmental artery between pyramids to interlobar arteries to arcuate arteries to cortical radiate arteries which supplies blood to the nephron

What is the function of the nephron tube?

Contains transport channels that move salts into and out of the blood to control water movement which controls blood volume which controls blood pressure

What is the pathway through the nephron?

Capillary bed that enters the nephron to bring blood > bowman’s capsule that surrounds the glomerulus > proximal convoluted tubule > loop of Henle > distal convoluted tubule > collecting duct

What is the nephron made of?

Renal corpuscle and renal tubule to filter blood and excrete waste

Renal corpuscle

Made of capillary bed [glomerulus] and surrounded by bowman’s capsule that starts filtering blood plasma

Bowman’s capsule is made of

Two layers

Inner (visceral layer)

Made of podocytes – cells that allow for filtration of the blood and start blood filtration that wrap around the capillaries of the glomerulus

Outer (parietal layer)

Simple squamous epithelium, tightly bound together and is continuous with the proximal convoluted tube

Diffusion in renal corpuscle

No diffusion

Glomerular filtrate

Collects in capsular space and then flows into the proximal convoluted tubule

Afferent vs efferent arteriole

Afferent arteriole [incoming blood] is larger than the efferent arteriole [leaving blood/waste]

Afferent arteriole being larger ensures

Larger RBC and plasma proteins stay within bloodstream while smaller salts leave the bloodstream

Tubular Reabsorption

Process in which essential substances are recovered from the filtrate and returned to the bloodstream.

Tubular Secretion

Process of moving additional waste and toxic substances from the bloodstream into the tubular fluid.

Glomerular Filtrate

Fluid within glomerular capsule space that is a plasma-like fluid without proteins.

Obligatory Water Reabsorption

The kidney's process of reabsorbing water from filtrate back into the blood regardless of hydration status.

Renal tubule

A series of long coiled tubes/ducts that converts the filtrate into urine and leads away from the glomerular capsule and is divided into four regions

Proximal convoluted tubule

Contain many microvilli to increase surface area within PCT to increase absorption of solutes and movement of solutes within this tubule

Nephron loop / loop of Henle

U-shaped portion of renal tubule that comes off the PCT to aid in water reabsorption

Thick segment of loop of Henle

Lined with simple cuboidal epithelium which aids to absorb salts and has many mitochondria

Thin segment of loop of Henle

Lined with simple squamous epithelium which aids to reabsorb water because its cells are very permeable to water

Distal convoluted tubule

Final region of tubule which balance solutes

Collecting duct

Last region of the tubules before excreting water into the ureter to urinary bladder which mainly reabsorbs water

Flow of filtrate within kidney

Glomerulus to PCT to loop of Henle to DCT to collecting duct to papillary duct to minor calx to major calx to renal pelvis to ureter to bladder to urethra out of body

Papillary duct

Comes off renal pyramid to collect filtrate from multiple nephrons

Nephron types

Found in different regions of kidney either cortical/cortex [outer] or medulla [inner area]

Important note about medulla

The deeper you go into the medulla of the kidney, the higher the concentration of salt [Na+]

Water and salt in medulla

Water follows/osmosis salt so water is also present in medulla

Cortical nephron

85% of all nephrons which have short nephron loops which stay mostly within the cortex of the kidney

Juxtamedullary nephron

15% of all nephrons which have very long nephron loops that extend into the medulla of the kidney to reabsorb more water

Water movement in juxtamedullary nephron

Water within the juxtamedullary nephron will want to leave the nephron to follow the salt which leaves behind waste products within the nephron leading to higher concentration of urine

Glomerular filtration

Process of moving solutes and water from the glomerulus into the tubule

Tubular reabsorption

Process in which essential substances are recovered from the filtration and returned to the bloodstream
• Tubule to blood

Tubular secretion

Process of moving additional waste/toxic substances from the bloodstream back into the tubule to be excreted in urine
• Blood to tubule

Water conservation

Removed water from the urine and returns it to the blood

Glomerular filtrate

Fluid within glomerular capsule space that is a plasma-like fluid which is the blood plasma without proteins

Tubular fluid

Fluid found from PCT to loop of Henle to DCT in renal tubules which is like the blood plasma without proteins, but some proteins and substances have been removed or added

Urine

Fluid that is found in collecting duct only and that has water removed
• This fluid is only called urine if it makes it to the collecting duct

Aldosterone

A hormone that stimulates the kidneys to reabsorb sodium, which also leads to increased water reabsorption.

Antidiuretic Hormone (ADH)

A hormone that makes the collecting duct more permeable to water to reabsorb more water into the bloodstream.

Cortical Nephron

85% of all nephrons, primarily located in the outer cortex of the kidney.

Juxtamedullary Nephron

15% of all nephrons with long loops that extend deep into the medulla and aid in reabsorbing water.

Filtration Pressure

The pressure within the glomerulus that facilitates the movement of filtrate into the nephron.

Glomerular Filtration Rate (GFR)

The rate at which the glomerulus filters solutes and water.

Solvent Drag

The process where water moves across the renal tubule epithelium by osmosis, carrying dissolved solutes along with it.

Microcirculation

Circulation of capillary beds surrounding nephron tubule and loop of Henle to aid in reabsorption and secretion.

Proximal Convoluted Tubule (PCT)

The part of the nephron where most reabsorption of water, ions, and nutrients occurs.

Loop of Henle

Structure in the nephron that aids in the reabsorption of water and salts to concentrate urine.

Collecting Duct

The last part of the nephron that primarily reabsorbs water before urine is excreted.

Sodium-Glucose Transport Protein (SGLT)

Transporter that moves sodium and glucose into the cell of the PCT.

Fenestrated Capillaries

Capillaries in the glomerulus with tiny holes allowing small molecules and substances to pass.

Net Filtration Pressure (NFP)

The total pressure that leads to the filtration of blood in the glomerulus.

Efferent Arteriole

Blood vessel through which blood exits the glomerulus.

Afferent Arteriole

Blood vessel through which blood enters the glomerulus.

Is aldosterone directly responsible for the reabsorption of water

No, it absorbs NA, and water follows.