Ch 20

The urinary system excreted (1)__________ while retaining (2)__________

(1) wastes (2) nutrients

The five steps of filtration in the nephron

1.Blood enters the glomerulus through the afferent arteriole. 2.Water, salt, nutrients (glucose, amino Acids) and wastes are filtered out into the glomerular (Bowman's) capsule. This material (filtrate) then flows into the proximal tubule. 3. The formed elements and some water remain in the efferent arteriole. 4.The good stuff (water, glucose, amino acids and salts) is reabsorbed back into blood vessels by a process called tubular reabsorption. The good stuff enters into the peritubular capillaries from proximal tubule and loop of the Henle. 5.Any thing that was not filtered out of the blood but needs to be taken out is secreted from the capillaries into the tubules by a process called tubular secretion.

glomerulus

A ball of capillaries surrounded by Bowman's capsule in the nephron which is part of the blood supply of the nephron

collecting duct

A segment of the nephron that delivers urine to the renal pelvis

Which hormones are secreted and regulated by the urinary system?

Aldosterone, calcitriol, erythropoietin

Distal tubule

Between the loop of Henle and the collecting duct; Selective reabsorption and secretion occur here, most notably to regulate reabsorption of water and sodium

vasa recta

Capillaries from the efferent arterioles that supply the loop of Henle and collecting duct

acute renal failure

Condition that occurs when something, such as a blockage, toxins, or sudden loss of blood flow causes a change in the filtering function of the kidneys

Glomerular capsule (Bowman's capsule)

Cup-shaped, hollow structure surrounding glomerulus; where fluid is filtered

What are the primary functions of the urinary system?

Filters blood and eliminates metabolic wastes from the plasma Secretes and regulates hormones Helps regulate blood water levels Helps regulate blood salt levels Helps with acid-base equilibrium in the blood Regulates blood pressure

renal medulla

Middle layer, contains the renal pyramids, inner dense tissue

The ascending limb is permeable to

NaCl and urea

dialysis

Process for removing waste from the blood for people with renal failure

pertubular capillaries

Remove water, ions, and nutrients, which are reabsorbed by the proximal and distal tubules.

kidney stones

Solid crystalline masses formed in the kidney, resulting from an excess of insoluble salts or uric acid crystallizing in the urine; may become trapped anywhere along the urinary tract.

glomerular filtrate

Substances that filter out of the blood through the thin walls of the glomeruli

glomerular filtration

The movement of a protein-free solution of fluid and solutes from the glomerulus into the space within the glomerular capsule

efferent arteriole

The small artery that carries FILTERED blood away from the capillaries of the glomerulus, away from the nephron

afferent arteriole

The small artery that carries blood toward the capillaries of the glomerulus to supply the nephron

Ureters

The tubes that carry urine from the kidneys to the bladder.

What wastes does the urinary system filter out of blood and plasma

ammonia, urea, bilirubin, creatine, uric acid

The process of reabsorbing water is regulated by

antidiuretic hormone (ADH)

Process of reabsorption

begins with the active or passive extraction of substances from the tubule fluid into the renal interstitium that surrounds the nephrons. then, these substances transport from the interstitium into the bloodstream

what drives filtration?

blood pressure

renal artery and vein

bring blood to or carry blood out of kidney

podocytes

cells in the Bowman's capsule in the kidneys that wrap around capillaries of the glomerulus

parts of the kidney

cortex, medulla, renal artery, renal vein, ureter

Rate of filtration is regulated in two ways:

during rest: pressure sensitive cells in the arterioles and flow sensitive cells in the tubule walls can release chemicals to adjust the diameter of the afferent arterioles. During stress: blood flow to the kidneys falls substantially as blood is redistributed to more critical organs. Afferent and efferent arterioles are constricted to reduce blood flow and the rates of glomerular filtration and urine formation.

Renin

enzyme secreted by the kidney; it raises blood pressure by influencing vasoconstriction (narrowing of blood vessels)

proximal tubule

first section of the renal tubule that the blood flows through; starts at the glomerular capsule and ends at the renal medulla; reabsorption of water, ions, and all organic nutrients

parts of a nephron

glomerular capsule, proximal tubule, loop of Henle, distal tubule. The it attaches to the collecting duct

The filtration of urine involves three processes:

glomerular filtration, tubular reabsorption, tubular secretion

chronic renal failure

gradual and progressive loss of kidney function

juxtaglomerular apparatus

in the nephron, the complex of cells from the distal tubule and the afferent arteriole which helps regulate blood pressure by secreting renin in response to blood pressure changes in the kidney; located near the glomerulus

Aldosterone

increases reabsorption of sodium by kidney tubules

antidiuretic hormone (ADH)

increases the permeability of the collecting duct to water

urinary tract infection (UTI)

infection of one or more organs of the urinary tract

The renal vain connects to the...

inferior vena cava

What makes up the urinary system?

kidneys, ureters, bladder, urethra

Renal pelvis

large tube that collects all the urine from the individual nephrons

nephrons

long, thin, tubular structure. Each one consists of a thin hollow tube of epithelial cells, called a tubule, plus the blood vessels that supply the tubule The function of the nephron is to produce urine.

filtration barrier consists of 2 types of cells:

modified epithelial cells and podocytes

renal cortex

outer layer of the kidney, surrounds the renal pyramids

proteinuria

protein in the urine

where does most tubular reabsorption occur?

proximal tubule

how do kidneys regulate acids and bases

reabsorption of filtered bicarbonate and excretion of acid as ammonium

loop of Henle

section of the nephron tubule that conserves water and minimizes the volume of urine; extends into the medulla and comes back up near the capsule

What salts does the urinary system regulate in blood

sodium, potassium, calcium, chlorine, phosphorus

aquaporins

special water channels in membrane proteins that aids in water reabsorption

tubular secretion

the addition of certain solutes from the peritubular capillaries or vasa recta into the tubule

countercurrent exchange

the opposite flow of adjacent fluids that maximizes transfer rates

reabsorption of water, salt, glucose, and amino acids in the proximal tubule all depends on just one metabolic energy-using process:

the primary active transport of sodium out of the tubular epithelial cell

tubular reabsorption

the return of filtered fluid and solutes back into the blood of the peritubular capillaries or vasa recta

nephron

the structural and functional unit of the kidney

renal pyramids

triangular-shaped areas of tissue in the medulla of the kidney

What is the major waste product excreted by the kidneys?

urea

The descending limb is permeable to

water