Medic 14 A&P Chapter 18

a cup of flowers; minor calyx

to push down; detrusor muscle

a window; fenestrated capillaries

a ball; glomerulus

angle;trigone

near; juxtaglomerular aparatus

to urinate;micurition

kidney;nepron

small, nipple-shaped projections; renal papillae

foot;podocyte

straight;vasa recta

kidney;renal artery

behind;retroperitoneal

vessels;vasa recta

removing the organic waste products generate by cells throughout the body.

• Regulate blood volume and blood pressure
• Regulate plasma concentration of ions
• Help stabilize blood pH
• Conserve valuable nutrients

• Adjusting the volume of water lost in urine
• releasing EPO
• releasing renin

• Na+, K+, Cl-, and other ions are regulated by controlling the quantities lost in the urine.
• Plasma concentration of calcium ions is regulated by synthesis of calcitriol.

pH is stabilized by controlling the loss of H+ ions and HCO3-(bicarb) in urine.

Glucose and amino acids are conserved by preventing their excretion in urine while organic waste products are eliminated

• Two kidneys, produce urine
• Urine travels through paired ureters
• to the urinary bladder for temp storage
• urination occurs, contraction of muscular bladder forces the urine through the urethra and out of the body

• on either side of the vertebral column between the last thoracic and third lumbar vertebrae.
• The right kidney often sits lower then the left.
• Both lie between the muscles of the doral body wall and the peritoneal lining

behind the peritoneum

• overlying peritoneum
• contact with adjacent organs
• supporting connective tissue

a dense fibrous renal capsule and its packed in a soft cushion of adipose tissue

• Damage to the suspensory fibers may cause the kidney to be displaced.
• Dangerous because ureters or renal blood vessels may become twisted of kinked during movement.

reddish brown and about 10 cm long, 5.5 cm wide and 3 cm thick in adults and weighs about 150 g

• indentation that is the site of exit for the ureter
• site which the renal artery and renal never enter and where the renal vein exits

covers the surface of the kidney and lines the renal sinus

internal cavity within the kidney

• the renal cotex
• renal medulla

18 conical renal pyramids, that projects into the renal sinus

tip of each renal pyramid

renal sinus between adjacent renal pyramids

renal pyramids and overlying areas of the renal cortex

minor calyx

major calyx

funnel shaped chamber formed by the calyxs

the ureter through which urine drains out of the kidney

nephrons

1.25

1200 mL

renal artery that originates from the abdominal aorta

interlobar arteries

arch along the boundary lines between the cortex and medulla

supply the cortex given rise from arcuate arteries

branch from each interlobular artery deliver blood to the capillaties that supply individual nephrons

Leaves each nephron

• recieves blood from efferent arterioles,surround the proximal and distal convoluted tubules 
• provide route fro pickup or delivery of substances that are reabsorbed or secreted by these portions of the nephron

located mostly within the cortex

located near the renal medulla

• cortical nephrons 
• juxtamedullary nephrons

vasa recta, long straight capillaries that parallel the loop of henle deep into the medulla

concentrated urine

interlobular veins

arcuate , interlobar, and renal veins

Basic functional unit of the kidney

• a renal corpuscle
• Renal tubule composed of two convoluted segments separated by a single U-shaped tube
• Convuluted segments are in the cortex and U shaped tube extends partially or completely into the medulla

nephron begins here,round structure that consists of a cup shaped chamber (bowman's capsule) that contains a capillary network, or Glomerulus

Afferent and Efferent arterioles

filtration

Product of filtration, a protein free solution

• Proximal convoluted tubule (PCT)
• Loop of henle
• Distal convoluted tubule(DCT)

tubular fluid

• Each nephron empties into a collecting duct
• collecting duct leaves the cortex and descentds into the medulla, and carries  tubular fluid from many nephrons toward a papillary duct that delivers the fluid now called urine, into the calyces and on to the renal pelvis

is the site of filtration

• reabsorbing all of the useful organic molecules from the filtrate
• reabsorbing over 90% of water in the filtrate
• secreting into the tubular fluid any waste products that were missed by the filtration process

• capillary network of the glomerulus
• structure known as bowmans capsule

forms the outer wall of the renal corpusvle and encapsulates the glomerular capillaries

the capsule and is continious with a specialized epithelium that covers glomerular capillaries

separates the two epithelia, which revieves the filtrate and empties into the renal tubule.

epithelium that covers that capillaries consists of sites called podocytes

• long cellular processes called pedicels that wrap around invidual capillaries 
• thick basemnet membrane separates cappillaries and podocytes

fenestrated, they contain pores

• the pores of endothelial cells
• fibers of basement membrane
• filtration slits between the slender process of the podocytes

• fenestrated capillary, basement membrane, and filtration slits
• that prevents the passage of blood cells and most plasma proteins but permits water,metabolic wastes,ionsmglucose,fatty acids, vitamens and other solutes into the capsular space.

PCT proximal convoluted tubule

PCT proximal convoluted tubule

organic nutrients,plasma proteins and ions from the tubular fluid and release them into the intersitital fluid the surrounds the renal tubule

osmosis

loop of henle

descending limb that travels toward the renal pelvis and ascending limb that returns to the cortex

• is not permeable to water and solutes actives transports sodium and chloride ions of of the tubular fluid
• as result intersitial fluid of the medulla will contain unusually high solute concentrations

• permeable to water
• as it descends into the medulla waters moves out of the tubular fluid by osmosis

DCT begins and its passes immediately adjacent to the afferent and efferent arterioles

• active secretions of ions,acids,drugs, and toxins
• selective reabsorption of sodium ions from tubular fluid

tubular fluid

Epithelial cells of the DCT are closest to the glomerulus

• macula densa and juxtaglomerular cells (in the wall of the afferent arteriole)
• endocrine structure secretes hormone EPO and enzyme Renin

collecting system

a a papallary duct which delivers urine to the minor calyx

composition of urine by reabsorbing water and reabsorbing  or secreting sodium,potassium,hydrogen, and bicarbonate ions

Filtration of plasma to initiate urine formation

Reabsorbtion of ions,organic molecules, vitamens,water

• descending limb: reabsorption of water from tubular fluid
• ascending limb: reabsorption of ions; creates concentration gradient in the medulla, which enables the kidney to produce concentrated urine

reabsorption of sodium ions;secretiomn of acids, ammonia, drugs

Reabsorption of water and of sodium, and bicarbonate ions

conduction of urine to minor calyx

maintain homeostasis by regulating volume and composition of the blood

• Urea
• Creatinine
• Uric Acid

• most abundent organic waste
• generate about 21 grams of urea daily
• most of it during breakdown of amino acids

• generated in skeletal muscle tissue through the breakdown of creatine phosphate. 
• Body generates roughly 1.8 g daily

• Produced during the breakdown and recycling of RNA
• you generate about 480 mg of uric acid daily

4 to 5 times more concentrated then normal body fluids.

• Filtration
• reabsorption
• secretion

Bp forces water across the filtration membrane in the renal corpuscle

• removal of water and soulute molecules from the filtrate and their re entry into the circulation at the peritubular capillaries 
• Filtrate occurs after filtrate enters the renal tubule.
• passive through osmosis

is the transport of solutes out of the peritubular epithelium and into the filtrate.

• filtration
• reabsorption
• secretion proceed in proper balance

renal corpuscle, across the capillary walls of the glomerulus

PCT

DCT

loop of henle and collecting system

capsular space

the outward force must exceed any opposing pressures such as osmotic pressure of the blood.

the net foce that promotes filtration

• of the slight difference in the diameters of the afferent and efferent arterioles.
• Efferent are slighly smaller in diameter
• result creates backup that increases BP in glomerular capillaries

10 mmHg

kidney function will stop

minor variations in blood pressure

is one of the mechanims that responsible for regulating BP and blood volume

process of filtrate production at the glomerulus

• The ammount of filtrate produced in the kidneys each minute. 
• 6 square meters of filtration surface
• GFR averages around 125 mL per min

extremely important process

Diabetes insipidus(caused by inadequate ADH secretion)

diffusion,osmosis, and carrier mediated transport.

intersititial fluid that surrounds the renal tubule

peritubular capillaries

60-70%

ions, including sodium,calcium,bicarb,magnesium,phosphate amd sulfate ions

regulated and may be influenced by circulating ion or hormone levels

regulation of pH,

Uric acid and urea

half and 2/3

is permeable to water but not other solutes

water and solutes

sodiumand chloride ions out of the tubular fluid and into the interstitial fluid of the renal medulla

descending limb

ascending limb

1/3  of the concentration of plasma

• 80 water
• 85 solute

drains into the renal pelvis

compostion and concentration, composition depends on the types of solutes present, concentration depends on volume of water in which the soultes are dissolved

• active reabsorption or secretion
• Primary function of DCT is active secretion

potassium or hydrogen ions

Aldosterone, produced in the adrenal cortex

sodium ion concentraions or elevated potassium ion concentraions in the blood

more sodium ions reclaimed and more potassium ions are lost

ADH

impermeable to water

concentraited the urine

• Glomerular filtration produces a filtrate that resembles blood plasma byt contains few plasma proteins
• filtrate has same osmotic concentration as plasma or intersitial fluid

• PCT, 60-70% of water is reabsorbed and almost all of the dissolved nutrients are reabsorbed.
• osmotic concentration of tubular fluid remains unchanged

PCT and descending limb of the loop of henle, water moves into the surrounding intersititial fluid and leaves a small fluid volume of highly concentrated tubular fluid (20% of origional flitrate)

• Ascending limb of henle, impermeable to water and solutes
• tubular cells actively pump Na+ and Cl-  out of tubular fluid
• because Na+ and Cl- are removed urea accounts for a greater proportion of the solutes in the tubular fluid

• DCT and collecting duct determine final composition and concentration
• these segments are impermeable to solutes but ions may be actively transported into or out of the filtrate under the control of hormones such as aldosterone

• Concentration of urine controlled by variations in water permeability of the DCT and collecting ducts
• Segments are impermeable to water unless exposed to ADH
• absence of ADH= no water reabsorption occur, produces diluted urine
• High concentrations of ADH= collecting ducts become freely permeable to water and produces small volume of conentraited urine.

is a deteriroation in renal function over hours or days that causes the accumulation of toxic wastes and causes the loss of internal homeostasis

a decline in blood flow

result from lack of bloodflow to the kidney

Problem with the kidney itself

problem in urine flow

renal cell ischemia and death

restoration of renal blood flow

glomerular filtration rate (GFR)

• By local automatic adjustments in glomerular pressure
• through activities of the sympathic devision of the ANS
• throught the effects of various hormones (hormonal mechanisms result in long term adjustments)

• minor variations in blood pressure
• for example reducation in blood flow and decline in glomerular filtration pressure trigger dialtion of afferent arteriole and glomerular capillaries and constrict efferent arteriole

sympathetic division of the ANS

direct and indirect

• is powerful constriciton of afferent arterioles ,which decreases the GFR and slow production of filtrate
• Triggered by crisis such as acute reduction in BP or a AMI
• Sympathetic activation can overide the local regulatory mechanism that act to stabilize GFR
• as crisis passes, GFR will return to normal

• Angiotension II
• ADH
• aldosterone
• ANP

• angiotension II
• Aldosterone
• ADH

• If GFR remains low the juxtaglomerular apparatus releases the enzyme reninin into circuation
• Renin converts angiotensiogen to angiotension I
• ACE concerts Angiotension I to II

• Brief powerful constriction in peripheral capillary beds, that elevates Bp in renal arteries
• triggers constriction of efferent arterioles awhich elevates glomular pressure and filtration rates
• Trigers release of ADH in the CNS which stimulates reabsorption of water and soium ions and induces senation of thirst
• at the adrenal gland, stimulates secretion of aldosterone by the adrenal cortex and E and NE by the adrenal medullae, sudden dramatic increase in BP
• at the kidneys aldoserone stimulates sodium reaborption along the DCT and collecting system

• inceases the water permeability of the DCT and collecting duct which stimulates the reabsorption of water from the tubular fluid
• induces sensation of thirst

• under angiotension II stimulation
• and independently when hypothamic neurons are stimulated by a reducation in bp or incease in solulte concentration of circulating blood
• specialized hypothalmic neurons are called osmoreceptors

• stimulates reabsorption of sodium ions and secretion of potassium ions along the DCT and collecting duct
• occurs primarily under angiotension II stimulation and inresponse to a rise in potassium ion concentration of the blood

• opposes those of the renin angiontension system
• released by atrical cardiac muscle cells when blood volume and bp are too high
• ANP affects the kidney by a decreasein the rate of sodium ion reabsorption in the DCT,leads to increased sodium loss in the urine
• dilation of the glomerular capillaries which resulse in increased flomerular filtration and urinary water loss
• inactivation of the renin angiotension sysmtem through the inhibition of renin,aldosterone, and ADH secretion
• net loss of sodimm ions 
• lowers bp and blood volume

transport,storage,and elimination of urine

pair of muscular tubes that conduct urine from the kidneys

is a shape that prevents backflow of urine when the bladder contracts

transitional epithelium , middle later of longitudal and circular bands of smooth muscle and outer connective tissue layer continues with renal capsule

peristaltic

kidney stones,presence is known as nephrolithiasis

hollow muscular organ that sotres urine prior to urination. demensions depends on destention

triangular area that the urinary bladder is bounded by the ureteral openings and enternce to the uretha

contains the internal uretharl sphincter, surrounds the urethral entrance

provides involuntary control over dischage of urine from the bladder