Chapter 26 & 27

Renal anatomy

• kidneys

• ureters

• bladder

• urethra

What are the kidneys responsible for 

Maintaining fluid and electrolyte homeostasis and ridding the body of water-soluble wastes, to maintain normal limits

What functions do the kidneys do

It is a multitasking organ:

• Urine formation

• Regulation of blood pressure

• Stimulation of red blood cell production

• Calcium absorption from the gut

Removal of toxic metabolites from the blood while maintaining bodies of water, electrolytes, and acidity balance

Urine formation

Intricately adjusts water/electrolyte balance in response to changes in blood pressure 

regulation of blood pressure 

produces Erythropoietin (EPO)

Kidney stimulation of red blood cell production

• when low blood oxygen levels are detected (hypoxia) 

Converts Vitamin D to its active form

Calcium absorption from the gut

What two important endocrine functions can the kidneys perform

1) Production of erythropoietin

• regulator of RBC quantity

2) Activation of Vitamin D

• cofactor for intestinal calcium absorption

what is a cofactor for intestinal calcium absorption

the activation of vitamin D - which is an endocrine function of the kidneys

what regulations RBC quantity

the production of erythropoietin - which is an endocrine function of the kidneys

The pelvis is composed of urinary collecting structures

true

The interlobular arteries branch multiple times to form afferent arterioles for each of the million kidney glomeruli 

true 

What is the function of the descending loop of Henle

• transports water

• delivers concentrated filtrate to the ascending loop of Henle

What is the Nephron

• is functional units of the kidney 

• 1 million per kidney, but decreased with age 

• each one consists of glomerulus and tubules 

What are the functions of the nephrons

• filtration → in glomerulus of water. waste, ions, and glucose 

• Reabsorption → in tubules of water. glucose, and ions 

• Secretion → H+, K+, and some drugs from blood in tubules 

• Collection → of urine 

the glomerulus in the nephron what do they do

they filtrate water, waste, ions, and glucose

the tubules in the kidneys what do they do

reabsorb the water, glucose, and ions 

Kidney health is primarily assessed by measurements of its function

true

What are the function of the kidney controlled by

hormones in response to changes in blood pressure

In response to blood pressure changes which hormones are affected which then affects the functions of the nephron

1) in response to low blood pressure and water tonicity the hormones affected are aldosterone and ADH (anti-diuretic hormone) → causing the reduction in urine volume

2) in response to high blood pressure the hormone affected is ANH (atrial Natriuretic hormone) → causing an increased in urine volume 

in response to high blood pressure what hormone is affected

ANH

in response to low blood pressure and water tonicity what hormones are affected

• Aldosterone

• ADH

which loop of Henle is more affected by crystallization (kidney stones)

the ascending loop of Henle

The glomerular filtration rate (GFR) is most informative

true

what is GFR

The Glomerular Filtration rate

• how much blood passes through the glomeruli each minute 

what is the normal GFR

90-120 ml/min/1.73 m²

Which waste product is used to estimate GFR

creatinine

what is also used for primary assessment of kidney health besides GFR

urine analysis

What should normal urine include 

• Ammonia

• Urea

• Creatinine

• Uric acid

• Appropriate amounts of mineral ions

  • Na+, Cl-, K+

What should the urine not contain

• glucose

• Blood proteins 

  • albumin

• Blood cells

• Any molecule > 70,000 Daltons 

What are the factors regulating filtration pressures

• Blood volume

• autoregulation

• plasma oncotic pressure 

What happens during the transport across renal tubules

Reabsorption and secretions of substances occur across the tubules of nephron

• transcellular routes: Na+ - K+ pump (activate process)

• Paracellular routes: in between tight junctions of tubular cells (passive process) 

What is the active process of transport across the renal tubules

the transcellular routes → Na+-K+ pump

What is the passive process of transport across the renal tubules

the paracellular routes → in-between tight junctions of tubular cells

Nephrons cannot regulated their own GFR

false, they can

What is reabsorption of substances occurring across the tubules of the nephron a process of

transporting substances from filtrate to renal capillaries

what % of filtrate is reabsorbed 

99%

What does reabsorption of ions and solutes of substances occurring across the tubules of the nephron create 

an osmotic force to pull water passively across the tubular epithelium 

How do the kidneys regulate blood volume and osmolality

By altering GFR and reabsorption of the urinary filtrate

What happens when changes in blood volume after the filtration pressure in the glomerulus

this results in high filtration urine output when blood volume is high and in reduced filtration and in reduced filtration and fluid conservation when blood volume is low 

Glucose is filtered freely across the glomerular membrane

true

ADH

antidiuretic hormone or also known as vasopressin

• secreted from pituitary gland

• increases permeability of the collecting tubule to water → resulting in increased reabsorption and reduced blood osmolality (dilution of blood) 

what happens when blood osmolality is low

ADH secretion is completely inhibited and collecting tubules become impermeable to water

What do Aldosterone an Angiotensin II increase

both sodium and water reabsorption

what do Natriuretic peptides and Urodilatin inhibit

both sodium and water reabsorption

What alters blood volume without affecting its concentration

• aldosterone

• angiotensin II

• Natriuretic peptides

• urodilatin

What are the tests of renal structure and function 

• urinalysis 

• Serum creatinine, BUN and GFR

• Diagnostic testing

Urinalysis

• is a test of renal structure and function

• provides info on kidney function

• Normal urine - pale yellow/amber, slightly acidic, may contain few cells

• abnormal measurements - cloudy, malodorous, contain protein, RBC, crystals/stones 

Serum creatine, BUN, and GFR

• useful indicators of renal function

• accurate measurement of GFR us the BEST parameter for the assessment of kidney function 

Diagnostic tests

• ultrasonography

• CT scan

• MRI

• renal biopsy 

Intrarenal disorders

occur primarily within the kidney and have potential to result in renal insufficiency or failure

Categories of intrarenal disorders

• congenital

• neoplastic

• infectious

• obstructive

• glomerular 

What happens to excess hydrogen ions

excreted in the urine in combination with phosphate and ammonia buffer

aldosterone and angiotensin II decrease sodium and water reabsorption

false

what do thiazide-like diuretics do

Block Na+ reabsorption

What do the kidneys normally excrete

• erythropoietin

  • a growth factor for red cells and active vitamin D

  • a necessary cofactor for calcium absorption from the intestine 

What are common manifestation of kidney disease

pain and abnormal urinalysis findings 

What is the term for kidney and renal pain

nephralgia

where is the pain felt by someone who has nephralgia

• Transmitted to T10 and L1 dermatomes by the sympatric afferent neurons

• May be felt throughout the skin innervated by a specific spinal cord segment 

what us nephralgia usually due to

the distension and inflammation of the renal capsule and has a dull constant character 

what does abnormal urinalysis findings do

• provides a foundation for the differential diagnosis of renal disfunction 

• shows the color

  • dark or strong smelling → decreased renal function 

  • cloudy pungent → infectious and/or indication of Prescence of WBC in urine

    • glucose, protein, pH, Nutates (indicates UTI)

Name some renal congenital abnormalities 

• Renal agenesis

• renal hypoplasia

Renal Agenesis

kidneys do not develop in the fetus

• congenital abnormality

• bilateral (no kidneys) 

  • not compatible with extrauterine life 

• Unilateral (one kidney) 

  • compensatory hypertrophy of functional kidney 

Bilateral agenesis is compatible with extrauterine life 

false

unilateral agenesis is not compatible with extrauterine life

false, it is by compensatory hypertrophy of functional kidney

What is hypoplasia

some fetal kidney development but they are smaller than normal

• Increases the risk of developing renal failure

• gene mutation is likely responsible

• a single normal kidney can maintain normal renal function

• required lifelong kidney monitoring 

What is cystic kidney disease

• genetically transmitted renal disorder resulting in fluid-filled

  • may be localized to one area or affecting both kidneys

• can lead to renal failure → needing dialysis or translation

• more in men

• increased prevalence with aging

What are the two most common forms of cystic kidney disease

1) Autosomal recessive forms → evident at birth

2) Autosomal dominant types → usually manifests at 40-59 years

what are benign  renal  neoplasms

• many non-cancerous growths 

  • cystic growths 

  • adenomas

  • nephromas

• symptoms depend on size, could be asymptomatic until large enough to form palpable abdominal mass, hematuria, and flank pain

• diagnosis → renal ultrasound and/or CT

• treatment → nephrectomy 

Malignant forms of neoplasms

• renal cell carcinoma 

• nephroblastoma (Wilms’ tumor)

Renal cell carcinoma

• metastatic disease

• Great majority of kidney diseases

• May have familial pattern

  • risk factors: smoking, obesity, hypertension

• Asymptomatic until advanced 

  • tenderness/pain, hematuria, palpable mass

• staging system is I-IV

• Treatment → nephrectomy 

what is the staging system for Renal cell carcinoma

I-IV

• I → tumor with capsule

• II → tumor invaded perirenal fat

• III → Tumor extends into renal vein or regional lymphatics 

• IV → invades other organs:

  • lung, heart, liver, bone, other kidney 

Wilms tumor is the most common kidney cancer in adults

false, in children

Nephroblastoma

• Wilms tumor 

• Most common kidney cancer in children

  • 75% of cases occur in children less than 5 years old

  • associated with genes WT1 and WT2

• Clinical manifestations → identified by palpable abdominal mass 

  • abdominal pain, hypertension, and/or hematuria 

• Diagnosis → detected during routine physical

• treatment → nephrectomy, radiation therapy, chemotherapy `

Infection of the kidney is known as

pyelonephritis

what is the most common cause of infection of the kidney

ascending infection from the lower urinary tract

• most common causative agent are serogroups of e coli

• sometimes fungal infections or other anerobic bacteria are occasionally responsible 

What is the etiology and pathogenesis of acute pyelonephritis

Occurs when there is an obstruction or ureteral reflux that allows contaminated urine to get into the kidneys 

urosepsis

organisms in the bloodstream originating from a UTI

Clinical manifestations, diagnosis, and treatment of acute pyelonephritis

Clinical manifestations → fever, chills, dehydration, nausea, vomiting

Diagnosis → Prescence of WBC casts in the urine indicative of upper UTI

Treatment → promptly managed with antimicrobials to avoid decreased renal function 

Chronic pyelonephritis 

Characterized by small atrophied kidneys with diffuse scarring 

Etiology an pathogenesis of chronic pyelonephritis

chronic reflux of infected urine into the kidney (renal pelvis) is the typical cause

Clinical manifestations, diagnosis, and treatment of chronic pyelonephritis

Clinical manifestations → maybe vague, inconsistent or similar to acute pyelonephritis

diagnosis → urinalysis parallels that of acute pyelonephritis ; renal ultrasound

treatment → promptly managed with antimicrobials to avoid decreased renal function 

Obstruction disorders of the urinary tract are what

conditions that interfere with the flow of urine

• might be congenital in children or acquired by adults 

• changes result from

  • location and degree → partial or complete, unilateral or bilateral

  • duration and timing (acute or chronic) 

what do obstructive processes cause

urine stasis

• predisposes to infection and structural damage

common causes of obstructions

• stones (most common)

• tumors

• prostatic hypertrophy

• strictures of the ureters or urethra 

what happens to structures proximal to the obstruction

they dilate

what does complete obstruction result in 

enlarged kidney → hydronephrosis 

partial obstruction is

much more common than complete

• renal pelvis may become very dilated 

• structural and functional disruption is minimal 

partial or complete obstructions can cause 

• GFR and renal perfusion decline

• portions of the kidney to become ischemic

• acute tubular necrosis and chronic kidney disease will develop if obstruction is not treated 

What is renal calculi or lithiasis

crustal aggregates composed of organic and inorganic material located within the urinary tract

• renal stones

Pathogenesis of renal stones (renal calculi or lithiasis) 

urinary supersaturation → essential for stone formation

• crystallization is enhanced when dehydration occurs (decreased solvent)

when do stones tend to form

in urinary tract because of solute supersaturation, low urine volume, and abnormal urine pH

• usually from the concentrating areas of the nephron 

Glomerular disorders

Glomerulonephropathies

• results from alterations in structure and function of glomerular capillary circulation 

• responsible for a great majority of cases of end-stage renal disease (ESRD)

• pathogenic changes to glomeruli may occur insidiously, altering function over the course of months or years

• may have acute onset 

what are causes of glomerular disorders 

• hereditary factors

• environmental factors

• infectious

• hemodynamic

• toxic

• autoimmune

How many layers do the membranes of glomerular capillaries have

3 layers

what are the layers of the membranes of glomerular capillaries

1) Endothelium

2) basement membrane

3) epithelial cells with foot-like projections (podocytes)

What is glomerulonephritis

inflammation of the glomeruli

• immune response to variety of potential triggers

• produces inflammation in glomeruli 

• may have primary or secondary etiology

  • autoimmune

  • malignancy

  • infectious systemic disorders

what are the types of glomerulonephritis

acute and chronic

What does glomerulonephritis produce

inflammation of the glomeruli

Acute glomerulonephritis

• immune response to variety of potential triggers

  • infections (post hemolytic streptococci, viruses)

• Inflammation results in lysosomal degradation of the basement membrane

• GFR may fall as a result of contraction of mesangial sells resulting in decreased surface area for filtration