Urinary System

Biology 202 with Washo-krupps at Arizona State University - Tempe

About this deck

By: Amanda Holleb
Textbook:

Anatomy & Physiology: The Unity of Form and Function

Anatomy and Physiology Revealed Version 2.0 CD
Created: 2011-04-03
Size: 65 flashcards
Views: 76

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Antomy of urinary system

2 kidneys
2 ureters
urinary bladder
urethra

Kidney functions

Filters blood plasma–separates and eliminates waste; returns useful chemicals to blood

Regulates blood volume and pressure-eliminates or conserves water as needed

Regulates osmolarity of body fluids–Controls amounts of water/solutes eliminated

Secretes renin, activates angiotensin, aldosterone–controls BP, electrolyte balance
Secretes erythropoietin-controls RBC count
Regulates PCO 2 (amount of CO) & acid base balance
detoxifies
Promotes gluconeogenesis
regulates blood calcium levels

Wastes

•Any substance that is useless to the body

–Toxins

–Drugs

–Hormones

–Salts

–Hydrogen ions

–Excess water

•Metabolic Wastes– produced by the body

–CO2 – most expelled by lungs, but some in urine

–Nitrogenous wastes

Nitrogenous Wastes

•Urea

–50% of nitrogenous wastes

–protein catabolism

–proteins®amino acids ®NH2 removed ®forms ammonia, liver converts to urea

• Uric acid

–nucleic acid catabolism

• Creatinine

–creatinine phosphate catabolism

Renal failure

•Kidneys fail to eliminate wastes from the blood

•Azotemia– build up of nitrogenous wastes in the blood

•Uremia- toxic effects as wastes accumulate

–Diarrhea, vomitting, dypsnea, cardiac arrythmia, convulsions, coma, death

–If kidneys fail, dialysis must be started to artificially remove wastes from the blood

excretion

•Separation of wastes from body fluids and eliminating them

–respiratory system: CO2

–integumentary system: water, salts, lactic acid, urea

–digestive system: water, salts, CO2, lipids, bile pigments, cholesterol

–urinary system: many metabolic wastes, toxins, drugs, hormones, salts, H+ and water

•Position, weight and size

–Retroperitoneal. level of T12 to L3

–Right kidney slightly lower due to liver

–about size of a bar of soap (12x6x3 cm)

•Shape – kidney bean

–lateral surface - convex; medial – concave

–Hilum– point of entry/exit for nerves, blood vessels, lymphatic vessels and ureter

•Adrenal Glands located on superior surface

connective tissue

•3 layers for protection

• Renal fascia

–Tough, fibrous outer layer

–binds to kidney, ureters and bladder to abdominal wall

• Adipose capsule

–fatty middle layer

–cushions kidney

• Renal capsule

–fibrous inner sac

–encloses kidney like cellophane wrap

Renal Parenchyma

•Kidney tissue that forms the urine

•2 Zones

–Cortex– outer 1 cm

–Medulla– encircles the renal sinus

•Renal sinus– cavity within the kidney

–contains blood & lymphatic vessels, nerves, urine collecting ducts and fat

•Renal columns– extensions of the cortex that project toward the renal sinus

–divide medulla into renal (medullary pyramids)

•Lobe– a pyramid and its overlying cortex

Lobe of kidney

•Broad side faces cortex

•Papilla (pointy end) faces the renal sinus

–Nestled in the minor calyx

Lobes empty to...

•1 pyramid and its overlying cortex

6-10 lobes in each adult kidney

↓

2 or 3 pyramidal papilla empty into a minor calyx

↓

2 or 3 minor calyxes empty into a major calyx

↓

Major calyxes empty into the renal pelvis

↓

Renal pelvis empties into the ureter

lyx

Kidney: Frontal Section

•Minor calyx: cup over papilla collects urine

Path of blood through kidneys

® interlobar arteries (up renal columns, between lobes)

® arcuate arteries (over pyramids)

® interlobular arteries (up into cortex)

® afferent arterioles

® Glomerulus (cluster of capillaries)

® efferent arterioles (near medulla ® vasa recta)

® peritubular capillaries

® interlobular veins ® arcuate veins ® interlobar veins

Blood Supply Diagram

Definition

Blood Supply

Definition

Nephron

•Functional unit of kidney

•1.2 million nephrons per kidney

•Each nephron contains

– Blood vessels

– Renal corpuscle

•Cortical nephrons (85%)

–short nephron loops

–efferent arterioles branch off peritubular capillaries

•Juxtamedullary nephrons (15%)

–very long nephron loops, maintain salt gradient, helps conserve water

Renal Corpuscle

•Glomerulus enclosed in a 2-layer sac

•Bowman’s capsule or Glomerular capsule

•Glomerular filtrate collects in capsular space and flows into renal tubule

Renal Tubule

•Duct from glomerulus to tip of medullary pyramid

1.Proximal Convoluted Tubule

2.Nephron Loop (Loop of Henle)

3.Distal Convoluted Tubule

4.Collecting Duct

•

•#s 1-3 only one each per nephron

•#4 – collects from several nephrons

Renal (Uriniferous) Tubule

•Proximal convoluted tubule (PCT)

– longest, most coiled, simple cuboidal with brush border

•Nephron loop - U shaped; descending + ascending limbs

–Thick segment (simple cuboidal) initial part of descending limb and part or all of ascending limb, active transport of salts

–Thin segment simple squamous) very water permeable

•Distal convoluted tubule (DCT) - cuboidal, minimal microvilli
•Collecting duct: several DCT’s join

Flow of urine

1.glomerular capsule

2.PCT

3.nephron loop

4.DCT

5.collecting duct

6.papillary duct

7.minor calyx

8.major calyx

9.renal pelvis

10.ureter

11.urinary bladder

12.urethra

4 Processes: Blood Plasma à Urine

• Glomerular filtration

–plasma-like filtrate

• Tubular reabsorption

–returns solutes to the bloodstream

• tubular secretion

–removes additional wastes from the blood

• Water conservation

–returns water to the bloodstream

•99% of glomerular filtrate is reabsorbed into the bloodstream

Filtration membrane

•Fenestrated endothelium- 70-90nm pores

–like other fenestrated capillaries

–Pores are small enough to exclude blood cells

•Basement membrane- proteoglycan gel

–excludes molecules > 8nm

–a few large particles may penetrate, but most are held back

–negatively charged

–blood plasma 7% protein, glomerular filtrate 0.03%

• Filtration slits

–podocyte arms have pedicels with negatively charged filtration slits to exclude large anions

Filtration membrane passing molecules

•Most any unbound molecule smaller than 3 nm can pass

–water, electrolytes, glucose, fatty acids, amino acids, nitrogenous wastes, vitamins

Filtration pressure

•Blood pressure is higher in the glomeruli of the kidneys than in other body capillaries

•Afferent arteriole is larger than the efferent arteriole

–large inlet, smaller outlet

•Lots of filtration, little or no reabsorption

•Kidneys are especially vulnerable to hypertension

Which of the following would cause the highest blood pressure in the glomeruli?

Dilated afferent arteriole, constricted efferent arteriole

Glomerular Filtration Rate (GFR)

•Filtrate formed per minute

•GFR = NFP x Kf »125 ml/min or 180 L/day, male

•GFR = NFP x Kf »105 ml/min or 150 L/day, female

–NFP = net filtration pressure

–filtration coefficient (Kf) depends on permeability and surface area of filtration barrier

•99% of filtrate reabsorbed

• 1-2 L urine excreted/day

Effects of GFR Abnormalities

•GFR

–urine output rises ®

•¯GFR

–Wastes reabsorbed (azotemia possible)

•GFR controlled by adjusting glomerular blood pressure

–autoregulation

–sympathetic control

–hormonal mechanism - renin and angiotensin

Renal Autoregulation of GFR

•If BP rises

–constrict afferent arteriole, dilate efferent

• If BP drops

–dilate afferent arteriole, constrict efferent

•Stable for BP range of 80 to 170 mmHg (systolic)

•Cannot compensate for extreme BP

Negative Feedback Control of GFR

Definition

Sympathetic Control of GFR

•Strenuous exercise or acute conditions (circulatory shock) stimulate afferent arterioles to constrict

•¯ GFR and urine production, redirecting blood flow to heart, brain and skeletal muscles

Hormonal Control of GFR

Definition

Tubular Reabsorption and Secretion

Definition

Proximal Convoluted Tubules (PCT)

•Reabsorbs 65% of GF to peritubular capillaries

•Great length, prominent microvilli and abundant mitochondria for active transport

•Reabsorbs greater variety of chemicals than other parts of nephron

–transcellular route - through epithelial cells of PCT

–paracellular route - between epithelial cells of PCT

•Transport maximum- when transport proteins of plasma membrane are saturated

–ie. glucose > 220 mg/dL remains in urine (glycosuria)

Tubular Secretion of PCT and Nephron Loop

• Waste removal

–urea, uric acid, bile salts, ammonia, catecholamines, many drugs

• Acid-base balance

–secretion of hydrogen and bicarbonate ions regulates pH of body fluids

•Primary function of nephron loop

– waster conservation

–also involved in electrolyte reabsorption

DCT and Collecting Duct

•Effect of aldosterone

–¯ BP causes angiotensin II formation

–angiotensin II stimulates adrenal cortex

–adrenal cortex secretes aldosterone

–aldosterone promotes Na+ reabsorption

–Na+ reabsorption promotes water reabsorption

–water reabsorption ¯ urine volume

–BP drops less rapidly

DCT and Collecting Duct 2

•Effect of atrial natriuretic factor (ANF)

– BP stimulates right atrium

–atrium secretes ANF

–ANF promotes Na+ and water excretion

– BP drops

•Effect of ADH

–dehydration stimulates hypothalamus

–hypothalamus stimulates posterior pituitary

–posterior pituitary releases ADH

–ADH water reabsorption

Collecting Duct Concentrates Urine

•Osmolarity 4x as high deep in medulla

•Medullary portion of CD is permeable to water but not to NaCl

Control of water loss

•Producing hypotonic urine

–NaCl reabsorbed by cortical CD

–water remains in urine

•Producing hypertonic urine

–GFR drops

–tubular reabsorption

–less NaCl remains in CD

–ADH CD’s water permeability

–more water is reabsorbed

–urine is more concentrated

Countercurrent Multiplier

•Recaptures NaCl and returns it to renal medulla

•Descending limb

–reabsorbs water but not salt

–concentrates tubular fluid

•Ascending limb

–reabsorbs Na+, K+, and Cl-

–maintains high osmolarity of renal medulla

–impermeable to water

–tubular fluid becomes hypotonic

•Recycling of urea: collecting duct-medulla

–urea accounts for 40% of high osmolarity of medulla

Countercurrent Exchange System

•Formed by vasa recta

–provide blood supply to medulla

–do not remove NaCl from medulla

•Descending capillaries

–water diffuses out of blood

–NaCl diffuses into blood

•Ascending capillaries

–water diffuses into blood

–NaCl diffuses out of blood

Beavers have little need to conserve water. Therefore it is expected that they would have ____ than humans.

Shorter nephron loops

Composition and Properties of Urine

•Appearance

•Odor

•Specific gravity

•Osmolarity

–Lower than blood when hydrated

–Higher than blood when dehydrated

•pH - range: 4.5 - 8.2

–usually 6.0, which is slightly acidic

•Chemical composition

Appearance

•Clear to deep amber is normal

•Urochrome- yellow pigment produced from breakdown of hemoglobin of dead erythrocytes

•Pink, green, brown, black

–food, vitamins, drugs, metabolic disease

•Cloudy – bacterial growth

–Pyuria– pus present due to kidney/bladder infection

•Hematuria– blood present

–caused by infection, trauma, kidney stones

Odor

•Should normally have little odor

•Pungent odor – bacteria

–bacteria convert urea to ammonia

•Foods may cause odor

–ie. asparagus

•Sweet, fruity odor – glucose present

–diabetes

•Foul odor -

Specific gravity

•1.001-1.035

•Distilled water is 1.000

•1.001 is very dilute

•1.035 is very concentrated

Chemical composition

• 95% water, 5% solutes

•Normal solutes

–urea, NaCl, creatine, uric acid, phosphates, sulfates calcium, magnesium, bicarbonate, H+

•Abnormal solutes

–Glucose

–Free hemaglobin or whole RBCs

–Albumin

–Ketones (ok during pregnancy)

–Bile pigments

Urine Volume

•Normal volume - 1 to 2 L/day

•Polyuria - excess of 2L/day

–disease long term (ie. Diabetes)

–drugs - temporary

•Oliguria – less than 500 mL/day

•Anuria - 0 to 100 mL

–disease

–dehydration

–circulatory shock

–enlarged prostate gland (males only)

Diuretics

•Effects

– Increase output

–¯ blood volume

•Uses

–Hypertension and congestive heart failure

•Mechanisms of action

– GFR

–¯ tubular reabsorption

Urine Storage and Elimination

• Ureters

–Muscular tube from renal pelvis of kidney to bladder

–passes dorsal to bladder and enters it from below

–about 25 cm long

–3 layers

• adventitia - CT

•muscularis - 2 layers of smooth muscle

–urine enters, it stretches and contracts in peristaltic wave

•mucosa - transitional epithelium

–lumen very narrow, easily obstructed

Increased ADH secretion should cause urine to have:

A higher specific gravity

Urinary Bladder

•Muscular sac on floor of pelvic cavity

•3 layers

–Parietal peritoneum on flat superior surface

–Fibrous adventitia everywhere else

–Muscularis (detrusor muscle) - smooth muscle

–Mucosa with rugae (wrinkles)

•relaxed bladder in wrinkled – highly distensible

•Trigone- triangular area on floor where ureters enter and urethra exits

•Normally holds up to 500ml before urination, but can hold 700 - 800 ml maximum

• 3 to 4 cm long

• External urethral orifice

–between vaginal orifice and clitoris

•Internal urethral sphincter

–thickened

•smooth muscle

•involuntary control

•External urethral sphincter

–skeletal muscle

–voluntary control

Male Bladder and Urethra

• 18 cm long

•Internal urethral sphincter

•External urethral sphincter

•3 regions

– prostatic urethra

•during orgasm receives semen

– membranous urethra

•passes through pelvic cavity

– penile urethra

•~15 cm through the penis

Micturition in Infants

•Micturition – voiding the bladder

•Micturition reflex

1) 200 ml urine in bladder - stretch receptors send signal to spinal cord

2) parasympathetic reflex arc from spinal cord - stimulates contraction of detrusor muscle

3) relaxation of internal urethral sphincter

4) voids bladder

vNote: The signal does not go all the way to the brain!

Voluntary Control of Micturition

•Children/Adults and Bladder stretches

•Receptors send stretch signals via pelvic nerves to micturition center in pons of brain

•Micturition center receives stretch signals and integrates cortical input

•If urination is appropriate, pons sends signal for stimulation of detrussor and relaxes internal urethral sphincter

•If urination is inappropriate, impulses sent to external urethral sphincter keep it contracted
When urination becomes appropriate, impulses are inhibited

•Valsalva maneuver

is a voluntary control of micturition

•aids in expulsion of urine by pressure on bladder

•activates micturition reflex voluntarily when there is no urge to void bladder

Kidney stones

•Renal Calculi

•Calcium, phosphate, uric acid and protein crystallize

•Form in the renal pelvis

•Most are small, but some can be several centimeters

•Causes blockages that destroy nephrons

•Jagged à pain and hematuria

•Causes

– hypercalcemia

– dehydration

– pH inbalance

–frequent urinary infections

–enlarged prostate (males only)
Treatment: stone-dissolving drugs, surgery and/or lithotripsy (ultrasonic vibrations)

Acute Glomerularnephritis

Renal Disorder
•Acute Glomerularnephritis– destruction of glomeruli

–autoimmune disease

–may follow an infection

–usually temporary – most recover

Hydronephrosis

Renal disorder

•Hydronephrosis – increased fluid pressure due to blockage in kidney

Nephroptosis

Renal disorder

•floating kidney

–too little body fat to hold kidney in place (ie anorexia)

–prolonged vibration – truck drivers, jackhammer operators

Nephrotic Syndrome

renal disease

•Nephrotic Syndrome – glomerular injury causes large amounts of protein to be excreted in urine

–leads to hypotension, edema, increased susceptibility to infection

Renal failure

•Acute Renal Failure – sudden onset

–traumatic damage to nephrons

–great blood loss

•Chronic Renal Failure

– slow, progressive

–irreversible loss of nephrons

–trauma

–metal poisoning

–glomeruli blocked by protein

–atherosclerosis

Urinary Incontinence

•Inability to control urination

•Causes:

–Incompetence of urethral sphincters

–Bladder irritation due to infection

–Pressure during pregnancy

–Obstruction

• Stress Incontinence

–uncontrollable urination due to brief surges in bladder pressure

–laughter, coughing, sneezing

Diabetes

•Chronic polyuria of metabolic origin

•With hyperglycemia and glycosuria

–diabetes mellitus I and II- insulin hyposecretion/insensitivity

–gestational diabetes - 1 to 3% of pregnancies

–pituitary diabetes - hypersecretion of GH

–Adrenal diabetes - hypersecretion of cortisol

•With glycosuria but no hyperglycemia

–renal diabetes - hereditary deficiency of glucose transporters

•With no hyperglycemia or glycosuria

–diabetes insipidus- ADH hyposecretion; CD ¯ water reabsorption

About this deck

By: Amanda Holleb
Textbook:

Anatomy & Physiology: The Unity of Form and Function

Anatomy and Physiology Revealed Version 2.0 CD
Created: 2011-04-03
Size: 65 flashcards
Views: 76

About StudyBlue

“Simply amazing. The flash cards are smooth, there are many different types of studying tools, and there is a great search engine. I praise you on the awesomeness.”
Dennis