The excretory system
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The Excretory System. Excretion- removal of waste produced during body functions. Occurs through: Intestine - digestive wastes, salts Skin (sweat glands)- water, electrolytes Lungs - carbon dioxide, water Kidneys - toxins, water, N cmpds, electrolytes. Urinary System Functions.

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The Excretory System

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The excretory system

The Excretory System


Excretion removal of waste produced during body functions

Excretion- removal of waste produced during body functions

Occurs through:

  • Intestine- digestive wastes, salts

  • Skin (sweat glands)- water, electrolytes

  • Lungs- carbon dioxide, water

  • Kidneys- toxins, water, N cmpds, electrolytes


Urinary system functions

Urinary System Functions

  • maintain water concentration in blood

  • maintain concentration of ions like Na & K

  • form urine

  • influence rate of secretion of hormones like ADH

  • alter pH (acid- base balance)

    Why bother with all of these?


Basic anatomy of the urinary system

Basic Anatomy of the Urinary System


Gross anatomy kidney

Gross Anatomy- KIDNEY

  • lie in retroperitoneal position

  • Fat cushion holds it in position

  • medial surface with concave hilus

Not that type….


Gross anatomy kidney1

Gross Anatomy- KIDNEY

  • Cortex- outer and lighter

  • Medulla- inner and darker

1. Cortex region of kidney

2. Medulla region of kidney


Gross anatomy kidney2

Gross Anatomy- KIDNEY

6. Most of the medulla is made up of RENAL PYRAMIDS with a base facing outward and papilla facing the hilus


Gross anatomy kidney3

Gross Anatomy- KIDNEY

7. Cortical tissue dips into the medulla between the pyramids, forming RENAL COLUMNS


Gross anatomy kidney4

Gross Anatomy- KIDNEY

8. Each renal papilla juts into a cup-like CALYX

  • Urine leaving the renal papilla collects here before leaving the body


Gross anatomy kidney5

Gross Anatomy- KIDNEY

9. The calyces join to form the renal pelvis. It narrows as it exits the hilum to become the ureter.


10 blood vessels

10. BLOOD VESSELS

Renal artery brings ¼ of all blood to kidney/min.

Branches into

Interlobar arteries- extend toward the cortex

Changes names

Arcuate arteries- base of pyramids

Changes names

Interlobular arteries- afferent arterioles that branch into the glomerulus where blood is filtered


10 blood vessels continued

10. BLOOD VESSELS (continued)

Efferent arterioles

Peritubular capillaries (vasa recta) Interlobular veinArcuate veinInterlobar veinrenal vein

Blood flows into

But, I am not going to test you on this stuff!


Macroscopic kidneys

Macroscopic Kidneys

A. Capsule & hilus

B. Renal sinus

1. renal pelvis

2. major calyces

3. minor calyces

C. Renal medulla

1. renal pyramids

a. papilla

2. Renal column

D. Renal cortex


B gross anatomy ureter

B. Gross Anatomy- URETER

  • 28 cm long

  • Allows urine to travel from kidney to urinary bladder

  • 3 layers of tissue:

    • Mucous lining

    • Smooth muscle middle

    • DWF outer layer


C urinary bladder

C. URINARY BLADDER

  • behind symphysis pubis

  • mostly smooth muscle aka detrusor muscle lined with transitional epithelium

  • 3 openings: 2 from ureters and one into the urethra

  • Has valve to prevent backflow into kidney

  • Functions

    • urine reservoir

    • aided by urethra, expels urine from body


Male urethra

Male Urethra

Female Urethra


Gross anatomy urethra

Gross Anatomy- URETHRA

  • 3 cm in females; 20 cm in males

  • Male urethra (URINE) passes through prostate gland where it is joined by 2 ejacuatory ducts (SEMEN) then travels through penis and ends at the urinary meatus at the tip of the penis.

  • In females, completely separate from vagina


4 micturition urination

4. Micturition- urination

  • Voluntary relaxation of external sphincter muscle of bladder

  • Detrusor muscle contracts

  • Parasympathetic nerve control

  • Incontinence


Microscopic structure of the nephron

Microscopic Structure of the NEPHRON

  • Filtering unit of kidney

  • Process blood plasma

  • Form urine

  • 1.25 million per kidney

  • Looks like a funnel with a

    long, winding stem


Nephron

Components

1. renal corpuscle

2. PCT

3. loop of Henle

4. DCT

5. Collecting tubule & duct

NEPHRON


The nephron

The Nephron

  • The nephron is the functional unit of the kidney, responsible for the actual purification and filtration of the blood.

  • About one million nephrons are in the cortex of each kidney.


The nephron1

The NEPHRON

RENAL CORPUSCLE- in the cortex

  • Bowman’s capsule

    • Cup-shaped mouth of nephron

  • Glomerulus

    • capillaries in BC

    • Pores (fenestrations)

    • Basement membrane


The glomerulus

The Glomerulus


Microscopic structure of the nephron1

Microscopic Structure of the NEPHRON

PROXIMAL TUBULE- in cortex

  • Closest to BC (“proximal”)

  • Aka PCT (proximal convoluted tubule)

  • Brush border (microvilli) face lumen- increase surface area


The nephron2

cortex

medulla

The NEPHRON

LOOP OF HENLE (LOH)

  • Renal tubule beyond the PCT

    • Descending limb (thin)

    • Sharp turn

    • Ascending limb (thick)

    • Dips into medulla


The nephron3

THE NEPHRON

DISTAL TUBULE

  • Aka DCT (distal convoluted tubule)

  • Beyond LOH (“distal”)

  • Juxtaglomerular apparatus


The nephron4

THE NEPHRON

COLLECTING DUCT

  • Straight tubule joined by distal tubules of several nephrons

  • Fuse to form papillary ducts which deliver urine to the calyces


Overview of kidney function

Overview of KIDNEY FUNCTION

1. FILTRATION

  • Occurs in glomerulus

  • Dependent on Glomerular Filtration Rate (GFR)

  • Filter water and solutes from blood into renal tubule

    • Glucose

    • Amino acids

    • Nitrogen wastes


Kidney function filtration

KIDNEY FUNCTION-Filtration

  • FILTRATION

    • What’s left in the blood?

      • Blood cells

      • Most plasma proteins

    • What causes it?

      • Pressure gradient (high to low)

      • Related to blood pressure


Filtration

Filtration

GFR is directly dependent on blood pressure.a. If GFR (BP) is too high, filtrate flows too fast and substances are NOT reabsorbed

urine flow increases water is lost blood volume drops  blood pressure drops.

b. If GFR (BP) is too low, filtrate flows too slow and substancesare retained too much

urine flow decreases  water is preserved  blood volume increases  blood pressure increases.


Overview of kidney function1

Overview of KIDNEY FUNCTION

2. REABSORPTION

  • Occurs in mostly in PCT and little in LOH, DCT, CD

  • Put good things in the renal tubule back into the blood (peritubular capillaries)

    • Water

    • Electrolytes

    • Nutrients


Overview of kidney function2

Overview of KIDNEY FUNCTION

  • REABSORPTION

    • Healthy kidneys reabsorb

      • Glucose (if not…)

      • Amino acids

      • Sodium

      • Water


Overview of kidney function3

Overview of KIDNEY FUNCTION

  • REABSORPTION

    • Substances that are NOT reabsorbed fully

      • Things that lack carriers

      • Things that are not lipid soluble

      • Things that are too large

      • Examples: urea, creatinine, uric acid


Overview of kidney function4

Overview of KIDNEY FUNCTION

  • REABSORPTION

    • ADH causes the distal and collecting tubules to become more permeable to water

    • This allows hypertonic urine to be formed


Overview of kidney function5

Overview of KIDNEY FUNCTION

  • SECRETION

    • PCT mostly

    • Reabsorption in reverse

    • Movement of small molecules out of the peritubular blood and into the tubule for excretion

      • Including K, H, urea, ammonia

      • Dispose certain drugs

      • Helps control blood pH


Review questions

Review Questions

  • Do you know the names of the structures?

  • What is GFR? What regulates it?

  • Why is reabsorption important?

  • Where is the only place glucose is reabsorbed?

  • Where does ADH act? What does it do?


Making urine

Making Urine

  • Choose your water solution (Normal or Dehydrated)

  • Fill the cup 2/3 of the way with that solution

  • Add ½ dropper of Urea + vitamins

  • Add ½ dropper of acid

  • Check pH with pH paper

  • If you desire, pimp your urine with 1 dropper of the following:


Answer the following questions on a piece of paper and turn it in

Answer the following questions on a piece of paper and turn it in?

  • Did you drink the urine?

  • What type did you make?

  • How did it taste?

  • Did it taste like you expected?

  • If you did not drink it, why not? (please provide at least three reasons)


Urine composition

URINE COMPOSITION

  • Water- 95%

  • Other substances- 5%

    • Nitrogen wastes

    • Electrolytes

    • Toxins

    • Pigments

    • Hormones

    • Abnormal stuff like blood, glucose, casts, calculi


Urine composition1

URINE COMPOSITION

  • Characteristics

    • Color

    • Compounds

    • Slight odor

    • 4.6-8.0 pH (fresh is acidic)

    • 1.001- 1.035 specific gravity


Fluid electrolyte and acid base balance

FLUID, ELECTROLYTE, and ACID-BASE BALANCE

  • FLUID

    • Water accounts for 50-60% total weight (why less in obese people?)

      • 37% of this is ECF

      • 63% of this is ICF


Fluid electrolyte and acid base balance1

FLUID, ELECTROLYTE, and ACID-BASE BALANCE

  • Mechanisms to maintain fluid balance

    • Volumes of ICP, ECF, plasma, and total volume of water relatively constant

    • Adjust output (urine volume) to intake

    • Adjust fluid intake (liquids we drink, water in food we eat, water formed by catabolism)


Anatomy of micturition incontinence

Anatomy of Micturition & Incontinence

  • Detrusor muscle with an External and Internal sphincter

  • Normal capacity 300-600cc

  • First urge to void 150-300cc

  • CNS control

    • Pons - facilitates

    • Cerebral cortex - inhibits

  • Harmonal effects - estrogen


Bladder pressure volume relationship or how to hold it

Bladder Pressure-Volume Relationship: Or how to hold it


Treatment options

Treatment Options

  • Reduce amount and timing of fluid intake

  • Avoid bladder stimulants (caffeine)

  • Use diuretics judiciously (not before bed)

  • Reduce physical barriers to toilet (use bedside commode)

1


The excretory system

Pessaries


Predisposing conditions to uti

Predisposing conditions to UTI

  • Female

  • Short urethra, proximity to anus, termination beneath labia

  • Sexual activity

  • Pregnancy

    • 2-3% have UTI in preg, 20-30% with asx bacteriuria

  • decreased ureteral peristalsis, temp. incomp ofvesicoureteral valves


Urethritis

Urethritis

  • 􀂃 Acute dysuria, frequency

  • 􀂃 Often need to suspect sexually

  • transmitted pathogens esp. if sx more than 2 days, no hematuria, no suprapubic

  • pain, new sexual partner, cervicitis


Cystitis

Cystitis

  • Sx: frequency, dysuria, urgency, suprapubic pain

  • Cloudy, malodorous urine (nonspec.)

  • Leukocyte esterase positive = pyuria

  • Nitrite positive (but not always)

  • WBC (2-5 with sx) and bacteria on urine microscopy


Nephrolithiasis kidney stones

Nephrolithiasis: kidney stones

  • Supersat. of urine by stone forming constituents

  • Freq. stone types: Calcium (most common), struvite, oxalate, uric acid

  • Risk factors: metabolic disturbances, previous UTI, gout, genetic

  • Incidence = 2-3%

  • Hematuria (rarely dangerous by itself)

  • Dangerous combo = obstruction + infection


Addison s disease

Addison’s Disease

Addison's disease occurs when the adrenal glands do not produce enough of the hormone cortisol and, in some cases, the hormone aldosterone


Cystocele

Cystocele

the wall between a woman’s bladder and her vagina weakens and allows the bladder to droop into the vagina

  • mild—grade 1—when the bladder droops only a short way into the vagina.

  • severe—grade 2—the bladder sinks far enough to reach the opening of the vagina.

  • advanced—grade 3—cystocele occurs when the bladder bulges out through the opening of the vagina.


Nocturnal enuresis

Nocturnal enuresis

  • Hormonal problems.

  • Bladder problems.

  • Genetics.

  • Sleep problems.

  • Medical conditions

  • Psychological problems.


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