ANATOMY OF THE EXCRETORY SYSTEM.pptx

8/10/2019 ANATOMY OF THE EXCRETORY SYSTEM.pptx

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The Urinary System

Jay P. Jazul, MSc., CPS

University of Santo Tomas

Faculty of Pharmacy

Copyright 2010, John Wiley & Sons, Inc.


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Urinary System


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The Urinary System

Paired kidneys

A ureter for each kidney

Urinary bladder

Urethra


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Main Functions of Urinary System

Kidneys filter blood to keep it pure Toxins

Metabolic wastes

Excess water

Excess ions Dispose of nitrogenous wastes from blood

Urea

Uric acid

Creatinine Regulate the balance of water and

electrolytes, acids and bases


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Functions of the Kidneys

1) filter blood plasma, separate

wastes, return useful materials

to the blood, and eliminate the

wastes.

Toxic ni t rogenou s wastes

- ammonia, urea, uric acid, creatine, andcreatinine

- cause diarrhea, vomiting, and cardiac arrhythmia,

convulsions, coma, and death.


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1) filter blood plasma, separate

wastes, return useful materials

to the blood, and eliminate the

wastes.

2) regulate blood volume and

osmolarity.


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3) produce hormones1. renin

2. erythropoietin

3. calcitrol


4) regulate acid-base balanceof the body fluids.

5) detoxify superoxides, free

radicals, and drugs.


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Kidneys are retroperitoneal organs (see next slide) Superior lumbar region of posterior abdominal wall

Lateral surface is convex

Medial surface is concave Hilus* is cleft: vessels, ureters and nerves enter and leave

Adrenal glands*lie superior to each kidney(the yellow blob in pic)

*

*


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Transverse sections

show retroperitoneal

position of kidneys

Note also: liver,

aorta muscles

on CT

Note layers of

adipose (fat),

capsule, fascia


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Kidney

Divided into cortexouter portion

Medulla- inner portion

Contain renal pyramids & renal columns

Urine goes into renal pelvis

Edges are made of major & minor calyces

Then out ureter


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- The medial surface of the kidney is concave

with a hilumcarrying renal nerves and blood

vessels.

The renal parenchyma is divided into an outer cortex

and inner medulla.


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Extensions of the cortex

(renal columns) project

toward the sinus, dividing

the medulla into 6-10 renal

pyramids. Each pyramid isconical with a blunt point

called thepapillafacing the

sinus.


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The papilla is nestled into a

cup called a minor calyx,

which collects its urine.

Two or three minor calyces

merge to form a majorcalyx. The major calyces

merge to form the renal

pelvis.


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The Arteries

Aorta gives off right and left renal arteries

Renalarteries divides into 5segmentalarteries as enters hilus ofkidney

Segmentalsbranch into lobar

arteries

Lobarsdivide into interlobars

Interlobarsinto arcuate injunction of medulla and cortex

Arcuatessend interlobular

arteries into cortex

Cortical radiatearteries giverise to glomerular arterioles


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Vasculature of the kidney

The glomerular capillary bed is unusual in havingarterioles going both to it and away from it (afferent

and efferent), instead of a vein going away as most It is also unusual in having two capillary beds in

series (one following the other)


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RenalBlood

Supply


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The kidney contains 1.2 million nephrons, which are

the functional units of the kidney.A nephron consists of

i. Blood vessels

Afferent arterioleGlomerulus

Efferent arteriole

ii. Renal tubules

Proximal convoluted tubule

Loop of Henle

Distal convoluted tubule

The Nephron


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Nephron

Unit of renal function: corpuscle & tubule

Corpuscle: forms filtrate

Glomerulus & Glomerular capsule (cortex)

Proximal convoluted tubule (cortex)

Descending Loop of Henle (into medulla)

ascending Loop of Henle (into medulla)

Distal convoluted tubule (cortex)

Collecting ductminor calyx


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Nephron


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afferent arteriole

glomerulus

efferent arteriole

proximal

convoluted

tubule

distal

convoluted

tubule

Loop of Henle

blood

blood

The Nephron


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Basic Operation

Glomerular filtration-filter plasma Tubular reabsorption

Reabsorb needed compounds & water from

filtrate Tubular Secretion

Secrete some materials into filtrate


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Basic Operation


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Glomerular Filtration

Two layers of capsule surround glomerulus

Between is capsular space

Podocytes support capillary epithelium

Form filtration membrane

Permeable to water & solute

but not most proteins & blood cells


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Podocytes (Glomerulus)


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Filtration Pressure

Blood pressure for filtration

Opposed by colloid osmotic pressure and

capsular pressure

Efferent and afferent arteriole diameters

adjust to maintain a net filtration pressure

Even with small changes in blood pressure


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Glomerular Filtration Rate

= GFR 105-125 ml/min

Determines net reabsorption because itdetermines filtrate flow

ANP increases GFR Responds to increased blood volume

Sympathetic stimulation

vasoconstriction decreased GFR Urine production


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Glomerular Filtration

T b l R b ti


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Tubular Reabsorption

Proximal tubule ~65% Na+& H2O

Normally 100% nutrients

~100% HCO3-(depends on blood pH)

Active transport of solutes

Osmosis moves water

Cells distal to proximal tubule fine tunereabsorption under control


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Tubular Reabsorption


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Tubular Secretion

Takes place all along tubule

Major substances : H+, K+, ammonia, urea,

creatine, drugs like penicillin Helps regulate plasma pH 7.35-7.45

Diet is acid urine is typically acidic


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Filt ti R b ti


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Filtration, Reabsorption,

Secretion


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The kidney produces urine through 4 steps:


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Urine Route


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Urinary Bladder Collapsible muscular

sac

Stores and expelsurine

Lies on pelvic floor

posterior to pubicsymphysis

Males: anterior torectum

Females: just anteriorto the vagina anduterus


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Males: urethra has three

regions (see right)

1. Prostatic urethra__________

2. Membranous urethra____

3. Spongy or penile urethra_____

_________trigone

female


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With all the labels


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- When glucose in tubular

fluid exceeds the transportmaximum (180 mg/100 ml),

it appears in urine

(glycosuria).

- Glucose in tubular fluid

hinders water reabsorption

by osmosis, causing

polyuria.

high urine

volume

high glucose

high glucose in

filtrate

Retain H2O by

osmosis

DIABETES MELLITUS


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Glucose in urine

high glucose in blood

high glucose in filtrate

Exceeds Tm for glucose


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Components of Urine

Urine = 1-2 l /day

95% water

+ urea, creatine, K+, ammonia, uric acid,Na+, Cl-, Mg2+, sulfate, phosphate & Ca2+

Depends on diet and state of health


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Hormonal Regulation

Angiotensin II & aldosterone

Angiotensin II- stimulates NaCl in proximal tube

Aldosterone- increases Na+ reabsorption & K+

secretion in DCT & CD More ions reabsorbedmore water

ANP-increases GFR & inhibits aldosterone

action

less Na+

reabsorbed ADH- responds to increased concentration of

solute in blood + fall in BP


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Hormonal Regulation

ADH: important to body water balance

Increased concentration of solute in blood+ fall in BP ADH

With no ADH: DCT & CD walls areimpermeable to waterdilute urine

With ADH: water reabsorption occurs

concentrated urine


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Micturition = Urination

Autonomic reflex- internal sphincter

Responds to stretch like rectum

Parasympathetic detrusor musclecontraction

Conscious control-external sphincter


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Aging

Kidneys shrink- decrease in capacity Thirst decreases dehydration

urinary tract infections

Males: prostate enlargementfrequenturination & slow flow

Females: more prone to leakage ofexternal sphincter (incontinence)

Both: nocturia


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For studying

Parts of the kidney:

1. Renal pyramid

2. Efferent vessel

3. Renal artery

4. Renal vein

5. Renal hilum6. Renal pelvis

7. Ureter

8. Minor calyx

9. Renal capsule

10. Inferior renal capsule

11. Superior renal capsule

12. Afferent vessel13. Nephron

14. Minor calyx

15. Major calyx

16. Renal papilla

17. Renal column
http://en.wikipedia.org/wiki/Renal_pyramidhttp://en.wikipedia.org/wiki/Efferent_vesselhttp://en.wikipedia.org/wiki/Renal_arteryhttp://en.wikipedia.org/wiki/Renal_veinhttp://en.wikipedia.org/wiki/Hilum_of_kidneyhttp://en.wikipedia.org/wiki/Renal_pelvishttp://en.wikipedia.org/wiki/Ureterhttp://en.wikipedia.org/wiki/Minor_calyxhttp://en.wikipedia.org/wiki/Renal_capsulehttp://en.wikipedia.org/wiki/Inferior_renal_capsulehttp://en.wikipedia.org/wiki/Superior_renal_capsulehttp://en.wikipedia.org/wiki/Afferent_vesselhttp://en.wikipedia.org/wiki/Nephronhttp://en.wikipedia.org/wiki/Minor_calyxhttp://en.wikipedia.org/wiki/Major_calyxhttp://en.wikipedia.org/wiki/Renal_papillahttp://en.wikipedia.org/wiki/Renal_columnhttp://en.wikipedia.org/wiki/Renal_columnhttp://en.wikipedia.org/wiki/Renal_papillahttp://en.wikipedia.org/wiki/Major_calyxhttp://en.wikipedia.org/wiki/Minor_calyxhttp://en.wikipedia.org/wiki/Nephronhttp://en.wikipedia.org/wiki/Afferent_vesselhttp://en.wikipedia.org/wiki/Superior_renal_capsulehttp://en.wikipedia.org/wiki/Inferior_renal_capsulehttp://en.wikipedia.org/wiki/Renal_capsulehttp://en.wikipedia.org/wiki/Minor_calyxhttp://en.wikipedia.org/wiki/Ureterhttp://en.wikipedia.org/wiki/Renal_pelvishttp://en.wikipedia.org/wiki/Hilum_of_kidneyhttp://en.wikipedia.org/wiki/Renal_veinhttp://en.wikipedia.org/wiki/Renal_arteryhttp://en.wikipedia.org/wiki/Efferent_vesselhttp://en.wikipedia.org/wiki/Renal_pyramid

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