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3.4 BreathingSystem and

Excretion

ObjectivesAt the end of this sub section students should be able to:

3.4.5 Plant Excretion 1. Say why plant leaves are flattened2. Give the role of leaves as excretory orans of plants.3. Give the role of lenticels as excretory orans of plants

3.4.! "he ExcretorySyste# in the$u#an

1. Explain the role of the excretory syste# in $o#eostasis2. Give the function of the luns% s&in and urinary syste#3. Give the location of the luns% s&in and urinary syste#4. Give the excretory products of the luns% s&in and urinary syste#5. Explain the need to drin& water before% durin and after exercisin6. 'raw the structure of the urinary excretory syste# in hu#ans7. (abel these parts )) &idney% ureter% urinary bladder% and urethra

. Give the basic function of the urinary excretory syste# in hu#ans!. Explain the role of the &idney in reulatin body fluids1". Explain the role of the &idney extractin wastes and toxins fro# the blood and

recyclin valuable substances11. Explain the ter#s filtration% reabsorption and secretion )) thus reulatin the

body fluids and che#istry of the body12. *dentification of the site of filtration and reabsorption in the cortex% #edulla and

renal pelvis13. *dentify the position of secretion in the &idney14. 'escribe the pathway of urine fro# the &idney to the urethra15. +rite an essay report on ,nhealthy ,rinary Syste#s - reference to acterial

urinary tract infections% /or#ation of &idney stones% 0enal tubule failure% 'ialysisand 1idney transplants.

3.4.2.$ "he ephron 16. 'raw the ephron and its associated blood supply17. Explain how urine is for#ed1. +hy the blood is under pressure in the lo#erulus1!. +hy the plas#a is force)filtered2". Say what co#ponents of the plas#a are not filtered and why21. Explain the ter#s Glo#erular filtrate% convoluted tubule% proxi#al convoluted

tubule 22. Explain what substances are reabsorbed into the blood23. Explain how substances are reabsorbed into the blood24. Give the roles of the (oop of $enle and the distal convoluted tubule

25. Give so#e of the co#ponents found in urine26. Give the pathway for urine fro# the nephron to the &idney27. Explain how reabsorption of water in the collectin duct is under hor#onal

influence2. Give the full na#e for A'$2!. Say what conditions sti#ulate A'$ release3". Say what conditions inhibit A'$ release31. Explain how A'$ secretion action6 depends on the water content of the blood.32. Explain the ter# os#oreulation

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33. Show how os#oreulation is an exa#ple of a ho#oeostatic #echanis#

Excretionis ettin rid of the waste products of #etabolis# fro# the body. Excretion is an i#portant part ofho#eostasis. +ithout excretion wastes would 7uic&ly build up and interfere with the internal che#ical and fluidbalances of the oranis#.

%&antsproduce very little waste. Plant excretion consists #ainly of carbon dioxide by niht% and oxyen durin the day.Store so#e wastes in vacuoles and lose #ore when dead structures fall off.

Organs o' excretion Excretory (rod)cts

8. (uns carbon dioxide and water

9. (iver bile and excess a#ino acids% water andcholesterol

3. S&in salt% water and so#e urea

4. 1idneys salts% urea% water% uric acid

,ric acid is a nitroenous waste produced durin the brea&down of adenine and uanine. p$ of urine is !.; and yellowdue to urochro#e ) a pi#ent produced durin protein #etabolis#

*rinary system

lood% hih in waste products% enters &idneys throuh renal arteries.

1idneys filter out waste and reabsorb useful substances.Purified blood leaves &idneys throuh renal veins and the urine flows fro# &idneys via ureters to bladder s#all of the bac&?% left &idney slihtly hiher than the riht and both covered by aprotective layer of fat.Str)ct)re

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@ortex ) outer fibrous part% dar& red in colour.edulla ) inner reion% briht red in colour.Pyra#ids ) cone)shaped areas proBectin into pelvis of &idney.Pelvis ) hollow cha#ber% expanded head of ureter.

-)nctions both homeostatic$

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So#e substances pass fro# blood into nephron.Proxi#al tubule H $ydroen ions are secreted in response to chanes in the blood plas#as p$

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wo#en feel an unco#fortable pressure above the pubic boneMa s#all a#ount of urine is passedMurine itself #ay be cloudy

A fever #ay #ean that the infection has reached the &idneys. Cther sy#pto#s include pain in bac& or side below ribs%nausea or vo#itin. "reat#ent usin antibiotics and lots of fluids. Acidic drin&s such as cranberry Buice can be of so#ehelp.

+idney stonesost co##on type is excess calciu# co#binin with excretory products. NellowDbrown% 9 c# in dia#eter. A stone #ay stay in the &idney or travel down the urinary tract. *t #ay pass out of the body unnoticed or et stuc& andbloc& the flow of urine and cause reat pain."reat#ent:Surery or shoc&wave lithotripsy ) stone crushin usin ultrasound. *f prone to &idney stones drin& lots of water and eatless #eat.

3.4.6 The Excretory System in the HumanExamination QuestionsSE Sam(&e %a(er O,

15.

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2"1" /,

H 3.4.8 The Nephron as a Unit of Kidney Function

2""4/,

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aintainin water balance or explained D 3[Note: Osmoregulation = 2 points]

9b: 9i: 0iagram of nephron 3< "0iagram of blood supply 3< "&abe&s 391:

9ii: -i&tration$lood in arteriole D under pressureD plas#a

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13.