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Topic 22: Excretory System

� Urogenital integration

� How does the excretory system develop?

� How has the excretory system evolved?

� What is the gross anatomy of the kidney?

� What are the functional units of the kidney

and how do they work?

� What are the possible excretory products?

� Who excretes what?

Urogenital Integration

� Urogential structures

� ______________

� ______________

� Functions differ

� Some structures shared

� ____________

� ____________

� ____________

� Common developmental origin

� What does the excretory system do?

© infovisual.info

How does the excretory

system develop?

Liem et al. Fig. 20- ; Wolpert 1998

Intermediate

Mesoderm

_________

_________

__________

__________

___________

Nephron/

Renal Tubule

Drains kidney

or testis

Segmentation Evagination

How does the excretory system develop?

� Nephrotomes form along much of length of body

� Archinephric ductruns along anteroposterior axis

� Anteroposterior formation:

� _________________

� _________________

� _________________

Liem et al. Fig. 20-1

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Mammalian Kidney

Development

1. _______________

� Develops from nephric ridge

� Anterior & not functional

� Drained by archinephric duct

2. _______________

� Middle part of nephric ridge

� Functional in embryo

� Drained by archinephric duct

3. _______________

� Posterior end of nephric ridge

� Functional in adult

� Drained by ureter

� Archinephric duct

� Drains testes in males

� Degenerates in femalesLiem et al. Fig. 20-6

1

2

3

Excretory Ducts

� Ureter

� Always drains __________

� Ureteric bud � evagination

of archinephric duct

� Opening becomes independent from archinephric duct

� Homologous to _________ ____________________ in anamniotes (shark)

Liem et al. Fig. 20-7

How has the kidney evolved?

Liem et al. Fig. 20-5

� _______________

� Hypothetical ancestral condition

� Segmental

� Entire nephric ridge

� Drained by archinephric duct

� ___________________

� Hagfishes

� Anterior tip not functional

� Segmental

� Drained by archinephric duct

Liem et al. Fig. 20-5

� _______________________

� Fishes & Amphibians

� Posterior end of nephric ridge

� Multiplication of renal tubules � no longer segmental

� Drained by accessory urinary duct in males

� ______________________

� Amniotes

� Degeneration of all but posterior end of nephric ridge

� Drained by ureter

� What happens to archinephric duct in amniotes?

How has the kidney

evolved?

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Human Excretory Gross Anatomy

� Superior to inferior position

� Dorsal body wall & __________________

� Kidney

� Ureter

� Ventral body wall

� ___________________

� Through body wall

� Urethra

© spanglerscience.com

What is the gross

anatomy of the kidney?

� What kind of kidney do each of these animals have?

� Shape is variable within types of kidney

� Always retroperitoneal

� Always paired

© infovisuals.info; web-books.com; grassfedtraditions.com; pc.maricopa.edu

Human

Cow Frog

Shark

What are the functional units of the kidneys?

� ______________

� Tubular

� Recieves filtrate from blood

� Concentrates urine

� Proximal to distal

� _______________

� Proximal convoluted tubule

� _______________

� Distal convoluted tubule

� _______________

© bisbio.in

Human Kidney Gross Anatomy

� ________________� Superficial

� Bowman’s capsules

� Proximal convoluted tubules

� Distal convoluted tubules

� Renal ___________� Deep

� Loops of Henle

� Collecting ducts

� Renal ___________� Receives urine from

collecting ducts

� Drains into ureter

Liem et al. Fig. 20-13

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A Detailed Look at the Nephron

� _________________

� Glomerulus

� Bowman’s capsule

� Filtration of blood plasma

� Nitrogenous waste

� Ions & Water

� Blood flow

� Renal artery

� Afferent arteriole

� Glomerulus

� Efferent arteriole

� Vasa recta (resorption)

� Renal vein

© D Proffitt 1994; Benjamin Cummings 2001

Nephron

Function

Liem et al. Fig. 20-14

Blood Flow

Diffusion

Active

Transport

NH4+

K+

H+

Na+

Cl-

Glucose

Amino A

Na+

Cl-

HCO3-

Ca+

PO2-

NA+

1. Filtrate with all small water-soluble molecules

2. Resorption of useful ions & molecules

3. Water diffusion out along loop of Henle

� Due to salt gradient

� Established in ascending loop

� Water carried away via vasa recta �countercurrent

4. Adjustment of ions

5. Further concentration

1

5

4

3

2

Salt Gradient

What are the possible excretory products?

What animals would you expect to excrete each type of waste?

Liem et al. Fig. 20-9

Waste Structure

Solubility in Water Toxicity

Water Usage

Ammonia NH4

+

Urea CO(NH2)2

ModeratelyHigh

Low Medium

Uric Acid C5H4N4O3

Myxiniformes

Petromyzontif.

Testudines

Lissamphibia

Dipnoi

Actinistia

Actinopterygii

Chondrichthyes

Aves

Crocodylia

Lepidosauria

Mammalia

Who Excretes W

hat?

Liem et al. Fig. 3-1,

Table 20-2

Kidney Type

Environ-ment

1o

Waste2o

Waste

Primitive Opistho~

Marine

(M)Ammonia

(A)Urea

(U)

Advanced Opistho~

(AO)M

AOFresh Water

(FW)

AO M

AO FW

AO FW

AOTerrestrial

(T)

Meta~ T

Meta T

Meta T

Meta T

Meta T

Larva

Adult

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Excretion in Fishes

Liem et al. Fig. 20-11

� Excretory structures

� Gills

� Kidneys

� Excretion depends on medium

� Fresh water is hypoosmotic relative to fish blood

� Sea water is hyperosmotic

� Where does water tend to move if a fish is in fresh water?

� Salt water?

� Why?

Excretion in Fishes

Liem et al. Fig. 20-11; usace.army.mil; costaricafishing.info

� ___________________

� Does not drink (some with food)

� Lots of dilute urine with ammonia

� Lots of water & ammonialost at gills

� Active uptake of salts at gills

� ___________________

� Drink lots of water

� Comes with lots of salt

� Less dilute urine with ammonia

� Lots of water & ammonialost at gills

� Salts actively excreted at gills

Excretion in Fishes

Liem et al. Fig. 20-11; costaricafishing.info; derm.qld.gov.au

� _________________

� Adapted to excrete urea

� Do not drink (some water & salt with food)

� Lots of dilute urine with urea

� Salt enters at gills

� _______________________

� Sea water is hypoosmotic, so diffuses in

� Need to pass a lot of urine

� What else would rush in?

� Digitiform gland