Osmoregulation and Excretion

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In insects and other terrestrial arthropods, Malpighian tubules remove nitrogenous wastes from hemolymph and function in osmoregulation.

Insects produce a relatively dry waste matter, an important adaptation to terrestrial life.

Slide 31

Malpighian tubules of insects

Rectum

Digestive tract

Hindgut

Intestine

Malpighian

tubules

Rectum

Feces and urine

HEMOLYMPH

Reabsorption

Midgut

(stomach)

Salt, water, and

nitrogenous

wastes

Slide 32

Kidneys : Nephrons = the Functional Unit

Kidneys = excretory organs of vertebrates, function in both excretion and osmoregulation.

Mammalian excretory systems center on paired kidneys, which are also the principal site of water balance and salt regulation.

Each kidney is supplied with blood by a renal artery and drained by a renal vein.

Urine exits each kidney through a duct called the ureter.

Both ureters drain into a common urinary bladder, and urine is expelled through a urethra.

Slide 33

Overview: mammalian Excretory System

Posterior

vena cava

Renal artery

and vein

Urinary bladder

Ureter

Aorta

Urethra

Excretory organs and major associated blood vessels

Kidney

Slide 34

The mammalian kidney has two distinct regions: an outer renal cortex and an inner renal medulla

Kidney structure

Section of kidney

from a rat

4 mm

Renal

cortex

Renal

medulla

Renal

pelvis

Ureter

Slide 35

Nephron = the Functional Unit of the Kidney

Cortical

nephron

Juxtamedullary

nephron

Collecting

duct

Nephron types

To

renal

pelvis

Renal

medulla

Renal

cortex

10 µm

Afferent arteriole

from renal artery

Efferent

arteriole from

glomerulus

SEM

Branch of

renal vein

Descending

limb

Ascending

limb

Loop of

Henle

Filtrate and blood flow

Vasa

recta

Collecting

duct

Distal

tubule

Peritubular capillaries

Proximal tubule

Bowman’s capsule

Glomerulus

Slide 36

The nephron = the functional unit of the vertebrate kidney, consists of a single long tubule and a ball of capillaries called the glomerulus.

Bowman’s capsule surrounds and receives filtrate from the glomerulus capillaries.

Slide 37