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Gas exchange in fish
Gill
Gill  Gas exchange organ in fish; extends into filaments
Filament  made of flattened plates called lamellae
Lamellae  the gas exchange surface
*Counter current system: when two fluids are moving in
opposite directions and some compound, or heat, is
transferred from one fluid to the other.
Gas exchange in insect
Trachea
Tracheae series of air-filled tubes in insects, branches
into tracheoles.
Spiracles special inlets allow air to enters the body and
moves into trachea.
Tracheoles gas exchange surface; position in close
contact with cells
Air sac expands and contracts with up and down of wing
beats; these actions force air to move from trachea into
tracheoles.
Excretory System

You have two kidneys.

Each receives blood from
the renal artery.

Kidneys act like filters,
removing urea.

The urea is diluted with
water and is called urine.

Urine is sent to the
bladder for storage via
the ureter.
Structure of kidney

Cortex – the outer layer, consists of functional
units, nephrons. Filters the blood.

Medulla – the middle layer which has the tubes
carrying filtered wastes to the centre of the
kidney. Contains Loop of Henle

Pelvis – area where all collecting ducts come
together and connect with ureter.

Ureter – transports urine to the bladder.
Renal artery
Glomerulus
Bowman’s capsule
Distal
convoluted
tubule
• Blood
arrives
Capillaries
off renalfrom the renal artery.
artery
• Blood
enters a ball of capillaries called Glomerulus.
• Theses
capillaries
sit in a filter called the
Proximal convoluted
tubule
Bowman’s or renal capsule.
• Small molecules leave the capillary and enter the
capsule – glucose, amino acids, salts, urea and
Loop of Henle
Urine collecting duct
water.
The diameter of the
arteriole as it leaves
Bowman’s
capsule is less than
its entering diameter.
This increases blood
pressure to force
large quantities of
plasma out of
capillaries into
Bowman’s capsule.
Renal artery
Glomerulus
Bowman’s capsule
Capillaries off renal
artery
Convoluted or
kidney tubule
• The filtered blood
moves down the
nephron.
• In the convoluted
tubule cells reabsorb
the good stuff –
glucose, amino
Distalacids,
most salt andconvoluted
water.
tubule
• The rest – water and
urea – moves on
through the nephron.
Urine collecting duct
• As the urine moves
on more water is
saved in the loop of
Henle and collecting
duct
Glomerulus
• This adjusts water
Bowman’s
loss
to suitcapsule
the level of
water in the body.
Loop of Henle
Convoluted
tubule
Urine collecting duct
Renal artery
Glomerulus
Bowman’s capsule
Capillaries off renal
artery
Distal
convoluted
tubule
Proximal convoluted tubule
Loop of Henle
Urine collecting duct

Renal artery: brings blood to the kidneys
Contains waste products.

Renal Vein: takes blood away from the kidneys.
Purified blood

Glomerulus: cluster of small capillaries.

Bowman’s Capsule: This is where filtration takes place.
The filtrate contains useable & waste products

Convoluted Tubules: reabsorption of useful substances
happens here; including Glucose, most water and some
salts

Collecting duct: collects urine from nephrons and
transports it to the pelvis
Excretion in fish
Freshwater
Seawater
Excretion in insects