Download Excretion - Ardsley Schools

Excretion
What is the difference between
Excretion and Elimination?
• Elimination of unabsorbed and undigested
food in the form of feces.
– These materials have never entered the body
cells, therefore they are NOT metabolic
waste.
Metabolic Waste:
• CO2, water (respiration)
• Nitrogen Compounds: ammonia, urea, uric
acid, (breakdown amino acid)
• Mineral salts: sodium chloride, potassium
sulfate (metabolism)
• All of these waste products are poisonous in
excess.
Excretion in Protists
• Diffusion through cell
membrane into
surrounding water
• Waste: CO2, Mineral
Salt, ammonia*
Ammonia:
• chief nitrogenous waste of microorganisms
• poisonous to cells, but soluble in water
• excreted as waste if water is present to wash it
away
Excretion in Hydra
• Surface Area surrounded by
water!
• Diffusion through cell
membrane of each cell into
surrounding water.
Excretion in Earthworm
• Most of cells are not in contact with surroundings: need
specialized excretory organs
• Nephridia:
– Structures found in pairs: one on each side
– In most of segments, and extends slightly into next segment.
Nephridia of Worm
1) Metabolic wastes and nutrients in body fluid
2) Body fluid enters the nephristome (funnel shaped opening)
3) Cilia move the fluid through funnel into nephridium
4) Nephridium loops and widens into bladder
5) Bladder drains to outside of body through Nephridiopore
Exchange going on!
• Capillaries reabsorb nutrients that entered
nephridia
Worm Pee
•
•
•
•
water
mineral salts
ammonia
urea
CO2 Excretion
• Across Skin
Worm X-Section
Nephridium
Nephridiopore
Excretion in Grasshoppers
• Excretory organs of grasshoppers and
other insects: Malpighian tubules
Grasshopper
1. Wastes and nutrients enter the Malpighian Tubules by
diffusion and active transport.
2. Material is passed into intestine
3. Nutrients are reabsorbed from the tubules and
digestive tract and returned to body fluid.
4. Dry nitrogenous waste product, uric acid, feces pass
out through anus.
Grasshopper
• Urine:
– Solid Uric acid crystal
– Out the anus
– Least poisonous nitrogenous waste
– Not water soluble (saves water)
Human Excretory System
Metabolic wastes:
• CO2
• Urea
• Water
• Mineral Salts
Organs of Excretion
1.
2.
3.
4.
Lungs
Kidneys
Liver
Skin
The Liver
• Regulates the makeup of body fluid
• Detoxification: Liver detoxifies the blood
• Removes harmful substances: bacteria, certain
drugs, hormones, from the blood
• Liver changes these substances into less harmful
ones
• Inactive forms are returned to the blood and
excreted via the kidneys
Overworked liver….
• Alcohol causes Cirrhosis.
– liver becomes overgrown with excess tissue
– excess tissue cuts down blood flow
– limits amount of detoxification it can perform
– lead to death
The Liver
• Bile is made by the liver.
– Contains bile salts, cholesterol,
part of hemoglobin (worn out
RBC).
– Some of these products are
metabolic waste.
Bile Cycle
•
•
•
•
Bile collects in gallbladder.
Passes into small intestine.
Emulsifies of fats
Bile salts are reabsorbed from small intestine
into the blood
• Return to liver
• (recycling!)
• The rest of bile excreted through large intestine
Liver not working right…
• Jaundice:
– when bile is NOT excreted properly.
Reabsorbed hemoglobin fragments in blood
cause skin to yellow.
Formation of Urea
• Amino acids are the
breakdown products
of proteins. We can
not store excess
protein.
• Breakdown occurs in
the liver.
From each amino acid:
• The amino group (NH2) is changed to
Ammonia (NH3), then to Urea (much less
harmful).
• Urea diffuses into blood stream to the
kidneys.
• Kidneys filter the urea and excrete as
urine.
• Remainder of amino acid is changed to
either: pyruvic acid, glycogen, or fat.
Urinary System
• Kidneys (2)
• Bladder
• Urethra
Kidneys:
• Bean shaped
• Located in posterior aspect of
abdomen, just below the
diaphragm.
• Functions:
– Remove waste of cellular
metabolism from the blood
– Regulate the concentrations of
the substances found in body
fluids including water, salts
– Maintain homeostasis
Structure of Kidneys
• Cortex:
– outer part
– Blood is filtered
• Medulla:
– middle part
– Made of tubes called collecting ducts
– Carry filtered substances & filtrate to pelvis
• Pelvis: inner region
– Cavity connected to the ureter
– Urine formed from filtrate drains from pelvis into
ureter
• Nephrons
– Kidney contains1.25 million nephrons
– Filters waste from the blood
– Part is in cortex, remainder is in medulla
Nephron
Parts of Nephron
1. Glomerulus: a group
of capillaries that form
a tight ball.
2. Bowman’s capsule:
a double walled cup
shaped structure
surrounding the
glomerulus
Filtration at Bowman’s Capsule
• Pressure pushes out “filtrate”
• Large substances (Proteins, cells, etc) do
not enter Bowman’s capsule
• Filtrate includes: water, urea, glucose,
amino acids, and various salts (like
plasma! Just without the protein)
• Filtrate moves in Proximal Renal Tubule
Parts of Nephron
3. Proximal Renal Tubule:
NaCl,H2O,Glucose,
Potassium
Reabsorption
Parts of Nephron
4. Loop of Henle:
middle section that
forms a long loop
• Water reabsorption
with help of salt
pumping
• Extends into the
medulla region of
Kidney
• Filtrate enters distal
renal tubule
Parts of Nephron
5. Distal Convoluted Tubule
• H2O and Sodium reabsorption
Parts of Nephron
6. Collecting Duct
• Some urea
reabsorption
• More H2O
reabsorption
• Many collecting ducts
fuse
• Urine exits out Ureter
of Kidney
• Site of ADH action
Kidney Threshold Level
• If the concentration of a substance in the
blood is greater than a certain level: it is not
reabsorbed.
• The excess remains in the Urine
Imbalance in Homeostasis
• Blood sugar level of a person who has
diabetes is so high that not all the glucose in
the filtrate can return to the blood.
• Glucose in the Urine.
Urine:
• The fluid remaining in the tubules: water,
urea, various salts
• Substances that crystallize out of the
Urine: kidney stones
• Dialysis
Ureters
• Bring urine
to urinary
bladder
• Urine exits
through
urethra
Lungs:
• Lungs are considered part of the excretory
system because they get rid of C02 and
water (vapor)
Skin
Excretes small amount
of urea and salts in
sweat
Skin
•
•
Structure:
Two Layers:
1. Epidermis
2. Dermis
Epidermis: outer layer
• Tightly packed epithelial cells.
• Deepest portion is rapidly
dividing.
• As they push farther and farther
from Dermis, they received less
and less nourishment.
• Before dying, they produce
Keratin: tough water proof protein
• Wears away, replaced by new
cells.
• Protects Dermis.
Dermis
• Made of elastic connective tissue
• Binds to the muscle and bone beneath it.
• Contains: blood vessels, lymph vessels,
nerves, sense receptors, sebaceous glands,
sweat glands, hair follicles.
Sebaceous Glands
• Produce oily secretions that provide a
protective coating to the skin and hair
keeping them soft and pliable
Sweat Glands
• Made of coiled tubes that open to
the surface through pores.
• Sweat is released through these
pores
Subcutaneous Layer
• Adipose ( fat-storing) Cells
Heat Loss:
• Blood vessels in the skin
open wider
• Increases the blood flow
through the skin’s capillaries
(flush)
• Allows more heat to be
given off to the air
• Sweat begins to evaporate:
cooling the body
Heat Retained:
• blood vessels in the skin narrow
• body sweats less
• Video1\
• Video 2