Transcript excretion - biorocks

EXCRETION
1. The process by which metabolic wastes
and excess substances are removed from
an organism.
2. Excretion also removes excess heat from a
body which helps keep the body
temperature constant.
3. Excretion helps maintain homeostasis.
Metabolic wastes are:
1. Carbon dioxide (CO2)
 from cellular respiration
2. Water
 from cellular respiration and
dehydration synthesis
3. Nitrogen compounds (ammonia, urea,
uric acid)
 from the breakdown of amino acids
4. Mineral salts
 built up during metabolism
ELIMINATION
(defecation)
• Removal of undigested or
unabsorbed material in the form of
feces from the digestive tract.
ADAPTATIONS
IN THE FAB FIVE
EXCRETION IN PROTISTS
Wastes diffuse out of the cell through the cell
membrane into surrounding water
Wastes include
• Carbon dioxide
• Mineral salts
• Ammonia (is soluble in surrounding water)
Water constantly diffuses into the cell by
osmosis
• Requires active transport to pump excess
water out of the cell
• Contractile vacuole fill with water
• When full, they will inject water from the
cell
PARAMECIUM
CONTRACTILE VACUOLES
EXCRETION IN A HYDRA
Wastes diffuse out of the cells into the
surrounding water
Wastes include:
• Carbon dioxide
• Mineral salts
• Ammonia
Water constantly diffuses into the cells by
osmosis
Water is pumped out by an unknown method of
active transport
– Contractile vacuoles have not been seen in
hydras
CO2
O2
THE
HYDRA
ammonia
Mineral salts
endoderm
Gastrovascular cavity
ectoderm
EXCRETION IN EARTHWORMS
Nephridia = the excretory organs of the earthworm
• A pair of nephridia are in each section of the
earthworm’s body
Wastes from the body cells diffuse into the fluid of the body
cavities
• Wastes from the body fluid enters the nephridia at the
nephrostrome
• Fluid travels through the tubule loops and into the
bladder
• The bladder drains to the outside of the body through an
external opening called a nephridiopore
• Dilute solution called urine
– Urine made up of water, mineral salts, ammonia, and
urea
EXCRETION IN EARTHWORMS
Wastes from the blood stream pass from the
capillaries into the nephridium
Useful substances (glucose and water) pass
from the body fluid to the nephridium to
the blood
Carbon dioxide is excreted through the
moist skin
EXCRETION IN EARTHWORMS
EXCRETION IN GRASSHOPPERS
Malpighian tubules = excretory organs of
grasshoppers and insects
• The malpighian tubules are bathed directly by
the blood in the open circulatory system
• Wastes and water from the blood move into the
tubules by diffusion and active transport
• Wastes then pass into the intestines
– Water and any useful materials are
reabsorbed back into the body fluids from the
digestive tract
• Dry nitrogenous wastes (uric acid) pass out of
the body through the anus with other digestive
waste (feces)
EXCRETION IN GRASSHOPPERS
4. SKIN
LUNG
LIVER
KIDNEY
HUMAN URINARY SYSTEM
3. Cortex
1. Renal artery
2. Renal vein
4. Medulla
7. Adrenal gland
5. Pelvis
8. Kidney
9. Ureter
6. Ureter
10. Urinary bladder
11. Urethra
EXCRETION
Definition: The process by which wastes
and excess substances are removed from
an organism.
Role of the Liver
1. DETOXIFICATION
2. SECRETION OF BILE
3. FORMATION OF UREA
DETOXIFICATION
• removes harmful substances from the
blood (bacteria, drugs, hormones)
• changes harmful substances to less
harmful forms
• substances are returned to the blood and
excreted through the kidneys
 Cirrhosis – overloading of the body with toxins,
the liver becomes overgrown with excess tissue
and it decreases function, may eventually fail
leading to death
DETOXIFICATION
Cirrhosis of the Liver
Cirrhosis – overloading of the body with toxins, the liver becomes
overgrown with excess tissue and it decreases function, may eventually fail
leading to death
Secretion of bile
• bile salts, cholesterol, hemoglobin molecule
parts are secreted to the gallbladder (where they
are temporarily stored)
• secreted to the small intestine where it assists in
lipid digestion
• bile salts reabsorbed and returned to the liver
• rest of materials pass to the large intestines are
excreted with feces
 Jaundice – if bile wastes are not excreted properly
and the hemoglobin is reabsorbed, the skin takes on
a yellowish color
Secretion of bile
Jaundice
if bile wastes are not excreted properly and the hemoglobin
is reabsorbed, the skin takes on a yellowish color
Formation of Urea
• amino acids (from protein digestion) are
broken down in the liver
• each NH2 group changed into NH3 which
is used to form urea
• urea in the liver diffuses into the blood that
flows to the kidneys and is excreted as
urine
Formation of Urea
ADRENAL GLANDS
KIDNEYS
INFERIOR VENA CAVA
URETER
AORTA
URINARY BLADDER
URETHRA
Function
1. Kidneys (produce urine)
• Remove cellular respiration waste from the
blood
• Regulate concentration of substances in
body fluids
2. Ureter
• Passage way from the kidneys to the bladder
3. Urinary bladder
• Storage of urine
4. Urethra
• Passage way for urine from the bladder to
outside the body
Structure of the Kidneys
I.
Three parts of the kidney
1. Cortex – blood is filtered through the nephrons located here
2. Medulla – made up of collecting ducts that send the filtrate (filtered
material) to the pelvis
3. Pelvis – urine drains from here into the ureter
CORTEX 1.
MEDULLA 2.
PELVIS 3.
RENAL VEIN 4.
RENAL ARTERY 5.
URETER 6.
NEPHRONS
The filtering of wastes from the blood takes
place in the nephrons.
Part of the structure is in the cortex and part is
in the medulla.
NEPHRONS
1. Glomerulus – tight ball of capillaries
where blood is filtered
2. Bowman’s Capsule – collects filtrate that
has been filtered from the blood
3. Renal Tubule – passes filtrate from
Bowman’s Capsule to the collecting duct
4. Loop of Henle – a loop of renal tubule
5. Collecting duct – one collecting duct
receives filtrate from many different
nephrons and drains it from the medulla
The Major Functional Unit of the
Kidney is the Nephron
Bowman’s Capsule
Collecting Tubule
Collecting Duct
Glomerulus
Renal Artery
Renal Vein
Capillary network
Loop of Henle
The Nephron
1. Bowman’s capsule
10. collecting tubule
2. arterioles
3. renal artery
4. glomerulus
9. collecting duct
5. capillary network
to pelvis
7. venule
8. Loop of Henle
URINE FORMATION
1. FILTRATION
2. REABSORPTION
URINE FORMATION
Filtration
• Takes place in the glomerulus and the Bowman’s
capsule
Bowman’s capsule
water
amino acids
urea
salts
*molecules are small
enough to pass through
the capillary to wall
into Bowman’s capsule
capillary
*blood cells and proteins are too large to
pass from the capillary to the Bowman’s capsule
Urine Formation
II. Reabsorption
• While filtrate travels down the renal tubules, the volume of filtrate is
reduced
• 99% of the water, all glucose and amino acids, and many salts are
passed back into the blood
renal tubules
capillary
glucose
water
a. a.
salts
Water is reabsorbed by osmosis
Other materials are reabsorbed by
active transport
Filtrate left is highly concentrated (urine)
Urine flows from the renal tubules to the collecting duct
Urine passes from the kidneys into the ureters and on to the bladder
Control of kidney function
• The kidneys are responsible for keeping
homeostasis, which is achieved by regulating
the volume and concentration of body fluids;
which is controlled by selectively filtering and
reabsorbing materials from the blood.
The kidney has an auto-regulation mechanism
o The rate of filtration and reabsorption
responds to changes in blood pressure and
the composition of the blood
Control of kidney function
In other words; kidney function is
controlled primarily by the composition
of the blood.
The kidneys are also controlled by
The nervous system and hormones
o When cells in the hypothalamus (part of the
brain) are in a hypertonic environment (cells
are losing water), they stimulate thirst.
o Changes in blood volume also stimulates
receptors in the heart that in turn stimulate the
release of certain hormones that affect the
rates of reabsorption in the kidneys (therefore
changing the blood volume)
• Substances that crystallize are called
kidney stones
• If kidneys fail – artificial kidney function
through dialysis
Kidney Stones
Kidney Dialysis
HAIR
EPIDERMIS
Structure of
the Skin
DERMIS
PORE
KERATIN
NERVES
SEBACEOUS
GLAND
HAIR FOLLICLE
SWEAT GLAND
Structure of the Skin
Epidermis
• Tightly packed epithelia
cells
• Deepest level made up of
rapidly dividing cells
• As cells push up, they die
off
• Produce keratin (tough,
waterproofing protein) for
protection of the dermis
EPIDERMIS
Structure of the Skin
Dermis
• Made of elastic, connective
tissue
• Supports skin
• Contains blood vessels, lymph
vessels, nerves, sense
receptors, sebaceous glands
(oil secretions), sweat glands
(coiling tubes that open to
pores), and hair follicles
DERMIS
Structure of the Skin
Adipose tissue
• A layer of fat
Adipose tissue
Functions of the Skin
1. As a barrier
– Keeps microorganisms out
– Keeps water in
2. Removal of heat
– Increased blood flow to the surface of the
skin cools the blood
– Sweat evaporates off the skin causing
cooling
3. Keeps the body warm
– Decreased blood flow to the skin keeps the
core warm
The most important
function of the skin
(as an organ of excretion)
is
Removal of heat
primarily by sweating