Download Excretory System

Excretory System
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An organism’s way of breaking down nitrogenous
wastes
When proteins are broken down, they form
ammonia
Birds and reptiles convert ammonia to uric acid and
mammals convert it to urea
Malpighian tubules are found in arthropods
Nephridia are found in earthworms
Flame cells are found in flatworms
Human Excretory System
Kidney regulate excretion
 Kidneys are made up of nephrons
Areas of the nephron
Renal cortex
1.
Bowman’s capsule
2.
Proximal convoluted tubule
3.
Collecting duct
Renal Medulla
1.
Loop of Henle
2.
Distal convoluted tubule
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Cortical
nephron
Renal cortex
Renal medulla
Renal pelvis
Fibrous capsule
Collecting
duct
Renal
cortex
Proximal
convoluted
tubule
Glomerulus
Distal
convoluted
tubule
Loop
of Henle
Ureter
Renal
medulla
Juxtamedullary
nephron
(a)
Figure 15.3a
Flow of blood through a nephron
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Blood enters at the Bowman’s capsule
The renal artery leads to the kidney and branches
into arterioles then into a ball of capillaries called
the glomerulus
Blood is filtered and plasma passes from the
capillaries into the Bowman’s capsule – it is now
called a filtrate
Path of the filtrate
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Passes through the B. capsule, through the proximal
convoluted tubule, then the loop of Henle, then the
distal tubule, and finally the collecting duct.
As it travels, it is modified to form urine.
Then the urine travels through ureters to the
bladder, to the urethra
Peritubular
capillaries
Proximal
convoluted
tubule (PCT)
Glomerular
capillaries
Distal
convoluted
tubule
(DCT)
Glomerular
(Bowman’s) capsule
Efferent arteriole
Afferent arteriole
Cells of the
juxtaglomerular
apparatus
Cortical radiate artery
Arcuate artery
Arcuate
Cortical radiate
vein
vein
Collecting duct
(b)
Loop of Henle
Figure 15.3b
How urine is made
1.
2.
3.
Filtration – small substances such as ions, water,
nutrients, salts pass from the glomerulus to the
Bowman’s capsule, proteins and blood cells are too
big
Reabsorption – as the filtrate moves through the
proximal convoluted tubule, the small substances are
re-absorbed by the blood in the peritubular
capillaries (what remains is urine)
Secretion – as the filtrate moves through the remaining
tubules, H ions, K ions, ammonium ions are secreted
from the capillaries into the tubule
Proximal tubule
Glomerular
Glucose and
HCO3–
capsule
NaCl
H2O amino acids
Blood
Filtrate
H2O
Salts (NaCl, etc.)
HCO3– (bicarbonate)
H+
Urea
Glucose; amino acids
Some drugs
Reabsorption
Active transport
Passive transport
Secretion
(active transport)
Some drugs
and poisons
Distal tubule
NaCl
K+ and
some
drugs
H+
Cortex
Collecting
duct
Medulla
Loop of
Henle
H2O
NaCl
NaCl
H2O
K+
NaCl
Urea
H2O
Urine
(to renal pelvis)
Figure 15.5
Hepatic veins (cut)
Inferior vena cava
Adrenal gland
Renal artery
Renal hilum
Aorta
Renal vein
Kidney
Iliac crest
Ureter
Rectum (cut)
Uterus (part
of female
reproductive
system)
Urinary
bladder
Urethra
(a)
Figure 15.1a
Hormones of the Kidney
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Regulation occurs primarily by hormones
 Antidiuretic
 Prevents
hormone (ADH) - vasopressin
excessive water loss in urine
 Causes more water re-absorption from the collecting duct
 If you are dehydrated, ADH will work to re-absorb the
water and urine will be concentrated
 If your fluid intake is high, ADH will be low, the body won’t
re-absorb most of the water and your urine will be dilute
Hormones cont.
 Aldosterone
 Regulates
sodium ion content of the distal convoluted tubule
 Sodium is the electrolyte most responsible for osmotic water
flows
 Aldosterone promotes reabsorption of sodium ions
 Remember, water follows salt!
Skin
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Epidermis, dermis, subcutaneous layers
Sweat glands are found in the dermis
Stratum corneum is in the epidermis and forms are
barrier against invading microorganisms
Hair shaft
Dermal papillae
Epidermis
Papillary
layer
Dermis
Pore
Appendages of skin
• Eccrine sweat gland
• Arrector pili muscle
• Sebaceous (oil) gland
• Hair follicle
• Hair root
Reticular
layer
Hypodermis
(superficial fascia)
Nervous structures
• Sensory nerve fiber
• Lamellar corpuscle
• Hair follicle receptor
(root hair plexus)
Cutaneous vascular plexus
Adipose tissue
Figure 4.3
Excretory Bingo
1.
2.
3.
4.
5.
6.
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12.
13.
Ammonia
Uric acid
Urea
Malpighian tubules
Nephridia
Nephron
Renal cortex
Renal medulla
Bowman’s capsule
Loop of Henle
Renal artery
Glomerulus
Filtrate
14.
15.
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21.
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24.
Ureters
Bladder
Urethra
Filtration
Reabsorption
Secretion
ADH (vasopressin)
Aldosterone
Epidermis
Dermis
Subcutaneous layer