Excretory System
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 nephronsAreas of the nephronRenal cortex1. Bowman’s capsule2. Proximal convoluted tubule3. Collecting ductRenal Medulla4. Loop of Henle5. Distal convoluted tubule
Figure 15.3a
Renal cortex
Renal medulla
Renal pelvis
Renalcortex
Ureter
Renalmedulla
Corticalnephron Fibrous capsule
Collectingduct
Proximalconvoluted tubuleGlomerulusDistalconvoluted tubuleLoopof Henle
Juxtamedullarynephron
(a)
Flow of blood through a nephron 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
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
Figure 15.3b
Proximalconvolutedtubule (PCT)Glomerular
capillaries
Glomerular(Bowman’s) capsule
Efferent arteriole
Afferent arteriole
Cells of thejuxtaglomerularapparatus
Cortical radiate artery
Arcuate artery
Cortical radiatevein
Arcuatevein
Collecting duct
Loop of Henle
Distalconvolutedtubule(DCT)
Peritubularcapillaries
(b)
How urine is made
1. 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
2. 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)
3. Secretion – as the filtrate moves through the remaining tubules, H ions, K ions, ammonium ions are secreted from the capillaries into the tubule
Figure 15.5
Proximal tubuleGlomerularcapsule
Blood
FiltrateH2OSalts (NaCl, etc.)HCO3
– (bicarbonate)H+
UreaGlucose; amino acidsSome drugs
Reabsorption
Active transportPassive transportSecretion (active transport)
Urine (to renal pelvis)
Glucose andamino acids
HCO3–
H2ONaCl
Some drugsand poisons
H+
Cortex
Medulla
Distal tubule
NaCl
K+ andsomedrugs
Loop ofHenle
H2O
NaCl
NaCl
H2O
Urea
K+
NaCl H2O
Collectingduct
Figure 15.1a
Hepatic veins (cut)
Inferior vena cava
Adrenal gland
Aorta
Iliac crest
Rectum (cut)
Uterus (partof femalereproductivesystem)
(a)
Renal artery
Renal hilum
Renal vein
Kidney
Ureter
Urinarybladder
Urethra
Hormones of the Kidney
Regulation occurs primarily by hormones Antidiuretic hormone (ADH) - vasopressin
Prevents 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
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
Epidermis
Papillarylayer
Reticularlayer
Dermal papillae
Pore
Adipose tissue
Cutaneous vascular plexus
Dermis
Hypodermis(superficial fascia)
• Sensory nerve fiber• Lamellar corpuscle• Hair follicle receptor (root hair plexus)
Nervous structures
Appendages of skin• Eccrine sweat gland• Arrector pili muscle• Sebaceous (oil) gland• Hair follicle• Hair root
Figure 4.3
Excretory Bingo
1. Ammonia2. Uric acid3. Urea4. Malpighian tubules5. Nephridia6. Nephron7. Renal cortex8. Renal medulla9. Bowman’s capsule10. Loop of Henle11. Renal artery12. Glomerulus13. Filtrate
14. Ureters15. Bladder16. Urethra17. Filtration18. Reabsorption19. Secretion20. ADH (vasopressin)21. Aldosterone22. Epidermis23. Dermis24. Subcutaneous layer
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