Chapter 25: Control of
the Internal Environment
NEW AIM: How do organisms deal with metabolic waste?
I. Excretion
A. removal of metabolic waste
i. Carbon dioxide
ii. Nitrogenous waste
a. produced from breakdown of proteins and nucleic acids
Chapter 25: Control of
the Internal Environment
NEW AIM: How do organisms deal with metabolic waste?
b. Forms of nitrogenous waste
1. Ammonia (NH3)
- highly toxic
- highly water soluble
- formed by deamination of AAs
- secreted by most aquatic animals
Fig. 25.8
Chapter 25: Control of
the Internal Environment
NEW AIM: How do organisms deal with metabolic waste?
b. Forms of nitrogenous waste
2. Urea
- 100,000X less toxic than NH3
- Highly water soluble
- mammals, adult amphibians,
sharks, some fish
- convert NH3 to urea (liver)
- urea travels in blood and is
removed by kidneys
- why don’t all organisms just make
urea??
- certain toads switch back and
forth
Compare hypothetical storage of NH3 to
storing urea in bladder.
Fig. 25.8
Chapter 25: Control of
the Internal Environment
NEW AIM: How do organisms deal with metabolic waste?
b. Forms of nitrogenous waste
3. Uric acid
- relatively non-toxic
- Largely INSOLUBLE in water
- birds, insects, many reptiles, land
snails, amphibians in deserts
- secreted as a paste or dry powder
- costs a lot to make
- savings is in water
- great for external development
(egg)
Birds don’t urinate!
Fig. 25.8
Chapter 25: Control of
the Internal Environment
NEW AIM: How do organisms deal with metabolic waste?
b. Forms of nitrogenous waste
Summary
Form of
nitrogenous
waste
toxicity
Solubility in
water
Energy cost
to make
NH3
(ammonia)
high
high
none
urea
low
high
high
Uric acid
Very low
low
Very high
Fig. 25.8
Chapter 25: Control of
the Internal Environment
AIM: How do organisms deal with metabolic waste?
II. Excretion in other organisms
A. Protists
- diffusion through membrane
- ammonia and CO2
- use contractile vacuoles
Chapter 25: Control of
the Internal Environment
AIM: How do organisms deal with metabolic waste?
II. Excretion in other organisms
B. Cnidaria (hydra)
- entire body in contact with water
- diffusion of ammonia and CO2
Chapter 25: Control of
the Internal Environment
AIM: How do organisms deal with metabolic waste?
II. Excretion in other organisms
C. Annelida (Earthworm)
- Nephridia = excretory organs of Earthworm
- one pair in each segment
- excrete urine (urea and ammonia) out the nephriopores
- CO2 excreted through skin (skin-breathers)
Chapter 25: Control of
the Internal Environment
AIM: How do organisms deal with metabolic waste?
II. Excretion in other organisms
F. Arthropod (Grasshopper)
- CO2 diffuses into tracheal tubes and expelled through
spiracles
- Malpighian tubules = excretory organs
- expels URIC ACID with fecal matter
Chapter 25: Control of
the Internal Environment
AIM: How do organisms deal with metabolic waste?
II. Excretion in other organisms
Summary
Organism
Form of
nitrogenous
waste
Method of
excretion
Protist
NH3 (ammonia)
diffusion
cnidaria
NH3
diffusion
annelida
Urea, NH3
nephridia
arthropoda
Uric Acid
Malpighian
tubules
Humans
Urea
kidneys
Chapter 25: Control of
the Internal Environment
NEW AIM: How do organisms deal with metabolic waste?
III. Human Excretory System
Fig. 25.9
*LIVER - makes urea from ammonia (site of deamination)
- flow chart from duodenum to ammonia
**Skin and lungs also involved in excretion
Chapter 25: Control of
the Internal Environment
NEW AIM: How do organisms deal with metabolic waste?
III. Human Excretory System
A. Kidneys
i. Site of urine formation
ii. maintains the homeostatic balance of blood
1. Regulates metabolic waste
-filters out metabolites (urea)
2. Regulates osmolarity
- filters out minerals/water
3. Regulates blood pressure
4. Regulates pH
iii. 1100-2000L of blood filtered
per day
Fig. 25.9
Chapter 25: Control of
the Internal Environment
NEW AIM: How do organisms deal with metabolic waste?
III. Human Excretory System
B. Flow of the excretory system
i. Blood enter via renal artery
ii. Urea, water and salts extracted
by nephrons of kidneys (filtrate)
iii. Blood leaves via renal vein
iv. Filtrate drains into renal pelvis
(urine now) -> ureter -> bladder ->
urethra -> toilet
Chapter 25: Control of
the Internal Environment
AIM: How do organisms deal with metabolic waste?
III. Human Excretory System
C. How does the kidney extract filtrate?
1. The Nephron
i. Functional unit of the kidney
ii. ~1,000,000 per kidney
Fig. 25.9
Chapter 25: Control of
the Internal Environment
AIM: How do organisms deal with metabolic waste?
III. Human Excretory System
C. How does the kidney extract filtrate?
1. The Nephron
i. Functional unit of the kidney
ii. ~1,000,000 per kidney
iii. Each extracts tiny amount of filtrate
Fig. 25.9
Chapter 25: Control of
the Internal Environment
AIM: How do organisms deal with metabolic waste?
III. Human Excretory System
C. How does the kidney extract filtrate?
1. The Nephron
** Fig. 25.9
http://www.sickkids.ca/childphysiology/cpwp/urinary/kidney.swf
Chapter 25: Control of
the Internal Environment
AIM: How do organisms deal with metabolic waste?
III. Human Excretory System
C. How does the kidney
extract filtrate?
1. The Nephron
- Flow chart through nephron
Fig. 25.9
http://www.sickkids.ca/childphysiology/cpwp/urinary/kidney.swf
Chapter 25: Control of
the Internal Environment
AIM: How do organisms deal with metabolic waste?
III. Human Excretory System
C. nephron
Practice Labeling
http://www.sickkids.ca/childphysiology/cpwp/urinary/kidney.swf
Fig. 25.9
Chapter 25: Control of
the Internal Environment
AIM: How do organisms deal with metabolic waste?
III. Human Excretory System
C. nephron
Urine is produced in 4 major processes
Fig. 25.10
Chapter 25: Control of
the Internal Environment
AIM: How do organisms deal with metabolic waste?
III. Human Excretory System
C. nephron
A closer look at urine formation
Fig. 25.11
Chapter 25: Control of
the Internal Environment
AIM: How do organisms deal with metabolic waste?
ADH = antidiuretic hormone = vasopressin
III. Human Excretory System
D. Regulating the nephron (water reabsorption)
i. Under hormonal control
ii. Regulate osmolarity (solute concentrations)
- Solute sensors in brain (ex. too little solute = too much water)
iii. Regulates blood pressure also
- low blood volume = low BP = reabsorb more water = secrete ADH
Chapter 25: Control of
the Internal Environment
AIM: How do organisms deal with metabolic waste?
III. Human Excretory System
D. Regulating the nephron (water reabsorption)
i. Under hormonal control
ii. Solute sensors in brain (too little solute = too much water)
iii. Regulates blood pressure
High [water] = high BP
Negative feedback
Alcohol inhibits release
of ADH
ADH = vasopressin
Chapter 25: Control of
the Internal Environment
AIM: How do organisms deal with metabolic waste?
III. Human Excretory System
D. Regulating the nephron (water reabsorption)
Q. What type of feedback?
Quick Fact: Alcohol
inhibits release of ADH
Q. Predict what would
happen to a person
drinking a lot of alcohol.
Caffeine also inhibits ADH release…
Chapter 25: Control of
the Internal Environment
AIM: How do organisms deal with metabolic waste?
III. Human Excretory System
D. dialysis
i. Kidneys are damaged
a. toxic waste builds up, unregulated BP, unregulated pH,
unregulated salt/water concentration
b. causes
- hypertension and diabetes (60%)
-prolonged use of pain relievers, alcohol, other drugs and
medicines
ii. Artificial kidney
a. Dialysis = separation
b. 3 times a week, 4 to 6 hours a session
Chapter 25: Control of
the Internal Environment
AIM: How do organisms deal with metabolic waste?
III. Human Excretory System
D. dialysis
Chapter 25: Control of
the Internal Environment
AIM: How do organisms deal with metabolic waste?
III. Human Excretory System
E. gout
i. Hyperuricemia
- elevated levels or uric
acid in blood
- causes
1. Accelerated generation of uric acid
2. Impaired excretion in kidney
3. Consumption of purine-rich diet
- crystals of uric acid form in joints (pain)
Chapter 25: Control of
the Internal Environment
AIM: How do organisms deal with metabolic waste?
III. Human Excretory System
E. gout
Chapter 25: Control of
the Internal Environment
AIM: How do organisms deal with metabolic waste?
III. Human Excretory System
F. Kidney Stones (for Joel)
i. AKA renal calculi
ii. Form inside kidneys or bladder
iii. Most made of Calcium oxalate crystals
Chapter 25: Control of
the Internal Environment
AIM: How do organisms deal with metabolic waste?
IV. The liver
A. More functions than any other organ
i. Bile production
ii. Deamination and synthesis of urea from ammonia
iii. Detox of alcohol and other drugs
iv. Synthesize blood clotting factors
v. Involved in blood glucose regulation (stores glucose as glycogen)
vi. Forms lipoproteins
- transport fat and cholesterol to body tissues
Chapter 25: Control of
the Internal Environment
AIM: How do organisms deal with metabolic waste?
IV. The liver
A. More functions than any other organ
i. Bile production
ii. synthesis of urea from ammonia
iii. Detox of alcohol and other drugs
iv. Synthesize blood clotting factors
vi. Forms lipoproteins
lipoprotein
Chapter 25: Control of
the Internal Environment
AIM: How do organisms deal with metabolic waste?
IV. The liver
A. More functions than any other organ
i. Bile production
ii. Deamination and synthesis of urea from ammonia
iii. Detox of alcohol and other drugs
iv. Synthesize blood clotting factors
v. Involved in blood glucose regulation (stores glucose as glycogen)
vi. Forms lipoproteins
- transport fat and cholesterol to body tissues
So where do you think your blood goes straight after absorbing
molecules at the small intestines?
Chapter 25: Control of
the Internal Environment
AIM: How do organisms deal with metabolic waste?
IV. The liver
A. More functions than any other organ
First “stop”…the liver.
The hepatic portal express
- nutrients and harmful chemicals go
straight to liver from duodenum
- detox before entering body, and
modify nutrients (deamination,
lipoprotein synthesis, etc…)
Fig. 25.13
Chapter 25: Control of
the Internal Environment
AIM: How do organisms deal with metabolic waste?
IV. The Skin (not in book)
Fig. 25.13
Chapter 25: Control of
the Internal Environment
AIM: How do organisms deal with metabolic waste?
IV. The Skin
a. epidermis
i. Top layer of skin
ii. Protects body, keeps in moisture
iii. Couple layers of living cells topped
with many layers of dead cells
iv. Holds skin pigment
Chapter 25: Control of
the Internal Environment
AIM: How do organisms deal with metabolic waste?
IV. The Skin
b. dermis
i. Layer underneath epidermis
ii. Connective tissue
iii. Nerve endings for heat/pressure/pain
iv. Glands (pores)
- sebaceous (oil) gland - associated with hair
- eccrine (sweat) gland
-sweat = 99% water, bit of NaCl, waste products (urea)
- thermoregulation, excretion, protection
v. Blood vessels