Transcript Excretion - BellaireAPBio

•Thermoregulation
•Osmoregulation
•Excretion
Regulators & Conformers
Regulation of Body Temperature
Transfer of heat
by air or water
movement
Emission of
electromagnetic
waves
Removal
of heat from
the surface
of a liquid
Direct transfer
of heat
Endotherms:
High metabolic
rate to maintain a
high and very
stable internal
temperature
Ectotherms:
Low metabolic rate,
body temperature
determined by
environment
Thermoregulation
1.
•
•
Adjusting the rate of heat exchange between the
animal and its surroundings
Vasodilation/vasoconstriction
Countercurrent heat exchanger
2. Cooling by evaporative loss (skin, breathing)
3. Behavioral responses (basking, hibernation,
migration)
4. Changing the rate of metabolic heat production
(endotherms only)
Countercurrent heat exchangers
Bird
legs
Marine
mammal
flippers
ENDOTHERMY
•Shivering
•Movement
•Brown fat
•Insulation (hair,
fat, feathers)
•Goose bumps
•Vasoconstriction
•Vasodilation
•Blubber
•Sweat glands
•Panting
FISHES
•Most conformers
•Endothermic fishes
circulatory adaptations
Invertebrates
aquatic – thermoconformers; terrestrial – behavioral
endothermic – many flying insects
Human Thermoregulation
Torpor – physiological state (low activity)
Hibernation – long term torpor (winter)
Estivation – summer torpor
WATER BALANCE & WASTE
DISPOSAL
Osmoregulation – management of body’s water
content & solute composition
 Contractile vacuoles
 Transport epithelium –

◦ layer(s) of specialized cells that regulate solute
movement
◦ move specific solutes in controlled amounts in
particular directions
◦ joined by impermeable tight junctions forming a
barrier at the tissue-environment boundary
Salt secreting glands
in marine birds
Blood flow and salt
flow counter
current
Note tight junctions
in epithelium
Nitrogenous wastes
correlated to
phylogeny & habitat
Ammonia – very soluble,
very toxic, aquatic
species
Urea – produced in the
liver, land animals, less
toxic, conserves water
Uric acid – largely
insoluble, excreted as
semi solid paste, minimal
water loss, birds &
reptiles
EXCRETORY SYSTEMS
Filtration – pressure filtering
body fluid, largely nonselective,
produces filtrate
Reabsorption – reclaims valuable
substances by active transport
Secretion – extraction of toxins
& excess ions from blood
Excretion – removal from body
Flame-Bulb System
of a Planarian
Metanephridia of an Earthworm
Malpighian Tubules
in Insects
HUMAN EXCRETORY SYSTEM
www.bioengineering.canterbury.ac.nz/graphics
http://www.lakemichigancollege.edu/liberal/bio/anat/urin.html
NEPHRON – functional unit of a kidney
•Glomerulus – ball of capillaries, very porous
•Bowman’s capsule – cup shaped swelling
surrounding glomerulus
•Filtration – blood pressure provides the force,
nonselective: glucose, aa, salts, ions, urea, H2O
etc.
•Filtrate (essentially lymph) pathway – PCT,
Loop of Henle, DCT, collecting duct
•Cortical nephrons (cortex) – 80% of human’s
•Juxtamedullary nephrons – extend into medulla
•Blood vessels – afferent arteriole, efferent
arteriole, peritubular capillaries, vasa recta
1. PROXIMAL TUBULE
Reabsorption:
•of salt (most imp)
•Active or passive
•Nutrients
•Bicarbonate ions
Secretion:
•H+ ions (pH)
•Ammonia (pH)
•Drugs, poisons
Epithelium:
Exterior side smaller
surface area,
minimizes leakage
Active
Passive
2. DESCENDING LIMB - LOOP OF HENLE
Reabsorption of H2O
continues
Epithelium not very
permeable to salts
Interstitial fluid –
osmolarity ↑ as fluid
moves down from
cortex to medulla
Active
Passive
3. ASCENDING LIMB - LOOP OF HENLE
Transport epithelium
permeable to salt NOT
water
Thin segment – passive
Thick segment – active
Filtrate becomes more
dilute as it moves into
cortex
Active
Passive
Active
Passive
4. DISTAL TUBULE
Secretion & reabsorption
Regulation of:
K+ (secretion) and
NaCl (reabsorption)
pH regulation
(H+ & HCO3-)
5. COLLECTING DUCT
Active
Passive
•Carries filtrate
through medulla into
pelvis
•Actively reabsorbs
NaCl
•Epithelium (cortex)
permeable to H2O
but NOT salt, urea
•High conc. of urea
causes some to
diffuse out
Concentration
of urine in
the human
kidney based
on urea &
salt
Concentration
of urine in the
human kidney
based on urea
& salt
Concentration of
urine in the
human kidney
based on urea
& salt
REGULATION OF KIDNEY
Antidiuretic hormone (ADH) – DCT & collecting duct
Juxtaglomerular apparatus (JGA) – near afferent
arteriole, responds to low blood pressure or volume
Angiotensin II – activated by renin, constricts
arterioles, reabsorption of NaCl in PCT, triggers
release of aldosterone
Aldosterone – adrenal medulla, DCT reabsorption of
NaCl
Renin-angiotensin-aldosterone system (RAAS)
Atrial natriuretic factor (ANF) – oppose RAAS
Hormonal control
of the kidney by
negative feedback
circuits
ADH enhances fluid
retention by making the
kidneys reclaim more
water
RAAS – JGA responds to
in blood pressure/volume
Vampire bat excretes
a)dilute urine while feeding (shedding weight
for flight home)
b)concentrated urine while roosting