Lecture 23, 07 Nov 2006
Vertebrate Physiology
ECOL 437 (MCB/VetSci 437)
Univ. of Arizona, Fall 2006
Housekeeping, 07 Nov 2006
Kidney/Urine Lab on 08 November, Term Paper drafts (2 with codenames)
Don’t forget to do seminar write-up! (due 10 November)
(Eckert 14-17)
Upcoming Readings
Kevin Bonine & Kevin Oh
today: Text, Ch. 25-27 (osmoregulation, kidney)
Wed 08 Nov: Kidney/Urine lab, (Heart), Term Paper
Thurs 09 Nov: Text, chapter 25-28, kidney, excretion, deserts
Tues 14 Nov: begin 4+5 (feeding, nutrition, metabolism)?
Thurs 16 Nov: Exam 3
1. Osmoregulation
(Chap 25-26)
2. Kidney Function
(Chap 27)
1
Lab oral presentations 08 Nov
9am – none
2pm – none
2
http://eebweb.arizona.edu/eeb_course_websites.htm
Vertebrate Physiology 437
Osmoregulation
-Ionic and
Osmotic Balance
Osmoregulation
-Kidney Function
(Eckert, 14-18)
3
Osmoregulation
4
Obligatory Osmotic Exchanges
-life arose in salty sea
1-Gradients
-Frog in freshwater
-Fish in ocean
-extracellular fluids ~ similar
2-Surface-to-Volume Ratio
-Small animals dehydrate or hydrate more rapidly
-dist’n limited by temperature and osmotic pressure
(dehydration, ionic composition)
-Skin, and Respiratory surface
(higher metabolism with higher per/gram
respiratory surface)
-terrestrial organisms (and their descendents) regulate
internal environment (homeostasis)
3-Integument Permeability
-Transcellular or Paracellular
-Aquaporins = water channel proteins
-salt and water regulation (waste excretion)
-kidneys, salt glands, gills
5
-Frogs vs. Lizards, Pelvic Patch etc.
6
1
Obligatory Osmotic Exchanges
Osmoregulation
4-Feeding, Metabolism, Excretion
-metabolic waste products
ammonia, urea, etc.
-metabolic water (desert!)
-ingestion of salts
-kidneys, salt glands, gills (more later)
-Water Breathing
1. Fresh
Ambystoma tigrinum
Blood osmolarity 200-300 mosm/L
Water ~ 50 mosm/L
5-Respiration
-internalize respiratory surface
-temporal countercurrent system
(dry and cool IN, becomes moist and warm; recover)
(countercurrent blood flow also)
-temperature regulation vs. water conservation
-ectotherm vs. endotherm (in deserts)
-
hyperosmotic animals, danger of swelling, losing salts
get their water across skin
dilute urine
active uptake of salts across epithelium
fish gills, frog skin, etc.
7
Osmoregulation
8
Osmoregulation
-Water Breathing
-Air Breathing
2. Salt (~1,000 mosm/L)
Have to lose water to allow gas exchange
- Marine reptiles and marine birds can drink
seawater and secrete salts in high [ ]
Most marine vertebrates hypo-osmotic
(e.g., teleost or bony fishes)
- SALT GLANDS
-
- Mammals rely on kidney
danger of losing water, gaining too many salts
drink saltwater
excess salts actively secreted (gills, kidneys)
chloride cells for salt secretion
(Pelis et al. paper)
(14-8)
9
10
Hill et al. 2004, Fig 26.15
(16-7)
Mouse-to-Elephant Curve
4g shrew eats 2g/day
elephant is 1 million x larger
11
12
2
Camel
Water
K-rat
Free
Preformed
Oryx
Metabolic
C6H12O6 + 6O2 ÅÆ 6CO2 + 6H20
Hopping Mouse
13
14
ORGANS THAT CONTRIBUTE TO OSMOREGULATION
IN VERTEBRATES
K-rat
Lab rats
Group
Osmoregulatory Organs
Fish
Kidneys
Gills
Bladder
Intestine
Kidneys
Gills
Bladder
Skin
Intestine
Amphibians
Reptiles
Kidneys
Salt Glands
Intestine
Birds
Kidneys
Salt Glands
Intestines
Mammals
Kidneys
15
Osmoregulation
16
Water
-Air Breathing Desert Mammals
Behavior and Physiology
(Eckert 14-9)
Lose water:
evaporation
urine
feces
salt glands
Role of
microhabitat
eyes
Eleutherodactylus coqui
Pough et al., 2001
Alter behavior and physiology to minimize water loss
Water balance limits activity in time and space
Kangaroo Rat
-Reduce Activity
-Remain in Cool Burrow
-Highly concentrated urine
-Very dry feces (rectal absorption)
-Metabolic water
17
Amphibs lose most water via evaporation
- cutaneous resistance
1 dried mucus
2 cocoon
3 wax
18
3
Water
Phyllomedusa
Phyllomedusa sauvagi
Chuckwalla
Less
evap.
(lizards have more lipids in skin)
Monkey Tree Frog
Anolis lizard
Alligator
Softshell Turtle
More
evap.
Pough et al., 2001
Bufo, Spadefoots, Rana
19
(free water surface)
Pough et al., 2001
20
Osmoregulatory Mechanisms
Apical surface (faces lumen and outside world)
Basal surface (faces body and extracellular fluid)
Kidney Function
- Active movement of ions/salts requires ATP
- Movement of water follows movement of ions/salts
Volume Regulation
Osmotic Regulation
Ionic Regulation
How do these differ?
21
Gradients established and used…to move ions, water
22
(14-11)
Fish Gills
active
Chloride cells involved in osmoregulation
-(recall lab paper on smolting)
-lots of mitochondria to power ATPases
-mechanism similar in nasal glands (birds
and reptiles), and shark rectal gland
(14-14)
passive
2
1
4
(Eckert 14-12)
Mammalian Kidney
3
5
23
24
4
(Eckert 14-17)
(Eckert 14-17)
Mammalian Kidney
-Paired
-1% body mass
-20% blood flow
Kidney Functions:
-Osmoregulation
-Blood volume regulation
-Maintain proper ion concentrations
-Dispose of metabolic waste products
-pH regulation (at ~ 7.4)
-Dispose of toxins and foreign substances
-urine contains:
water
metabolic byproducts (e.g., urea)
excess salts etc.
-from ureter to urinary bladder
(smooth muscle, sphincter, inhibition)
-out via urethra during micturition
How does the kidney accomplish this?
25
26
Mammalian Kidney Anatomy
FUNCTIONAL UNIT
(~ 1 million)
extracellular
intracellular
(Eckert 14-17)
Urine
27
28
Hill et al. 2004, Fig. 27.6
Nephron Anatomy
1 -Proximal tubule
2 -Loop of Henle
-descending
-ascending
3 -Distal tubule
-numerous nephrons
empty into collecting duct
-collecting ducts empty
into renal pelvis
29
(Eckert 14-18)
30
5
Nephron Anatomy
1
2
6
3
7
4
5
Vasa recta
Countercurrent
exchange
31
Knut Schmidt_Nielsen 1997
32
Knut Schmidt_Nielsen 1997
Kidney Processes- overview
Mosm = x1000
U/P
Filtration plus secretion
1. FILTRATION
blood --> filtrate
2. REABSORPTION
filtrate --> blood
+
3. SECRETION
blood --> filtrate
All 3 involved in final
Urine Composition
Dipodomys
(Eckert 14-21)
34
Knut Schmidt_Nielsen 1997
33
Humans:
125 ml/min
or
180 L/day
(14-20)
Hill et al. 2004, Fig 25.7
35
Sympathetic
innervation tends
to constrict
36
6
Filtration:
Bowman’s capsule
Bowman’s capsule
3 layers
1. Glomerular endothelial cells
-100x leakier than other capillary walls
2. Basement membrane
-negatively charged glycoproteins
-repel plasma proteins by charge
3. Epithelial cells
-podocytes create slits
(Eckert
14-23)
Filtrate = protein-free and cell-free plasma
Glomerular Filtration Rate (GFR)
Humans: 125 ml/min or 180 L/day (60x plasma vol.)
37
38
Bowman’s capsule
proteins and
larger molecules
remain
About 20% of the plasma
and solutes that enter
glomerulus end up in BC
(Eckert 14-22)
39
7