A.Physical constraints on gas exchange: partial pressure of gassses – pressure exerted by a particular gas in a mix of gases
21% O2 P02=760mm Hg*.21 = 159.6 mm Hg
B. Respiratory medium
1. air : 21% 02, low density, low viscosity, easy to move over a surface and thru vessels 2. water: 4-8ml 02/L, 02 solubility decreased by higher temp and higher salt conc., water dense, viscous, more work to move over surface
C. Diffusion rates
– all 02 and C02 exchange occurs by diffusion
– Fick’s law of diffusion
Qs= DA C2-C1/x *t
Qs= quantity of substance
d= diffusion constant, A= area of surface, C2-C1 conc gradient , x=thickness of surface, t = time Characteristics of respiratory membranes
– large surface area (A)
– large concentration difference (c2-c1)
-thin(small x)
II. Respiratory surfaces
A. Body surface
– amphibians, earthworms
B. Specialized surface
-must be ventilated : respiratory medium moved across surface – maintains high C2-C1
I. Aquatic animals
– gills-projections of body surface
Counter current flow in fish gills
– fig 42.23, blood flow thru and water flow over gill filament is counter current, maximized o2 exchange 2.Terrestrial animals
The Essay on Gas Diffusion
OBJECTIVES: Determine the gas diffusion coefficient of acetone using the established Winkelmann’s method KEYWORDS Diffusivity, Gas Diffusion Coefficient, Winkelmann’s method OVERVIEW The knowledge of physical and chemical properties of certain materials is important because very often process engineering deal with the transformation and distribution of these materials in bulk. One such property is ...
a.insects- branching system of air tubules, all body cells w/i diffusion distance tracheole end b. mammals,birds,reptiles lungs: branching system of air tubules, ends in alveoli=air sacs of surrounded by capillaries -alveoli are site of gas exchange
III. Respiratory pigments
A. Structure: metalloproteins that increase solubility of O2 in blood, hemocyanin: metal = Cu, arthropods hemoglobin – metal = Fe, vertebrates, most invertebrates Hemoglobin
– 4 subunits, proteins with quaternary structure, each contains Fe and bins (1) O2 B.Properties
1. Cooperativity – (1) O2 binds, Hb molecule changes shape, easier for 2nd,3rd,4th,02 molecs to bind % saturation of Hb with 02- 25% saturation=25% of 02 binding sites in a hemoglobin solution are occupied x axis- P02 (mm Hg)
y axis- % saturation of Hb with O2
graph goes up and curves off at the end like an (S) shape fig 42.31
2. pH sensitivity: Bohr effect
-pH affects O2 affinity of Hb
lower ph decreases Hb O2 affinity
Significance of pH sensitivity
* RBC pH decreases in capillaries supplying body tissues
* co2 +h2o = H2CO3 = HCO23- + H+
* H+ binds to Hb, changing its shape so 02 is relased and diffuses * in lungs O2 diffuses into RBC
* High O2 displaces H+ from Hb
CO2 diffuses out of RBC and into alveoli
*
CH.44- Osmoregulation
– controlling solute conc and water gain/loss from body fluids A. Purpose
– Cell fxn requries specific, stable solute conc.
B. Osmolarity
– moles solute/L
– units: mOs m/L
C. Osmotic challenges
1. Conformers & regulators
x axis= external mOsm/L
y axis = internal mOsm/L
2. Marine animals
a.Shark
– body fluid (salt) < seawater
– body fluid osmolarity = 1000 mOsm
– high (urea) and (trimethylamine oxide)
– no water loss
