Respiratory and circulatory Flashcards
problems of aquatic environment with gas exchange
- O2 low solubility in water
- (Blood has hemoglobin to help)
- increase temperature, decrease amount of O2
- saltwater holds less O2
- partial pressure– O2can have higher partial pressure in water than in air, so leaves
- more photosynthesizers–more o2
- currents mix oxegen
- depth–shallow have more 02 b.c high sa/v ratio
- rapids–splashing oxegenates water
Diffusion is insufficient for
supplying large active animals with O2 and nutrients.
- Fick’s law
- high rates of diffusion when
- A is large
- D is small
- P2-P1 is large
gills
- present a large surface area for diffusing
- countercurrent
- most of the oxygen in the incoming water has diffused into the blood
- makes fish gills efficient at extracting oxygen because it ensures a difference in partial pressure of oxygen and co2
how do vertebrates ventilate
- actively ventilate by pumpaing air via muscular contractions
- negative pressure ventilation
- diaphram creates a lower pressure within the chest cavity and causes air to flow in
cooperative binding
- binding of each successive O molecule to a subnit of hemoglobin causes conformational change in the protein that makes the remaining subunits more likely to bind to oxygen
- makes hemoglobin sensitive to changes of the PO2 in tissues
bohr shift
- decreases in pH alter hemoglobins conformation, making hemoglobin more likely to unload O2
- makes hemoglobin more likely to release oxygen during exercise where ph is high
maternal vs fetal hemoglobin
- fetal hemoglobin binds to O2 more tightly
- maternal hemoglobin facilitates transfer from mother to fetus
CO2 transfer
co2 produced by cellular respiration enters blood and reacts w/ water to form carbonic acid, dissociates into bicarbonate and H+
carbonic anhydrase
- catalyzes formation of co2 in water
- Important b/c
- protons produced by the reaction induce the bohr shift
- partial pressure of co2 drops when converted to bicarbionate ions, making a pressure gradient favoring the entryof co2 into blood
- makes CO2 uptake from tissues more efficient
most co2 is transfered in the blood as
bicarbonate
how is hemoglobin a buffer
when carbonic acid dissociates and the pH lowers, hemoglobin releases its O2 and has an affinity for protons
systematic gas exchange
- tissue fluid contains CO2
- CO2 diffuses into bloodstream
- forms into H+ and HCO3- from carbonic anhydrase
- blood ph falls, hemoglobin releases O2, H+ stick to hemoglobin and carbon dissolves to plasma as HCO3-
open circulatory system
hemolymph comes in direct contact with tissues, so molecules don’t have to diffuse across a wall of a vessel
closed circulatory system
blood flows in continuous circuit through body under pressure generated by the heart
