Ch. 24 - Gas Transport

Front 1

Henry's Law

Back 1

- solubility of gas depends on its partial pressure above the solution
- partial pressure of a gas in solution is equal to partial pressure of that gas in gas phase with which the solution is in equilibrium
- amount of dissolved gas dependent directly on partial pressure because blood temperature constant
- at equilibrium plasma and alveolar PO2 is 100 mmHg
- at 37C, plasma will contain about 0.3 mL O2/100 mL of fluid

Front 2

oxygen dissolved

Back 2

- can't dissolve enough oxygen in blood
- pigments help with this

Front 3

four chemical categories of respiratory pigments

Back 3

- hemoglobin
- hemocyanin
- hemerythrin
- chlorocruorin

Front 4

hemocyanin

Back 4

- second most common of respiratory pigments in animals
- no heme iron or porphyrin ring
- copper binds directly to protein
- contain copper
- mostly clear but turn bright blue when oxygenated
- always dissolved in blood plasma/hemolymph
- multiple subunits

Front 5

two types of hemocyanin

Back 5

- arthropod hemocyanin: crabs, lobsters, crayfish, horseshoe crabs, spiders and some other arthropods
- mollusk hemocyanin: squids, octopus, many snails, and some other mollusks

Front 6

chlorocruorins

Back 6

- close chemical similarities to hemoglobin
- iron porphyrin ring but differ in heme
- sometimes called green hemoglobin
- only in four families of marine annelid worms
- always dissolved in blood plasma
- heme like group

Front 7

hemerythrins

Back 7

- non-heme iron containing respiratory pigments
- located intracellularly in blood or coelomic cells
- oxygen binding site is binuclear iron center
- iron atoms are coordinated to protein through the carboxylate side chains of glutamate and asparate, and five histidine residues
- colorless when deoxygenated but reddish violet when oxygenated
- heme like group: 2 irons

Front 8

myoglobin

Back 8

- single-chain globular protein of 153 amino acids
- contain a heme
- primary oxygen-carrying pigment of muscle tissues
- doesn't exhibit cooperative binding oxygen
- binding of oxygen is unaffected by oxygen pressure in surrounding tissue
- often cited as having "instant binding tenacity" to oxygen
- hyperbolic oxygen dissociation curve
- higher affinity for oxygen
- doesn't have to change its shape

Front 9

hemoglobin

Back 9

- most widespread respiratory pigment
- multiple forms of hemoglobin differ not in heme but in globin portion
- protein portion changes through lifetime
- 4 polypeptides
- 2 alpha ad 2 beta chains
- each chain has a heme group

Front 10

human developmental changes

Back 10

- change in types of globin synthesized for blood hemoglobins

Front 11

animal size and O2 affinity

Back 11

- smaller bodies species tend to exhibit lower oxygen affinity and thus higher P50 than larger bodied ones
-maybe due to relationship between weight specific metabolic rated and body size
- lower affinity Hg in smaller species unload oxygen to tissues more readily due to lower affinity
- higher the P50, the lower the affinity

Front 12

factors affecting loading and unloading to hemoglobin

Back 12

- cooperativity
- pH effects
- haldane
- temperature
- 2,3 DPG

Front 13

oxygen equilibrium curve

Back 13

- 4 polypeptides of oxygen bind at different rates
- diosteric change from binding of 1 allows for 2 and 3 to bind faster
- 2 and 3 binding help the 4
- total saturation include Hg and plasma
- plateau means there is wide range of blood oxygen partial pressures that is sufficient to saturate blood hemoglobin

Front 14

oxygen delivery by human blood at rest and during exercise

Back 14

- O2 released to tissues by each 100 mL of blood
- drop in blood [O2] as it passes through tissues
- deoxygenation in tissues is increased
- as O2 partial pressure of blood falls, less of a drop is required to cause unloading of 5% vol O2

Front 15

loading and unloading are cooperative

Back 15

- shape of oxygen equilibrium curve depends on oxygen binding site cooperativity

Front 16

- O2 affinity of hemoglobin

Back 16

- decrease can aid O2 delivery to systemic tissues
- reduced affinity shows decrease in percent saturation

Front 17

Bohr effect

Back 17

- CO2 blown off as you move away from lungs
- more CO2 in tissue
- more basic = higher affinity
- more acidic = lower affinity
- tissue has lower pH then lungs
- tissues experience a lower affinity
- typically enhances O2 delivery
- oxygen unloading is greatest

Front 18

shift to right in oxygen equilibrium curve

Back 18

- reflects a decrease in O2 affinity
- oxygen partial pressure needed to saturate is higher
- P50 is higher

Front 19

root effect

Back 19

- up or down affect
- maximum saturation you can get due to pH
- used to inflate swim bladders
- lactate acid can change pH
- lowered pH and increased CO2 decrease O2 carrying capacity
- acidification lowers oxygen-carrying capacity of hemoglobin

Front 20

temperature

Back 20

- cause right to left shift, up and down shift
- lower affinity for oxygen at higher temperatures
- increase in temperature typically causes a decrease in O2 affinity

Front 21

2,3 - DPG

Back 21

- normal p50 of human hemoglobin within RBC depends on normal intracellular concentration of 2,3-DPG

Front 22

concentrations of specific inorganic ions

Back 22

- can allosterically modulate O2 affinity
- Cl- hemoglobin
- bicarbonate (HCO3-) in crocodilians
- Ca2+ and Mg2+ in hemocyanin

Front 23

fetal hemoglobin

Back 23

- higher affinity than maternal
- can't bind to 2,3-DPG
- loads in fetal and unloads in maternal

Front 24

CO2 transport

Back 24

- most CO2 in blood is in form of bicarbonate
- extent of bicarbonate formation depends on blood buffers
- blood of mammals effective in buffering H+ generation from CO2
- buffer groups on hemoglobin are major buffers
- terminal amino group and imidazole groups found where histadine occurs

Front 25

imidazole groups

Back 25

- dominate buffer
- very efficient
- allow large amounts of CO2 to be transported

Front 26

haldane effect

Back 26

- deoxygenation promotes CO2 uptake by blood
- oxygenation promotes CO2 unloading
- enhances CO2 transport by Hg
- promote uptake in tissues and release in lungs
- add oxygen to become more acidic
- add CO2 to become more acidic

Front 27

normal blood pH

Back 27

- temperature dependent variable
- higher the temperature = lower the pH

Front 28

fluctuation ins [H+]

Back 28

- profound effects on body chemistry
- excitability of nerve and muscle cells
- depresses CNS
- increases levels cause over-excitability and muscle spams
- enzyme activity
- allosteric changes
- renal tubules secrete H+ and K+, usually more K+ but opposite when [H+] increased
- increase in [K+] alters cardiac function

Front 29

chemical buffers

Back 29

- act as first line of defense agains changes in [H+]

Front 30

4 buffer systems in human body

Back 30

- H2CO3: HCO3 system = extracellular
- protein buffer system = intracellular
- hemoglobin buffer system = generated from carbonic acid
- phosphate buffer system = urinary buffer

Front 31

respiratory system

Back 31

- regulates [H+] by controlling rate of CO2 removal from plasma
- adjust pulmonary ventilation
- eliminates metabolically produced CO2 so the H2CO3 doesn't accumulate in body

Front 32

kidneys

Back 32

- third and most powerful line of defense agains shifts in [H+]
- eliminate H+
- regulate HCO3-
- during acidosis is secretes H+ and adds HCO3- to blood
- during alkalosis it conserves H+ and eliminates HCO3-

Front 33

4 types of acid base imbalances

Back 33

- respiratory acidosis
- respiratory alkalosis
- metabolic acidosis
- metabolic alkalosis

Front 34

respiratory acidosis

Back 34

- abnormal CO2 retention
- hypo-ventilation
- lung disease like COPD
- anesthesia and drugs
- nerve or muscle disorders that reduce efficiency of respiratory muscles
- holding ones breath

Front 35

respiratory alkalosis

Back 35

- excessive loss of CO2
- fever
- aspirin poisoning that stimulate ventilation
- hyperventilation

Front 36

metabolic acidosis

Back 36

- reduction in plasma [HCO3-]
- severe diarrhea
- diabetes mellitus
- strenuous exercise
- sever renal failure

Front 37

metabolic alkalosis

Back 37

- vomiting
- ingestion of alkaline drugs or substances like baking soda