Ch. 13 Regulation of Gas Transfer Flashcards
the rate of blood perfusion of the respiratory surface is related to ….
the requirements of the tissues for gas transfer
the amount of O2 delivered to the respiratory surface must equal …
the amount taken away from the blood
the ventilation to perfusion ratio in humans is
1 b/c the O2 contnet of blood is approximately that of air
the ventilation to perfusion ratio in fish is
10:1 to 20:1
water over gills:blood over gills
to compensate for a decrease in PO2 in air or water…
ventilation increases
and vice versa
why can the pattern of capillary blood flow change in gills and lungs
maintain equal blood and inhalent flow over the respiratory surface
how does hypoxic vasoconstriction of blood vessels in the lung help to maintain an ideal ventilation to perfusion ratio?
low alveolar O2 level causes vasoconstriction so blood doesnt flow to this area of the respiratory surface
neuronal regulatuion of breathing 2 types
pattern generator
rhythm generator
pattern generator
sets depth and amplitude of each breath
rhythm generator
controls breathing frequency
pre-Botzinger complex in brain stem
medullary respiratory center
sends signals to spinal motor neurons that control the diaphragm and intercostal muscles
Hering-Breuer reflex
reflex to prevent overinflation of the lungs
pulmonary stretch receptors sense over-stretching during large breaths and inhibit the vagus nerve
phrenic nerve
affects diaphragm via inspiratory neuronal activity
inspiratory neuronal activity
controls muscles of inspiration
amphibian and reptile episodic breathing
intrinsic property of brainstem
fluxes in O2 and CO2 levels in animals lead to ______ changes in ventilation
reflex
two types of receptors that affect rate and depth of breathing
carotid bodies
aortic bodies
carotid bodies and aortic bodies are ____________ that measure changes in __ and ____
chemoreceptors, O2, CO2, and pH
“central” chemoreceptors CSF
in medulla
respond to decreases in pH of CSF (high CO2) detect H+
accurate b/c no buffer system in CSF
peipheral chemoreceptors monitor
arterial blood
do peripheral chemoreceptors react to high CO2 or low pH
they think low pH, not the actual CO2 level
carotid body chemoreceptors respond greater to…
pH/CO2 changes
leads to inc ventilation via medullary resp center
increases in _____________ and _______ can also stimulate carotid chemoreceptors, and stimulation of the carotid nerve causes release of _____
temperature, osmolarity, ADH
in mammals does CO2 or O2 dominate breathing rate
CO2
in aquatic vertebrates does CO2 or O2 dominate breathing rate and why
O2
O2 is limiting in water b/c less soluble and concentration fluctuates a lot more
fish exposed to high O2…
reduce breathing until there is a high PCO2 in blood
CO2 effect on mammal pulmonary stretch receptors
reduces their inhibitory effect to increase depth of breathing and lung ventilation
lung irritant receptors
stimulation by mucous or dust causes bronchioconstriction and coughing
type J receptors in the lungs
stimulation causes a feeling of breathlessness
responds to increased interstitial fluid (pulmonary edema)
hypoxia definition
reduced oxygen levels
fish exposed to hypoxia do what
stop feeding and inhibit protein metabolism (growth is impaired)
stop breeding
swim less
move to cooler water (lower temp reduces metabolism)
in general, animals reduce ______ expenditure and use _________ metabolic pathways to survive hypoxia
energy, anaerobic
what 2 systems do animals adjust to survive hypoxia
respiratory
cardiovascular
ex. fish increase gill ventilation and ram-ventilated fish open mouth gap wider
high altitudes are associated with lower…
temperatures and pressures
acute altitude sickness symptoms
fatigue
headache
dizziness, nausea
insomnia
chronic altitue sickness
memory loss
confusion
mountain sickness is common in _________ populations but not _________
Andean, Tibetans
decrease in blood PCO2 and resultant increase in CSF pH does what to ventilation, and what happens at high altitude
reduces it
blood and CSF pH returned to normal after days-1wk by excretion of bicarbonate…gradual increase in ventilation
cardiovascular effects of high altitude
increase in CO, then 1/3 increase in blood volume
vasodilation
humans living at altitude usually have ______ bodies and _______ lungs
small, normal
most vertebrates respond to altitude with ________ RBC, and blood hemoglobin
increased (improve O2 carrying capacity)
triggered by reduced blood O2 –> EPO from kidney/liver
Andean adaptations
inc RBC + Hb
many unsaturated RBC –> viscous blood
More O2 attached to Hb
Tibetan adaptations
Breathe more air and faster (larger lung volume)
low O2 saturation
240x NO levels –> vasodilation (more flow)
Kenyan adaptations
increased O2 transfer from alveoli to blood
HIF-1
stimulate EPO
stim vascular endothelial growth factor (VEGF) –> capillary growth for inc flow
what 3 places do diving animals store O2
blood
lungs
tissues
diving animals have high levels of
Hb and myoglobin
during a dive, where is O2 preferentially delivered
brain
heart
during a prolonged dive what happens to heart rate and CO
heart rate slows (bradycardia)
lower CO
why must air-breathing animals have enough O2 stores during a dive and metabolism reduced
support aerobic metabolism b/c they can’t handle the lactic acid production from anaerobic metabolism
why do some animals exhale before diving to reduce O2 stores in lungs and compress the lungs
air stored in trachea and bronchi which are more rigid than alveoli
this is so rapid ascent doesn’t cause formation of bubbles in the blood (which would happen if air was in alveoli cause they would be compressed on ascent)
where are receptors that detect presence of water and inhibit inspiration during a dive
near the glottis
near the mouth or nose
mammals during birth
move from an aqueous environment to air
short period of anoxia from stopping of placental circulation and 1st breath of air
behaves like a diving animal during this time
what is symmorphosis
we are designed so function doesn’t exceed our requirements
ex. gas transfer systems
fish are denser than surrounding water and must do what to maintain position
swimming and using fins –> costs energy
solution: buoyancy device
3 ways aquatic animals maintain neutral buoyancy
swimbladder
large lipid bilayers
ammonium chloide
what does it mean that a swim bladder is compressible
volume changes with depth and therefore so does the buoyancy of the animal
hydrostatic pressure increases by _atm for every depth of __m
1atm, 10m
when a fish on the surface dives to 10m…
pressure in swim bladder goes from 1atm to 2atm
volume reduced by 1/2 and density of the fish increases –> sinking
problem with swim bladder instability
volume changes is potentially dangerous
solution: adding or removing gas into the bladder during descent or ascent to maintain volume
why doesnt gas partial pressure or gas in water vary with depth
water is incompressible
what kind of gas is in a swim bladder
usually O2 but sometimes N2
if a fish dives to a depth of 100m, does O2 need to be added or removed to maintain buoyancy
added
supplied from environment against a pressure difference (bladder 10atm, water 0.228 atm)
structure of a swim bladder
tough wall impermeable to gas but slow leak out at inc depth
easily expanded if pressure inside > pressure outside
rete mirabile
present in fish that can move O2 into the bladder vs. a high pressure gradient
bundles of capillaries arranged for countercurrent flow btw arterial and venous blood
what happens btw a rete and gas gland (secretory epithelium in swim bladder)
blood passes through arterial capillaries of rete
goes to secretory epithelium in swim bladder wall
then back through venous capillaries to liver
in the rete, arterial and venous blood are separated by a large or small distance
very small… 1.5micrometers
what does rete structure allow
blood to flow into the swimbladder wall without loss of gas
how is O2 secreted into the swim bladder (low mitochondria is gas gland cells so glycolysis)
gas-gland cells make CO2 and H+ that lower pH so O2 is released by Hg (root-off effect)
also causes increase in ionic concentration –> reduce O2 solubility
therefore PO2 in gas gland > than swim badder so O2 diffuses from blood into the bladder
what molecule transfers drop in pH in rete to RBC
CO2 b/c RBC impermeable to H+
blood leaving gas gland to venous capillaries high in CO2
arterial (afferent) rete to venous rete steps
H+ produced by gas gland and CO2 diffuses from venous (efferent) rete
low pH from CO2 causes O2 release from Hb causing local high pO2 and O2 into swim bladder
when venous CO2 flows into afferent, pH raises and Hb picks up O2 again causing low pO2 (root-on)
EPAS1 gene of Tibetans
Prevents overproduction of RBC
