11 Human Adaptations (Feb 4th) Flashcards
(1) Why is oxygen “reduced” at altitude and what historical evidence helped lead to this understanding?
Oxygen around 21% of air. High pressure, high oxygen density.
There is lower pressure at high altitude. Lower pressure= lower oxygen density at high elevation
Barometric pressure: higher elevation, decreased barometric pressure
Composition of air
Nitrogen 78%, oxygen 21%, argon 0.9, co2- 0.03%
(2) Describe the steps along the oxygen cascade and how oxygen moves from the air to the tissues that use it.
Oxygen moves from higher concentration to lower concentration- concentration gradient.
Diffusion principles
- Diffusion is inversely related to distance between two space (diffusion distance). Increased distance, oxygen moves more difficult. The alveoli and lung is only 1 cell think. Lung is designed to facilitate diffusion.
- Diffusion is primary influence by concentration gradient. Diffusion positively related to SA. Larger SA, easier diffusion. Lung designed optimally to do this. The SA of alveoli stretch out like a tennis court SA.
partial pressure
weight of oxygen as fraction of air.
Normal conditions- At sea level: 140-o2 partial pressure.
oxygen move
Oxygen moves from air to tissues: Lung moves oxygen in alveoli, alveoli to blood capillaries limited by diffusion.
Aka: ambient air (140 oxygen pp), alveolar gas (100), arterial blood (80)
A:Concentration gradient air to alveoli: mx gas in the lungs, oxygen leaving the lung into blood.
B: Concentration gradient from alveoli to blood smaller gradient, thus diffusion not limited
Blood: 55% plasma. Buffy coat leukocytes and platelets (less 1%). Erythrocytes 45%.
RBC aka erthyrocytes: ( make of hemoglobin ( 2 beta chain. 2 alpha chain, , and 4 02 binding heme group on each chain. )
Hemoglobin: high affinity for 02 therefore they are statured under normal conditions. 97% oxygen transported in blood by hemoglobin (3% dissolve in plasma)
• They love oxygen
C: tissue (alveolar gas) to atrial blood- oxygen go to cell and it is used up. Partial pressure is around 80%
(3) Give examples of adaptive processes important for acclimatization.
short term responses: when oxygen drops ( correction vs compensation)
correction: short term
compensation long term
- Correction: mechaims designed to counter drop in 02 availability.
• Carotid: on the neck, pheripheral chemoreceptor and the most perfused tissue in body. Adaptive responses to low oxygen and change blood oxygen.
It is perfused: it gets more blood than any organ in the body.
• Taking deeper breath: If we increase title volume: 150ml still constant for deadsapce, but the increase/ taking deeper breath increases what is going into the alveoli. Thus more efficient way of breathing is taking deeper breaths, not longer.
• Drug: acetazolamide increase oxygen saturation of hemoglobin.
I. Adaptations
• Ventilation: adaptive process to low oxygen volume initially panic and breath a lot, afterwards increase ventilation by taking deeper breaths to increase O2 in lungs.
• Increased heart rate: increases ventilation and oxygen enter lungs, pump more blood and RBC through lungs for increased ventilation-faster heart rate.
• Higher Cardiac output and stroke volume response due to ventilation increase. Cardiac output is the amount of blood pumped out of the heart (ventricles) to the body per minute, and stroke volume is the amount of blood pumped out of your heart with each heartbeat.
II. Retirbution of blood.
• shut down blood flow/ limited to other parts of the body. Focus on the brain.
• Blood vessel shrink: vasoconstriction
Long term responses for acclimatizing to alititude:
Compensation: mechanism designed to preserve function of critical organs
mechanism designed to preserve function of critical organs
i. Oxygen transport:
• At higher altitude: Blood is richer in oxygen and more blood pumped. Overtime this RBC increase occurs. – Time to acclimatization- complete acclimatization takes 11.5 days.
Hermatocite (amount of blood in RBC) increase
Concentration fo hemoglobin in RBC increase
Fluid volume decrease: blood thicker.
Recommendations for proper acclimatization:
• Take prophylactic drugs, no more than 500m sleeping elevation gain per day. Rest day for 1000m gained. Avoid resipatory depressant-alcohol. Don’t ascend and descend is symptoms persist.
(4) What are the common altitude illnesses and ways to prevent / treat them?
- Acute mountain sickness (ams
- High altitude pulmonary edema
- High altidude cerebral Edema
AMS
syndrome of symptoms occur above 2500m. indicate acclimatization is not working. ¼ develop AMS above 25000m.
• Lake Louise Score for diagnosis of AMS: First symptom is headache, must have it. Other symptoms: Headache, gastrointestinal symptom, fatigue and weakness, dizziness/ lightheadedness.
• Underlying cause not known, can’t predict who will develop it.
• Importance of ventaliation: study done with those that have AMS and those don’t. normal people breathing a lot more with better oxygen saturation. People who don’t breath will get AMS, due to less ventaliation.
High altitude pulmonary edema (HAPE):
over 2500m, prevalence 4%, life threatening.
• Hypoxia: blood pressure in lungs go up, high BP starts to leak fluid in lung. The lung is very think, distance for one cell to exnchage air with lung. Leaked fluid cause distance to increase for oxygen.
High altitude cerebral Edma (HACE)
- Hypoxia: defficieny in oxygen reaching tissues.
- Individual pump blood in brain and leaks fluid out of capillaires. Affect distance of oxygen moving to tissue.
- Symptom: slurring of speech, can’t walk in straight line. Descend to where oxygen is more available.
Treatment for failed acclimatization
- Acetazolamide- respiratory stimulant
- Nifedipine: vasodilator
- Sildenafil- vasodilator
- Dexamethasone- anti inflammatory, glucocorticoid.
Evangeslista Toreicelli
was an Italian physicist and mathematician, best known for his invention of the barometer. Measure vapour pressure for weather testing.
Balise Pascal
study of fluids, and clarified the concepts of pressure and vacuum by generalising the work of Evangelista Torricelli. Pascal also wrote in defence of the scientific method.
sherpa vs quechua people
- Nepal: Sherpa people reside altitude 25000yrs. Kown as the king of the mountains.
- The Quechua people: resided high altidude for 11000 yrs. Can develop chronic mountain sickeness. Portion of them become declimatized when they get older due to excess RBC-elevated Hemogolobin, less fluid plasma and thus blood is slongish
biodiversity
basically the variety within and among life forms on a site, ecosystem, or landscape. Biodiversity is defined and measured as an attribute that has two components — richness and evenness.
refugia
places that have maintained favorable conditions during periods of past. environmental change, often associated with periods of glaciation
• Ex: bellflowers speciation specifilaition associated with geopgrhaic isolation due ot production of various refugia.
endemic specie
Species that have evolved in isolation to inhabit specialized alpine environments. Ex: Banff springs snail
biodiversity hotspot
a biogeographic region with significant levels of biodiversity that is threatened with destruction. With high concentration of endemic species at rapid rates of loss. 35 hotpsot in world, half in mountain regions. Hotspot cover 2% of eath’s land but with half world’s endemic species. Human wiped out 60% of animal population since 1970
cryoconite holes
debris absorbing heat, microbes living in it produce heat and debris go down. Description. Cryoconite is powdery windblown dust made of a combination of small rock particles, soot and microbes which is deposited and builds up on snow, glaciers, or ice caps.
biofilm
is defined as a community of microorganisms attached to an inert or living surface by a self-produced polymeric matrix
high elevation ecosystem
tree-less ecosystem above the natural climatic forest limit (alpine and nival belts)
Plant forms for high elevation adaptation:
cushion plants
avoid wind and freezing. Genetically inherited not due to harsh conditions. Avoid wind and stay warm. Looks like umbrella. Can trap own dead mass to secure nutrients. Ex: Moss campion.
rosette form
looks like flower, leaves on the ground, trap solar energy and stay warm avoid wind as in colder temp soil is warner than air temp. ex: white mountain saxifrage.
graminoids
grass, tussock forming/ bunched grass. Advantage is that they have flexible stem and leaves for wind protection and microclimate regulation. Ex: evergreen sedge.
