Flashcards in Diving/Space/Altitude Deck (84):
What is the human free dive record?
What is the human breath hold record?
6 minutes 30 seconds
How fast does water pressure increase?
1 atmosphere for every 10 meters of depth
What is one issue with the high pressure of water, and how have animals adapted?
It makes it difficult to draw air through a snorkel because it is difficult to expand the chest. Elephants have adapted with fibrous, cartilaginous tissue rather than air in the interpleural space- this helps them to generate higher negative pressures.
When was the first commercial diving/salvage business set up?
Name three problems associated with human diving
1) The Bends
2) Rapture of the Deep (narcotic effect of gases)
3) Oxygen toxicity
How are the Bends caused?
With increased pressure, more nitrogen dissolves in the blood. When we ascend rapidly, nitrogen comes out of the blood quickly and forms bubbles. Can cause pain, stroke, and death.
At what depth does the Bends become an issue?
What is Rapture of the Deep and what causes it? How do we avoid it?
A narcotic effect of gasses. Nitrogen at high pressure has narcotic effects. Use a helium/ oxygen mix
What is oxygen toxicity?
Breathing pure oxygen irritates the lungs (can't do it for more than a few hours)
What is a nickname for the Bends?
What are three ways of avoiding the Bends?
1) Ascend slowly (in 20-30 minute stages)
2) Use an inert gas other than nitrogen (could use helium)
3) Breathe liquid?
What are antarctic seals called? Where do they live?
Weddell Seals. the Ross Ice Shelf
Describe the dive characteristics of a Weddell Seal (time and depth)
Most dives last 20-25 min (max 1 hr)
70% of dives are 200m or less, can hit 600m.
What is a seal that can dive deeper than a Weddell Seal? What is its longest and deepest dive?
Elephant Seal. Dives to 1000m, can dive for up to 2 hrs.
Why do most Weddell Seal dives last about 25 mins?
This is their AEROBIC DIVING LIMIT (ADL)
What happens after the aerobic diving limit is passed?
Blood lactate levels rise
What are the two things that we see happen in seals while diving? Be specific about location
Oxygen depletion and lactate accumulation occur in skeletal muscle, but not in the blood!
Do Weddell Seals alter blood flow to the kidney during dives? How can we tell experimentally?
Yes, they reduce blood flow to the kidney, but only on longer dives. We can test by measuring INULIN concentration!
Do Weddell Seals alter blood flow to the liver during dives? How can we tell experimentally?
They reduce blood flow a bit. We can tell by measuring INDOCYANIN GREEN clearance
What is a second way to test blood flow to the kidneys during a dive?
Simulate dive by putting head underwater, image blood flow using a dye.
What happens to a seal's heart beat during a dive? What do we call this?
It slows down.
What happens to blood co2 content and blood o2 content during a dive?
The co2 content rises, while the o2 content falls
What can we say about where oxygen is stored in diving animals (lungs, blood, muscle)
Roughly similar amount stored in lungs. Much more oxygen stored in blood and muscle though!
What are three cardiovascular adaptations common to diving animals?
1) large blood volume (2-7x greater)
2) high hematocrit (55-60%)
3) lots of myoglobin
What happens to the lungs at great depths?
The lungs and alveoli actually collapse, forcing air into the dead spaces, and making gas exchange negligible!
What do seals have to prevent heat loss?
An insulating layer of BLUBBER
What are two adaptations to the seals head area?
They are located on the top of the head, so that the seal can easily see the ice above.
Also, have protruding teeth to open diving holes in the winter!
What two organs do the seals maintain blood flow to? What three organs do they reduce blood flow to?
Heart and brain
Kidney, liver and muscles
Why do the seals reduce blood flow to the muscles?
To prevent lactate buildup in blood until post-dive
Name three ways in which seals avoid the Bends
1) EXHALE before diving
2) Lung collapse at 25-30 meters
3) Very little blood to lungs during dive
Name a large diving penguin. How long/deep can it dive
Emperor Penguin: 23 minutes, 500 meters deep
Name four adaptations that allow birds to dive
1) high HEMATOCRIT
2) high MYOGLOBIN concentration
3) diving BRADYCARDIA
4) limited blood flow to skeletal muscle (to avoid lactate buildup in blood)
What organs do the birds increase blood flow to? What do they decrease blood flow to?
Kidney, Intestine, Muscles (PERIPHERAL)
What is one adaptation to diving birds' brains?
Small cerebral O2 requirement
What happens to body temperature during diving?
Name three diving birds
Loons, Cormorants, Penguins, Puffins, Eiders, Murres
How tall is Mt. Everest (ft and meteres)
What bird migrates over Mt. Everest? How high does it reach?
Bar-headed goose (9500 m)
What is one high altitude mammal? How high up does it live?
the PIKA (6000 meters)
What are the highest elevations that humans live at?
What was human's first experience with really high altitudes?
In hot air balloons (1860s)
What is another term for mm Hg?
What is atmospheric pressure at sea level? How about at the top of Mt. Everest?
760 mm Hg
250 mm Hg
What percent of air is oxygen?
What is arterial saturation at sea level? How about at the top of Mt. Everest?
What height are most commericial flights at? How quickly would humans lose consciousness at that level?
Humans would go unconscious after 30 seconds
Describe the air flow though the avian lung. What does this allow for?
The air goes thorough the ANERTIOR AIR SACS, LUNG, and POSTERIOR AIR SACS. This allows for efficient gas exchange during both inhalation and exhalation.
What is another adaptation that helps birds be more efficient at gas exchange?
THINNER MEMBRANES, made possible by more SUPPORT for alveoli and pulmonary capillaries
What kind of exchanger are bird lungs?
CROSS CURRENT EXCHANGER
Name two cardiovascular adaptations that allow high altitude birds to tolerate low oxygen conditions
1) Proportionally larger hearts
2) Hemoglobin has a higher affinity for O2
What two things separate high altitude birds from humans at low co2 levels
1) Tolerant of respiratory alkalosis
2) Maintain normal blood flow to brain
What are the two main effects of low oxygen pressure in the human body? What is interesting about these two effects?
Chemoreceptors fire to increase ventilation, wihch decreases the arterial co2 pressure (Alkalosis) and should increase hemoglobin affinity. However, more 2,3-DPG is produced, which decreases hemoglobin affinity for O2. These are COMPETING EFFECTS.
What is alkalosis?
It is blood that is too basic
What signals for a higher hematocrit? Where is this produced?
ERYTHROPOIETIN, synthesized in kidney
What do we call it when people adapt to high altitude conditions over a period of weeks?
What are 8 changes that occur during acclimatization?
1) increase in ventilation (2-7x)
2) alkalosis from low pCO2
3) increased hematocrit (45% to 60%)
4) increased blood volume
5) increased lung volume
6) increased cardiac output (initially)
7) increased vascularity of peripheral tissues
8) increased efficiency of o2 use by tissues
How long does it take for the human hematocrit to increase from 45% to 60%?
What breathing pattern do we see at high elevations (name and description)? What causes this?
Rapid bursts of breathing activity because O2 levels are low, then inhibition of breathing because the increased ventilation leads to lower CO2 levels. Eventually fades after a couple of days.
What is a sickness that occurs if you ascend too rapidly. Describe the symptoms
ACUTE MOUNTAIN SICKNESS
- Feel euphoria, tiredness, dizziness nausea. Worst case can get PULMONARY EDEMA, where pulmonary arterioles vasoconstrict, which leads to hypertension and leaks in lung capillaries, and you can actually drown in fluid
What is a sickness associated with long periods at high altitude, describe
CHRONIC MOUNTAIN SICKNESS
Hypoventilation, hypertension, heart hypertrophy, headaches, diziness
What is a disorder involving high hematocrit?
What is a disorder involving blue tinted skin?
What are three pulmonary/cardiovascular adaptations in people living at high altitudes?
1) Pulmonary hypertension (elevated pressure due to vasoconstriction b/c low o2)
2) Increased muscle in pulmonary arteries
3) Cardiac hypertrophy
4) Elevated hematocrit
5) Higher hemoglobin affinity for o2
What two physical adaptations can we see in high elevation populations?
Smaller body size, increased chest size
What is one interesting difference between Tibetan and Andeans?
Tibetans don't have higher hemoglobin levels, but Andeans do!
What transcription factor do Tibetans have? What is its purpose?
HIF (hypoxia inducible factor). It regulates genes involved in red blood cell production. Interestingly HIF reduces red blood cell produciton, so that it avoids extra work on the Tibetan's hearts!
What is the term for red blood cell production?
What is the highest a human has ever free fallen?
What is the elevation at which blood will boil?
What are five physiological stresses humans would experience in space?
1) No atmosphere
2) Fluid/mineral homeostasis
3) No gravity (if in free fall)
How cold is space?
-270 degrees C
What happens to fluids when in low gravity? How does the boy react?
Move from legs to chest and head. Reacts with increased urination and decreased water intake
What happens to red blood cell production and cardiac output?
What do astronauts have trouble doing when they first get back to earth?
Standing (orthostatic intolerance)
What happens to muscle and bone density in space?
Muscles atrophy, bones become less dense.
What happens to height in space?
People get taller
Why do we lose bone mass?
DIMINISHED OSTEOBLAST ACTIVITY
What happens to the risk of kidney stones, why?
Increased risk of kidney stones due to Ca concentration in urine from bone breakdown
What happens to sacromere length and myofibril diameter?
Sacromere length is normal, but myofibril diameter is smaller
What is responsible four our balance?
the VESTIBULAR SYSTEM
What are the three bumps called in the vestibular system? What does each respond to? What is inside these swellings?
Ampullae (x3) (rotational acceleration)
Utricle (verticle movement)
Saccule (horizontal movement)
What two changes do we see having to do with orientaion?
1) changes in vestibular system function
2) altered activity in hippocampus