Zool 241 final Flashcards
Diving Duration Frequency
It’s energetically costly and painful to dive for a long period of time. It must be worth the cost!
Hemoglobin
Heme: an organic ring containing an iron molecule, which can bind to O2 Within red blood cells (RBC)
Hemoglobin-O2 Equilibrium Curve
P50 is like Km for enzymes! It shows binding affinity for O2
Diving in mamals aerobic or anaerobic
Dive is aerobic because lactic acid is constant. After the dive, lactic acid washout- deal with consequences of being underwater
Spike in lactic acid
Spike in lactic acid after dive- EPOC, INCURRING AN OXYGEN DEBT DUING DIVE AND DEAL WITH REPRUCCUSSIONS AFTER dive.
Bradycardia
A near instantaneous reduction in HR (bradycardia)
Grey seal HR on land
119beats/min
Why is this drop in heart rate important?
minimize use of oxygen, metabolic rate, not wasting energy transferring blood throughout the body -Oxygen is restricted to where its needed most -BRAIN oxygen is not restricted during dive. CANNOT CUT OFF OXYGEN AND ENERGY SUPPLIES. Chronic tissue damage occurs very fast, have to keep glucose in the brain - Others not as crucial, have some oxygen to keep them alive - Only need brain and muscles for movement - Lungs not as necessary- collapse of lungs further restrict amount of oxygen
Why not storing oxygen in the lungs?
For humans, we have to transport oxygen to the muscles which takes a faster heart rate. Diving ANIMALS already store oxygen in muscles and blood, so can keep bradycardia and dive longer
Myoglobin
P50 is lower than hemoglobin System has to be severely oxygen derived before myoglobin releases oxygen Constant, supplies at a moderate rate, supply of oxygen- beneficial for hypoxic environment Diving have lots of myoglobin- store a lot of oxygen in muscle, have lower heart rate
Spleen stores…
storage sites for RBC
Spleen acts as a ____ ______.
Acting as scuba tanks, provide more oxygenated blood to diving animals
relationship between norepinephrine and spleen thickness
-More time spent in the water- more norepinephrine- reduces spleen thickness (inverse relationship)
Why don’t you just store all RBC in the blood?
-You would need a faster heart rate -If all RBC in blood, Viscosity of blood will increase, more energy required to move blood around, cannot be bradycardia -So store RBC in the spleen, transports blood more efficiently
Preventing the bends in diving mammals
-When you resurface quickly, pressure goes down suddenly, components of nitrogen will bubble in your blood Diving mammals: They allow lungs to collapse, air is trapped in trachea, bronchus and bronchioles -Prevents oxygen from forcibly mixing with blood, slows buildup of pressure, helps prevent the bends.
Antioxidant radicals when resurfacing
Diving increase radicals after resurfacing -By-product of aerobic metabolism during EPOC for diving animals -Radicals will increase in this process -Enzymes to the rescue: antioxidant enzymes help with these problems so they can dive deeper
Solution to antioxidant radicals
- Enzymes to the rescue: antioxidant enzymes help with these problems so they can dive deeper
Why dive deeper?
More access to food Less predators in deeper water
Myoglobin found in what tissue
muscle tissue
Myoglobin in diving mammals is a ___ relationship whereas in humans, it is _____ more dive duration- ____ myoglobin concentration
linear hyperbolic
Peripheral vasoconstriction _____ oxygen transport, causing muscle tissue to become ______ thus decreasing P50 of oxygen in the muscle, then
decreases hypoxic Mb will give up bound oxygen supplying the muscle oxygen for aerobic metabolism
Myoglobin has ____ oxygen affinity comapred to hemoglobin, THUS HOLDS _____ to oxygen until it reaches ____-
higher affinity to oxygen compared to hemoglobin hold on to oxygen tightly until it reaches hypoxia
what are the 4 response causes of diving?
bradycardia(decreased heart rate) Apnea Peripheral vasoconstriction Lactic acid washout
Peripheral vasoconstriction definition and maintains flood flow to 3 areas
during diving, there is a large decrease in blood flow to peripheral tissues ****maintains blood flow to heart brain and adrenals
bradycardia is ___ of resting heart rate
1/10 or 10%
Lactic acid increases upon submergence - forced dive
Dives were first considered to be anaerobic- evidence was a lactic acid washout but NO Only forced dives had lactate washout Forced submergence- stress response, primitive response to asphyxiation
ADL stands for ____ ____ _____ and Definition
Aerobic Dive Limit Maximum breath-hold that is possible without any increase in blood lactate during or after a dive indicating aerobic metabolism
Voluntary dives
majority of voluntary dives in seals are entirely aerobic, did not generate lactate
Dives exceed ADL, (long dives)
they performed anerobic metabolism and started to generate lactate features: -longer between dive recovery times -lactate washout
Dives within ADL are advantageous
because they minimize time of recovery maximize foraging time
Voluntary Dives
Dive response is less pronounced most dives are within the ADL Organs continue to function physiological homeostasis is maintained
Why is Hypometabolism in dives that exceed ADL lower than expected?
- suppression of metabolism to limit lactate production
Hypothermia in diving penguins and diving seals why?
certain body regions are intentionally cooled during a dive decrease oxygen demand by decreasing temperature
Summary Forced versus Voluntary Dives
-Bradycardia was not as pronounced in voluntary dives -Peripheral vasoconstriction was present in both forced and voluntary dives -Lactic acid washout was present in forced dives but only present in voluntary dives that surpassed the ADL
Physiological Challenges of Diving
-Temperature -Hypoxia -Build-up of metabolic wastes -Increased pressure at depth -Increased solubility of gases -Isolation from oxygen source due to breath-hold
RETIA MIRABILIA- cardiovascular adjustments
- a system of closely-aligned blood vessels that allow the animal to trap oxygen via countercurrent exchange Bradycardia and peripheral vasoconstriction together result in significant decrease in blood tissue to the tissues
Diving mammals store most of oxygen in ___ and ___
blood and muscle, very little in respiratory (lungs)
myglobin desaturation, a ____ not a ____. Thus, it _____ releases oxygen from muscle stores
linear not a hyperbolic desaturation slowly
Myglobin as a ____ store Greater myglobin concentration is associated with ____ aerobic capacity
energy supplying the diving animal with a source of fuel for aerobic metabolism increases dive duration - greater
Epaxial muscles of the harbor seal
Type I (slow twich oxidative lipds for ATP production) and Type IIa (fast twich oxidative but with enhanced anaerobic) DIVING MAMMALS lost Type IIB (fast twich glycolytic- glucose for anaerobic ATP)
Swimming Behavior
- During deep dives seals sink rather than propel themselves downwards (up to 90% of the time they are gliding rather than actively swimming)
Why diving mammals sink during diving?
-This has a clear advantage in terms of energetic costs and conservation of oxygen -This behaviour is more prevalent during times where the animal has smaller fat deposits, and is therefore less buoyant
Hematocrit
ratio of volume of RBC to total volume of blood increases viscosity of blood
Norepinephrine Epinephrine
drops heart rate, increases vasoconstruction increases heart rate decreases vasoconstruction During dive, norepinephrine happens
catecholamine regulation
regulates HR and vasoconstriction
Bajou indigenous people and hematocrit
optimize blood O2 store higher hematocrit
Habour seal vs Dog capillary density
harbour seal- 60% reduction in capillary density
Oxygen concentration and Lactic acid concentration in muscle and blood
Notice that within the first 5-10 minutes, all of the O2 in the muscles were used up, while we see arterial blood O2 is still high and only is low after 20 or so minutes Once muscle O2 are used up, they undergo anaerobic metabolism producing lactic acid
•Why does arterial blood oxygen content decrease more gradually?
Because muscle not perfused with blood, O2 can’t move from blood to muscle, instead muscles use up O2 within itself and it’s drained quickly.
•what is ADL?
longest time one can dive without running out of O2 (aka. when blood [lactate] increases)
•Why does [lactic acid] stay low in the blood?
Because blood moves to only to a few places (brain, heart, lung), arterial blood PO2 drops much slowly and lactic acid build ups is a lot slower
What happens to lactate after a dive?
Vasoconstriction stops when dive is completed, and lactate within muscle release into blood to become metabolized once they resurface following concentration gradient (so initially there is a rise in lactate in blood while lactate in skeletal muscle decreases).
what happens in alveoli collapse?
- Air is pushed into non-respiratory bronchioles, bronchi and trachea
- Gas exchange between lungs and blood can’t occur
- Good because minimizes O2 depletion and N2 can’t enter blood (prevents bends)
Recall air is mainly made up of N2 and causes bends during diving
Insulation
Lateral rete mirabele
as venous blood goes outward from red swimming muscle, it loses heat to the close arterial blood, which carries heat back into the red swimming muscles.
***red muscles produce heat in tuna
