Animal - Section C - Diving Flashcards
What is the Arapaima gigas?
An amazonian fish that will drown in around 10 mins
if denied access to the water surface.
It has a swimbladder modified for breathing air and its gills are completely non-functional for aquatic respiration.
Amphibian circulation consists of a three-chambered heart.
Oxygenated and deoxygenated blood are kept seperate by a spiral valve in the conus arteriosus.
Oxygen saturation is around 86% in the aorta and only 47% in the pulmocutaneous.
Blood flow is shunted between lungs or skin in the pulmocutaneous circuit depending on aquatic oxygen tension.
In hypoxic water, blood flow to the skin is shut off to reduce loss to the water.
Diving in Marine Iguanas
- Iguanas are Poi-kilo-thermic
- Animals undergo a cyclical pattern of dives interspered with periods of sun basking on shore.
During dives
-Peripheral vasoconstriction
Reduces heat loss to water and oxygenates vital organs
Reduces aerobic metabolism in swimming muscles
-Bradychardia
Reduced metabolic cost
The heart of a crocodile is almost completely divided except for the _______ of _______ between the left and right aortae.
The foramen of Panizza (named for anatomist Bartolomeo Panizza) is a hole that connects the left and right aorta as they leave the heart of all animals of the order Crocodilia.
When the crocodile is breathing air, greater pressure in the ____ ventricle forces the _____ ventricular semilunar valve closed.
Deoxygenated blood is diverted to the _____
Oxygenated blood shunts from the ________ through the ______ on _____ to the _______
in the left ventricle
forces the right ventricular semilunar valve closed
diverted to the lungs
Oxygenated blood shunts from the left (right aorta) through the Foramen on Panizza to the right (left aorta)
Improving diving is about improving oxygen storage
Increasing lung volume mostly increases nitrogen storage
It is much more efficent to increase 02 by?
- Increasing red blood cell mass
- Increasing blood volume (doping)
- Increasing spleen storage capacity
Increasing O2 storage on myoglobin in muscles
(Storing oxygen not nirogen)
Mammalian divers discovered in 2013 that their myoglobin..
..carries a net positive surface charge that allows these animals to accumulate very large concentrations of myoglobin in their muscles. This surface charge causes electrostatic repulsion that prevents myoglobin molecules sticking together.
Yellow fin tuna
Food down at 250m, why not just stay there?
- Yellowfin tuna is tropical species
- Dives down to 1200m
- Water 28oc at surface (warm)
- 1000m down temp is 5oc
- Fish is warm bodied, can maintain muscle temperature well
- Tunas heart is close to surface of body (chest outside wall)
- When fish gets to 5oc water, muscles stay warm the heart cools down. Supply of blood to fuel the muscle in order for fish to swim efficently is affected. Heart cools down, heart rate drops, poor swimming and feeding as a result.
Fish comes back to surface in order to warm back up and get the heart warm enough to start pumping blood fast enough again to supply oxygen to the muscles. Not that it needs to come to the surface in order to breathe oxygen.
The Weddell Seal
Lives in Antartica, live right next to research station.
Two types of dives, what are they?
Deep
(short, aerobic, feeding dives)
Shallow
(long, shallow, anaerobic, exploratory dives/territory/breathing holes)
Adaptations for diving in the weddell seal
- Large blood volume (stores O2) 2x as much as human
- Myoglobin in muscles (stores O2) 10x more than human
- Use stored O2 rather than air (No bends, narcosis/toxicity)
- Large red blood cell storage in the spleen (released during dive)
Weddell Seal
No big breath, exhale before submerge
Why not take a big breath?
- Although whales breathe in before they dive, the lungs compress at depth and air is forced into non-respiratory passages
- A buoyancy aid
- Most oxygen is carried on haemoglobin in the blood and on myoglobin in the muscles.
Conserving oxygen during the dive
Diving mammals reduce oxygen use by..
The diving reflex
- Bradychardia
- Peripheral vasoconstriction
Having efficient underwater locomotion
- Streamlined shape
- Efficent propulsion - gliding dives/effortless
- Neutral buoyancy
The Diving (trigeminal) Reflex
- Bradycardia
- Apnoea
- Peripheral blood vessels constrict
Blood flow to non-essential areas is almost totally shut down during dive. Name the non-essential parts.
- Diaphragm
- L ventricle
- Kidney
- Liver
- Intestine
- Skeletal Muscle
(Brain increases)
Countercurrent vasculature in extremities reduces heat loss and regional heterothermy reduces oxygen yse in extremeties.
Not only physiological adaptations, also anatomical.
Dorsal fin on dolphin arrangment of blood vessels where arteries surrounded by veins acts as heat exchanger.
Hot blood coming from the body core will exchange heat with the cold blood coming back from the veins in order to pre cool the arterial blood before it gets back to the edge of the dorsal.
Flipper has large surface area which acts as heat sink sending heat out into the water to minimise that we have counter current heat exchange.
- Anaerobic metabolism cannot be maintained for a very long time.
- Aerobic metabolism is fueled by fat, virtually no limit to how much you can store.
DIVING INVERTS 1
Arapina Gigas and the Aerobic Dive Limit (ADL)
(aka ancient amazon river monster)
*with an ancient/primitive physotome swimbladder, this is important
Fish such as the Arapina Gigas maximise 02 by having a physotome swimbladder. Physotome swimbladders are primitive and mostly associated with fresh water fish such as the Arapina Gigas. The swimbladder is conected to the gut via the pneumatic duct which allows the fish to swallow air at the surface and burp air out. The gills of the Arapina Gigas are not used for breathing and are used for osmoregulation.
DIVING INVERTS 2
Amphibians and the Aerobic Dive Limit
Amphibians such as frogs increase O2 storage by shunting blood between the lungs and the skin in the pulmocutaneous circuit, depending on aquatic oxygen tension.
In hypoxic water, blood flow to the skin is shut off to reduce O2 loss to the water.
