7: Cardiovascular System Flashcards
how many chambers?
4
right ventricle flow goes to…
lungs
left ventricle flow goes to
systemic side
what is the heart size of great whales as a percentage of body mass?
0.3 - 0.5%
what is the heart size of small cetaceans and pinnipeds as a percentage of body mass?
0.5-1.0%
- who has cardiac fat?
2. when is it used?
- All animals have this around their heart
more noticeable in marine mammals - when stressed this fat is rapidly used.
Stroke volume
volume of blood ejected from LV per heart beat (mL/hb)
Heart rate
number of heat beats per min (hb/min)
resting cardiac output stroke bul
stroke volume x HR
L/min
Relative to their body masss, how do chamber sizes, SV, resting cardiac output and HR of marine mammals differ from those of land mammals?
marine mammals are within land mammals measurements, relative to their body mass
Heart: great stores of glycogen in hearts of some seals, suggests…
a higher capacity of anaerobic capability (ability to maintain cellular life without o2 compared to land mammals)
pericardium
tough flailed filled sac surrounds heart
What is the purpose of the pericardium
fluid serves to:
- lubricate heart (facilitate movement)
- amount similar in all species
- except manatee (have more)
Are there any differences between species on thickness of pericardium or amount of fluid found?
yes,
varies:
humans relatively thin, whereas pinnpeds vary: sea lion are very thing, grey seal thicker.
Valves
- what are they?
- purpose?
prevents blood from flowing in the wrong direction
How many valves are there in mammalian heart?
name, location, shape structure
4
- tricuspids (RA –>RV)
- pulmonary valve (RV –> PA)
- mitral valve (LA –> LV)
- aortic valve (LV–> aorta)
leaflets = mitral and tricuspid
semilunar valves = pulmonary and aortic
What is the chordae tendinae?
location and purpose?
(tendinous chords), or heart strings, are cord-like tendons that connect the papillary muscles to the tricuspid valve and the mitral valve in the heart.
- What is the purpose of papillary muscles? (location and fn)
- are these different from trabecular carneae?
muscles that pull the leaflets of valves
prevents inversion and prolapse
similar to papillary muscles
- What is the myocardium?
- how many layers are there?
- describe them
- muscles of the heart
- 3 layers (epicardium, subendocardiun and endocardium)
- outer, middle, inside layer
- What is the trabeculae carnae?
- Where is it located?
- State its function
- /2. muscles bundles inside the heart
3. reinforce and help heart to pump efficiently
Arteries
supplies heart muscles with blood (provides o2 and energy)
Veins
removes waste products
Left and right coronary arteries
supply LV and RV
Left and right coronary veins
- drain LV and RV myocardium
- join to empty into coronary sinus which then empties into left atrium
Aorta
largest artery
- originates from LV
- extends down through chest and abdomen
When the blood from the aorta reaches pelvic area branches into what in the following:
- in species with hind limbs (i.e.: pinniped)–> ??
- in cetaceans; sirenians continues as ??
- sends branches known as _____ to GIT
- common iliac arteries
- sacral or caudal artery to tail.
- hypogastric arteries
Aorta
what is critical structural property the aorta has to have and why?
needs to be very elastic, able to stretch to adjust to differing volumes (Windkessels effect)
contrast the pattern of branching of the thoracic aorta in humans vs some marine mammals such as certain seals
humans: branching randomly
seals: specific patter (paired) purpose is unknown
In pinnipeds, describe the differences in the shape of the aorta near heart compared to humans?
ascentding aorta of hear increase 30-40% and forms an elastic bulb (arotic arch in land mammals)
after aortic arch, it decreases in diameter by 50% and continue as a slender tube in the abdomen.
Aortic arch: what is the formal name of this structure in seals and its function?
aortic bulb
fn: adaptation for diving which allows for:
- increase lung perfusion while on surface
- maintains blood pressure t/o dives
compare the size of the aortic bulb between the leopard seal and weddell seal
Size of bulb and dividing habits correlates
leopard seal is a shallow diver = smaller bulb;
weddell seal –> deeper diver –> larger bulb
Aortic bulb:
- does this structure exist in cetaceans
- and if so describe any differences structurally
- yes
2 subtle differences from pinnipeds –> thickness of bubbles walls and organization of elastic tissues
Hearts of sirenians:
describe the 2 structural differences
- deep inter-ventricle cleft along the full length of the ventricles 2. dorsally located left atrium
hearts of sirenians:
What is different between manatees and dugongs?
manatees have a bulbous swelling of aorta which IS NOT found in dugongs
The most notable changes from normal mammalian cardiovascular systems are associated with… (3)
- diving responses
- thermoregulation
- larger body mass
What are adaptations in marine mammals?
6
- larger blood volumes
- larger blood holding structures such as spleen and venous sinuses
- venous sphincter muscles
- aortic windkessel effect
- vascular retina mirabilia
- vascular changes to help with thermoregulation (countercurrent heat exchange)
What is unique in the arteries of pinnipeds ?
There are dense amount of nerves at: both the proximal (toward or close to the body) and distal (away or farther from the body) ends arteries
Pinnipieds arteries: during dives what is this allow for?
2. what is the advantage of this to the animal?
BV to stay closed when it would normally to be open to allow blood to flow through to extremities or organ
2. during dives, blood would be sent to important organs such has brain and heart.
What is Venous capacitance ?
- describe this…
or areas to “store” blood is highly developed especially in certain seals
- incldues a large hepatic sinus and inferior vena cava where it is estimated that …. 1/5th of seal’s BV can be “stored”
What does the venous capacitance allow for?
blood to be quickly squeezed into circulatory system to maintain bp which due to greater external pressures drop during dives.
What percent of body weight can the spleen be in sea lions and seals?
large
4.5%
What is the function of the spleen in sea lions and seals?
serves as a storage site for oxygenated RBC
what percent of blood volume can be stored in the spleen of Weddell seals
30%
what species of seal has the largest spleen?
elephant seal
3 time as big as a terrestrial mammal
In which grouping of seals has research shown that diving capacity is strongly correlated with spleen size?
Phocid seals
NOT otariids
spleen size is strongly correlated with diving capacity
Cetaceans spleens
very small (0.02% bw) when compared to terr. mammals. NO correlation to their diving capacity
- What is the extradural venous system (EVS)
2. which marine mammals categories have this?
- receives blood from brain, back and pelvic area
system is very complicated and its function is unclear but it is thought that it may help in thermoregulation of the brain - seals and whales
contrast the exact anatomical location of the EVS between pinnipeds vs cetaceans
pinnipeds: lies dorsal aspect of SC but outside the dura mater, between it and periosteum lining of SC
cetaceans: central aspect
- What is unique about the venous system of pinnipeds?
2. what are the differences in pinniped posterior vena cava to accomplish that?
- enlarged and increased to enhance its capacity.
- Their posterior vena cava
- is frequently developed a pair of vessels
- have thin elastic walls capable of considerable distensions
- receive blood draining from plexi (networks of veins) within their flippers, pelvis, kidneys and abdominal wall
What are other adaptations that pinnipids have on their enhance capacity of the venous system.
hepatic sinus
caval sphincter
pericardial plexis
Hepatic sinus
Location and purpose
along posterior vena cava
posterior to diaphragm
collects blood to send to heart
Caval Sphincter
location, purpose
anterior to diaphragm
- is muscular which surrounds the vena cava
- innervated by right phrenic nerve
Pericardial Plexus (location, purpose, and structure)
anterior to vena cava,
- where veins enter into vena cava
- forms a ring around base of pericardium (protective ac around heart) where t sends out leaf like projections into pleural cavities which contains lungs
What are retia mirabilia in marine mammals?
unique system of BV foudn in marine mammals.
other animals –> in limbs as heat exchangers and NOT blood/oxygen reserves
where is the retia mirabilia found?
in specific tissue (usually in dorsal wall of thoracic cavity and extremeties)
What is the purpose of retia mirabillia in marine mammals?
Tissues contains BV (mostly arteries but also very thin walled veins) that for man extensive network of contorted spirals
- serve as blood reservoirs to increase o2 stores during diving
which species has the most developed thoracic retia of all cetaceans?
Sperm whales
What is the pericardial plexus?
Where is it located?
protective sac around the hear where it sends out leaf like projections into the pleural cavities which contain the lungs
Describe how walrus differs or is similar with the above adaptations.
Also do they have the other plexi and if so are that same in extent?
large hepatic sinus
developed naval sphincter
since vena cava; no pericardial plexus NOR stellate plexus
Contrast the veins of cetaceans compared to pinniped
veins of cetaceans are not a enlarged as pinnipeds although their vena cava is enlarged in hepatic area in SOME species
NO caval sphincter pr hepatic sinus
- pair of large beings that run venally to SC that may assist int their diving abilities (EDV)
Blue shark e
-explain the cardiovascular system
Not a mammal no hepatic sinus, no venous sphincter no plexus heart is not a 4 chambered heart
Describe the blood volume in marine mammals and its role?
larger blood volumes contribute toe increased o2 stores
In diving marine mammals – what are the 2 largest oxygen storage sites?
Describe the difference between them?
- o2 with HB in RB
- O2 with myoglobin (found in muscles)
- gives muscles deep red appearance.
How many oxygen molecules can hemoglobin bind?
What is the implication of this? What is the effect of this on plasma osmotic pressure?
4
increases o2 capacity by 100% without increasing plasma osmotic pressure
- Are there differences in relative blood volume between marine mammals and humans?
- What is the implication of this?
marine mammals are 2-3x greater than the avg human value
generally larger in very active and longer dividing species (i.e.: sperm whales, elephant seals, weddell seals )
What is difference between myoglobin vs hemoglobin
myoglobin is fixed within muscles
HB circulated through arterial regulation (allows for the delivery of HB bound O2 to reach organs that require it the most)
Differences in RBCs between diving mammals vs non-diving?
- are same size
- but some diving mammals have relative higher BV
0 relatively higher BV can be correlated to species diving capabilities
What effects does the differences in RBCS have on their…
- hematocrit (packed RBC volume)
- total Hb volume?
- increases hematocrit
- increase total HB volume
when you have more RBCs per unit of blood in diving mammals
During dives much of total stored oxygen is bound to _____?_______ in muscles
myoglobin
What is known about the role of myoglobin content in marine mammals?
There is higher myoglobin concentration in animals that give >100m
this suggest that myoglobin is a key adaptation to diving.
Are skeletal muscles tolerant to hypoxic (low oxygen) conditions that they experience during dives?
Yes, they are VERY tolerant to hypoxic (low o2) conditions that they experience during dives.
They and other organs (kidney, intestines, etc) may be deprived of o2 from HB in circulatory systems.
Why do skeletal muscles see lower o2 ostores?
myoglobin might remove most of o2 from circulating plasma and prevent much needed o2 from reaching important organs such has brain or heart.
But this does not happen because there is a brief period of repercussion of skeletal muscles may occur to help maintain proper metabolic stability.
Humans
- BV
- hemotocrit
- 70
2. 40%
Elephant seals
- BV = ? (mL/kg)
- hematocrit =? (%)
- 100-175
2. 50-62
Sea Lions
- BV = ?(mL/kg)
- hematocrit = ? (%)
- no data
2. 48
Sperm whales
- BV = ?(mL/kg)
- hematocrit = ? (%)
- 204
2. 52
Dolphin
- BV = ?(mL/kg)
- hematocrit = ? (%)
- 71-95
2. 42-52
grey whales
- BV = ?(mL/kg)
- hematocrit = ? (%)
- 61-81
2. 38-46
