Ianowski - theme 11 and 12 Flashcards
Components of circulatory systems that are common to all animals:
Fluid, pump, vessels
Different kinds of circulatory systems:
Gastrovascular cavity, open system, closed system
Main difference between open and closed systems:
Capillaries!
Gastrovascular cavity:
Simplest circulatory system. Found in cnidarians.
Fluid: water
Pump: body
Vessels: cavity
Open system:
Found in many invertebrates.
Fluid: hemolymph
Pump: heart(s)
Vessels: hemocoel (blood vessels that open to the body cavity)
Main disadvantage of open system:
Can’t direct blood to specific places.
Insect open system:
Circulatory system doesn’t fuck wit O2, so metabolic rate can be very high.
Transports nutrients, hormones, waste, and immune molecules. Wound repair, heat transfer, and CO2 sink. Hydraulic skeleton in larvae.
Closed system:
Found in vertebrates and cephalopods.
Fluid: blood
Pump: heart
Vessels: blood vessels and capillaries
Different closed systems and which organisms use them:
Single circulation - fish
Parallel circulation - amphibians
Double circulation - mammals, birds, crocodilians
Double circulation:
Pulmonary and systemic blood are separated.
What supplies the heart with O2?
Coronary arteries, a part of the systemic circuit.
How do the volumes of blood in pulmonary vs systemic compare?
Must be equal, or there would be buildup in one circuit.
What is the main advantage of having separate circuits (with the same volume)?
Systemic circuit can have high pressure so flow can go fast
Pulmonary circuit can have low pressure and low resistance (so nothing blows up)
Congestive cardiomyopathy:
70% normal fraction ejection - only 30% is ejected. Swelling in left ventricle.
Parallel circulation, a beautiful story:
Body tissue circuit: ventricle pushes oxygenated blood to the tissues, and deoxygenated blood goes to the right atrium. Low pressure.
Lung circuit: ventricle pushes mixed blood (from right atrium) to the lungs, where it is oxygenated. It returns to the left atrium. Moderate pressure.
Cutaneous circuit: ventricle pushes mixed blood (from right atrium) to the skin, where it is oxygenated. It returns to the right atrium to mix with deoxy body blood. Low pressure.
Pros and cons of parallel circulation:
Pros: systemic and pulmocutaneous systems are separate. Periodic ventilation (divert blood to or away from lungs).
Cons: can’t have very high pressure with only one ventricle.
Single circulation:
One atrium and one ventricle. Ventricle pushes deoxy blood to gills. Oxy blood travels to body tissue. Deoxy blood travels to atrium. Low pressure the whole time.
Classification of blood vessels:
Artery, arteriole, continuous capillary, fenestrated capillary, venule, vein
Which vessels are: pressure reservoirs? blood reservoirs? sites of exchange with interstitial fluid?
Arteries are pressure reservoirs. Capillaries are exchange. Veins and venules are blood reservoirs.
What is the function of arterioles?
Controls where blood flow goes by opening/closing access to capillaries.
Let’s talk about how tiny capillaries are.
Consist of a single layer of endothelial cells. So smol that RBCs have to travel in single file.
Muscles help return blood to the heart.
Muscles contract to push blood in veins. A venous valve closes to stop backflow and another venous valve opens to allow blood to be pushed towards the heart.
Lymphatic system:
Collects excess interstitial fluid and returns it to the venous blood.
Tissues and organs of the lymphatic system:
Lymph nodes, spleen, thymus, tonsils. They remove bad guys from lymph and blood.
Where do white blood cells like to hang out?
Lymph nodes
Where do the thymus and spleen guard?
Thymus - inhaled bad guys
Spleen - blood bad guys
Neurogenic hearts vs myogenic hearts:
Neurogenic can’t contract spontaneously. Insects and crustaceans.
Myogenic have pacemaker cells.
Pacemaker cells:
Membrane potential changes as Na and Ca come in more and K leaves less. AP is produced when L-type Ca2+ channels open at threshold.
Are heart valves energy dependent?
NO! They open when blood flows the right way, and close against backflow PASSIVELY.
Cardiac cycle:
Systole: contraction. max pressure.
Diastole: relaxation. min pressure.
Vertebrate heart walls:
Myocardium between endo and epicardium.
Myocardium:
Interlacing bundles of cardiac fibres arranged in spirals. Intercalated discs contain desmosomes and gap junctions.
Functional syncytium:
All myocardial cells that are connected by gap junctions (so impulses spread to all of them).
Electrical conduction system in heart:
Electrically non-conducive tissue band between atria and ventricles. SA node in right atrium propagates charge to both atria and to the AV node. AV node sends signals to the ventricles.
Consequences of nodey electrical conduction:
Contractions happens from right to left, and the atria contract slightly before the ventricles.
ECG interpretation:
P wave - atrial depolarization
QRS complex - ventricular depolarization
T wave - ventricular repolarization
PR segment - AV nodal delay
ST segment - plateau phase
TP interval - passive ventricular filling, total rest
What cells relay charge from AV node to the bottom of the heart?
Purkinje cells
