Cardiovascular system Flashcards
What are the 2 main forms of bulk transport?
Ventilation and circulation
What are the 2 main contributions circulation has?
Bypasses diffusion
Enhances ΔP by moving fluids with different gas contents
What are the 5 main parts of the vertebrate cardiovascular system?
Muscular heart Arterial system Venous system Systemic circulation Pulmonary circulation
Describe the muscular heart
Pumps blood around the body
Consists of multiple chambers
Thin auricles/atria
Thick ventricles
Describe the arterial system
Transports materials such as O2, nutrients, and hormones at a high pressure
Describe the venous system
Removes waste materials such as CO2 and respiratory H2O at a low pressure
Has capacitance
What is capacitance?
The ability to store an electric charge
Describe systemic circulation
The movement of blood to and from body tissues
Ideally at high flow rates thus at a high pressure
Describe pulmonary circulation
The movement of blood to and from the lungs
Ideally at high flow rates but a low pressure
Describe the structure of arteries
Lots of elastic tissue and smooth muscle to withstand high pressures
Describe the structure of veins
Some have valves to prevent backflow as they operate under low pressure
What is vasoconstriction?
The reduction in the diameter of veins
What is vasodilation?
The increase in the diameter of veins
How many chambers does a fish heart have?
4
What are the chambers in a fish heart?
Sinus venosus
Atrium
Ventricle
Conus arteriosus
Describe the sinus venosus in fish
The thin-walled venous chamber that receives blood from the duct of Cuvier, coronary veins, and hepatic veins
Describe the atrium in fish
A large and thin-walled chamber
Is the 1st chamber that provides the initial acceleration of blood flow around the body
Describe the ventricle in fish
The 2nd chamber which is the main propulsive force for cardiac flow
Pumps into the conus arteriosus- continuous with the aorta
Chambers are separated by valves
Describe the conus arteriosus in fish
It is short in bony fish and amphibians
Not present in adult amniotes
Capacitance vessel-smooths flow of blood to the gills
What is different in the lungs of lungfish versus fish?
Modifications of the partial or complete partition of the atrium into the left and right atria
What did the advent of lungs bring?
Double circulation
Modification to the conus arteriosus to separate the flow
Semi-lunar valve modified to shunt deoxygenated blood to the lungs (spiral valve)
How many chambers are in the amphibian heart?
3
2 atria
1 ventricle
Describe the structure of the amphibian heart
2 atria
1 ventricle
Spiral valve to direct oxygenated blood to enter the ventricle from the left atrium
Conus arteriosus (bulbus cordis) is a swelling of the ventral aorta and is made of smooth muscle
Describe the reptilian heart
Functionally divided double circulation but there is an additional chamber- cavum venosum
The cavum pulmonae, cavum arteriosus and cavum venousum make up the ventricle
Describe the movement of blood through the reptilian heart
Venous blood is collected from the body through the sinus venosus
Then to the right atrium
Then to the cavum pulmonae
The into the pulmonary artery into the lungs
Then oxygenated blood returns through the pulmonary veins into the left atrium
Then into the cavum arteriosus
Then into the cavum venosus into the right and left aortic trunks
Describe the crocodile heart
They have a completely divided ventricle
The left and right sides of the heart are still connected through the Foramen of Panizza
The pressure changes in the pulmonary circulation can change the flow of blood in the heart
What is the Foramen of Panizza?
A valve between the aortic trunks used to divert blood
Allows the left ventricle to pump to both arches when the right ventricle is shut
What happens to the crocodile’s circulation when diving?
The lungs are not utilised
Blood is not pumped to the lungs
The right ventricle helps to pump systemic blood
How many chambers does the mammalian and avian hearts have?
4
2 atria
2 ventricles
What happens to the left and right atria in embryos?
They are not separated
Describe the venous system
Fluid is squeezed out of the capillary by blood pressure at the arteriole end
Fluid is pulled back into the capillary by osmotic pressure at the venule end
Describe the flow chart of the effects of a low pH, increased waste products and localised depletion on blood flow
Low pH, increased waste products, and localised depletion of the blood occurs
This leads to vasodilation of the capillaries
This increases the blood flow
This replenishes the blood, removes waste products, and returns the blood to a normal pH
This leads to vasoconstriction of the capillaries and the cycle begins again
Describe the flow chart of the effects of lowering arterial pressure and how it leads to the production of vasopressin
The arterial pressure is lowered
Firing in arterial stretch sensors decreases
The hypothalamus released vasopressin
Vasopressin stimulates the kidneys to reabsorb water
This increases the arterial pressure
Describe the flow chart of the effects of lowering arterial pressure and how it leads to the production of renin
The arterial pressure is lowered The kidneys release renin Renin activates angiotensin Angiotensin causes vessels to constrict This increases the arterial pressure
Describe the flow chart of the effects of lowering the arterial pressure leads to the widening of vessels
The arterial pressure is lowered
There is a decrease in blood flow to the tissue
There is a local accumulation of metabolic waste
There is then autoregulatory widening of vessels
The arterial pressure is then lowered again
What is a respiratory protein?
A metalloprotein that binds reversibly with oxygen at specific sites
Describe haemoglobin Fe
Turns from blue to red when oxygen is bound
Present in all vertebrates
Describe haemrhythrin Fe
Turns from colourless to red/violet when oxygen is bound
Present in sipunculid worms, brachiopods, and priapulids
Describe haemocyanin Cu
Turns from colourless to blue when oxygen is bound Present in arthropods and molluscs
Describe chlorocruorins Fe
They are green
Present in fan and feather worms
Describe the affinity of respiratory pigments to oxygen
Each subunit can bind one oxygen molecule allosterically
Binding of 1 or 2 oxygen molecules changes the shape of haemoglobin to increase the affinity for oxygen
Describe the sigmoid dissociation curve of oxygen
The closer to the y-axis it is the higher the affinity for oxygen
What is myoglobin?
A respiratory pigment found in muscles
A single globin unit
No allosteric effect
Describe the Bohr shift
Respiring tissues will release CO2 which decreases the pH
This causes the Bohr shift in the curve to the right which causes the haemoglobin to increase unloading and enhances oxygen delivery
Describe the Root shift
Usually, the change in pH does not affect the maximum capacity of oxygen
However, there is an exception in teleost fish blood
Where the acidity decreases the haemoglobin’s maximum capacity for oxygen
How is carbon dioxide transported in the blood?
Very little is transported as CO2
Most is transported as bicarbonate ions HCO3-
What is the equation for CO2 dissociation?
CO2 + H2O ⇌ H2CO3⇌ H+ + HCO3-
Describe the equation for CO2 dissociation
A slow reaction
Enhanced by Carbonic Anhydrase which is present in the endothelium of capillaries and red blood cells
