Cardiovascular System Flashcards
Pulmonary circulation
- Deoxygenated blood from heart to lungs
- Oxygenated blood back to the heart
Systemic circulation
- oxygenated blood to the body (from heart)
- return of deoxygenated blood from body to heart
Order of blood vessels
- Heart
- Arteries
- Arterioles
- Capillaries
- Venules
- Veins
- Heart
Structure and function of arteries
- Smaller lumen to maintain high blood pressure
- More of an elastic layer to cope with high blood pressure as can stretch + recoil
- Carry oxygenated blood away from the heart
- Thick walls withstand high pressure
Structure and function of veins
- To transport deoxygenated blood back to the heart
- Thinner muscle/elastic layer as blood is at low pressure
- Valves to prevent back flow
- Wide lumen to reduce resistance to blood flow and maximise blood volume
Structure and function of capillaries
- Exchange substances between blood and body tissues
- Very narrow (allow 1 rbc) to slow blood flow for exchange of nutrients
- One cell thick for a short diffusion pathway
- Highly branched do have a large surface area
Vasoconstriction
When the arteries narrow (caused by precapillary sphincters) to reduce blood flow to inactive areas
Vasodilation
When arteries widen (caused by precapillary sphincters) to maximise volume of blood available to active areas
What are the mechanisms that assist venous return
- Skeletal muscle pump - muscles contact forcing more blood to return to heart
- Valves - prevent back flow of blood
- Respiratory pump - increased respiration/changes in pressure in the thorax compresses the veins to push blood back towards the heart
- Gravity
How does performing a cool down help venous return
It maintains the respiratory and muscle pumps, therefore maintaining an increased venous return
Plasma
The fluid part of blood that transports rbc and can carry O2
Haemoglobin
Iron containing pigment found in rbc which combines with o2 to form oxyhemoglobin or combines with co2 to form carbaminohaemoglobin
Myoglobin
Iron containing muscle pigment which has a higher affinity for o2 than oxyhemoglobin. Stores o2 in muscle fibres which can be used quickly when exercise begins. Stores o2 for mitochondria
Mitochondria
Utilises the o2 to resynthesise ATP (respiration)
Describe oxyhaemoglobin disassociation
During exercise the conditions of blood changes (increase in co2, decrease ph, increase temp.) which causes oxyhemoglobins’ affinity for o2 to decrease. So deposits the o2 which diffuses into the muscle cell and is absorbed by myoglobin (has a high affinity) and is used in aerobic respiration as more o2 is delivered to muscles
Bohr shift
Curve shifts to the right due to haemoglobin disassociating with o2
Myoglobin curve
Myoglobin has a higher affinity for o2 and can re saturate at low partial pressure o2. It is readily resaturated when o2 disassociates with haemoglobin
What factors determine blood pressure in arteries during exercise
- Can vasodilate + constrict
- Increased cardiac output
- Blood viscosity
Why does blood flow to the brain remain the same during rest and max effort
Brain is required for control and needs o2 and nutrients as a constant supply as a muscle
Why should performers not eat immediately before exercise
Arteries to digestive system vasoconstrict so less blood goes to gut to allow for more blood to reach the working muscles. But blood is needed in gut for digestion leading to nausea
Blood pressure
The force exerted by the blood on the walls of the blood vessels
Blood pressure, cross sectional area and blood velocity graph
- Fluctuates from aorta, artery and aretioles then decreases from arterioles, capillaries, venules, veins venae cavae
- Increases until capillaries then decreases
- Decreases until capillaries and then increases again
A-VO2 diff
The difference between the o2 content of arterial and venous blood
Difference between A-VO2 diff at rest and during exercise
During exercise A-VO2 diff is larger than at rest due to increased disassociation of o2
