circulatory system Flashcards
what is the skeletal muscle pump?
when muscles contract and relax meaning they change shape and press on nearby veins to make a pumping effect. This squeezes blood towards the heart
what is the respiratory pump?
when muscles contract and relax during breathing in and out, pressure changes in the thoracic (chest) and abdominal (stomach) cavities.These changes in pressure press on nearby veins and assist blood return to the heart.
what are pocket valves?
the presence of valves in veins to prevent the back flow of blood which ensures the blood travels towards the heart and not away from it.
what mechanisms aid with venous return?
- skeletal muscle pump
- respiratory pump
- pocket valves
- gravity
what is venous return?
the return of blood to the right side of the heart via the vena cava.
What is pulmonary circulation?
Deoxygenated blood moving from the heart to the lungs and oxygenated blood moving back to the heart.
What is systemic circulation?
Oxygenated blood moving from the heart to the body and then the return of deoxygenated blood from the body to the heart.
Flow chart showing the order of the key blood vessels:
Heart -> Arteries -> Arterioles -> capillaries -> venules -> veins -> heart
What is the structure of arteries?
They have a thick outer layer to be able to carry blood at a higher pressure.
Outer layer is also elastic to cope with fluctuations in pressure
What is the structure of capillaries?
Only wide enough to allow one blood cell through at a time to slow down blood flow and allow time for diffusion. Walls are only one cell thick to allow a short distance for diffusion. There are also a lot of them to allow quicker diffusion.
What is the structure of veins?
Thinner muscle/outer layer as blood is at a lower pressure. They also have valves and a wider lumen to allow blood flow to easily return back to heart.
What is the definition of blood pressure?
The force exerted by the blood against the blood vessel wall
What is systolic pressure?
The pressure in the arteries when the ventricles are contracting
What is diastolic pressure?
The pressure in the arteries when the ventricles are relaxing
What happens to blood pressure during aerobic activity?
Systolic pressure will increase but diastolic pressure will remain relatively constant
What happens to blood pressure during anaerobic activity?
The skeletal muscle pump is working harder causing an increase in venous return which causes an increase in both systolic and diastolic blood pressure
what is the largest artery in the body called?
The aorta
What is the largest vein in the body called?
The vena cava
what are pre-capillary sphincters?
rings of smooth muscle which help direct blood flow into capillaries.
They also control the redistribution of blood
how would a cool down help venous return?
a cool down helps to keep the skeletal muscle pump and respiratory pump working which prevents blood pooling
what is blood pooling?
when blood stays in veins and is not sent back to the heart properly. It can cause nausea, dizziness
How does blood redistribution occur?
Through vasoconstriction and vasodilation which is controlled by the pre-capillary sphincters
what is vasoconstriction?
the narrowing of the blood vessels to reduce blood flow into the capillaries (e.g. to the digestive system during exercise)
what is vasodilation?
the widening of the blood vessels to increase the flow of blood into the capillaries (e.g. to working muscles during exercise allowing more oxygen to be delivered)
Why should you not eat just before doing exercise?
Just after eating, blood flow will be aimed mainly at the digestive system in order to digest the food. If you do exercise whilst the food is still digesting, more blood flow will be required to go to the muscles meaning the food cannot digest. Or the muscles won’t be able to receive the oxygen they need as blood is going the digestive system
what is plasma?
the fluid part of the blood (mainly water) that surrounds blood cells + transports them
what is haemoglobin?
an iron-containing pigment found in red blood cells and transports oxygen
what is oxyhemoglobin dissociation?
when oxygen is released from oxyhaemoglobin
what is myoglobin?
Where oxygen is stored in the muscles so it can be quickly used when exercise begins.
what has a higher affinity for oxygen, haemoglobin or myoglobin?
Myoglobin
what is the Bohr shift?
When the oxygen dissociation curve shifts right during exercise as haemoglobin dissociates with oxygen due to the increased partial pressure of CO2 and decreased partial pressure of O2 in the muscles meaning haemoglobin experiences a reduced affinity for it and therefore more oxygen goes into muscles
what 3 conditions cause the Bohr shift?
decrease in pH, increase in carbon dioxide, increase in temperature
what effect does the Bohr shift have on working muscles during exercise?
oxygen delivery increases to working muscles as the oxygen that leaves haemoglobin diffuses into the myoglobin which is found in the working muscles
what is atria-venous oxygen difference?
the difference between the oxygen carried by the blood in arteries and veins. It also represents the amount of oxygen delivered to working tissue in the capillary system
what 3 factors are responsible for an increase in the dissociation of oxygen from haemoglobin
- increase in blood temp => when blood and muscle temp increases, oxygen dissociates more readily
- partial pressure of carbon dioxide increasing
- decrease in pH
