(3.2) Circulatory Systems Flashcards
Why do we need transport systems?
- Size
- SA:V
- Level of metabolic activity
What are the common features of a circulatory systems?
- Fluid
- Pump
- Exchange surfaces
What is the role of fluid in circulatory systems?
To transport dissolved nutrients
What is an example of an organism that has an open circulatory system?
Insects
What is an example of an organism that has a closed circlulatory system?
Fish
What is a closed circulatory system?
When the fluid is trapped in vessels
What is an open circulatory system?
The fluid is not enclosed in vessels
What are the disadvantages of an open circulatory system?
- Less efficient
- Low blood pressure
- Can’t direct the flow of fluid and it is rather affected by body movement
What are the disadvantages of an open circulatory system?
- Less efficient
- Low blood pressure
- Can’t direct the flow of fluid and it is rather affected by body movement
What is a single circulatory system?
Where the fluid only enters the pump once per circuit
What is an example of an organism with a single circulatory system?
Fish
What is an example of an organism with a double circulatory system?
Mammals
What are the disadvantages of a single circulatory system?
The blood pressure decreases as the blood gets further away from the heart
What is peristalis?
The way in which the fluid within an insect’s circulatory system moves - in waves as the pump contracts
What fluid is within the circulatory system of an insect?
haemolymph
What are the two parts of a mammilian circulatory system?
- Systemic circulation
- Pulmonary circulation
Why are there two circulatory systems within the mammilian body?
- they have a high metabolic rate
- to change blood pressure
What happens if blood pressure is too high when entering the lungs?
If the blood pressure is too high, the lungs will be damaged. This is because the capillaries start to leak fluid into the alveolus space and they can no longer carry out gaseous exchange. This is called pulmonary adema.
What is the flow of blood within a humans circulatory system?
- deoxygenated blood is pumped into the lungs
- oxygenated blood enters back into the heart
- the oxygenated blood leaves the heart and enters the systemic circulation
- the blood travels past the tissues and oxygenates then
- the deoxygenated blood then returns to the heart
What are the advantages of a double circulatory system?
- blood pressure in lungs is not too high to damage them
- heart can boost pressure before it travels around the body
- body circulations are at a high pressure
What are the materials within the Arteries and Veins?
- lumen
- endothelium
- elastic fibres
- smooth muscle
- collagen fibres
What is the lumen like in an artery and why?
Narrow to maintain a high blood pressure
What is the role of an artery?
Carry blood away from the heart
What is the role of a vein?
Carry blood towards the heart
What is the role of a capillary?
Site of exchange and how tissue fluid is produced
What is the structure of the endothelium and why in the arteries and veins?
- flattened
- smooth - blood flow has minimum resistance due to friction
What is the role of the elastic fibres in an artery?
To allow flexibility of the vessel as it can stretch and recoil when a wave of blood is pushed through
What is the role of the smooth muscle in an artery?
- constricts and controls direction of blood flow
- narrowed by the nervous system
- e.g. directs blood to skin when it is hot
What is an arteriole?
A vessel between an artery and capillary
What is the role of collagen fibres?
Allows the artery to withstand high pressure and toughens the artery
What is the tunica intima layer?
- endothelium
- elastic fibres
What is the tunica media layer?
- smooth muscle
What is the tunica externa layer?
- collagen fibres
What is the lumen like in the veins and why?
It is wide as blood pressure doesn’t need to be maintained
What is the role of the valves and how does blood flow in a vein?
- veins are there to prevent the backflow of blood due to low blood pressure
- as muscles contracts on the outside of vein blood is forced through the valves
What is the diametre of a capillary’s lumen and why is it significant?
- 7 micrometres
- It is the same diametre as a red blood cell and therefore the diffusion distances are short for creation of tissue fluid
What are the collagen fibres like in the vein and why?
They are thin as the vein does not need to withstand high pressure
Why are the elastic fibres thinner in a vein?
The lumen is wide and blood pressure is low therefore the vessel does not have to be as flexible to allow the passage of cells
What is the endothelium like in the capillary and why?
They are leaky to allow exchange at tissues and create tissue fluid
Where are continuos capillaries found?
- fat
- muscle
- nervous system
Where are fenestrated capillaries found?
- intestinal villi
- endocrine gland
- kidney glomeruli
What is special about fenestrated capillaries?
They are extra leaky
Where are discontinuos capillaries found?
- liver
- bone marrow
- spleen
What is the role of the lymphatic system?
To drain excess tissue fluid where it is drained into the lymph nodes and lymph then drained to the heart
What is plasma made of?
- water
- ions
- sugars
- gas
- most proteins (excluding large)
What is the difference beween plasma and tissue fluid?
Tissue fluid is plasma once is has left the capillary and is the liquid form in blood
Describe the process of tissue exchange
- hydrostratic pressure that is larger than oncotic pressure causes plasma to be forced out of the capillary
- the plasma then becomes tissue fluid
- towards the end of the capillary the hydrostatic pressure is the same/less than oncotic pressure therefore some tissue fluid is moved back into the capillary
- this is why there is a need for a lymphatic system as there is excess left due to not as much being reabsorbed back into the capillary than there was released
What is hydrostatic pressure?
The physical effect
What is oncotic pressure?
The osmotic effect
What is atrial systole?
- the atria contracts
- forces open the Atrial Ventricular valve
- blood goes into the ventricles
What is ventricular systole?
- ventricles contract
- the Atrial Ventricular valve closes
- blood exits the heart through the semi-luna valve
What is diastole?
- the muscles within the heart relax
- the atria refills with blood
Describe how a heart beat is created
- the Sino-atrial node (SAN) creates and excitation
- this travels across the walls of the atrium
- then the excitation reaches the Atrio-Ventricular node (AVN)
- The electrical wave travels down the septum
- Then it travels up the ventricle walls through the purkyne fibres
What is tachycardia?
When a heart rate is fast
What is bradycardia?
When a heart rate is slow
What is atrial fibrilation?
When the atrial excitation is not present
What is an ectopic heartbeat?
When the heart rate is irregular and skips beats
How can you see the closing of the AV valves on a pressure graph?
Where the pressure in the left atrium and ventricle are equal in atrial systole
How can you see the opening of semi-lunar valves on a pressure graph?
When the pressure in the left ventricle and aorta are equal during ventricular systole
How can you see the closing of the semi-lunar valves on a pressure graph?
When the pressure of the left ventricle and aorta are equal during diastole
How can you see the Atrio ventricular valves open on a pressure graph?
When the pressure of the left ventricle and the left atrium are equal during diastole
Which oxygen binds the easiest to haemoglobin and why?
The 4th oxygen binds the easiest as it is a cooperative process meaning that as one oxygen binds the shape is slightly altered giving the haemoglobin a higher affinity for oxygen
Why does fetal haemoglobin have a higher affinity for oxygen?
Otherwise the mother’s blood would use up all the oxygen and there would be none left for the fetus
When does loading of oxygen into haemoglobin take place?
When there is a high partial pressure of oxygen
When does unloading of oxygen from haemoglobin take place?
When there is a low partial pressure of oxygen
What is partial pressure?
The concentration of a gas
Describe the Bohr shift
- when respiring cells produce CO2
- Carbonic anhydrase converts water and carbon dioxide into carbonic acid
- Carbonic acid dissociates into H+ ions and CO3- ions
- CO3- leaves the red blood cell into plasma
- H+ is haemoglobinic acid
- Haemoglobinic acid causes oxygen to be unloaded due to the dissociation of oxyhaemoglobin
What is haemoglobin that is bound with oxygen called?
oxyhaemoglobin
