Transport in Animals Flashcards
What is a double circulatory system
The blood passes through the heart twice for each complete circuit of the body
What is a single circulatory system
The blood passes through the heart once for each complete circuit of the body
What is the need for the cardiovascular system
To transport nutrients, hormones oxygen and to remove waste metabolites such as CO2
What do animals need a specialised transport system
Large animals have a small surface area to volume ratio and a high metabolic rate. This means simple diffusion will not be sufficient enough to meet their metabolic demands.
What are some features of a good transport system
A fluid or medium to carry nutrients
A pump to create pressure in order to push fluid round the body
Exchange surfaces that can allow substances to enter and be removed from the blood
What are advantages of a double circulatory system
Oxygen and nutrients will get delivered to parts of the body where it’s needed quickly due to pressure generated by the heart. The heart can increase the pressure once it’s been oxygenated at the lungs
The systemic pressure can be much higher as it needs to supply blood to the rest of the body. Pulmonary pressure has to be lower so it doesn’t damage capillaries at the lungs
In a single circulatory system blood pressure falls as it passes through the capillaries so blood will have a low pressure as it flows to the body
What is a open circulatory system what are the disadvantages
Blood isn’t enclosed in blood vessels example being insects where their blood is called haemolymph. Its cells are bathed in fluid.
Blood pressure and flow is low
The blood isn’t directed so circulation can be affected by body movements or lack of movements
What are elastic fibres, smooth muscle and collagen
Elastic fibres - stretch and recoil to even out the surge and maintain the pressure
Smooth muscle - contract and relax to maintain blood flow
Relaxing is vasodilation (more blood flow)
Contracting is vasoconstriction (less blood flow)
Collagen is a thick layer of fibrous protein that can withstand the high pressure of the blood
What is a closed circulatory system and what are some advantages
Blood is enclosed in vessels, a separate fluid called tissue fluid bathes the cells.
The blood is under higher pressure
Their is a rapid delivery of oxygen and nutrients and removal of waste metabolites
Circulation is unaffected by body movements
What do all blood vessels have in their tunica intima
All vessels having a lining of endothelium cells.
They are smooth in order to reduce friction
Describe the function and structure of arteries
Function
To carry blood away from the heart. The vessels are called the aorta and pulmonary artery
Structure
As the blood leaving the heart is under high pressure the artery wall has to be thick
Tunica intima - Layer of endothelium
Tunica media - Thick layers of smooth muscle
Tunica externa - Thick layer of collagen and elastic tissue
Narrow lumen
Further away from the heart they contain more smooth muscle
Describe the function and structure of arteries
Function
To divert the blood from the arteries into the capillaries
Structure
Contain smooth muscle which can constrict its diameter to divert the blood.
Resistance is increased and the rate of flow of blood is reduced
Describe the function and structure of capillaries
Function
They allow exchange of materials between tissue fluid and the blood
Structure
Consist of squamous epithelial cells which are one cell thick which provide a short diffusion pathway
Narrow lumen which allows one red blood cell to pass through at a time maximising rate of diffusion in a given time
Walls contain pores allow plasma and dissolved substances to leave the blood
Describe the function and structure of venules
Function
Collect the blood from the capillary bed and return the blood to the veins
Structure
Consists of a thin layers of muscle and elastic tissue outside the endothelium and a thin layer of collagen
Describe the function and structure of veins
Function
Return the blood back to the heart
Structure
The blood is under low pressure so doesn’t need to be thick
Lumen is relatively large in order to easy the flow of blood
Have thinner layers of elastic tissue, collagen and smooth muscle
They contain valves to prevent the backflow of blood - these thin walls are surrounded by skeletal muscles that contract forcing the blood in the correct direction
How is plasma different from tissue fluid
Large molecules can’t pass through the capillaries into tissue fluid
e.g. large plasma proteins, white blood cells
Describe the formation of tissue fluid
Arteriole end
The hydrostatic pressure is higher then the oncotic pressure so the net movement of blood out forming tissue fluid. The fluid that is being pushed out leaves through gaps in the endothelium.
The blood leaving contains O2 and nutrients dissolved in it and it’s exchanged with CO2 and other waste
Venule end
The oncotic pressure remains the same as the large plasma proteins remain in the capillaries
The hydrostatic pressure is much lower due to loss of fluid so the net movement of tissue fluid is to enter the capillaries reforming plasma
Lymphatic system
Not all of the fluid renters the capillaries some is drained into the lymphatic system.
It is then returned to the blood system in the subclavian vein in the chest
Describe the composition of the fluid in the lymphatic system
The fluid is called lymph, it is similar composition to tissue fluid but will contain more lymphocytes as they are produced in the lymph nodes
Lymph nodes are swellings found along the lymphatic system
If a tissue is infected that capillaries become more leaky and fluid is directed towards the lymph nodes directing bacteria towards it.
This is part of the non specific immune response
What muscle is external of the heart and what vessel supplies this with oxygen and nutrients
Cardiac muscle and coronary artery supplies it
List the internal features of a heart starting at the top and going clockwise
Consists of 4 chambers 2 ventricles and 2 atriums
When describing the heart the left side is on the right and the right side is on the left
Aorta, left atrium, pulmonary vein, left ventricle, right ventricle, vena cava, right atrium and pulmonary artery.
Contains a tri (right) and bi (left) cuspid valve that separate the atria and ventricles
Contains semi lunar valves separating the arteries and ventricles
A septum separates both sides and the bottom of the heart is called the apex
Which side of the heart do we usually measure heat changes from
We measure the pressure changes at the left side of the heart.
The left ventricle has a much thicker wall as it has to has to generate more force in order to contract and send the blood around the body
Therefore systemic pressure is bigger then pulmonary pressure
Describe the blood flow in the heart
Deoxygenated blood enters the right atrium from the vena cava flows to the right ventricle and out of the pulmonary artery
The blood gets oxygenated at the lungs and returns to the blood via the pulmonary vein.
The blood enters the left atrium then the right ventricle and out of aorta to be sent to the rest of the body.
Describe the cardiac cycle including pressure changes
Atrial systole - The atrium is contracting and the ventricle is relaxing therefore the pressure
is higher in the atria then the ventricles. As a result the a-v valves are open
and blood is emptied into the ventricles
Ventricular systole - The ventricles are contacting and the atria are relaxing. The pressure in
the ventricles is higher then atrial and aortic pressure so a-v valves
close and the semi lunar valves open
Diastole - Both atria and ventricles are relaxing but pressure is higher in the atria as blood
enters from the veins, the a-v valves open and blood enters the ventricles
passively
The cycle starts all over again
Atria pressure is always relatively low due to its thinner walls
Why is blood flow higher when you are standing up as opposed to sitting down
Blood flow has to move against gravity up to your head so blood flow increases
Describe the electrical activity of the heart up to the AVN
The SAN initiates the wave of depolarisation which spreads over the atrial walls forcing them to contract
The wave of depolarisation reaches non conductive tissue (collagen) at the base of the atria so the wave has to go to the AVN. It’s the only route that can be taken
The wave is delayed at the AVN to allow the atria to fully contract
Describe the electrical activity of the heart after the AVN
The wave of depolarisation is sent down the bundle of HIS down the septum towards the apex.
The waves then spread outwards and up purkinje fibres causing the ventricles to contract from base upwards so all of the blood is pushed to the arteries
What does ECG stand for, how would you recognise a healthy persons one
Electrocardiograms
It consists of a P - atrial systole QRS - ventricular systole T - diastole waves
What are the types of other ECG’S
Tachycardia - Fast heartbeat
Bradycardia - Slow heartbeat
Ectopic - Heat skips or adds a beat
Fibrillation - Irregular heartbeat tends to fast
Describe a typical graph of saturation against pO2
The curve is a sigmoid
At low pO2 there is a low saturation as this is usually at respiring cells and tissues where oxygen needs to be unloaded
As pO2 increase saturation increases even quicker due to cooperative binding but then levels off as a higher pO2 is needed to become 100% saturated
How does fetal haemoglobin differ from adult haemoglobin
In the placenta there is a lower pO2 of oxygen so fetal haemoglobin needs to have a higher affinity then adult haemoglobin so it can bind to it when the oxygen is unloaded
What are the three ways of transport of CO2
In the plasma
Convert to carbonic acid
carbamino haemoglobinic acid
What is the effect when CO2 is present at respiring cells what happens
Co2 diffuses into erythrocytes and combines with water to form carbonic acid
This reaction is catalysed by carbonic anhydrase
Carbonic acid dissociates into H+ ions and HCO3-
The HCO3- diffuses out and is exchanged with Cl- (chloride shift)
The Hb has a lower affinity for oxygen so binds with H+ forming HHB
Also acts as a buffer
As a result oxygen is unloaded at the cells by oxyhaemoglobin
What is the effect when CO2 is present at respiring cells what happens
Co2 diffuses into erythrocytes and combines with water to form carbonic acid
This reaction is catalysed by carbonic anhydrase
Carbonic acid dissociates into H+ ions and HCO3-
The HCO3- diffuses out and is exchanged with Cl- (chloride shift)
The Hb has a lower affinity for oxygen so binds with H+ forming HHB
Also acts as a buffer
As a result oxygen is unloaded at the cells by oxyhaemoglobin
