Transport In animals Flashcards
Define mass transport
Movement of oxygen nutrients hormones waste and heat around the body
What are the three main reasons for a mass transport system
- diffusion distance is too far to meet demands
- surface area to volume ratio is low
- metabolic demands of large organisms is high
What makes a efficient circulatory system
A pump
A means of maintaining pressure
A transport medium
An exchange surface
What is an open circulatory system
The blood is not always maintained inside vessels but circulates the body cavity
What is a closed circulatroy system
The blood is always maintained inside vessels (arteries/ capillaries/ veins)
What is haemolymph
Blood and cell fluids
What happens in a open circulatory system
The heart pumps the transport medium, haemolymph into vessels, but vessels then empty into large cavities containing organs
What is the name for a open body
Haemocoel
What are the advantages of a closed circulatory system
1) maintenance of higher blood pressure
2) rate of flow/ delivery to certain organs can be controlled
3) flow can be directed to certain areas
What type of pressure is blood in a closed circulatory system under than in a open circulatory system
Higher pressure
Higher rate of flow
Why is a closed circulatory system better than an open circulatory system
More efficient at supplying the muscles
Deliver o2 and more quickly n remove CO2 and urea more quickly too
can direct blood to wherever needs more oxygen and nutrients
What is a single circulatory system
Blood passes through the heart once for each circulation of the body
What is a double circulatory system
Where blood passes through the heart twice for each circulation of the body
Give an example of a single and double circulatory system
Mammals- double
Fish-single
What are the advantages of a double circulatory system
The heart can increase the pressure of blood after it has passed through the lungs so blood flows more quickly
The systemic circulation can carry blood at a higher pressure than pulmonary circulation
Blood pressure may not be too high so not to damage the capillaries
Why is it that capillaries are easily damaged
Capillaries are one cell thick and so a high hydrostatic pressure here could be easily damaged
What causes the high pressure of the artery
The contraction of the ventricle muscle in the heart
Describe the structure of an artery which allows it to maintain and withstand a high pressure
Thick tunica externa with collagen
Thick elastic fibres
Thick smooth muscle
Folded endothelium
What happens when smooth muscle contracts
Lumen gets smaller: this maintains a high pressure
What do arterioles link
Links arteries and capillaries
What do arterioles have more of than arteries
What does this mean
Have more smooth muscle than arteries
So can constrict or dilate to control the flow of blood into individual organs
What blood vessel is responsible for vasoconstriction and vasodilation
Arterioles - smooth muscle contracts/relaxes limiting blood flow into organs
Why is the endothelium folded
So endothelium does not become damaged as artery wall stretches
How is wall adapted to withstand high pressure
Thick layer of collagen
Endothelium is folded
How is artery wall adapted to maintain high pressure
- Thick layer of elastic tissue( elastic fibres are able to stretch and recoil )
- Thick layer of smooth muscle to narrow lumen and construct artery
Where do veins carry blood
Back to the heart
Describe the blood in veins
Deoxygenated
Why is blood in the veins under low pressure
It has to be moved against gravity
Describe the structure of a vein
Thin elastic layer
Fibrous/tough outer layer of collagen
Thin smooth muscle layer
Smooth endothelium
Why do veins have valves
To prevent the back flow of blood
What do capillaries link
Links arterioles and venules in the tissue
Describe the wall of capillaries
One cell thick squamous endothelium
Small gaps between cells for passage of phagocytes and material in tissue fluid
Describe the lumen in capillaries
Small, so that one red blood cell flows at a time single file
Name four adaptations of the capillaries
Provide a very large SA for diffusion
Narrow lumen- blood flow decreases more time for diffusion
Lower pressure than arteries
One cell thick- short diffusion distance
What does the blood transport
Oxygen CO2 Waste Chemical messages ie Hormones Food molecules Platelets Cells and antibodies
What does the high pressure in the blood mean
A high hydrostatic pressure
This forces fluid out of the tiny gaps between endothelium cells in capillary
Name the components of tissue fluid
Glucose Amino acids Fatty acids Oxygen Neutrophils Hormones Vitamins
What moves across the cell surface membrane from the tissue fluid
Into-
Oxygen
Glucose
Amino acids
Out-
CO2
What is hydrostatic pressure
Pressure created by water in an enclosed system
What is oncotic pressure
The tendency of water to move into the blood by osmosis as a result of result of the plasma proteins that remain in the blood
What is the osmotic effect which plasma proteins have
Plasma proteins gives blood in the capillaries a lower water potential than tissue fluid
What is the formula for filtration pressure
Size of hydrostatic pressure- size of oncotic pressure
Describe pressure and movement of fluid at the:
Arterial end
Hydrostatic pressure bigger size than oncotic pressure
Fluid moves out from capillary
Describe pressure and movement of fluid at the:
At the venous end
Hydrostatic pressure smaller size than oncotic pressure
Fluid moves into Capillary
Name two examples of waste products that leave cells
Urea
CO2
What is the lymphatic system
A network of vessels throughout the body that absorb fluid and fatty acids
What happens to the contents of lymph
They are drained back into the bloodstream via two ducts that join a vein close to the heart
Why does the heart need constant supply of blood
The heart requires ATP to beat
The heart therefore requires a constant supply of oxygen in order to respite fatty acids
What is systole
A period of contraction of the cardiac muscle
What is diastole
A period of relaxation of the cardiac muscle
The heart muscle is myogenic what does this mean
How does it achieve this
It can initiate its own contraction
Pacemaker cells
Describe the cardiac cycle
Ventricular systole AV valve close SL valves open > Diastole Low pressure SL valve closed AV valve open > Atrial systole AV valve open sL valve closed t.
(Repeats)
In terms of pressure which way does blood flow
From a higher to a lower pressure
Describe the “lub-dub” sound we have as the heart beats
The first sound= atrioventricular valve close
Second sound= semilunar valve closes
Why does the left ventricle have a thicker wall
Because it needs to pump blood at a higher pressure
It also pumps blood further around the body
Why must the heart have constant blood supply
It is a working organ so requires ATP
Heart must have a constant supply of oxygen as muscle cells in the heart only respite fatty acids, to do this you need constant supply of oxygen
What is the units for heart rate
Bpm
What is stroke volume
The volume of blood pumped out by the left ventricle each time the hearts beats
what is cardiac output
The volume of blood pumped out by the left ventricle in one minute
Where is the sinoatrial node found
Top right of the atrium
What does the SAN do
Initiates a wave of excitation at regular intervals
How is the atria specialised so not to conduct the wave at the base of the atria
The base of atria is non conductive - prevents the spread over the ventricle walls
Where is the atrioventricular node
Top of the inter-ventricular septum
Describe the initiation and coordination of heart action
1) sinoatrial node initiates a wave of electrical excitation
2) spreads over the walls of the atria causing the cardiac muscle there to contract
3) the wave of excitation reach the AVN, it is delayed here to allow the complete contraction of the atria muscle, allowing blood to flow down into the ventricle before the muscle of ventricle starts to contract
4) the wave travels down conductive tissue called purkyne tissue
5) it reaches the base of the ventricles and spreads over the wall causing the muscle to contract from the base upwards (ventricular systole)
6) blood is pushed into the major arteries at top of the heart
7) heart goes into diastole
What is the job of electrocardiograms
Used to monitor the electrical activity of the heart
PQRST represents a normal ECG wave, explain what each letter represents
P- atria systole
QRS- ventricular systole
T- diastole
How does a ECG know when the heart contracts
It depolarises (loses electrical charge) when it contracts and
repolarises (regains charge) when it relaxes
What is tachycardia
When the heart rate is very rapid
More frequent peaks
What is bradycardia
When heart rate slows down
If a person has severe bradycardia, what may they need
An artificial pacemaker to keep the heart beating more steadily
What is ectopic heart beat
Extra heartbeats that are out of the normal rhythm
What is atrial fibrillation
When the beat is not coordinated the heartbeat is irregular and has lost its rhythm
Explain what happens in atrial fibrillation
Rapid electrical impulses are generated in the atria
The atria does not contract properly
Some of the impulses passed on to ventricles, which contract less often
What is arrhythmia an example of
Atrial fibrillation
What is the technical name for a blood clot in the coronary Artery
A myocardial infarction
Suggest the cause of an ECG which has a QRS complex that is smaller than normal
The ventricle muscle
Is not contracting properly
This could be because of muscle damage or because the AVN is not conducting impulses to the ventricle properly
How is a red blood cell specialised to achieve its function
It is biconcage shape
No nucleus- extra space inside for haemoglobin
Contain haemoglobin
What type of protein is haemoglobin
Quaternary protein
How many polypeptide chains and harm groups in haemoglobin
4 chains
4 haem groups
How many oxygen can one haemoglobin molecule carry
Each haem group can carry one
So each molecule of haemoglobin can carry 4 molecules of 02
How is the volume of oxygen measured, what are it’s units
Partial pressure
kPa
Finish the sentence:
The greater the volume of dissolved oxygen, the ……. its partial pressure
Higher
How does oxygen diffuse into the blood
There is a high partial pressure in the alveoli
Low Partial pressure in the blood
Diffuses from high to low
Haemoglobin associates oxygen
Haemoglobin has a high affinity, becomes saturated and forms oxyhaemoglobin
Where do erythrocytes take oxyhaemoglobin to
What happens here
Respiring tissues
It dissociates o2
What is the oxygen dissociation curve
% 02 saturation of haemoglobin plotted against the partial pressure of O2 in the surroundings
What shape is the oxygen dissociation curve
Sigmoid
S shaped
Why is the oxygen dissociation curve S shaped
Difficult for the first oxygen molecule to associate with haem group (which is in the centre of the molecule)
Binding of the first oxygen causes conformational change
Allows second n third oxygen molecules to associate with other haem groups more easily
But it’s very difficult for the fourth molecule to diffuse in and associate
describe fetal haemoglobin
Fetal haemoglobin associates with oxygen from the fluid in the placenta
Fetal haemoglobin has a higher affinity for oxygen
What is the partial pressure of oxygen like in placenta
Low partial pressure
In what partial pressure does fetal Hb associate
At lower partial pressure
How is carbon dioxide transported
5% dissolved into the plasma
10% is combined with haemoglobin to form carbaminoharmoglobin
85% transported in form of hydrogencarbonate ions
Describe the Bohr effect
Higher pCO2 due to more aerobic respiration
The curve shifts to the right
Haemoglobin has lower affinity for O2
So haemoglobin dissociates more O2 at a given partial pressure of oxygen
What is the advantage of the Bohr effect
Actively respiring tissue needs more oxygen
For aerobic respiration to make ATP
Actively respiring tissue creates more CO2
Lowered affinity of haemoglobin for oxygen
More O2 released at the same partial pressure of oxygen
Explain the formation of hydrogen carbonate ions
1) CO2 and H20 concerted by carbonic anhydrase into carbonic acid
2) carbonic acid dissociates into hydrogen ions and hydrogen carbonate ions
3) HCO3- carbonate ions diffuse into plasma
4) h+ bind with oxyhaemoglobin to release more oxygen
5) acid form haemoglobonic acid
6) low pCO2 at lungs causes reverse of the process
What can lower the affinity of haemoglobin for oxygen
CO2
