3.4.1 Mass transport in animals Flashcards
What type of organisms can rely on diffusion alone
Small organisms
Why do large organisms have to develop a transport system
Due to increasing size, their surface area to volume ratio has decreased to the point where the demand of the organism cannot be met by the body surface alone
What is a transport system required to do
To take materials from cells to exchange surfaces and from exchange surfaces to cells
What type of circulatory system do mammals have
A closed, double circulatory system
What does the term ‘closed’ mean when describing the circulatory system
All the blood vessels are connected in a circuit, meaning that the blood always remains in those blood vessels as long as there is no damage to the blood vessels
What does the term ‘double’ mean when describing the circulatory system
The blood passes through the heart twice in each circuit.
In mammals, where do the circuits deliver the blood to
- Delivers blood to the lungs
- Deliver blood to the rest of the body
Why do mammals require a double circulatory system
To manage the pressure of the blood
Why does the blood need to return to the heart after going to the lungs
Because when blood is passed through the heart, its pressure is reduced
Why does the blood flow through the lungs at a lower pressure (2 reasons)
- To prevent damage to the capillaries surrounding the alveoli
- Lower pressure = moving more slowly, enabling more time for gas exchange
What is the name of the circuit between the heart and the lungs
Pulmonary circulation
Why does the blood need be pumped again at the heart in order to get a higher pressure
To ensure that the blood reaches all the respiring cells in the body
In a circulatory system, what are the 3 key features
- Transport fluid
- Pump
- Series of tubes
In mammals, what is their pump
Heart
In mammals, what is their transport fluid
Blood plasma
In mammals, what is their series of tubes
Blood vessels
What is the name of the circuit between the heart and the rest of the body called
The systemic circulation
In pulmonary circulation, what type of blood is carried from the heart to the lungs
Deoxygenated
In pulmonary circulation, what type of blood is carried from the lungs to the heart
Oxygenated
In pulmonary circulation what vessel carries blood from the heart to the lungs
Pulmonary artery
In pulmonary circulation, what vessel carries blood from the lungs to the heart
Pulmonary vein
In systemic circulation, what type of blood is transported from the heart to the rest of the blood
Oxygenated
In systemic circulation, what type of blood is transported from the rest of the body to the heart
Deoxygenated
In systemic circulation, what vessel carries blood from the heart to the rest of the body
Aorta
In systemic circulation, what vessel carries blood from the rest of the body back to the heart
Vena cava
Where does the coronary arteries carry blood to
Supply the heart, the cardiac muscle, with oxygenated blood
What are the 4 major blood vessels that enter/ exit the heart
- Veins - Vena cava, Pulmonary vein
- Arteries- Aorta, Pulmonary artery
What are the 2 blood vessels connected to the lungs
- Pulmonary artery
- Pulmonary vein
What are the 2 blood vessels connected to the kidneys
- Renal artery
- Renal vein
What type of muscle is the heart made of
Cardiac muscle
What does the word ‘myogenic’ mean when describing the heart
Meaning that the muscle can contract or relax without any input from nervous system or hormones
What are the 2 unique properties of the cardiac muscle
- It myogenic (it can contract and relax without stimulation)
- It never fatigues, as long as it has a supply of oxygen
Where do the coronary arteries branch off from
The aorta
What is myocardial infarction
A heart attack
What causes a heart attack
Blockages in the coronary arteries- since oxygenated blood is not being supplied to the cardiac muscle so they can not respire
What are the 4 chambers in the heart called
- Left atrium
- Right atrium
- Left ventricle
- Right ventricle
Are the walls of the atria or the ventricle thicker
The ventricles have thicker muscular walls
Why are the muscular walls of the atria thinner than the muscular walls of the ventricles
As they don’t need to contract as hard as they aren’t pumping blood far (only to the ventricles)
Why does the atria have elastic walls
To stretch when the blood enters
Why do ventricles have thicker muscular walls compared to atria
To contract with greater force to push to blood out at higher pressure
Why do the ventricles need to create a higher blood pressure when contracting than atria
To enable blood to flow a longer distance (R ventricle to the lungs, L ventricle to the rest of the body)
Which ventricle wall is thinner the left or right
The right ventricle wall is thinner
Why does the right ventricle have thinner walls
Because it pumps blood to the lungs, and we don’t want too high of a pressure in the lungs (could damage capillaries, and it needs to be slow for gas exchange)
Why does the left ventricle have a thicker muscular wall
It needs to contract with the highest force to pump the blood out at the highest pressure. The blood is going to the rest of the body
What type of blood vessels bring blood into the heart
Veins
What type of blood vessels take blood away from the heart
Arteries
What are the 2 veins into the heart
- Vena cava
- Pulmonary vein
What type of blood does the vena cava carry
Deoxygenated blood
Where does the vena cava carry blood from and to in the heart
From the blood
Into the right atrium
What type of blood does the pulmonary vein carry
Oxygenated blood
Where does the pulmonary vein carry blood from and to in the heart
From the lungs
Into the left atrium
What are the 2 arteries connected to the heart
- Pulmonary artery
- Aorta
What type of blood does the pulmonary artery carry
Deoxygenated blood
Where does the pulmonary artery carry blood from and to
From the right ventricle
To the lungs (to become oxygenated)
What type of blood does the aorta carry
Oxygenated blood
Where does the aorta carry blood to and from
From the left ventricle
To the rest of the body
What are the 2 types of valves in the heart
- Semi- lunar valves
- Atrioventricular valves
Where are the semi-lunar valves located
Between ventricle and artery
Where are the atrioventricular valves found
Between the atrium and the ventricles
What is another name for the atrioventricular valves on the right side of the heart
Tricuspid valve
What is another name for the atrioventricular valves on the left side of the heart
- Bicuspid valves
- Mitral valve
How many flaps / membranes are on the left atrioventricular valve
2
How many flaps / membranes are on the right atrioventricular valve
3
What is the role of valves
To prevent back flow of blood
When do valves open
When there is a higher pressure from behind
When do valves close
When there is a higher pressure from in front
What is the septum (in the heart)
A piece of cardiac muscle that runs all the way down the middle, separating the left and right side of the heart, separating the oxygenated blood from the deoxygenated blood
Why is separating the oxygenated and deoxygenated blood (the septum) important
The oxygenated blood isn’t being diluted by the deoxygenated blood. There is a very high concentration of oxygen within the oxygenated blood, this maintains concentration gradient which enables diffusion at respiring cells
What are the 3 stages of the cardiac cycle
- Diastole
- Atrial systole
- Ventricular systole
What does diastole mean
Relaxing
What does systole mean
Contracting
What is the atria and the ventricles are doing during diastole
Both are relaxing
Why does the blood flow into the atria during diastole
Since the muscles are relaxing which increases the volume therefore decreasing the pressure and blood always flows down a pressure gradient
What does the blood flowing into the atria do the the pressure in the atria
It increases the pressure
What happens to the atria muscular walls and the ventricle muscular walls during atria systole
- Atria contract
- Ventricle are still in diastole
What does the contracting of the atria muscular walls do to the pressure in the atria
It increases it further (it increased when blood flowed into it) as the volume decreases
What does the pressure increase in the atria during atrial systole do to the atrioventricular valves
They’re forced open so blood can flow from the atrium into the ventricle
What happens to the atria and ventricles during ventricular systole
Atria- muscular walls relax
Ventricle- muscular walls contract
What does the contracting of the ventricular muscular walls do to the volume and pressure in the ventricles
Volume- decreases
Pressure- increases beyond that of the atria
What happens to the atrioventricular valves during ventricular systole
They close
What happens to the semi-lunar valves during ventricular systole
They open- the blood is pushed out of the ventricles into the arteries
What is the cardiac cycles
The sequence of events that happen in a single heart beat
What is cardiac output
The volume of the blood which leaves one ventricle in 1 minute
What is the calculation for cardiac output
Cardiac output= stroke volume x heart rate
What is meant by heart rate
Beats of the heart per minute
What is meant by stroke volume
Volume of blood that leaves the heart each beat
When do the atrioventricular valves open
When the pressure is higher in the atria compared to the ventricles
When do the atrioventricular valves close
When the pressure is higher in the ventricles compared to the atria
When do the semi- lunar valves open
When the pressure is higher in the ventricles compared to the arteries (pulmonary artery and aorta)
When do the semi- lunar valves close
When the pressure is higher in the arteries compared to the ventricles
What are the 5 types of blood vessels
- Arteries
- Arterioles
- Capillaries
- Venules
- Veins
What blood vessel is the site of exchange
Capillary
What happens to the total cross-sectional area as the blood flows away from the heart to the capillaries, and why
It increases since the vessels divide and divide so there are more vessels
Why does the pressure fall as the blood vessels get smaller
Because the friction increases
What does the lower pressure in smaller vessels do to the rate of blood flow
It slows it
Through which blood vessel does blood move through the slowest
The capillaries
What is the benefit of blood flowing through the capillaries slowly
Allow more time for exchange
In which vessel in the blood pressure the highest
The aorta
Why doesn’t blood pressure fall to zero in the aorta
Because the semi-lunar valves close during ventricular diastole so the ventricle volume increases so the pressure decreases but since the valve is closed the pressure remains high in the aorta
What is the lumen of the arteries/ arterioles like
Narrow in relation to total diameter, therefore HIGH RESISTANCE to blood flow which maintains blood pressure
What are the walls of arteries/ arterioles like
- THICK smooth muscle layer in walls which contract/ relax therefore altering the blood pressure
- THICK elastic tissue layer which expands with each pulse of blood and recoils- maintaining HIGH PRESSURE
What are the only arteries which valves
- Aorta
- Pulmonary artery
What is the lumen of veins/ venules like
WIDE lumen in relation to diameter, therefore LESS RESISTANCE to blood flow which helps blood return to the heart
What are the walls of veins/ venules like
- THIN smooth muscle layer- less muscle to contract so will not narrow lumen to resist blood flow
- THIN elastic tissue layer- as there is no need for expansion during each pulse of blood so no need for recoil
What valves do veins/ venules have
Semi-lunar valves that prevent the back flow of blood
What is the lumen of capillaries like
- NARROW lumen causes increase in total cross-sectional area, so more surface is in contact with blood, causing GREATER FRICTION between blood and capillary wall- causing a loss of blood pressure
What does the low blood pressure in the capillaries do to the flow of blood, and why is this good
It slows the flows, allowing more time for exchange
What are the walls of the capillaries like
- Made from SINGLE and FLATTENED layer of ENDOTHELIAL cells - which reduces diffusion pathway
- Has small pores (fenestrations) making it permeable so small molecules can filter out
Do capillaries contain valves
No
How do arteries WITHSTAND high pressure
They expand since they contain elastic fibres
How do arteries MAINTAIN high pressure
They recoil using their elastic fibres
What type of muscles contract and squeeze the vein
Skeletal muscle
How does the contraction of skeletal muscles aid venous return
- They bulge when they contract which squeezes the veins
- This decreases the volume of the veins, which increases the pressure of the vein
- This causes the blood to be forced through the valves in front of the point of contraction and the valve behind to point of contraction to close.
- Ensuring an unidirectional flow of blood
What 2 things create a suction effect during venous return
- Atria diastole- the pressure in atria is lower than the blood pressure- blood moves down a pressure gradient
- Inhaling- the pressure of thoracic cavity decreases and the volume increases, so blood is sucked back to the heart, that is located in the thoracic cavity
What are the 4 main functions of blood
- Transport fluid
- Immunological (immune system)
- Thermoregulation
- Maintaining pH of body tissues
What percentage of blood is made up of cells
about 45 %
What % of blood is made up of plasma
About 55%
What is the real name of RBC
Erythrocytes
What is the role of erythrocytes
To transport oxygen
What is the real name of WBC
Leukocytes
What is the role of leukocytes
Immune system
What is the name of the cells in blood that clot the blood
Thrombocytes
What 7 things are in blood plasma
- Water - 92 %
- Plasma proteins
- Ions (K+, Na+, Cl-, Ca2+)
- Nutrients (glucose and amino acids)
- Waste (urea)
- Hormones
- Gases (oxygen and carbon dioxide)
What are the 4 features of a erythrocyte
- Flattened, biconcave shape
- No organelles
- Diameter is greater than that of the walls of the capillary
- High concentration of haemoglobin
Why is a erythrocyte being flattened and have a biconcave shape beneficial
It increases the surface area to volume ratio which in turn increases the efficiency of oxygen exchange
Why is it beneficial to a erythrocyte to have no organelles
Allows for maximum space for haemoglobin so for oxygen transport
Why is the diameter of a RBC being greater than that of the walls of the capillaries a benefit
The RBC has to squeeze through which shortens the rate of flow allowing for more time for exchange
Why is a high concentration of haemoglobin beneficial to erythrocytes
It transports oxygen so the more haemoglobin the more oxygen
Is the hydrostatic pressure higher at the arterial end of the capillary or the venous end
Arterial end
What is tissue fluid
Fluid that surrounds the cells of the body. Its composition is similar to that of blood plasma except that it lacks proteins. It supplies nutrients to the cells and removes waste products.
What is the name of the process where tissue fluid is forced out of the capillary at the arterial end due to hydrostatic pressure
Ultrafiltration
What pressure is created by the heart pumping
Hydrostatic pressure
Capillaries contain pores, what is the scientific name for these pores
Fenestrations
What is the name of the membrane that surrounds the capillaries and stops large molecules from passing
Basement membrane
What 2 things remain in the capillary after ultrafiltration, and why are these left in there
- Large plasma proteins
- Blood cells
Since the basement membrane acts as a barrier to larger molecules
What happens to the water potential of the capillary as it flows from the arterial end to the venous end
The water potential decreases
What happens to excess glucose in the tissue fluid
It returns to the blood
What does the lymph system do
It drains excess tissue fluid and returns it to the blood
How are the contents of the lymphatic system moved (2 things)
- Hydrostatic pressure of the tissue fluid that has left the capillary
- Contraction of body muscles that squeeze the lymph vessels- valves in the lymph vessel ensures that the fluid inside them moves away from the tissues in direction of the heart
How do capillaries and lymph vessels differ
Capillaries have pores (fenestrations) whereas lymph vessels have overlapping walls which open under the weight of excess tissue fluid
Why are lymph vessels blinded-ended
This ensures that they have a unidirectional flow of lymph (excess tissue fluid)
What type is molecule is haemoglobin
A protein
How many polypeptides chains make up a haemoglobin molecules
4
What does haemoglobin transport
Oxygen
What ion does a haem group contain
Fe 2+
How many molecules of oxygen does each haem group combine with
One oxygen molecule
What is the name of process given to the process by which haemoglobin binds with oxygen
Association or loading
What is the name of the process by which haemoglobin releases oxygen
Dissociation or unloading
What does affinity mean with respect to haemoglobin
The ability of haemoglobin to attract, or bind, to oxygen
If haemoglobin has high affinity, what does this mean
Oxygen concentration is high- it will readily associate with oxygen and dissociate with it less easily
If haemoglobin has low affinity, what does this mean
Oxygen concentration is low- means that it will readily dissociate and associate less easily
To be good at transporting oxygen, what 2 characteristics must haemoglobin have
- Load with oxygen at the gas exchange surface
- Unload oxygen at respiring tissues
How does haemoglobin change its affinity for oxygen
By changing its shape when in the presence of certain substances (like CO2)
What is the name given to the increasing ease with which the 2nd, 3rd and 4th oxygen molecules combine with haemoglobin
Cooperative binding
What is the saturation of haemoglobin with oxygen
When haemoglobin is holding the maximum amount of oxygen it can bind
Describe the quaternary structure of haemoglobin
2 pairs of polypeptides (alpha and beta) link to form a spherical molecule. Each polypeptide has a game group that contains a Fe2+ ion
Describe the shape of the oxyhaemoglobin dissociation curve
Sigmoid (s-shaped)
When is the haemoglobin almost completely saturated
When oxygen is loaded in regions of high partial pressures of oxygen (e.g. in the alveoli)
If haemoglobin’s affinity is lower, what is the partial pressure of oxygen like
Lower partial pressure of oxygen
Where is oxygen unloaded (partial pressure and haemoglobins affinity)
In regions of lower partial pressure of oxygen, where haemoglobin has a lower affinity
Why is there a low saturation of oxygen at low partial pressures of oxygen
Since the 1st oxygen molecules to bind to haemoglobin is very difficult
Why is the 2nd and 3rd oxygen molecules easier to bind to the haemoglobin than the 1st oxygen molecule
Since haemoglobin is a protein so the shape changes.
What is the Bohr effect
When a high concentration of carbon dioxide causes the oxyhaemoglobin curve to shift to the right
When the oxyhaemoglobin curve shifts to the right, what happens to the haemoglobin’s affinity for oxygen
The affinity has decreased
What does the shift to the right of the oxyhaemoglobin curve do, does it make Hb more readily load or unload, and why
Unload since the affinity for oxygen has decreases
Why does the steepness of the curve, in the middle of the oxyhaemoglobin dissociation curve, help tissue function more efficiently
There is a small decrease in partial pressure of oxygen, results in a large decrease in % saturation so the oxygen goes to the tissue, so the tissues can aerobically respire which is more efficient than anaerobic respiration
What does increased partial pressure of carbon dioxide do to the pH of blood and to the Hb affinity for oxygen
-Lowers the pH of the blood
-Lowers the affinity of Hb for oxygen
At higher partial pressure of carbon dioxide is more or less oxygen unloaded at the same partial pressure of oxygen
More is unloaded, so overall more oxygen is released to the tissue
What 2 types of haemoglobin (on the spec) that causes a shift to the left in the oxyhaemoglobin curve
- Foetal
- Llama
How does foetal haemoglobin differ to adult haemoglobin
Foetal Hb has a higher affinity for oxygen, even at the same partial pressure of oxygen
Why does Foetal Hb need to have a higher affinity for oxygen that adult Hb
Because they can’t inhale so their only source of oxygen is from the mothers Hb in the blood supply through the placenta
How does llamas Hb differ from human Hb
Llamal Hb has a higher affinity for oxygen
Why do llamas need a higher affinity for oxygen than humans
Since they live in an oxygen deficit environment
Give 2 structural features of an aorta wall and explain how they are related to the function of an aorta (2 marks)
- Smooth muscle withstands high blood pressure
- Elastic tissue stretches and recoils to maintains blood pressure
- Smooth endothelium reduces friction
- Protein coat prevents artery wall splitting
High absorption of salt from the diet can result in a higher than normal concentration of salt in the blood plasma entering capillaries. This can lead to a build up of tissue fluid. Explain how (2 marks)
- (Higher salt) results in lower water potential of
tissue fluid; - (So) less water returns to capillary by osmosis
(at venule end);
OR - (Higher salt) results in higher blood
pressure/volume; - (So) more fluid pushed/forced out (at arteriole
end) of capillary;
