3 - ICH - Mammalian transport Flashcards
Why do large animals need transport systems but very small animals (single celled or composed of a few cells) don’t?
VERY SMALL ANIMALS:
- Cells are very close to the enviroment
- ∴ diffusion supplies enough oxygen and nutrients and allow the safe removal of any waste products
LARGE ANIMALS:
- Complex anatomy consists of many layers of cells which cannot rely on diffusion through body surfaces as diffusion distance is too long ∴ need transport systems
3 factors that influence the need for a transport system
Explain each of them
SIZE:
- Cells inside a large organism are furthur from its surface ∴ diffusion becomes too slow to supply all its requirements
SA : VOL RATIO:
- Small animals have large SA : Vol ratio
- Means for every gram of issue they have sufficient arrea of body surface through which exchange can take place
- Large animals have a smaller SA : Vol ratio
- Each gram of tissue has a smaller area of body surfacefor exchange
METABOLIC ACTIVITY:
- Need energy from food to carry out life processes
- This energy is released by aerobic respiration
- The more active the animal, the greater its requirement for energy meaning the rate of respiration in cells mst be higher
- Respiring cells require a supply of O2 and respiratory fuel and to get rid of CO2. The more active they are, the greater tje demand for efficient exchange
- 3 features of an effective transport system
- List 2 other ‘things’ an efficient transport system will inclde aside from the 3 features
Features of an effective transport system:
- A fluid (blood) to carry nutrients, O2 and wastes around body
- A pump (heart) to create pressure that will push the blood around the body
- Exchange surfaces that allow substances to leave and enter the blood via the capillaries
Will also include:
- Vessels to carry bloof by mass flow
- 2 circuits
- One to pick up O2 and another to delivery O2 to tissues
What is a:
Double/ single circulatory system
Open/closed circulatory system
Give an example of each
Double circulatory system = Blood passes through heart twice during one cycle e.g. humans
Single circulatory system = Blood passes through heart once during a cycle e.g. fish
Open circulatory system = Blood is not always in blood vessles e.g. a beetle
Closed circulatory system = Blood is always in lood vessles e.g. humans
Open circulatory systems:
- Define
- What is it
- Structure, function, how it works
- Example(2)
- Disadvantages (2)
Open circulatory systems = Circulatory system where blood is not always in blood vessles
S + F:
- In animals with open circulatory systems blood fluid circulates through the body cavity so that tissues and cells are bathed directly by the blood
- Movements of the body help to circulate the blood, when the animal is still the blood stops moving so the transport of O2, CO2 and nutrients stops
- Some animals with open circulatory systems have a muscular pumping organ like a heart
- Means circulation can continue even when animal is immobile
EXAMPLE:
E.g. insects have a long muscular tube lying just under the dorsal (upper) surface of the body
- Blood from body enters this heart through pores (ostia)
- Heart then pumps blood towards head by peristalsis
- Blood then returns to the body cavity
- This modification means the circulation continues when the animal is at rest
- E.g. larger active insects like locusts have open ended tubes attaches to the heart which directs blood towards active parts of the body*
- ve = Low blood pressure and slow blood flow
- ve = Circulation of the blood may be affected by body moments or the lack of them
Explain the mechanism behind how the circulatory system of insects work (5)
It supplies the insect’s cells with nutrients and transports substances around the body BUT doesn’t supply the insect’s cells with O2 though - that is done through the tracheal system
- Heart is segmented
- It contracts in a wave, strating from the back, pumping blood into a single main artery
- This artery opens up into the body cavity
- Blood flows around the insects organs, gradually making its way ack into the heart segments through a series of valves
Outline the basic structure of a closed circulatory system in a pathway type diagram
What type of animals have:
- Open circulatory systems
- Closed circulatory systems
All vertebrates have closed circulatory systems
Some invertebrates e.g. insects have open circulatory systems
In a simple diagram what do each of these include:
- Single circulatory system
- Double circulatory system
Use examples to illustrate each answer
SINGLE CIRCULATORY SYSTEM e.g. fish
Heart → Gills → Body → Heart
DOUBLE CIRCULATORY SYSTEM e.g. mammals
Heart → Lungs → Heart → Body → Heart
Single circulatory systems:
Explain through an example
- What is the blood pressure like throughout the system
- Rate at which materials are delivered / removed
E.g. Fish
Heart → Gills → Body → Heart
- Blood pressure drops as it passes through the gills
- Blood pressure is low as it enters the body so will only flow slowly
- The rate at which materials are delivered to and removed from the respiring tissues is limited
Why are fish able to function with a single circulatory system but humans wouldn’t be able to
- Fish are not as metabollically active as mammals and bird and don’t have to maintain their body temperature ∴ don’t require as much energy.
- Single circulatory system delivers sufficient oxygen and nutrients for their needs.
What is the double circulatory system split into?
Pulmonary circulation = Part of the circulatory system carrying blood fro heart → lungs then back to the heart
Systemic circulation = Part of the circulatory system carrying blood from the heart → rest of the body and then back to the heart
3 advantages + 1 disadvantage of a double circulatory system
+ve = Oxygenated / deoxygenated blood is kept completely seperate
- By not mixing the blood flowing to the tissues, it’s always saturated with O2
+ve = Blood always returns to heart at a very low pressure
- Having just passed through the capillary networks of the lungs or body, so needs to recieve a pressire boost before beign sent to the pulmonary or systemic circulations
-ve = Blood pressure must not be too high in the pulmonary circulation
- Otherwise it might damage the capillaries in the lungs
Systemic circulation can carry blood at higher pressure than the pulmonary circulation
Name the 5 blood vessels you need to know
Artery
Arteriole
Vein
Venule
Capillary
Structure + Function: (6)
Arteries and arterioles
Arteries / arterioles transport blood rapidly and under high pressure
Relatively thick elastic layer:
- When blood is forced into arteries, they expand, stretching elastic fibres. Recoiling of these elastic fibres helps smooth out the blood flow
Many muscle fibres in the elastic layer:
- Contraction of muscles in the walls of arterioles allows the amount of blood flowing to tissues to be controlled
Contains collagen fibres:
- Provides a tough outer layer and prevents the artery from rupturing under the pressure of the blood within it
Large overall thickness of wall:
- Resists rupturing of artery under high blood pressures
Relatively narrow lumen:
- Helps to maintain high pressure
Smooth inner single layer of endothelium cells:
- Is a very smooth layer and enables blood to flow with little friction
Structure + Function: (7)
Veins and venules
Vein / venules return blood under relatively low pressure from the tissues to the heart
Relatively thin elastic layer:
- Blood at low pressure in veins won’t rupture them
- Pressure is too low to crease a recoil action
Muscular wall is relatively thin:
- Veins carry blood away from tissues ∴ can’t control the flow of blood to tissues
Contains collagen fibres:
- Provides a tough outer protective layer
- Not to protect veins from internal pressure but from external damage as veins are found nearer to skin surface ∴ more likely to be damaged
Small overall thickness of wall:
- Low blood pressure means there’s little chance of bursting ∴ no need for thick wall
Semi-lunar valves throughout:
- Prevent backflow of blood as blood preasure is low
Large lumen:
- Reduces friction
Smooth inner single layer of endothelium cells:
- Enables blood to flow with little friction
What do these photos show?
1 = Artery
2 = Vein
Structure + Function: (5)
Capillaries
Capillaries are the site of exchange between the tissues / blood and blood / tissues
Walls are one cell thick (endothelial tissue) and are very thin:
- Reduce diffusion distance
CSM very permeable with small gaps between these cells:
- Allow substances to pass rapidly between the blood and tissue fluids
Large number of capillaries:
- Large SA for exchange by diffusion
No cell far apart from a capillary:
- Short diffusion distance
There’s a continual flow of blood through capillaries:
- Maintains high conc gradients needed for successful diffusion both into / outof the capillaries
How is the conc gradient required for succesful diffusion of substances between the blood and tissue fluid maintained?
The constant uptake of substances by the cells from the tissue fluid and theur release of waste products back into the tissue fluid - helps maintain the conc gradients required for the successful diffution of substances between the blood and tissue fluid
What is a sphincter?
Structure + Function?
Sphincter = a ring of circular muscle present in an arteriole supplying a capillary network
When sphincter is relaxed:
- Lumen of arteriole is open
- Blood flows through capillary network
When sphincter contracts:
- Lumen of artieriole is closed
- Blood won’t flow through capillary network and is diverted along a shunt vessel
State the components of the blood (2)
Approximately 55% plasma and 45% red and white blood cells
Structure + Function of the blood:
Plasma
What does it carry? Give examples
- Blood plasma = 90% water and 10% chemicals, which are either dissolved or suspended in it
- Function of plasma = to transport chemicals, along with heat.
Chemicals include:
- Nutrients - e.g. glucose amino acids & vitamins
- Waste products - e.g. urea
- Mineral salts - e.g. calcium & iron
- Hormones - e.g. insulin
- Plasma proteins - e.g. Fibrinigen, prothrombin (both used in blood clotting mechanism)
- Respiratory gases - e.g. O2 and CO2
Structure + Function of the blood: (4)
Erythrocytes
Distinct biconcace disc shape:
- Increases SA : Vol ratio for gas exchange
No nucleus, mitochondria and ER:
- Increases space available for more haemoglobin - red coloured globular protein responsible for transporting O2
There’s lots of them and they’re constantly being replaced as old ones die through apoptosis:
- Life span of approx 120 days
- Made in the bone marrow from special undifferentiated cells
Easily change shape:
- Need to squeeze through the narrowest capillaries
- On entering capillaries they become bell-shaped and flattened against capillary walls ∴ reducing diffusion distance & speading up gas exchange of O2 between RBC’s and the tissues
Structure + Function of the blood: (6)
Leucocytes
- Main function of white blood cells (leucocytes) = defence
- Larger than RBC’s and have all the organelles in a eukaryotic cell
- In most cases their nuclei are large and often spherical or irregular in shape
- Some types of leucocytes can leave the blood by squeezing through gaps in the capillary wall
Divided into 2 types:
-
Phagocytes e.g. neutrophile & monocytes
- Revoce microorganisms and other foreign material by phagocytosis
-
Lymphocytes
- __Act against microorganisms by secreting antibodies
What is tissue fluid
Tissue fluid = Solution that surrounds every cell in the body and forms a link beween blood in the capillaries and the cells themselves
Describe the sequence of events to the formation of tissue fluid
- Blood contains H2O and dissolved substances e.g. glucose and amino acids
- Blood enters capillary network from arteriole at relatively high pressure caused by the contraction from the heart - causes high hydrostatic pressure
- This hydrostatic pressure forces H2O and small molecules out through the walls of the capillaries itno the surrounding tissues
- This fluid forced out of the capillaries = Tissue fluid
- Blood still contains large suspended molecules e.g. plasma proteins which are too large to cross the capillary wall which makes the ψ inside capillaries more negative
- At some point the ψ inside capillaries will be more negave than ψ of tissue fluid ∴ H2O will diffuse down ψ grad back into capillaries. Some small moelcules may diffuse back into blood as well - this grad is called oncotic pressure
Arteriole end:
- hydrostatic pressure > oncotic pressure
- Net outflow of substances from blood into tissue fluid
Venule end:
- oncotic pressure > hydrostatic pressure
- Net inflow of substances from tissue fluid into blood
Why are tissues bathed in tissue fluid? How is this possible?
Arteriole end:
- hydrostatic pressure > oncotic pressure
- Net outflow of substances from blood into tissue fluid
Venule end:
- oncotic pressure > hydrostatic pressure
- Net inflow of substances from tissue fluid into blood
Movement of substances in solution out of the capillaries is greater than return flow ∴ excess fluid bathes the tissues
What happens to the excess fluid when forming tissue fluid? Where does it go? (5)
- Excess fluid drained into lymph vessels
- Lymph vessels merge to form large vessels which forma network around the body called the lymphatic system
- These vessels drain their contents back into the blood stream via 2 ducts in the thorax
- Before returning to the blood, lymph will have passed through ≥ 1 lymph node (these play a important part of body defence)
- As a result the volume of lmph in the lymph vessels remain constant
What are the 3 ways in which lymph is moved around the body?
- Hydrostatic pressure of the tissue fluid leaving the capillaries
- Contraction of body muscles squuezes the lymph along the lymph vessels. Valves prevent back-flow
- Enlargement of the thorax during breathing in which reduces pressure in the thorax, drawing lymph into this region and away from the tissues
EXAM TIPS ON TISSUE FLUID QUESTIONS:
What are the key points?
Describe the key structures of the mammalian heart (10)
- The heart functions as a pump which produces most of the pressure that pushes the blood through blood vessels in the body
- Made of specialised muscle = cardiac muscle which doesn’t tire
- 2 sides of the heart is seperated by a muscle wall called septum
- Each side contain 2 chambers:
- Atria at the top have thin muscle walls (only pumping blood to lungs)
- Ventricles at the bottom have very thick muscular walls (pumping blood around whole body)
- Atria and ventricles are seperated by the atrioventricular wall
- 2 types of valves present:
-
Atrioventricular valves between the atria and ventricles
- Bicuspid / mitral (2 flaps) = on the left
- Tricuspid (3 flaps) = on the right
- Semi-lunar valves at the base of the pulmonary artery and aorta
-
Atrioventricular valves between the atria and ventricles
Lable this basic diagram of the mammalian heart
Lable this diagram of the mammalian heart
Draw a large flow chart to represent where the blood goes in one full cycle
In terms systole and diastole summarise the cardiac cycle and the heart beat in 7 points
Describe the sequence of events that bring about the heart beat (7)
- Wave of excitation spreads out from SAN across both atria causing them to contract
- A layer of non-conductive tissue (septum) prevents the wave crossing to the ventricles
- The wave of excitation is allowed to pass through a second group of cells called the AVN - lies between the atria
- After a short delay, AVN conveys a wave of excitation between the ventricles along a series of specialised muscle fibres - Bundle of His
- The bundle of His conducts the wave through the septum to the base of the ventricles, wehre the bundle branches into smaller fibres - The Purkyne tissue
- Wave of excitation is released from the Purkyne fibres, causing ventricles to contract simultaneously from the apex of the heart upwards ∴ forcing blood through the semilunar valves into the pulmonary artey & aorta
NOTE: Short delay allow atria to contract before the ventricles contract so the ventricles can fill up with blood
What is the purpose of a electrocardiogram?
What does it measure?
What do the letters on the trace represent?
Use Electrocardiogram (ECG) to record the electrical activity of the heart, though ECG’s doesn’t measure it directly!
- It measures tiny electrical differences in your skin, which result from the electrical activity of the heart
- P wave = Caused by atrial systole
- QRS complex = Caused by ventricular systole
- T wave = Diastole
What is considered to be the normal heart rate?
Define
Tachycardia
Bradycardia
Ectopic heart beat
Arrhythmia
Normal heart rate = 60 - 100 bpm
Tachycardia = Heart beat too rapid > 100 bpm
Bradycardia = Heart beat too slow < 60 bpm
Ectopic heart beat = Extra heart beat
Arrhythmia = Abnormal rhythm of the heart
State the 5 different types of heart beat you can get from analysing a ECG - What will the ECG’s look like compared to the normal one?
Sinus rhythm (normal)
Tachycardia - fast HR
Bradycardia - slow HR
Ectopic heart beat - An early ventricular beat
Atrial fibrillation - No clear P wave seen
Desribe what’s happen from A - F
1 = Semilunar valves open
2 = Atrioventricular valves open
3 = Semilunar valves close
4 = Atrioventricular valves open
A:
- Atrial systole, blood is forced into ventricles ∴ atrial pressure is increasing
B:
- Ventricles start to contract so ventricular pressure > atrial pressure ∴ atrioventricular valves close
C:
- Pressure in ventricle > pressure in aorta ∴ aortic valve opens and blood flows from ventricles into the aorta and pulmonary artery ∴ volume in ventricles decrease
D:
- Aortic valve is closed as ventricular pressure < aortic pressure
E:
- Ventricular diastole ∴ pressure in ventricles are decreasing
- Volume of ventricles are increasing as it’s being filled with blood again by atrias
- Atrioventricular valves are open
F:
- Atria are filling with blood from either superior/inferior vena cava or the pulmonary vein
- Atrial pressure > ventricular pressure ∴ blood flows from atria into ventricles
Calculate the number of beats per minute
No’ of beats per minute = 60 / time taken for 1 heart beat
Time for one heart beat = 0.6s
No’ of beats per minute = 60 / 0.6 = 100 bpm
Describe what’s happening at points a, b and c
A:
- Low pO2
- Few haem groups are bound to oxygen ∴ haemoglobin doesn’t carry much oxygen
B:
- Higher pO2
- More haem groups are bound to oxygen, making it easier for more oxygen to be picked up
C:
- Haemoglobin becomes saturated at very high pO2 as all the haem groups become bound
Where does uptake of oxygen occur?
Where is oxygen released?
Uptake of oxygen - in capillaries in the lungs
- As pO2 increases, amount of oxygen that combines with haemoglobin increases
- Uptake is initially slow, then rapid and then it slows again
This is because:
- The 1st oxygen molecule binds to the haemoglobin causing a conformational change in its tertiary structure
- The makes the uptake of the next 2 molecules of oxygen more rapid
- The final molecule of oxygen binds more slowly as there is only 1 binding site remaining
Release of oxygen - occurs in capillaries adjacent to respiring tissues
- As pO2 decreases, the amount of oxygen that combined with haemoglobin decreases, oxygen is being released
- The rate of release is initially slow, then rapid, then slow again
- Release is slow until a critical oxygen conc is eached in the issues - unloading tension
- Causes rapid release of oxygen from oxyhaemoglobin in actively respiring tissues which have a high demand for oxygen
- In region Y - A small decrease in pO2 of oxygen results in the release of lots of oxygen
Summarise what’s happening on the left and right sides of the graph
The more to the left the curve is:
- The more readily the respiratory pigment associates with oxygen
- i.e. the more easily the pigment loads up the oxygen
- BUT the less likely it dissociates from oxygen
- i.e. the pigment doesn’t unload its oxygen easily
The more to the right the curve is:
- The less readily the respiratory pigment associates with oxygen
- i.e. the pigment doesn’t load with oxygen easily
- BUT the more easily it dissociates from oxygen
- i.e. the pigment unloads its oxygen easily
What does the Bohr effect illustrate?
Why is it important in the body? (2)
Bohr effect = As pCO2 increases, haemoglobin gives up O2 more easily
- In active tissues with high pCO2, haemoglobin gives up its O2 more easily
- In the lungs where the proportion of CO2 is relatively low, O2 binds to the haemoglobin molecules easily
Use a graph to explain the Bohr shift
The ability of haemoglobin to transport O2 is also affected by the amount of CO2 present
- With increased amounts of CO2, the curve shifts RIGHT
- This means with increased CO2 haemoglobin will unload O2 more easily (the unloading tension occurs at a higher pO2) OR more O2 is released at the same pO2
- Very important during exercise as level of activiy increases, so does the rate of respiration of the muscle and so doe the amount of CO2 they will be producing
- This will result in more O2 being unloaded from haemoglobin where demand for O2 is at it’s highest
The difference between fetal and maternal haemoglobin? (4)
- At the same pO2 fetal haemoglobin unloads O2 much more easily than amthernal haemoglobin
- Fetal haemoglobin will become saturated at lower partial pressures (point A on graph) than maternal harmoglobin
- Fetal mammals produce their RBC’s in the liver and the haemoglobin produced in these cells has 2 polypeptide chains instead of the standard 4 in adult harmoglobin.
- After birth, RBC production shifts to bone marrow and the haemoglobin produced will be resemble typical adult haemoglobin
Why dos fetal haemoglobin have a higher affinity for oxygen than adult haemoglobin?
Enables the transfer of oxygen to the fetus during developemnt as oxygen dissociates from haemoglobin in the mother’s blood in favour of haemoglobin in the fetus’s blood
What type of animals is this graph typical for? (2)
- Llamas
- Live at high altitude and ∴ in areas with low pO2
- Burrowing animals
- Live in confined spaces where breathing causes O2 levels in the air to drop
Draw the oxygen dissociation curve for myoglobin + explain why it is this shape
- Dog leg shape rather than S shape
- Acts as an oxygen store and is found in the muscles
Means myoglobin:
- Loads with oxygen at very low pO2 becoming fully saturated at a pO2 (point A on graph) well below the point when haemoglobin would be saturated
- Only begins to unload O2 at pO2 values below the point when haemoglobin has released the bulk of its O2
This means with a fall in pO2, haemoglobin first unloads it’s O2, followed by myoglobin.
Draw a diagram to show the relationship between CO2 and O2 release as well as the purpose of the chloride shift
Describe the pathway of the transport of CO2 in the blood through a flowchart (8)
