3.2 - Transport in Animals ( Part 2 ) Flashcards
What are the adaptations of erythrocytes ?
- Biconcave shape
- No nucleus
- Contains haemoglobin
Explain the effect of a biconcave shape for erythrocytes ?
- This provides large surface area for diffusion of gases
- Also helps erythrocytes pass through narrow capillaries
Explain the effect of no nucleus for erythrocytes ?
Having no nucleus maximises he amount of haemoglobin that fits into the cell
Explain the effect of containing haemoglobin for erythrocytes ?
It is a globular conjugated protein that can bind to four oxygen molecules forming oxyhemoglobin allowing erythrocytes to transport oxygen around the body
Explain how erythrocytes transport oxygen around the body ( oxygen moving into erythrocytes ) ?
- When cells enter capillaries in lungs Ov2 levels in the cell are low in comparison to air in alveoli creating a steep concentration gradient
- Ov2 moves into erythrocytes and binds with haemoglobin to form oxyhemoglobin
Write the reversible reaction between haemoglobin and oxygen ?
Hb + 4Ov2 ⇌ Hb(Ov2)v4
haemoglobin + oxygen ⇌ oxyhemoglobin
Explain how the arrangement of haemoglobin results in ‘positive cooperatively’ ?
- Arrangement of haemoglobin molecules means that when Ov2 molecules bind to a haem group, the molecule changes shape
- This makes it easier for the next Ov2 molecule to bind ( which is positive cooperatively )
Explain how the steep concentration gradient between the air in the alveoli and erythrocytes is maintained ?
- Since Ov2 is bound to haemoglobin, free Ov2 consternation remains low in cell
- This maintains the steep concentration gradient of free Ov2 between erythrocytes and the air in the alveoli until all haemoglobin is saturated with Ov2
Explain how erythrocytes transport oxygen around the body ( oxygen moving out of erythrocytes ) ?
- When erythrocytes reach body tissue, concentration of Ov2 in cytoplasm of body cells is lower than in erythrocytes
- therefore, Ov2 moves out of erythrocytes down the concentration gradient. Once one Ov2 molecule is released, haemoglobin changes shape making it easier to remove remains Ov2 molecules
What does an oxygen dissociation curve show ?
Oxygen dissociation curve shows the affinity of haemoglobin for Ov2
What is the partial pressure of Ov2 ?
It is the pressure exerted by oxygen in a mixture/ it can be though to oxygen concentration
Draw the oxygen dissociation curve ?
What is the trend shown by the oxygen dissociation curve ?
As the partial of Ov2 increases, haemoglobin’s affinity for oxygen increases which is indicated by the increase in percentage saturation of haemoglobin with Ov2
Explain the effect of the oxygen dissociation curve in the body ?
- At a high partial pressure of oxygen ( high concentration ) in the lungs, haemoglobin has a greater affinity for Ov2 so erythrocytes are rapidly loaded with Ov2
- At a low partial pressure of oxygen ( low concentration ) in they tissue, haemoglobin has a low affinity for Ov2 so Ov2 is rapidly unloaded from erythrocytes
What is the name for the effect of COv2 on the oxygen dissociation curve ?
The Bohr Effect
Explain the effect of carbon dioxide on the oxygen dissociation curve ?
- As the partial pressure of COv2 increases, haemoglobin’s affinity for Ov2 decreases for each value of partial pressure of Ov2
- The dissociation curve shifts to the right
Draw the effect of COv2 on the dissociation curve ?
What is the difference between haemoglobin and fetal haemoglobin ?
- Fetal hameoglboin has a higher affinity for Ov2 than adult haemoglobin
What is the effect of fetal haemoglobin ?
- Fetal haemoglobin has a higher affinity for Ov2 than adult haemoglobin
- There is a low partial pressure of oxygen in the placenta
- Ov2 is transferred from adult haemoglobin from maternal blood to fetal haemoglobin
- Ov2 is transported to fetus for respiration
Show the effect of fetal haemoglobin on the oxygen dissociation curve ?
What are the different way COv2 is transported from tissues to lungs ?
- 5% is carried by being dissolved in plasma
- 10-20% is combined with haemoglobin forming carbominohaemoglobin
- 75-85% is converted to HCOv3- ions in cytoplasm of erythrocytes
Explain how COv2 s transported from body tissue to the lungs ?
- COv2 diffuses into the blood and reacts with water to from carbonic acid ( Hv2COv3 )
- The cytoplasm of erythrocytes contains an enzyme called carbonic anhydrase which catalyses the reversible reaction/ breakdown of carbonic acid into H+ and HCOv3 ions
- HCOv3- ions then move out of erythrocytes into plasma via diffusion down the concentration gradient
- By removing COv2 in erythrocytes by converting it into H+ and HCOV3 - ions, this maintains a steep concentration gradient causing COv2 to move into erythrocytes from respiring tissue
Explain what is chloride shift ?
- HCOv3- ions move out of erythrocytes into plasma via diffusion down the concentration gradient
- TO maintain the electrical balance of the cell, Cl- ions move into erythrocytes
Write the equation for the reversible reaction between COv2 and H2O as well as the breakdown into H+ and HCOv3- ions ?
COv2 + Hv2O ⇌ Hv2COv3 ⇌ H+ + HCOv3-
Explain how COv2 is transported at the lungs ?
- When blood reaches the lungs where there is a low concentration of COv2, HCOv3- diffuse back into erythrocytes and react with H+ ions to form carbonic acid
- The reverse reaction is catalysed by carbonic hydrate, releasing COv2 and Hv2O which diffuses out of the blood into the lungs
- Cl- ions then diffuse back out of erythrocytes into the plasma down the electrical gradient
What is the role of haemoglobin in the transport of COv2 ?
Hameoglobin acts as a buffer and prevents changes in pH by accepting free H+ in a reversible reaction to form haemoglobic acid
What is the structure of the heart ?
The heart consists of two pumps that are joined and work together to pump blood around the body
What is the heart made up of ?
It is made up of cardiac muscle, which contracts/relaxes and does not fatigue
What is the role of the coronary artery ?
The coronary artery supplies cardiac muscle with oxygenated blood so it can continually contract and relax
Label the external structures of the heart ?
Label the internal structures of the heart ?
Explain how the heart functions when deoxygenated blood enters the heart ?
- Deoxygenated blood enters the heart from the upper body via the superior van cava/ from the lower body from the inferior vena cava into the right atrium
- Pressure builds up until the atrio-ventricular valve ( tricuspid valve ) opens to let blood pass into the right ventricle
- When both the atrium and ventricle are filled with blood, the atrium contracts forcing all blood into the right ventricle, stretching ventricle wall
- As the right ventricles starts to contract, the atrio-venticular valve closes preventing the back-flow of blood into the right atrium
- The right ventricle contracts pumping deoxygenated blood through semilunar valves into the pulmonary artery which transports it to the capillary bed of the lungs
What is the role of tendinous cords in the heart ?
They ensure valves are not turned inside out by pressure exerted when ventricles contract
Explain how the heart functions when oxygenated blood enters the heart ?
- Oxygenated blood enters the heart via the pulmonary artery into the left atrium
- Pressure builds up until left atrio-ventricular valve ( bicuspid valve ) opens allowig blood to pass into the left ventricle
- When both the left atrium and ventricle are full of blood, the left atrium contracts so all oxygenated blood is pumped into the left venricle
- The left ventricle contracts forcing all blood through semilunar valve into aorta and around the body
What is the difference in the thickness of the muscular wall on the left/ right side of the heart ?
The muscular wall of the left side of the heart is thicker than the right side
Why does the left hand side of the heart have a thicker muscular wall ?
- Extremities of the whole body are very far away so the left side of the heart has to pump blood across large distances
- The left side of the heart also has to overcome resistance of the aorta and arterial system of the whole body
Why does the right hand side of the heart have a thinner muscular wall ?
- The lungs are relatively small and close to the heart so the right side of the heat only has to pump blood a small distance
- The right side of the heart only has to overcome the resistance of the pulmonary circulation
What is the septum ?
It is the inner dividing wall of the heart which prevents mixing of deoxygenated and oxygenated blood
What are the three stages of the cardiac cycle ?
- Arteriol systole
- Ventricular systole
- Atrial/Ventricular Diastole
Explain what happens during atrial systole ?
- When both atria and ventricles fill with blood, the atria contract
- Blood pressure in the atria increases
- Atrio-ventricular valves open allowing all blood to be forced into ventricles
- The volume of ventricles increases as they fill up with more blood
- Pressure against ventricle walls increases
- Pressure in the arteries is at a minimum
Explain what happens during ventricular systole ?
- Ventricles contact
- Volume of ventricles decreases while blood pressure in ventricles increases
- Atrioventricular valves close and semi-lunar valves open
- Blood flows in aorta and pulmonary artery
- Blood pressure in the arteries is at the maximum
Explain what happens during diastole ?
- Atria and ventricles relax
- Atria-ventricular valves open allowing blood to flow into atria and ventricles passively
What is the equation for cardiac output ?
Cardiac output ( cm^3/min ) = heart rate ( bpm ) x stroke volume ( cm^3 )
What does it mean that cardiac muscle is ‘myogenic’ ?
It means it has its own intrinsic rhythm of 60 bpm preventing the body wasting resources on basic heart rate
What maintains the basic rhythm of the heart ?
It is maintained by a wave of electrical excitation
Explain how the basic rhythm of the heart is maintained by a wave fo electrical excitation ?
- Wave of electrical excitation begins at Sino-atrial node ( SAN ) causing atria to contract, initiating heartbeat
- Electrical activity from SAN is picked up by trio-ventricular node ( AVN )
- AVN imposes slight delay before stimulating bundle of His ( a bundle of conducting tissue made up of purkyne fibres ) which penetrate through septum between the ventricles
- The bundle of His splits into two branches, conducting wave of excitation to the apex of heart
- AT the apex, Purkyne fibres spread out through the walls of the ventricles on both sides
- Spread of excitation causes ventricles to contract starting at apex
What is the effect of the ventricles starting to contract at the apex ?
This allows for more efficient emptying of the ventricle
What is the effect of the AVN stimulating a delay ?
The stimulated delay ensures atria stop contraction before ventricles start
What are electrocardiograms ?
They are a recording of the electrical activity of the heart
Explain this diagram and what happen at each point ?
- The P wave, indicates atrial depolarisation and is when the atria contract
- The QRS wave indicates ventricular depolarisation and is when the ventricles contract
- The T wave and indicates ventricular repolarization and is when the ventricles relax
What does this diagram show ?
- Normal ECG
- Beats evenly spaced
- Rate 60-100 bpm
What is ‘Tachycardia’ ?
When the heartbeat is very rapid, over 100 bpm
When is ‘tachycardia’ normal/ what should you do if it’s abnormal ?
- This is often normal, when you exercise, feel fear, feel anger, have fever, etc…
- If abnormal, may be caused by problems in the electrical control of the heart and may need to be treated by medication/surgery
What does this diagram show ?
- Tachycardia
- Fast heart rate
- Beats are evenly spaced
- > 100/min
What is ‘Bradycardia’ ?
When the heart rate slows down to below 60 bpm
When is ‘bradycardia’ normal/ what should you do if it’s abnormal ?
- This is normal for people who are fit
- Severe bradycardia can be serious and may need an artificial pacemaker to keep the heart beating steadily
Explain why bradycardia can be normal for people who are fit ?
- Due to training, their heart has become more efficient at pumping blood around the body
- This results in a greater stroke volume, an increased volume of the ventricles and increased thickness/ strength of heart muscle
What does this diagram show ?
- Bradycardia
- Slow heart rate
- Beats evenly spaced
- Rate >60 bpm
What is ‘Ectopic heartbeat’ ?
Extra heartbeats that are out of normal rhythm
When is ‘ectopic heartbeat’ normal/ what should you do if it’s abnormal ?
- They are typically normal and people tend to have one a day
- If very frequent, they can be linked to serious conditions
What does this diagram show ?
- Ectopic heartbeat
- Alternated rhythm
- Extra beat followed by longer than normal gap before the next beat
What is ‘Atrial fibrillation’ ?
- An abnormal rhythm of the heart where rapid electrical impulses are generated int he atria
- They contract very fast however they don’t contact properly and so only some impulses are passed onto ventricles which contract less often
- This results in the heart not pumping blood very efficiently
What is ‘arrhythmia’ ?
Abnormal rhythm of the heart
What does this diagram show ?
- Atrial Fibrillation
- Abnormal irregular rhythm from atria
- Ventricles lose regular rhythm
