C9 - Transport In Animals
Write equations to show the formation of hydrogen carbonate ions in the plasma.
- Carbonic anhydrase enzyme catalyses: CO2 + H2O ⇌ H2CO3 (carbonic acid) - Carbonic acid dissociates: H CO ⇌ HCO - (hydrogen carbonate ions) + H+
Describe the structure of the protein haemoglobin
- Haemoglobin is formed as quaternary structure of protein - consists of 4 molecules of protein, 2 α & 2 β polypeptide (4 reddish Heme group with iron)
What are the advantages of a closed system?
- Lower blood volume required to keep system moving - Blood pressure can be controlled and maintained
What are the advantages of a double circulatory system?
- Maintains blood pressure around the whole body - Uptake of oxygen is more efficient - Delivery of oxygen and nutrients more efficient - BP can differ in pulmonary and systemic systems
Define the term "double circulatory system".
A circulatory system in which the blood flows through the heart twice in two circuits. Blood is pumped from the heart to the lungs before returning to the heart. It is then pumped around the body, after which it returns to the heart again. Double circulatory systems are found in mammals.
Define the term "closed circulatory system".
A circulatory system in which the blood pumped by the heart is contained within blood vessels. The blood does not come into direct contact with the cells. Closed circulatory systems are found in animals, e.g. vertebrates.
What is tissue fluid?
A fluid surrounding cells and tissues that contains glucose, amino acids, oxygen and other nutrients. It supplies these to the cells, while also removing any waste materials.
How is tissue fluid formed?
As blood is pumped through increasingly smaller vessels, hydrostatic pressure is greater than oncotic pressure, so fluid moves out of the capillaries. It then exchanges substances with the cells.
State and explain the differences between blood, tissue fluid and lymph
Both are two circulatory fluids of the body, Blood moves via blood vessels and lymph moves via lymphatic vessels. Blood transports gases, nutrients, and metabolic wastes. Lymph is draining of tissue fluid into the circulatory system.
What is the function of carbonic anhydrase?
Catalyses the reversible reaction between water and carbon dioxide to produce carbonic acid.
How does the leucocytes attack the pathogens ?
It can recognise one particular pathogen and respond it by secreting one particular type of antibody to attack.
What is the function of red blood cell ?
It contain haemoglobin so it can transport oxygen and carbon dioxide
Why is the chloride shift important?
It maintains the electrochemical equilibrium of the cell.
Describe and explain the shape of a dissociation curve for adult haemoglobin.
Sigmoidal curve (S-shaped): ● When first O2 molecule binds, it changes the tertiary structure of haemoglobin so that it is easier for the second and third molecules to bind ● Third molecule changes the tertiary structure of haemoglobin so that it is more difficult for the fourth molecule to bind
Describe what happens during atrial systole.
The atria contract, forcing the atrioventricular valves open. Blood flows into the ventricles.
Describe what happens during cardiac diastole.
The atrial and ventricular diastole muscles are relaxed. So the blood will enter the atria via the vena cava and pulmonary vein. When the blood flowing into the atria increases the pressure within the atria. So pressure and volume will increase. This cause the atrioventricular valves to open and the semilunar valve to close. And the ventricular diastole will sound as 'dub'
Describe the role of haemoglobin in carrying oxygen and carbon dioxide with reference to the role of carbonic anhydrase, the formation of haemoglobinic acid and carbaminohaemoglobin
The carbonic anhydrase is an enzyme that help haemoglobin to dissociate from oxygen and bind to carbon dioxide to form carbaminohaemoglobin instead. Carbonic anhydrase catalyse a reaction between carbon dioxide and water to produce carbonic acid. Carbonic acid will release H+ ions and the H+ ions will combine with haemoglobin to form haemoglobin acid. So this will encourages dissociation of oxygen from haemoglobin.
Describe what happens during ventricular systole.
The ventricles contract. The pressure increases, closing the atrioventricular valves to prevent backflow, and opening the semilunar valves. Blood flows into the arteries.
Describe and explain the significance of the higher red blood cell count of humans at high altitude
When at high altitude, the count of RBC will increases. This is because the fewer oxygen molecules, thus the partial pressure of of oxygen decrease. So more RBC are made so there is more haemoglobin for the oxygen to bind with
How does the Bohr effect work?
When the conc of CO2 is increase in our body, more oxygen will be releases at body tissues. The pH of the blood will decrease and it reduces the affinity of O2 in body tissue. The graph will shift to the right.
Describe the journey of blood through the human circulatory system with reference to the 4 major blood vessels of the heart.
heart (r) → pulmonary artery → lungs → pulmonary vein → heart (l) → aorta → body → vena cava → heart (r)
What is the chloride shift?
the exchange of Cl- for bicarbonate ions in erythrocytes, causing HCO3- to leave the cell
What is the Bohr effect?
the regulation of hemoglobin binding by hydrogen ions and carbon dioxide
Relate the structure of arterioles and venules to their function.
● Branch off arteries and veins in order to feed blood into and take blood away from the capillaries ● Smaller than arteries and veins so that the change in pressure is more gradual as blood passes through increasingly small vessels
Why does blood pressure fall along the capillary?
● Friction ● Lower volume of blood
Outline the different pressures involved in the formation of tissue fluid.
● Hydrostatic pressure - higher at arterial end of capillary than venous end ● Oncotic pressure - changing water potential of the capillaries as water moves out, induced by proteins in the plasma
Draw and describe the structure of neutrophils.
● Lobed nucleus for flexibility within blood vessels ● Granulocyte
What happens at the venous end of the capillary?
● Oncotic pressure is greater thanhydrostatic pressure ● Fluid moves down its water potential gradient back into the capillaries
Explain how the heart contracts.
● SAN initiates and spreads impulse across the atria, so they contract. Thick fibrous walls prevent impulse spreading directly to ventricles ● AVN receives, delays, and then conveys the impulse down the bundle of His ● Impulse travels into the Purkinje fibres which branch across the ventricles, so they contract from the bottom up.
Relate the structure of arteries to their function.
● Thick, muscular walls to withstand high pressure ● Elastic tissue allows them to stretch and recoil to prevent pressure surges ● Narrow lumen to maintain pressure ● Smooth muscle which enables them to vary blood flow ● Lined with smooth endothelium to reduce friction and ease flow of blood
How is tissue fluid removed?
● Tissue fluid drains into the lymphatic system where it is referred to as 'lymph' ● The lymph returns to the blood via the subclavian veins
Draw & describe the structure of lymphocytes.
● Very large nucleus ● Small amount of cytoplasm ● Agranulocyte
The walls of the chambers of the heart vary in thickness - explain this.
● Walls of both atria relatively thin, only have to cap blood in ventricles as ventricles fill mostly passively ● Left ventricle wall significantly thicker than right, left must provide pressure for systemic flow, right only has to supply pulmonary system. Both are thicker than the atria
Relate the structure of capillaries to their function.
● Walls only one cell thick giving a short diffusion pathway ● Narrow lumen, red blood cells squeeze through, decreasing the diffusion distance ● Numerous and highly branched, providing a large surface area
*Why is water important in body fluids?
● Water acts as a solvent in order to transport material in biofluids ● Water has a high specific heat capacity - a large amount of energy is required to change its temperature - facilitating the maintenance of homeostatic conditions
Relate the structure of veins to their function.
● Wide lumen eases blood flow ● Thin walls eases compression by skeletal muscles ● Require valves to prevent backflow of blood ● Less muscular and elastic tissue as they don't have to control blood flow
