transport in humans Flashcards
1
Q
what is the main functions of blood?
A
- acts as a transport medium transporting various substances from one part of the body to another
- it protects the body against disease causing organisms (pathogens)
- blood clotting of wounds prevent excessive loss of blood. It seals the wound and prevents entry of microorganisms into the bloodstream
2
Q
explain the importance of double circulation?
A
- allow blood pressure in lungs (pulmonary circulation) to be low so that there is sufficient time for exchange of gases to take place in lungs
- allow blood pressure going into systemic circulation (rest or body) to be high so that oxygenated blood is distributed rapidly to enter organs and extremities
- ensures oxygen level in blood is high enough to maintain rate of respiration (metabolic rate)
3
Q
what is the difference between pulmonary vs sytemic circulation?
A
pulmonary: - blood leaves from right side of heart - blood leaving heart is deoxygenated - blood leaves heart to go to lungs - shorter length of circuit - lower pressure systemic: - blood leaves from left side of heart - blood leaving heart is oxygenated - blood leaves heart to go to rest of body - longer length of circuit - higher pressure
4
Q
how do humans adapt to living at high altitudes?
A
- at high altitudes, concentration of oxygen in the atmosphere is low. Body cannot absorb sufficient oxygen to maintain its metabolic rate. Hence body needs to produce more red blood cells to compensate for lower concentration of oxygen. Increasing the proportion of RBC also increases the haemoglobin content per unit volume of blood. This means that more oxygen can be absorbed and be transported to the tissue cells per unit time. Thus having a larger number of RBC in their bodies over time
- long distance runners train at high altitudes for several months as it increases the amount of haemoglobin in their blood. Hence, when they run at lower altitudes, their bodies are able to transport oxygen at a higher rate, enabling them to run for longer periods
5
Q
what are the constituients of blood?
A
- plasma (55%)
- red blood cells
- white blood cells
- platelets
45%
6
Q
what is the structure of plasma? (55% of blood)
A
water(90%), dissolved substances (10%)
7
Q
what is the function of water in plasma?
A
- allows blood to be pumped by heart as it is imcompressible and hence allows transportation to occur
- high heat capacity to allow plasma to transport heat into causing a huge change to the blood temperature or composition, maintaining a constant temperature, preventing enzymes from denaturing as a lot of heat is produced from aerobic respiration of cells
- universal solvent allows substances to dissolve in it, allowing them to be transported
- water is needed in chemical reactions e.g. hydrolysis
8
Q
what is the function of dissolved substances in plasma?
A
transports:
- hormones from endocrine glands to respective target organs e.g. insulin to liver due to high blood glucose concentration
- excretory waste products e.g. urea, creatinine, carbon dioxide (in the form of hydrogencarbonate ions)
- nutrients e.g. glucose and amino acids to body cells
- dissolved mineral salts e.g. hydrogen carbonate and chloride ions
- antibodies made by lymphocytes to combat diseases
- soluble proteins like fibrinogen which is needed for blood clotting of wounds to prevent excessive bleeding
- heat from respiring tissues, especially muscles and liver
9
Q
what are the adaptations of red blood cells?
A
- circular, biconcave disc (to increase cell’s surface area to volume ratio to absorb and release O2 at a higher rate)
- absence of nucleus and other organelles (contain more haemoglobin and hence more oxygen)
- contains haemoglobin (binds reversibly with oxygen to form oxyhaemoglobin to enable O2 to be transported from lungs to all cells in the body)
- elastic (squeeze through blood vessels like capillaries, whose diameters are smaller than itself)
- produced by bone marrow. lifespan of 3-4 months. When worn out, they are destroyed in the spleen. Haemoglobin that is released from destroyed RBC is brought to liver and broken down into iron, which is stored in the liver
10
Q
what is the adaptations of white blood cells?
A
- can change its shape and squeeze through capillaries walls into spaces among tissue cells to defend body tissues. Colourless and irregular in shape
- lymphocytes are round in shape with a large rounded nucleus with non-granular cytoplasm
- detect toxins produced by disease causing bacteria and produce antibodies that kill bacteria and cause it to clump together
- antibodies also neutralise toxins produced by bacteria
- phagocytes have a genular cytoplasm and a lobed nucelus
- detect bacterial/foreign particles and engulf and ingest them through phagocytes
11
Q
explain what are platlets?
A
- cell grafments formed in bone marrow, have no nucleus
- help in clotting of blood and prevent excessive loss of blood and entry of bacteria at the wound
12
Q
what are the protective functions on blood?
A
- blood clotting
- phagocytes
- antibody protection
13
Q
describe the process of blood clotting?
A
- damaged tissue and platelets release thrombokinase
- thrombokinase, together with calcium ions, converts inactive prothrombin in the plasma to active thrombin enzymes
- thrombin catalyses the conversion of soluble fibrinogen to insoluble fibrin threads which forms a mesh to entangle blood cells to form a clot
- in undamaged blood vessels, the blood does not clot due to present of heparin, which is an anti-clotting produced in the liver. When thrombokinase is released, it neutralises the action of heparin so that clotting can take place. When blood clots, a yellow liquid called serum is left behind
14
Q
describe the process of phagocytosis?
A
- process of engulfing or ingesting foreign particles, e.g. bacteria by the infolding of cell membranes of white blood cells
- a phagocyte engulfs the bacteria by flowing over them and enclosing them
- ingested bacteria will be digested in the phagocyte
- dead phagocytes and dead bacteria form pus
15
Q
explain antibody production?
A
- when pathogens such as bacteria and viruses gain entry into the bloodstream, they stimulate lymphocytes to produce certain chemical substances called antibodies
- antibodies protect our bodies against diseases by:
- destroying the bacteria e.g. by attaching to them, causing bacterial surface membrane to rupture
- causing the bacteria to lump togehter or alluginate so that they can easily be ingested by the phagocytes
- neutralising harmful substances (toxins) produced by bacteria
- may stay in the blood long after the diseas has been overcome. person becomes immune
- some types of dead bacteria are sometimes injected to animals to induce formation of antibodies in the blood. Antibodies are extracted from serum of animals and injected into human beings to protect them from certain diseases
- antibody production may also be directly induced by the human body by exposing the person to dead or weakened forms of pathogens during immunisation/vaccination. Dead or weakened forms of pathogens stimulate the person’s immune system to produce antibodies against the pathogen
- immune system causes an immune response to foreign particles to keep body free from diseases
