transport in humans Flashcards
(34 cards)
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
16
Q
explain organ transplant and tissue rejection?
A
- when a person’s tissue or organ is damaged or diseased, it can be replaced by a healthy tissue or organ from a donor. This is called tissue/organ transplant. Transplantation of organs like heart, liver and kidney have saved many lives
- organ to be transplanted must not be rejected by the recipient’s immune system. Any organ from another person may be treated as a foreign body by the recipient’s immune system. The recipient’s lymphocytes may respond by producing antibodies to destroy the transplanted organ
- tissue rejection will not be a problem if tissue transplanted comes from the same person
17
Q
how to prevent tissue rejection?
A
- tissue match is necessary to reduce risk of rejection. Tissues of both the donor and recipient must be as gentically close as possible
- using immunosupressive drugs which inhibit the responses of the recipient’s immune system
BUT - recipient has lower resistance to many kinds of infection
- recipient has to continue taking the drugs for the rest of his or her life
18
Q
what are the various types of antigens and antibodies on different blood groups?
A
Group A: - antigen A on RBC - antibody b in plama Group B: - antigen B on RBC - antibody a in plasma Group AB (universal recipient) - antigen A+B on RBC - no antibody on plasma Group O (universal donor) - no antigen on RBC - antibody a+b on plasma
19
Q
what is agglutination?
A
- clumping of red blood cells that block up small blood vessels and obstructed blood flow
- occurs when blood containing rbc with a certain antigen is injected into an individual with the antibody that can recognise it in the plasma, antibody and antigen reacts
20
Q
what are the parts of the circulatory system?
A
- heart
- arteries (carry blood away from the heart)
- arterioles
- blood capillaries
- venules
- veins (carry blood back to the heart)
21
Q
what are blood capillaries?
A
- microscopic blood vessels that are found between cells of almost all tissues. Have walls made up of a single layer of flattened cells called endothelium
- partially permeable endothelium cells to enable quick diffusion of substances through the capillary walls
- capillaries branch repeatedly, provide a large surface for exchange of substances between blod and tissue cells
- when arteriole branches into capillaries, total cross section area increases, lowering the blood pressure in capillaries
22
Q
what are the characteristics of the arteries?
A
- thick, muscular and elastic walls to withstand high blood pressure
- muscles able to contract and relax to change the size of lumen
- smaller lumen than veins by the same cross section diameter
- highest blood pressure and high velocity of bloodflow
- carries oxygenated blood away from the heart, to other parts of body, except pulmonary artery: deoxygenated blood to lungs from heart
- valves absent, blood moves in pulses, reflecting rhythmic pumping action of heart
23
Q
what are the characteristics of the veins?
A
- thinner. less muscular and elastic than arteries as blood flow is slow and smooth
- larger lumen than arteries of same cross section area diameter
- lowest blood pressure and low velocity of blood flow
- carries deoxygenated blood back to heart from other parts of body, except pulmonary vein: oxygenated blood from lungs to heart
- valves to prevents backflow of blood (semi-lunar valves)
- prevent backflow of blood, ensure blood flows in 1 direction
- action of skeletal muscles on veins to facilitate movement of blood along the vein, allowing blood to flow more quickly back to heart
24
Q
what are the characteristics of capillaries?
A
- single layer of greatly flattened cells, aprtially permeable wall
- low pressure and low veolicty of vlood flow
- exchange of materials occurs at capillaries
- valves absent
25
describe the process of transfer of materials from blood to tissue cells?
- dissolve food substances and oxygen diffuse from blood in blood capillaries into tissue fluid then into cells. Tissue fluid is a colourless liquid that has lesser soluble proteins than plasma. All tissue cells are bathed with tissue in which carries substances in solutionbetween tissue cells and blood capillaries (phagocytes often move out of blood vessels as they can change their shape thus squeeze through capillary walls)
- at arterial end of capillaries, where bp is higher, blood plasma is force out through the capillary walls into intercellular spaces as tissue fluid. Body cells would absorb oxygen and nutrients from tissue fluid
- at venous end, blood pressure is lower, tissue fluid enters blood capillary along with waste products
- red blood cells change shape as they flow through narrow blood capillary: rate of blood flow reduced, giving more time for and thus increasing rate of exchange of materials between blood and tissue cells
- diameter of RBC reduced so that it can easily pass through lumen of blood capillaries. Increase surface area to volume ratio, speed up absorption or release of oxygen
26
list the parts that form the heart?
- aorta
- pulmonary artery
- pulmonary vein
- right atrium
- bicuspid valve
- chordae tedineae
- cardiac muscle
- left ventricle
- median septum
- semi- lunar valves
- right ventricle
- tricuspid vale
- inferior vena cava
- right atrium
- pulmonary arch
- superior vena cava
27
explain the cardiac cycle?
1. during atrial systole, muscle in atria contract, forcing blood into relaxed ventricles
2. after a short pause, ventricles ventricles contract durin ventricular systole. The rise in pressure cause atrio-ventricular valves to close to prevent backflow of blood. "lub" sound. The semi-lunar valves open, Blood flows from right ventricle and left ventricle to pulmonary arch and aortic arch respectively
3. as muscles in ventricles contract, muscles in atria relax during atrial diastole. Right atrium receives flood from vena cave while left atrium receives blood from pulmonary veins
4. muscles in ventricle then relax during ventricular diastole. Fall in pressure causes semi-lunar valves to close to prevent backflow of blood from the 2 arches into ventricles. "dub" sound. As valves open, blood flows from atria to ventricles
5. atria contract again, cycel repeats
28
describe how blood from lungs is forced through heart into aorta?
oxygenated blood from lungs is returned to the heart by pulmonary vein to left atrium. When muscles in left atrium contracts, pressure in left ventricle being lower than left atrium, causes bicuspid valve to open, allowing blood flow from left atrium to ventricle. During venticular systole, muscles in left ventricle contracts. As pressure in ventricle is now higher than pressure in aoritc arch, this causes semi-lunar valve in aortic arch to open, bicuspid valve forced to close, to prevent backflow of blood into left atrium. Thus all the blood being channeled to the ventricles. The blood is forced out of heart with great force into the aorta
BSSB COCO
29
what are the blood vessels that carry deoxygenated blood?
1. pulmonary artery (from heart to lungs)
2. superior vena cava (from forearms to heart)
3. posterior vena cava (from bottom half of body to heart)
4. hepatic vein (from liver to heart)
5. hepatic portal vein (from stomach to liver)
6. renal vein (from kidneys to heart)
30
what are the blood vessels that carry oxygenated blood?
1. pulmonary vein (from lungs to heart)
2. aorta (from heart to the rest of to the body)
3. dorsal aorta (continue)
4. hepatic artery (from heart to liver)
5. artery to gut
6. renal artery (from heart to kidneys)
31
what is the function of coronary arteries?
coronary arteries carry blood to muscles in walls of heart (+glucose and oxygen)
- blood supply to heart may be greatly reduced due to blockage of coronary arteries. can cause heart attack
- lumen is narrowed
- fatty deposits on the inner walls of artery
32
how does heart attack occur?
- blood flow to a particular part of the heart may be completely blocked due to blocked blood flow, part of heart does not receive sufficient oxygen and glucose, that region of heart muscle dies
- extensive heart muscle damage often fatal, as heart would not be able to pump blood to various parts of body
33
what are the causes of coronary heart disease?
- fatty substances like cholestrol and saturate fats may be deposited on inner surface of coronary arteries (atherosclerosis)
- narrow lumen, increases blood pressure
- such artery develop is rough inner surface. Increases risk of blood clot being trapped in artery --> thrombosis
- if it occurs in coronary arteries, supply of blood and oxygen to heart muscles may be completely cut off. Oxygen is needed in aerobic resiration to release energy for arteries of muscle cells. Without oxygen, heart muscles may be damaged, heart attack occurs
- diet rich in choleterol and saturated fats
- emotional stress
- smoking
34
how to prevent coronary heart disease?
- proper diet - low cholestrol diet + unsaturated fats
- proper stress management
- avoid smoking (nicotine and carbon monoxide --> increases risk of coronary heart disease)
- regular physical exericse. Strengthens heart, mainains elasticity of arterial walls, reduce risk of hypertension
