LSS2 Science- Circulatory System Flashcards
Transport of materials in unicellular orgaisms
- Do NOT need a transport system for exchange or distribution of materials
- No part of the cell is far from the environment outside
- Exchange of materials occur easily by DIFFUSION
Need for transport system in multicellular organisms
Diffusion is inadequate for transport; due to,
- Larger body (Reduced surface area to volume ratio)
- Cells are located deeper in the body, further away from the external environment
What does blood contain?
- Plasma
- White blood cells
- Platelets
- Red blood cells
White blood cells OR leucocytes
- Larger than red blood cells
- Fewer in numbers compared to red blood cells
- Production: Bone marrow
- Destroyed: Spleen
- Limited lifespan of a few days
- Colourless (No haemoglobin)
- Irregular in shape (Nucleus present)
- Mobile
White blood cells or leucocytes > Types
- Lymphocytes
- Phagocytes
White blood cells or leucocytes > Types > Lympocytes
- Large rounded nucleus
- Small amount of non-granular cytoplasm
- Produce antibodies against microorganisms
White blood cells or leucocytes > Types > Phagocytes
- Lobed nucleus
- Granular cytoplasm
- Able to ingest foreign particles
Blood platelets OR thrombocytes
- Not true cells
- Fragments of cytoplasm which are membrane bound
- Important for the clotting of blood
- Life span: 6 days
Plasma
About 90% water in which the following are dissolved and transported;
- Proteins: Fibrogen, Prothrombin & antibodies
- Mineral salts: chlorides and sulfates of calcium and sodium
- Food substances: Glucose, Amino acids and fats
- Waste products: Urea, uric acid and creatine
- Hormones
Red blood cells OR erythrocytes
- Constitute 99% cells in the blood
- Production: Bone marrow
- Destroyed: Spleen
- Limited lifespan of 120 days
Features of red blood cells
- Filled with red pigment haemoglobin
(Essential for binding oxygen) - Absence of nucleus
(Allows more haemoglobin to be packed into cell) - Biconcave shape
(increases surface area to volume ratio for efficient uptake of oxygen) - Elastic (Enable cells to squeeze through tiny blood capillaries)
Functions of blood
- Transport function
• to carry various substances from one part of the body to another - Protective function
• To protect the body against disease-causing organisms
• Blood clotting or coagulation prevents entry of bacteria into the bloodstream and excessive blood loss
Functions of blood > Transport function
Blood acts as a transport medium carrying various substances
- Digested food substances
- Excretory products
- Hormones
- Heat
- Oxygen
Functions of blood > Transport function > Transport of oxygen to body cells
- Blood passes through lungs, oxygen diffuses from the air sacs into the blood
- Haemoglobin combines with oxygen to form oxyhaemoglobin
- Blood transports oxygen to all the tissues of the body
- At the tissue cells, oxyhaemoglobin releases the oxygen
Functions of blood > Protective function of blood
- Blood clotting
- Phagocytosis
- Production of antibodies
Functions of blood > Protective function of blood > The clotting process
- Blood clots when exposed to air
- This seals the wound, prevents the entry of bacteria and further loss of blood
Functions of blood > Protective function of blood > Phagocytosis
‘Phagocytes’ is the process of engulfing and ingesting foreign particles by phagocytes
Transport systems in humans
Made up of ;
- Heart
- Veins
- Arteries
- Venules
- Capillaries
[S] Transport systems in humans > Heart
A muscular pump which pumps blood out of the heart into the circulation
[S] Transport systems in humans > Veins
Many Venules unite to form bigger veins which carry blood towards the heart
[S] Transport systems in humans > Venules
Capillaries are linked to small veins called venules
[S] Transport systems in humans > Arteries
Blood vessels that carry blood away from the heart
Aorta > Arteries > Arterioles
[S] Transport systems in humans > Capillaries
Microscopic blood vessels that arise from branches of the arterioles
At the capillary bed
Arterial blood:
- Oxygen
- Glucose
Venous blood:
- Carbon dioxide
- Metabolic waste products
Production of antibodies
- Production: Lymphocytes
- Bind to bacteria and cause their surface membranes to rapture
- Bacteria cells clump together in the presence of antibodies
- Toxins produced are neutralised
- Prevents viruses from binding to host cells
Organ transplant and tissue rejection
Tissue or organ transplant involves replacing damaged or diseased tissue organ with a healthy tissue or organ from the same person or a donor
- The body may produce antibodies to destroy the transplant
(Introduction to foreign substances)
Ways to reduce tissue rejection;
• Tissue match
• Immunosuppressive drugs
Blood vessels (In depth)
Artery- Carries blood away from the heart
Capillary- Allows exchange of materials between blood and tissue
Vein- Carries blood towards the heart
Arteries
- Transport oxygenated blood from the heart to other organs in the body
- Thick, muscular walls: Support blood from the heart [Higher in pressure]
- Muscles contract and relax to cause constriction and dilation of the artery respectively
Veins
- Transport deoxygenated blood back to the heart
- Thin walls with less elastic tissue: Slower blood flow [Lower pressure]
- Valves: Prevent blood from flowing backwards
[Folding of inner walls of the veins]
Capillaries
- Endothelium consists of a single layer of flattened cells and the walls are partially permeable, allowing dissolved substances to diffuse quickly through it
- Capillary network increases surface area and total cross sectional area: More efficient enchange
Double circulation
Blood passes through the heart twice as it moves from the pulmonary circulation into the systemic circulation
Advantages of a double circulation
- Blood enters the pulmonary circulation at a low pressure, ensuring sufficient time for the blood to be fully oxygenated before returning it to the heart
- Blood is pumped into the systemic circulation at a high pressure, ensuring oxygenated blood is quickly distributed to all tissues of the body
Coronary heart disease
- The tissues of the heart need oxygen for respiration
- The tissues of the heart are supplied by the coronary arterieds
- Excess cholesterol can build up in deposits in the artery walls, causing blockage and disruption and flow of blood
Coronary heart disease > Process
Buildup of fatty substances on inner surfaces of coronary arteries (atherosclerosis)
