Full revision notes with the corresponding points from the OCR specification. All that you need to know for the exam - whether end of topic test or the actual A Level. The topic covered is Animal Transport and explains everything with graphs and diagrams inserted into the document.
Easy to unders...
The need for transport systems in multicellular animals - an appreciation of size, metabolic rate
and surface area to volume ratio (SA:V).
Need due to:
Low SA:V (Large size)
High metabolic rate
Blood carries hormones/enzymes, food molecules and removes waste products
The different types of circulatory systems - single, double, open and closed circulatory systems in
insects, fish and mammals.
Open – Heart but few blood vessels
Closed – Blood flows through blood vessels – no contact with body cells
Single – 2 chambered heart – blood travels once through the heart for every circuit around the body
(more energy efficient as less muscles are being used) – LOW systemic pressure
Double – 4 chambered heart – blood travels twice through heart for every circuit around the body –
HIGH systemic pressure
Fish – single circulatory system
Mammals – double closed circulatory system
Insects – open circulatory system
Spiracles – trachea – tracheoles – body cells
No concentration gradient = slow and inefficient and cant change the flow of the haemolymph
(insect blood)
Haemolymph pumped heart – body cavity (haemocoel) Exchange of food and nitrogenous wastes
(NO GAS) directly at cell
The structure and functions of arteries, arterioles, capillaries, venules and veins - distribution of
different tissues within the vessel walls.
Artery – Away from heart with high oxygenation. High pressure. Pulse present. Thick muscle and
elastic layers. Narrow lumen.
Deoxygenated blood = pulmonary artery
Oxygenated blood = pulmonary vein
Artery that has valves = aorta, pulmonary artery
Vein – Into heart with low oxygenation. Low pressure. Thin muscle and elastic layers. Wide lumen
and valves present. Blood flow assisted via muscles in valves and breathing/muscular movements.
Tunica externa (Connective tissue)
Tunica Media (smooth muscle and elastic fibres) Different layers of blood vessels (starting
from the outside)
Tunica Intima (endothelium)
, Capillary – Exchanges materials e.g. oxygen and carbon dioxide. Thin tunica media. Lumen is 1 cell
thick = RBC travel in single file to increase diffusion time.
The formation of tissue fluid from plasma - reference to hydrostatic pressure, oncotic pressure and
an explanation of the differences in the composition of blood, tissue fluid and lymph
Plasma- Liquid in blood. Transport medium for CO2, hormones and urea. 55% of blood (contains
proteins and water etc)
Erythrocytes (RBC) – Delivers oxygen to tissues – picks o2 up from lungs – transports co2. Flattened
biconcave shape – no nucleus to have more space for oxygen.
Platelets – healing and repair of the tissues
Leucocytes (phagocytes) – WBC that destroys pathogens. Receptors on cell surface bind to antigens
on pathogen. Produced in bone marrow.
Leucocytes (lymphocytes) – produces antibodies. They attach to antigens. Labels pathogens so they
can get destroyed by phagocytes – stick together
Function of tissue fluid – bring o2 and nutrients to cell – remove waste products, releases metabolic
waste and exchanges substances
Hydrostatic pressure – Pressure of blood from heart contractions. Forces blood out of the capillaries.
Dissolved gases/nutrients move with it. (Arteries/arterioles and early capillaries) – TO CALCULATE =
subtract the pressure out by the pressure in.
Oncotic pressure – Tendency of water to move into blood via osmosis as a result of plasma proteins.
Water moves into capillaries to dilute the salty blood due to higher concentration. TO CALCULATE =
subtract the pressure out by the pressure in.
High hydrostatic pressure at arterial end of capillary due to contraction of the ventricles and the
narrowing of the vessels.
Ultrafiltration – useful substances e.g. glucose, water and o2) leave the blood to become tissue fluid.
Capillary – oncotic pressure -3.3kPa (no net movement)
Vein – hydrostatic pressure 2.3kPa – reabsorption into the blood vessels
Lymphatic fluid movement – there is no pump so it is only moved via contraction of skeletal muscles
Lymph functions – Removal of tissue fluid and the defence against pathogens.
Blood
Tissue Fluid
Lymph
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