Biology AS AQA
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1-1-biological-molecules-carbohydrates11 主题
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1-1-1-biological-molecules-key-terms
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1-1-2-biological-molecules-reactions
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1-1-3-monosaccharides
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1-1-4-glucose
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1-1-5-the-glycosidic-bond
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1-1-6-chromatography-monosaccharides
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1-1-7-disaccharides
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1-1-8-starch-and-glycogen
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1-1-9-cellulose
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1-1-10-biochemical-tests-sugars-and-starch
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1-1-11-finding-the-concentration-of-glucose
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1-1-1-biological-molecules-key-terms
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1-2-biological-molecules-lipids3 主题
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1-3-biological-molecules-proteins5 主题
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1-4-proteins-enzymes12 主题
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1-4-1-many-proteins-are-enzymes
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1-4-2-enzyme-specificity
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1-4-3-how-enzymes-work
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1-4-4-required-practical-measuring-enzyme-activity
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1-4-5-drawing-a-graph-for-enzyme-rate-experiments
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1-4-6-using-a-tangent-to-find-initial-rate-of-reaction
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1-4-7-limiting-factors-affecting-enzymes-temperature
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1-4-8-limiting-factors-affecting-enzymes-ph
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1-4-10-limiting-factors-affecting-enzymes-enzyme-concentration
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1-4-11-limiting-factors-affecting-enzymes-substrate-concentration
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1-4-12-limiting-factors-affecting-enzymes-inhibitors
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1-4-14-control-of-variables-and-uncertainty
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1-4-1-many-proteins-are-enzymes
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1-5-nucleic-acids-structure-and-dna-replication8 主题
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1-5-2-nucleotide-structure-and-the-phosphodiester-bond
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1-5-3-dna-structure-and-function
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1-5-4-rna-structure-and-function
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1-5-5-ribosomes
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1-5-6-the-origins-of-research-on-the-genetic-code
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1-5-8-the-process-of-semi-conservative-replication
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1-5-9-calculating-the-frequency-of-nucleotide-bases
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1-5-10-the-watson-crick-model
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1-5-2-nucleotide-structure-and-the-phosphodiester-bond
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1-6-atp-water-and-inorganic-ions4 主题
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2-1-cell-structure7 主题
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2-2-the-microscope-in-cell-studies4 主题
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2-3-cell-division-in-eukaryotic-and-prokaryotic-cells8 主题
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2-4-cell-membranes-and-transport9 主题
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2-4-1-the-structure-of-cell-membranes
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2-4-3-the-cell-surface-membrane
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2-4-4-diffusion
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2-4-5-osmosis
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2-4-7-osmosis-in-animal-cells
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2-4-9-required-practical-investigating-water-potential
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2-4-10-active-transport-and-co-transport
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2-4-11-adaptations-for-rapid-transport
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2-4-13-required-practical-factors-affecting-membrane-permeability
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2-4-1-the-structure-of-cell-membranes
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2-5-cell-recognition-and-the-immune-system7 主题
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2-6-vaccines-disease-and-monoclonal-antibodies6 主题
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3-1-adaptations-for-gas-exchange6 主题
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3-2-human-gas-exchange14 主题
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3-2-5-the-alveolar-epithelium
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3-2-1-the-human-gas-exchange-system
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3-2-2-dissecting-the-gas-exchange-system
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3-2-3-microscopy-and-gas-exchange-surfaces
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3-2-4-investigating-gas-exchange
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3-5-5-investigating-heart-rate
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3-5-6-blood-vessels
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3-5-7-capillaries-and-tissue-fluid
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3-5-8-cardiovascular-disease-data
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3-2-10-risk-factor-data
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3-2-11-correlations-and-causal-relationships
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3-2-6-ventilation-and-gas-exchange
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3-2-8-the-effects-of-lung-disease
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3-2-9-pollution-and-smoking-data
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3-2-5-the-alveolar-epithelium
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3-3-digestion-and-absorption5 主题
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3-4-mass-transport-in-animals6 主题
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3-5-the-circulatory-system-in-animals4 主题
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3-6-mass-transport-in-plants6 主题
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4-1-dna-genes-and-chromosomes10 主题
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4-2-dna-and-protein-synthesis3 主题
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4-3-genetic-diversity-mutations-and-meiosis7 主题
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4-4-genetic-diversity-and-adaptation6 主题
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4-5-species-and-taxonomy4 主题
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4-6-biodiversity9 主题
3-5-6-blood-vessels
Exam code:7401
Arteries, arterioles & veins
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The body contains different types of blood vessel, including:
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arteries
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arterioles
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veins
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The structure of each type of blood vessel is closely related to function
Blood vessel structure and function
Arteries
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Transport blood away from the heart at high pressure
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Structure |
Function |
|---|---|
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Thick walls containing smooth muscle and elastic fibres |
Can withstand high pressures generated by the contracting heart Elastic fibres allow stretch to expand around blood when heart beats Elastic enables recoil to maintain blood pressure when the heart is relaxed |
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Narrow lumen |
Helps to maintain high blood pressure |
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Folded inner lining (endothelium) |
Can stretch to allow increased blood flow |
Arterioles
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Arteries branch into narrower blood vessels called arterioles which transport blood into capillaries
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Structure |
Function |
|---|---|
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Walls contain a lower proportion of elastic fibres and a large number of muscle cells |
Pressure is lower than in arteries, so elasticity is less essential Muscle can contract to adjust blood flow to specific organs, e.g. during exercise blood flow to the intestine is reduced while flow to the muscles increases |
Veins
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Veins transport blood back to the heart at low pressure
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Structure |
Function |
|---|---|
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Walls are thin with fewer smooth muscle and elastic fibres |
The blood in veins is not at high pressure, so thick walls with elastic recoil are not needed |
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Lumen is much larger than that of an artery |
The large lumen allows a high volume of blood to flow through veins |
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Valves are present |
Valves prevent backflow of blood |
Examiner Tips and Tricks
Exam questions may ask you to explain the features of blood vessels; in this situation you should always make clear links between structural features and how they aid function.
Responses