Biology - Topic 6

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digestion

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1

digestion

series of biochemical reactions that convert large ingested food molecules into small, soluble molecules that can be absorbed by the body

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2

sequence of organs as food passes through

mouth oesophagus stomach small intestine large intestine anus

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3

types of enzymes found in digestive juices

amylase, protease, pancreatic lipase

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4

amylase

salivary glands or pancrease, and produces maltose and glucose

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5

protease

gastric glands and pancrease, produced polypeptides and amino acids

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6

lipase

found in pancrease, produced fatty acids and glycerol

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7

peristalsis

food passes along alimentary canal via longitudinal and circular muscles (antagonistic pair)

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8

villi structure

columnar epithelial cells, capillaries, lacteal, smooth muscle, arteriole and venule

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9

arteries

carry blood under high pressure, have strong muscle and elastic fibres, only 2 have valves, and are large with narrow lumen

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10

veins

carry blood at low pressure, contain few muscles and elastic fibres, have some valves preventing backflow, thin walls and wide lumen

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11

capillaries

carry blood under low pressure, walls are only one cell thick, no valves, diameter is 5 micrometres

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12

direction of blood flow, starting at RA

vena cava brings deoxygenated blood into RA, passes into RV through valve (bi), blood pumped through PA; oxygenated returns via PV into LA, into LV through valve (tri), into aorta to body

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13

sinoatrial node

pacemaker of heartbeat, located in wall of right atrium; sends signals to atriums and atrioventricular node, which signals to ventricles

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14

how does heart rate change

nerves of medulla connected to SA node; increases as active and decreases as resting; emotions can cause adrenal glands to release adrenalin to stimulate

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15

cardiac cycle

sequence of events that takes place during one heartbeat

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16

systole

contraction of the muscles of a chamber of the heart

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17

diastole

relaxation of muscles of heart

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18

pathogens

living organisms or viruses that cause disease. Most are bacteria and viruses but fungi and parasitic worms can also be pathogenic

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19

first line of defence

unbroken skin prevents pathogens from entering the body at first, but openins in body are protected by mucous membranes that contain enzymes to attack

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20

when skin is cut

clotting factors released from platelets and damaged tissue cells, prothrombin is turned into thrombin, which activated soluble fibrinogen with insoluble fibrin that creates a mesh to stop blood

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21

antigen

protein found in membrane or cell wall of a bacterium that enables the body to recognise the pathogen

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22

antibodies

proteins that are produced by lymphocytes in response to antigens.

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23

what triggers antibody production

antigens stimulate cell division of lymphocytes that produce specific antibody; a clone of them is plasma cells that secretes antibody

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24

how do antibodies kill pathogens?

cause bacterial cells to clump (agglutination), cause cell walls to rupture, prevent viruses from attaching to host cells

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25

antibiotics

kill or block bacterial growth. Some: block protein synthesis inside, prevent cell wall formation, rupture membrane or inhibit enzymes

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26

ventilation

maintains a concentration gradience of oxygen and carbon dioxide between the air in the alveoli and blood in capillaries

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27

pneumocytes

type 1 are adapted to gas exchange (flattened and thing), and type 2 create a moist surface (pulmonary surfactant)

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28

inhalation

lung pressure reduced, thorax volume increased, vacuum createrd. Diaphragm contracts to flatten, external intercostal muscles contract to raise ribs

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29

exhalation

lung pressure increased, air forced out, internal intercostal muscles contract to lower ribs, abs contract and diaphragm relaxes, to reduce volume of thorax and force air out

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30

lung cancer

tumours take up space in lungs, prevent gas exchanged and strain the heart (mitosis processes disturbed)

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31

emphysema

small alveoli replaced with larger air sacs of thick and unelastic walls

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32

neuron

a nerve cell that transmits electrical impulses along its length to the next neuron until it reaches a muscle

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33

resting potential

the potential difference across the plasma membrane of a neuron when an impulse is not being transmitted. For most this is 70mV

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34

action potential

rapid change in the membrane potential. It consists of two stages: depolarisation and repolarisation

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35
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