I remember writing these notes in Y12, I know first hand the amount of time that has to be invested into this subject and how difficult it can be to identify the key information. These notes are time savers, giving you more time to practice questions and past papers. The notes used for all my A-lev...
Active transport
Activetransportenables cells to move substances across membranes against a
concentration
or electrochemical gradientusingATP
tow does activetransportwork
carrier proteins for active transport can beveryspecific Eoronly one type of ion or
molecule or may work for several similar substances
cells that undergo lots of active transportusually have mitochondria to supply the
ATP needed ATPasecatalyses the hydrolisis of ATP
Active transportwill move substance in the direction
requiredby the cell The will move out againthrough
open channels down the concentration gradient that
has just been overcome Active transport can move
substances in Easter than they can move out by
difusion
Sodium pumpsactively move potassium ions
into the cell and sodium ions out
Nerve impulsesdepend on a influx of sodium
ions through the axon membrane these
ions have to be activelypumped out of
the neurone so that another impulse can
pass
Thanks to difusion facilitated diffusion and active
transport
cells con control what enters and leaves the
cell through the cell membrane
Evidence or active transport
Active transportrequiresATP without it it will not
YAative transport happens in living cells
2 Rate of active transportdepend on temperature
and oxygen concentrations as these affect the rateo respiration thus
the production of ATP
3 Cells known to carry out lots of active transport nave manymitochond
for ATP production
4 Poisons stoppingrespirationor thefunctioning of ATPase also stopactive
transport
ATPisconverted
into ADPthrough
reaf
a nyaroisis
tioncatalysed by
the enzymeATPase
,Endocytosis and exocytosis
Endocytosis is the transport of large molecules into the cellthroughvesicles
Pinocytosis is the absorptionthroughvesicles of the surroundingElvid to actas a
source of minerals and nutrients
Exocytosis is the emptying o a membrane bound vesicle at the surface of the
cellar elsewhere
in cellsproducing hormones vesiclescontaining the hormone
fuse with the cell surface membrane to release the
contents
Phagocytosis is the ingestion of bacteria felleating it is
a form of endocytosis
The formation of vesicles and the Eusing of same with the
Surface of the cell membrane are both active processes
requiring an input of ATP
, Atherosclerosis
he formation of atheroderosis
Atherosclerosis is a build upof plaques on theinsideoearteriesPlaquesarelikelyto form on coronary
arteries and carotidarteries theneck
Damage to the endothelialliningoe bloodvessels can becausedbyhighbloodpressurechemicals
Atherosclerosis occurs inarteriesbecauseblood lows at higher
pressures putting more strain on the endotheliumlining
Pressure in veinsis lower so it is lesslikely to occur
1 chite bloodcellsarrive at the site of damageThey
accumulate
chemicals from the blood particularlycholesterol
leadingto a plaque
2 Fibroustissue and calcium salts build up in theatheroma
hardening the plaque
Hardening will mean that the wall of theartery
also hardens and becomes less elastic
Lumen oeartery becomes much smaller increasing
bloodpressure and therefore increasing the risk of
damagein other areas oe the endotheliallining
aneurysms
An aneurysmis caused when bloodbuilds up behind a blockage thearterybulgesand th
wall is putunderhigh pressure weakening the artery It may cause the artery wall to
splitopenleading to internal bleeding
Bleeding will causebloodloss and a drop in pressure
raisedbloodpressure
Narrowedarterieswill cause a higherbloodpressurecausingseriousdamagein a numberof ath
organs IE vessels feedingthe kidneys narrow bloodpressureincreasesmayforceproteinsou
of the walls
Tinybloodvesselsin the retina can cause blindness if theybecomeblocked as they starve
retinalcells of oxygen and theydie
cartdisease
Two most common heart deseases are angina and myocardial infarction heart attack
i In
anginaplaques build up in coronary arteries reducingbloodflow to the heart
Symptoms are shownduringexercisewhen the muscle is working harderandneedsmoreoxy g
Arteries can'tsupplyenoughoxygenand the heartresorts to anaerobicrespirationcausin
gripping chestpain that can extendto the arms especiallythe leet
Angina can behelped with regularexercise loosingweightand not smoking
Drugs can beused to dilate blood vessels and reduce heart rate stents may beinserted
to hold arteries open
in myocardial infarction branches of thecoronaryartery are blocked As a result part of the
heart muscle is completely starved from oxygen
wall of artery is affectedby a plaqueis stiffened it is then likely to suffercracks
Platelets come to the damaged surface of the plaqueand theclottingcascadeistrigge
Plaquemay rupture and leak cholesterolreleasedwill also causeplatelets to triggerclotti
clot may also form simply due to damage oe the endothelial lining
, y y o s
Myocardialinfarction
Clots formed in bloodvessels are called thrombosis
Clots in a coronaryartery coronary thrombosis
Strokes
A stroke is an interruptionto the normal bloodsupply
to an area of the brain This may be caused due
to bleeding eran damagedcapillaries or a blockage
caused by a clot atheroma or both
Blood clots may form anywhere in the body and
Travel downstream until it get s stuck in arteries
in the brain
Symptomsmayincludediriness confusion slurred
speech or even paralysisSeverenessoe symptoms
will dependon how much of the brain has been
acected
E treatment is givenrapidly most of the people
that suffer from heart attacks may survive 75 of the people who survive the
first week after a heart attack can expect to be alive five years later
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