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AEROBIC RESPIRATION C6H12O6 + 6O2 6CO2 + 6H2O
Definition: Splitting of the respiratory substrate (e.g. glucose) to release carbon dioxide as a waste product and reuniting
of hydrogen with atmospheric oxygen with the release of a large amount of energy.
(1) Glycolysis (in the cytoplasm) [Produces: 2 x (3C) Pyruvate, 2NAD
(H), 2 ATP] (4) Oxidative phosphorylation (in the mitochondrial matrix) [1
-Glycogen from muscles and liver cells are converted to hexose sugar Glucose= 32 ATP]
(glucose).
-Two phosphate groups P(i) are added to glucose, this makes is Reduced NAD and FAD from other stages release their
UNSTABLE and REACTIVE. hydrogen atoms- which split into H+ and an electron.
-Splits into 2 molecules of (3C) compound. Each (3) compound is
Electrons move along 3 carrier proteins in the electron
oxidised to produce pyruvate (3C). The two hydrogen atoms lost are
collected by coenzyme NAD- forming two reduced NAD. Phosphate transport chain on the mitochondrial matrix and lose
groups, P(i) from the pyruvate are given to ADP> two molecules of energy.
ATP are formed through substrate-level phosphorylation.
(2) The Link reaction [Produces: Acetyl coA, 2NAD(H), CO2 ] Energy used by carriers to pump protons from
(3C) pyruvate is decarboxylated> so CO2 is released (waste product) mitochondrial matrix to the inter-membrane space. H+
AND dehydrogenated so 2 Hydrogen atoms are removed by NAD. concentration is greater in the inter-membrane space
Left with a (2C) compound. The (2C) compound combines with the which creates an electrochemical gradient.
coenzyme A- producing Acetyl-coA.
Protons move down the gradient- back into the
(3) The Krebs cycle (in the mitochondrial matrix) [Produces: 2CO2,
1ATP, 3NAD(H), 1FAD(H)]
mitochondrial matrix via ATP synthase on stalked particle.
-Acetyl coA combines with (4C) Oxaloacetate to regenerate coA and This movement drives the synthesis of ATP- this is called
form (6C) Citrate. the CHEMIOSMOTIC THEORY or CHEMIOSMOSIS.
-(6C) Citrate- is decarboxylated and dehydrogenated, forming a (5C)
compound.
-The (5C) compound is decarboxylated and dehydrogenated forming a At the end of the electron transport chain, in the
(4C) compound. This time two NAD(H) and one FAD(H) are made. mitochondrial matrix H+ combine with an electron and O2
There is an intermediate compound- gives a P(i) to ADP> forming ATP. from blood to form WATER.
The intermediate then becomes (4C) Oxaloacetate which goes back
into the Krebs cycle.…read more

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NORMAL ELECTRICAL ACTIVITY OF THE HEART
(4) Instead, these waves of electrical
activity are transferred from the SAN to
the AVN.
(5) The AVN is responsible for passing the
waves of electrical activity onto the
Bundle of His. There is a slight delay
before the AVN reacts, to make sure that
the ventricles contract only after the
atria have expired fully.
(6) The Bundle of His is a group of muscle
fibres responsible for conducting the
waves of electrical activity to the finer
muscle fibres in the right and left
ventricle walls- called the Purkeyne
fibres.
(7) The Purkeyne fibres carry the waves
of electrical activity into the muscular
walls of the right and left ventricles,
causing them to contract simultaneously,
(1) The Sino Atrial Node (SAN) is in the wall of the right atrium- it's the from the bottom to the top.
pacemaker of the heart. The SAN sets the rhythm of the heartbeat by
sending out regular waves of electrical activity to the atrial walls.
(2) This causes the right and left atria to contract at the same time.
(3) A band of non-conducting collagen tissue prevents waves of electrical
activity from being passed directly from the atria to the ventricles.…read more

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BREATHING RATE HEART RATE
Controlled by two ventilation centres in the medulla- the Controlled by the Cardiovascular Control Centre in the Medulla.
inspiratory and the expiratory centre.
· The inspiratory centre in the medulla sends impulses to pH decrease> Heart Rate increase:
intercostal muscles and diaphragm muscles, making A decreases is detected by chemoreceptors. These send
them contract= This increases the volume of the lungs> impulses to the medulla. The medulla sends impulses to the
lowers pressure in the lungs. Inspiratory centre also SAN to increase the heart rate.
send impulses to inhibit the expiratory centre.
· Air enters the lungs because of the pressure difference Blood pressure increase> Heart Rate decrease:
between lung air and the air outside. -Pressure receptors in the aorta wall and carotid sinuses
· As lungs inflate, stretch receptors in lungs are detect changes in blood pressure.
stimulated. These send nerve impulses back to the -If pressure is too high, receptors send impulses to the
medulla. These impulses inhibit the inspiratory centre. cardiovascular control central which sends impulses to the
· The expiratory centre is no longer inhibited- it sends SAN to SLOW DOWN the heart rate.
impulses to the diaphragm and intercostal muscles to -If pressure is too low, pressure receptors send nerve impulses
relax. This causes lungs to deflate, expelling air. As to the cardiovascular control centre which sends impulses to
lungs deflate, stretch receptors become inactive= the SAN to SPEED UP the heart rate.
inspiratory centre is no longer inhibited so the cycle
starts again. Cardiac output: total volume of blood pumped by a ventricle
Decrease in blood pH = Increase in breathing rate every minute.
During exercise, CO2 level in the blood increases> this Stroke Volume: volume of blood pumped by one ventricle
decreases the pH of blood. There are chemoreceptors each time it contracts.
that are sensitive to pH changes, in the medulla, aortic Cardiac Output = Heart Rate x Stroke Volume
bodies & carotid bodies. cm3/min b.p.m. cm3
· Chemoreceptors sense a pH decrease > send impulses
Cardiac Output increases with exercise because Heart Rate
to the medulla> medulla sends MORE FREQUENT
increases.
impulses to the intercostal muscles and diaphragm >
Ventilation rate: Volume of air breathed in or out in a period
this increases the RATE and DEPTH of breathing.
of time e.g. a minute.
· This speeds up gas exchange so the CO2 level drops
Ventilation rate increases during exercise because breathing
and extra O2 is supplied to muscles.
rate and depth increases.…read more

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THE HUMAN
When it's DARK, rod cells are NOT stimulated:
EYE · Sodium ions (Na+), are pumped out of the cell using active
transport. But these can diffuse back in through open (Na+)
channels.
· This makes the inside of the cell only slightly negative
compared to the outside- the cell membrane is
DEPOLARISED (not much difference in potential.)
· Depolarisation triggers the release of neurotransmitters.
· These neurotransmitter inhibit the bipolar neurone- so it
Light enters the eye through the pupil. The amount of cannot fire an action potential. No information is sent to the
light that enters is controlled by the iris muscles. brain.
Light rays are focused by the lens onto the retina, which
lies on the inside of the eye. The retina contains
photoreceptor cells. The fovea is the area in the retina When it's LIGHT, rod cells ARE stimulated:
that controls lots of photoreceptors. Impulses from the · Light energy causes Rhodopsin (purplish pigment) to break
photoreceptors are carried from the retina to the optic down into Retinal and Opsin- this is BLEACHING.
nerve to the brain. The optic nerve is a bundle of · Bleaching causes (Na+) channels to close. So (Na+) are
neurones. There are no photoreceptors where the optic actively transported out of the cell but they cannot diffuse
nerve leaves the eye- the blind spot. back in.
· This causes (Na+) to build up outside of the cell, making the
The human eye has TWO types of inside of the cell much more negative than the outside- the
photoreceptors cell membrane is HYPERPOLARISED.
· Rods- Found in the peripheral parts of the retina. · When a rod cell is hyperpolarised, it stops releasing
Gives information in black and white neurotransmitters. This means the bipolar neurone is not
(monochromatic vision.) inhibited so it depolarises.
· Cones- Found packed together in the fovea. Gives · If the change in potential difference reaches the threshold,
information in colour (trichromatic vision). There are an action potential is transmitted along the optic nerve to
3 types of cones: red, green and blue- sensitive. the brain.
They're stimulated in different proportions so you
see different colours.…read more

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Cerebrum-See, think, CT- Computed Tomography
BRAIN STRUCTURE learn, feel emotions. Uses x-rays to produce cross-sectional images of the brain. More
The heaviest part of the dense areas > absorbs more radiation > shows up lighter.
Structure: Shows the major brain structures.
brain, making up 2/3 of
Function: Doesn't show brain function directly but unusual scan
brain mass. Divided into
can be compared with patient's loss of function- it would imply
two parts called the left
that the function loss is due to damage to that area.
and right hemispheres. Diagnosis: Useful e.g. bleeding after a stroke- blood shows up
Each hemisphere lighter as it has different density to brain tissue. Can show
contains four lobes. location and extent of bleeding. Used to work out which blood
Cerebellum- Co-ordinates Surrounded by a thin vessels are damaged> which functions will be affected.
movement. Located under the layer- the cerebral
cerebrum. Also has a folded cortex which is highly MRI- Magnetic Resonance Imaging
cortex. Controls movement and folded= large surface Uses a magnetic field and radio waves to produce cross-sectional
balance. images of the brain. More expensive than CT.
area.
Structure: More detailed than CT- can clearly see the difference
Hypothalamus- Controls body temperature (thermo between normal & abnormal tissue.
regulation) automatically maintains body temperature at Function: Same with CT. Scan compared with condition.
the normal level. Produces hormones that control the Diagnosis: Useful e.g. tumour- tumour cells respond to a magnetic
pituitary gland just below it. field differently- show up lighter. Can show the exact location and
size of the tumour so the correct/ most effective treatment can be
Medulla- Controls breathing rate & heart rate. Ventilation given. Any resulting loss of function can be predicted.
and Cardiovascular Control Centre. Located at the base of
the brain and at the top of the spinal cord. fMRI- Functional Magnetic Resonance Imaging
Same as MRI but shows changes to brain activity as they happen.
Functions of the lobes: More oxygenated blood flows to active brain regions= molecules in
-Frontal- Reasoning, planning, decision-making, this respond differently to those in deoxygenated- appears lighter.
consciousness of emotions. Forming associations and Structure: Similar to MRI- good detail.
ideas. Also includes the primary motor cortex. Function: Function is carried out whilst in the scanner- brain
-Parietal- Orientation, sensation, calculation, movement, regions involved will be more active & COLOURED so they show up
some recognition, memory. more easily.
-Occipital- Visual cortex- vision, shape, colour, Diagnosis: Very useful. Shows abnormal brain regions & allows
recognition, perspective. scientists to study conditions caused by abnormalities- some
-Temporal- Auditory- sound recognition, speech, hearing. conditions don't have obvious structural causes.…read more

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