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MUSCLES

Muscles are antagonistic because they work in opposite directions, as muscles can only pull and
not push
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e Biceps
and 2 an extensor to extend the joint i
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The muscles contract to cause the action
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They are surrounded by synovial membrane which secretes
synovial fluid and acts as a lubricant so the bones can
movie easily
...


The difference between ligaments and tendons
•
•
•

Ligaments
Bone to bone attachment
More elastic
More flexible

•
•
•

Tendons
Bone to muscle attachment
Less elastic
Less flexible

Structure of skeletal muscle
•
•
•
•

The cell membrane of a muscle is called the sarcolemma and the
cytoplasm is called sarcoplasm
...

The sarcoplasm contains may nuclei, mitochondria and sarcoplasmic
reticulum which contains t tubules that have calcium ions
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Myofibrils

Myofibrils have thick protein filaments called myosin and thin protein filaments called actin
...
When the muscles contract actin will slide in between the myosin and the sarcomere will reduce in
length
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When muscles contract:
1
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I band and H zone will shorten
...

If there is not enough oxygen then the muscles rely on anaerobic respiration which happens in the
sarcoplasm and it releases a small amount of ATP
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When ATP
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ATP + H2O à ADP + PI

ADP + CP à ATP + Creatin

Creatin + Pi à CP

Muscle fibres

There are two types of muscle fibres:
1
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2
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•
•
•
•
•
•

Slow Twitch (Longer)
More mitochondria needed as more ATP is
needed to contract for long
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Fatigue resistant
Less glycogen content as it is converted into
glucose for aerobic respiration
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(Looks red in colour
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g
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Fatigue easily
More glycogen contents
Less myoglobin (looks white under the
microscope)
E
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Sprinter or weight lifter

Myoglobin

A pigment similar to haemoglobin, it has a high affinity (attraction) for oxygen
...

Myoglobin is a protein which has a Quaternary structure with more that 2 polypeptide chains, has a 3D shape,
Hydrophobic R group in the middle of the coil and a Hydrophilic R group inside the coil
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Mechanism for Muscle contraction

The sliding Filament theory

1
...
Ach will diffuse across the junction and bind to the receptors of the sarcolemma which will open sodium
channels so Na+ will diffuse in which will then generate an action potential
...
This action potential will travel into the T tubules and Ca2+ are released from the sarcoplasmic reticulum
into the sarcoplasm
...
Ca2+ will bind to the troponin of the actin and this will cause the tropomyosin of the actin to shift its
position so that the binding site is exposed
...
Myosin head will bind to the binding site to form a crossing bridge where ATP is used with the help of the
enzyme ATPase in the myosin head
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6
...
(The sarcomere becomes shorter)

RESPIRATION
Mitochondria structure

•
•
•

BMR (Basal metabolic rate) – The minimum amount of energy needed at complete rest for heartbeat,
breathing (KJg-1h-1)
Respiration – A series of enzyme controlled reactions in which glucose, proteins or lipids are hydrolysed to
give you energy
...
During respiration, NAD accepts hydrogen atoms (H+ + e-) so it becomes reduced
NAD which gives 3ATP
...
Carries hydrogen atoms (H+ + e-) leads to FAD to give 2ATP
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Glycolysis
2
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Kreb’s Cycle
4
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1
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2
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(Glycolysis is the only stage where ATP is used)
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2 Pyruvate (3C) + 2 NAD + 2CoA à Acetyl CoA (2C) + 2NAD + 2CO2
Decarboxylation – CO2 is released
Dehydrogenation – Hydrogen atoms are released from the pyruvate
The pyruvate becomes oxidized, hydrogen atom is then accepted by NAD to form reduced NAD
...
From the link reaction 2C acetyl CoA enters the kreb’s cycle
2
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3
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Oxidative phosphorylation\ETC
This stage provides the most ATP and happens in the cristae of the mitochondria
...
From the previous reactions hydrogen atoms carried by NAD to form reduced NAD which is then carried
along a series of electron carriers to undergo redox reactions until they reach oxygen which is the final
electron acceptor
...

2
...
These channel proteins with the ATPase
are found on the stalked particles

The use of ATP released during respiration

1 glucose molecule gives 38 ATP molecules most of this energy is used to maintain core body temperature (37) and
to increase the rate of metabolic reactions
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Electron carriers – NAD and FAD
Stalked particles – Channel proteins with ATPase used in chemiosmosis
Loop of DNA – genes to code for proteins
Ribosomes – Protein Synthesis

Substances in and out of mitochondria
IN
Pyruvate
Reduced NAD and Reduced FAD (Co enzymes)
O2

OUT
NAD and FAD
H2O (Water)

Incubation of mitochondria (Practical)

If glucose is incubated with mitochondria there is no reaction because glucose is used in glycolysis which happens in
the cytoplasm of the cell
...
If pyruvate is incubated with mitochondria the
link reaction would occur in the matrix of the mitochondria
...

Aerobic respiration has 4 stages that provide ATP hence more ATP is released and more NAD and FAD are
reduced releasing ATP
...


Anaerobic respiration in the muscles

Glycolysis happens and forms 2ATP and 4 H+ atoms released and reduced NAD
...


Effect of lactic acid

Lactic acid can reduce the pH of the blood which can affect the 3D shape of the enzyme and tertiary structure of the
enzyme, hydrogen, ionic and disulphide bonds are all affected
...


Fate of Lactic acid

CONTROL OF HEART RATE AND BREATHING RATE

Myogenic – Contracts on its own with no nervous stimulation
Aerobic captivity – the ability to take in, transport and use oxygen
...
3 litres)
VO2(Max) – The maximum volume of oxygen used per minute during exercise (3-6 litres)
Stroke volume – The volume of blood pumped out of the left ventricle each time the ventricle contracts
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Heart rate

Normal resting heart rate in a male is 70 bpm while in a woman it is 75 bpm
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SAN is the pacemaker of the heart as it starts the wave of electrical impulses, so the right atrium will contract
...
The wave is the passed on to the AVN, so the left atrium can contract which is called atrial systole and the tri
and bicuspid valves open to allow the blood to flow into the right and left ventricles
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Before the wave passes from AVN to the bundle of his there is a slight delay to ensure that both right and left
atria are fully contracted and both the ventricles are completely filled with blood
...
Once the wave has passed on to the bundle of his and purkinje fibres both the right and left ventricles contract
known as ventricular systole in which the semi lunar valves close
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The wave will then pass to the apex of the heart and the muscle will relax known as diastole
...
ECG can be performed at rest or during exercise
which is know as a stress test
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60
To find heart rate
Length
of
The length of the cycle is usually 0
...
8
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Brady Cardia – Hr < 60 bpm
• Heart disease
• Medicinal drugs
• Naturally or trained lover bpm E
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Athletes
2
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Ischaemia – A branch of coronary arteries are blocked
• Atheroma
• Thrombosis
• Heart muscles will not get enough oxygen hence the death of tissue
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Arrhythmia – (No rhythm ) When the electrical impulse produced by SAN is not evenly distributed leading to
the irregular heart beat
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This is detected by chemoreceptors in the medulla oblongata and the impulse is sent to the
cardiovascular centre and then the acceleratory centre
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During exercise the movement of the muscles are detected by the stretch receptors that also increase heart
rate
...

If the blood pressure is high in the carotid artery (pumps blood to the brain) it is detected by pressure receptors
so the impulse is sent from the Medulla Oblongata to the cardiovascular centre then the deceleratory centre
to the parasympathetic nerves (vagus nerves) so the SAN will produce less electric impulse and the heart rate
will decrease
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5 dm3)
Vital capacity – the maximum volume of air you can breathe in and out per minute (4 dm3)
Minute ventilation = Tidal volume X Breathing rate (the number of waves in 60 seconds)

Control of breathing rate of the nervous system

1
...

2
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The impulse is then sent to the diaphragm which contracts and goes down
and to the external intercostal muscles which will contract, and the ribcage goes up
...
The lungs are now filled with air which is detected by stretch receptors in the bronchiole and they send
inhibitory impulse (stop impulse) to the inspiratory centre so you can stop breathing in and the diaphragm will
relax and goes up
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How CO2 concentration increases H+

CO2 Dissolves in water from the red blood cells to form carbonic acid which is catalysed by the enzyme carbonic
anhydrase
...
The increased H+ will lower the pH of the
blood
...


Negative feedback

When there is a change in the set point (normal value) It is detected by receptors and the reversal of the change
happens to bring it back to the set point to maintain homeostasis
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• If testosterone concentration decreases the hypothalamus produces the hormone gonadotrophin which will
stimulate the pituitary gland to release more testosterone
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• During glycolysis when glucose is converted into pyruvate, enzyme phosphofructokinase (PFK) is used
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(Allosteric site is a place found anywhere on the enzyme besides the active site)

When ATP binds to the allosteric site the active site changes shape so the PFK cannot function and respiration stops
...


Positive feedback

When there is a change in the set point but the change is further increased and can be harmful
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• It can be beneficial such as during child birth, when the uterus contracts the pituitary gland releases oxytocin
hormone which makes the uterus contract even more until the cervix is dilated and the baby is born
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The platelets release a
chemical that will attract more platelets until a blood clot is formed
...

• Hairs on the skin stand up to trap air which is a good insulator to keep warm
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• Vasoconstriction so there is less blood flow to the capillary and the heat is lost by radiation and blood will be
diverted through the stunt vessels which will dilate
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This is an example of negative feedback
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• Sweating happens where sweat evaporates and the body heat goes down to keep us cool
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• Vasodilation there is more blood flow to the capillaries so more heat is lost by radiation and the stunt vessels
constrict
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High humidity and exercise

Due to high humidity in the air there is a lot of moisture content the sweat cannot evaporate as there is no
concentration gradient and this will lead to an increase in body temperature causing dizziness

Method of energy transfer

Conduction – When energy is transferred from one object to another Solid à Solid
Convection – When energy is transferred from Liquid à Liquid or Gas à Gas
Radiation – When energy is radiated to an object from an object through air or vacuum as electromagnetic radiation

EXERCISE AND THE IMMUNE SYSTEM
Benefits of exercise
•
•
•
•

Increase HDL (good) and decreases LDL so there is less risk of coronary heart disease
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Increases bone density, less risk of osteoporosis (weak bones)
Exercise can improve your immune system because it increases
Ø Number of T helper cells, B cells and T killer cells
Ø Producing more antibodies
Ø Number of natural killer cells which are used in the non-specific immune response against virus and
cancer cells
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RICE
Ø Rest
Ø Ice
Ø Compression
Ø Elevation
2
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Key hole surgery
4
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Due to the less number of T helper cells less B cells are activated so less antibodies are being produced and
also the number of natural killer cells decreases and at a higher risk of getting UVRTI (upper respiratory tract
infection)
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Patellar tendonitis -When the patella (knee cap) rubs against the femur (thigh bone) causing inflammation
from the cartilage wearing
...


Key hole surgery

Key hole surgery on joints are known as arthroscopy
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During surgery a very small incision is made through which a camera and surgery tools are inserted
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Anterior Cruciate – ensures the knee doesn’t bend too far forward
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Prosthesis

Artificial body parts are used to regain normal function
1
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Replace the entire knee cap and insert titanium and poly-ethene as cartilage
3
...


HORMONES

Glands
Endocrine
Releases hormones into the blood stream which will
then attach to complimentary receptors on the cell
surface membrane of a target organ
...
g
...
E
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The pancreas releases enzymes such as carbohydrase
protease into the pancreatic duct which goes into small
intestine
...

Gland
Hormone
Function
Pituitary gland
1
...
Stimulates growth
2
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Controls the ovaries and matures the eggs
3
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Controls the water absorption in the kidney
Thyroid gland
Thyroxine
Increases basal metabolic rate
Adrenal gland
Adrenaline
Prepares the body for fight or flight and increases heart and
breathing rate
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Insulin
1
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Glucagon
2
...

Testis
Testosterone
Promotes the development of the male secondary sensual
characteristics
...

Promotor
Operator
Genes coding for protein
(blocked) mRNA +RNA polymerase
Receptor proteins
OFF

Genes on

The repressor protein will not bind to the operator, so the promotor is unblocked and the mRNA and RNA
polymerase will bind to the promotor and transcription and translation happens and the genes are switched on
...


Types of hormones

Peptide hormones are made of amino acids
...
g
...
E
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Oestrogen, testosterone

Action of peptide hormones

A hormone ie insulin binds to the complimentary receptor on the cell surface membrane of the target organ to form
a hormone receptor complex
...
A second messenger called cAMP is activated which will enter the target organ and initiate transcription
initiation complex mRNA and RNA polymerase will bind to the promotor, transcription and translation happens and
the genes coding for proteins are switched on
...
This complex is lipid soluble so they can diffuse through the phospholipid bilayer and can activate
transcription initiation complex which will then start transcription, translation and the genes switch on
...
More
aerobic respiration releasing more ATP
• Difficult to test EPO in athletes because high EPO can be natural as it is produced by kidneys
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• EPO can also be used as a treatment for anaemia
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• It is illegal and can be tested via urine samples with the use of mass spectrometry
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• It can be used as a treatment for osteoporosis (weak bones)
Creatin – Legal Drug
• A peptide hormone naturally found in meat and fish
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• The side effects include nausea, vomiting and muscle cramps
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Athletes have the right to choose to take the
drug or not
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Some believe in equality hence in the
competition as each athlete gets different
resources such as training time and facilities
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• Some are under informed about the health
risks concerning and relating drug use
...

• Might be a burden on healthcare as symptoms
and side effects need treating

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