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Skeleton function
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Support
Protection
Framework for muscle attachment to allow movement
Types of skeleton
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Internal
External
External
- e.g. spiders, insects, crabs
External skeleton made of chitin, is protective supportive and allows for muscle attachment.
External skeleton does not grow, so animal has to shed it as it grows and form a new one.
Internal
Found in fish, birds, reptiles, amphibians, mammals.
Some fish e.g. sharks, dogfish, there skeleton is made entirely out of cartilage and not bone.
Bones and cartilage
Both of these are living tissue with blood vessels and nerves. Bones are moves when the
muscles that are attached to them contract and relax.
Bone growth (H)
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Embryos have skeletons made of cartilage (this is mainly protein).
From 6 weeks growing in the womb, minerals (mainly calcium phosphate) are
deposited into the cartilage, and the bone hardens (ossification).
Children have more cartilage at the ends of their bones than adults as they are still
growing (forensic scientists use the amount of cartilage still present to tell the age of
a dead person).
Bones and cartilage can be infected by pathogens.
Structure of the long bone
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Ends of the bones are covered in smooth cartilage to reduce friction when bones
move
The bone is hollow to it is light, but the hard outer layer is hard so the bone is still
strong.
In the centre of the bone is marrow and blood vessel. Fat is stored and new blood
cells are made here.
Bones fractures (breaks)
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Green stick- bone is bent. Often occurs in children with rickets (soft bones due to
lack of vitamin D and calcium in their diet)
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Simple fracture- bone is broken but does not stick out through the skin
Compound fracture- this is an open fracture where the broken bone sticks through
the skin.
Old people with osteoporosis (soft bones) are at greater risk of fractures.
Muscles and joints
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Bones cannot move without the muscles attached to them contracting or relaxing.
Tendons attach muscles to bone
Ligaments attached bone to bone
Moving the arm
Bending the arm- the bicep contracts pulling the radius bone upwards and the triceps
relaxes
Straightening the arm- the triceps contracts pulling the ulna downwards and the biceps
relaxes
Levers (H)
The hinge joint is like a lever
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Elbow is the pivot (fulcrum)
Muscles have to exert a greater force than the load for the bone to move
The hand moves a greater distance than the muscles
Joints
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Bones in skeleton could not move without joint
Types of joint
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Fixed- in the skull which are fused together (babies have a cartilage patch on top so
skull can be squeezed to fit through birth canal.
Hinge- at elbows and knees, and movement only in one plane (back or forwards)- is a
synovial joint
Ball and socket- hips and shoulders, can rotate bones in many directions- is a
synovial joint
(H) Synovial joints
Freely moving joints are also called synovial joints
Features
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Moving ends covered in cartilage (stops friction)
Joint is enclosed in a capsule
Capsule lined with a membrane that secretes synovial fluid (lubricates the joint)
The circulatory system
Organisms such a single –celled amoeba do not need a circulatory system as they have a
large SA/volume ratio, so substances can easy diffuse into it.
As organisms become multicellular their SA/vol ratio decreases (their volume is larger as is
filled with many cells), and they need a circulatory system to transport substances to the
cells.
Types of circulatory system
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Open- found in insects. Blood does not travel in blood vessels but bathes the cells.
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Closed – vertebrates. Blood travels in blood vessels (arteries, veins and capillaries).
Closed can be single or a double closed circulatory system
Single- e.g. fish. Two chambered heart and blood only goes through once. It goes from the
Heart gills body.
Double- e.g. humans. Four chambered heart and blood goes through it twice as there are
two circuits (circuit from heart to lungs and back, and circuit from heart to body and back).
(H) History of the circulatory system
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In 2nd Century, Galen, a Roman physician (doctor) of Greek origin dissected monkeys
and pigs and found blood in the veins was a darker colour compared to the arteries.
He thought the liver made the blood and pumped it through the veins to the organs- he
was wrong of course! His ideas influenced medicine for 1000 years.
• 16th Century, Leonardo da Vinci studied anatomy and made drawings of how blood
passed through the chambers, and how the heart valves worked.
• In 17th Century, Dr William Harvey published a book on how blood circulates in the
body i.e. a double circulatory system. He linked the pulse in the arteries to contraction
of the left ventricle. He discovered that veins had valves to prevent blood back flow. He
predicted that there were capillaries but as he did not have a microscope he did not see
them.
The cardiac cycle
LORD- left oxygenated, right deoxygenated
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The heart is made of powerful cardiac muscle which receives a continuous supply of
glucose, fatty acids, and oxygen from the coronary arteries, which allows the cardiac
muscles cells to respire aerobically, generating energy for contraction.
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Blood goes into the atria, the atria contract and forces blood into the ventricles. The
ventricles contract and forces blood into arteries that take blood around the body.
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When ventricles contract, blood goes away from the heart in arteries under high
pressure.
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Arteries divide into more arterioles, and these arterioles into even more capillaries
(high total cross-sectional area).
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This means that the circulatory system is becoming ever more branching and so the
time it gets into the many capillaries, blood pressure is low.
A=aorta
Art= arteries
C=capillaries
V= venuoles
Ven= veins
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The rate of blood flow is very low in the capillaries to allow exchange of substances
between the blood and the cells.
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Veins have wide lumens (holes running through them), and so blood pressure is low.
Due to this low blood pressure and as blood is sometimes returning to the heart
against gravity, veins have valves which shut when the heart relaxes, and keeps the
blood moving in one direction.
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Key Fact- left ventricle wall is made of thicker muscle than the right ventricle wall.
The left ventricle wall is thick as the muscle has to contact hard enough to force
blood out of it and around the whole body, while the right side has to contract and
push blood only as far as the lungs.
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Key fact -The pulse is a measure of heart rate. When the ventricles contact and push
blood into the arteries, the arteries which have elastic walls, expand and recoil (open
wider and the narrow again). This can be felt where vessels are near the skin.
The cardiac cycle
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Diastole- the heart relaxes and the atria fill with blood.
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Atrial systole- the atria contract and force blood into the ventricles
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Ventricular systole- ventricles contract and force blood into the arteries
Control of the cardiac cycle
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The pacemaker- Sinoatrial node (SAN) is a patch of specialised tissue that produces
electrical impulses, which spreads across the walls of the atria causing them to
contract (atrial systole).
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This contraction causes increased pressure inside the atria forces blood through
opened atrioventricular valves into the ventricles.
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When the electrical impulses have spread across the atria, a patch of muscle fibres
called the atrioventricular node (AVN), conducts these impulses along Purkyne fibres
to the tip of the ventricles, causing them to contract (ventricular systole).
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This contraction increases pressure inside the ventricles, which forces the
atrioventricular valves shut (this stops back flow of blood into the atria).
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Blood forces open semi-lunar valves in the arteries.
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The heart relaxes (diastole) and the atria fill with blood, and the cardiac cycle starts
again. Each cycle is one heart beat
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Electrical activity of the heart can be recorded and a trace recorded called an
electrocardiogram (ECG)
Artificial pacemakers and heart repairs
Artificial pacemakers- Our natural pacemakers can detect when a person is more active
and send out more electrical signals to make the heart beat faster.
If people have an irregular heartbeat, they can have a pacemaker which is implanted just
under the skin with a wire passed from it into a vein and into the right atrium. These
artificial pacemakers need replacing every 10 years.
Hole in the heart- Fetuses have a small hole between the right and left atrium and blood
does not need to go to the lungs. At birth, this hole closes so that blood from the right
side of the heart has to go to the lungs for oxygenation. In some people this hole does
not close properly which means that less oxygenated blood gets to the body tissue,
leaving a person tired and breathless. This hole can sometimes be repaired with surgery.
Damaged heart valves- as people age, their heart valves may become stiff, not close
properly and allow the backflow of blood. These faulty valves can be replaced with
valves from pugs or cows, or with artificial ones (no chance of rejection and no blood
supply to valves).
Blocked coronary vessels- Coronary vessels provide a blood supply for the heart muscle,
but they can become blocked (eating too much saturated fat and smoking). If these
narrowed arteries get blocked heart attack (or angina- pain in chest which goes down
the arms). Bypass surgery can correct this where are vein is used to bypass the
blockage.
Heart transplant- heart replaced with a healthy donor heart. Big operation, where
people have to take anti-rejection drugs for life.
Considerations- There is a shortage of donor hearts and replacements of faulty parts
such as valves is less traumatic and no risk of rejection.
Donor cards- opt in is where you sign up to say you would be willing to donate, and opt
out is where it is assumed you will donate unless you sign up to say otherwise (religious
reasons e.g. Jehovah’s Witnesses).
Blood donation
History•
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1818.Blundell- first successful blood transfusion
1840- first blood transfusion in a haemophiliac
1901- discovery of blood groups which meant safer transfusions
Anti-coagulants- we naturally have in blood in case we have a cut. We need vitamin K (from
green veg) for clotting (K for Klotting). Put into blood bags to stop blood clotting.
Abnormal clotting- haemophilia is inherited and blood does not clot well. Drugs such as
warfarin, aspirin and heparin are given to stroke and heart attack patients to break down
clots.
Blood groups-
Red blood cells have proteins on their surface called agglutinins. Blood has antibodies that
will react against agglutinins (but obviously not your own).
Group O- universal donors as have no agglutinins for other groups antibodies to react
against.
Group AB- universal recipients as have no antibodies against any agglutinins.
Group A and B cannot receive each others blood as they have antibodies that will react
against their agglutinins.
Rhesus factor- people not only have different group of blood but either have a rhesus factor
(a D protein) or not e.g. group O rhesus positive, or group O rhesus negative. People with
rhesus negative blood cannot receive rhesus positive blood as they make antibodies against
the D protein.
Gas exchange
First forms of life on Earth (3.5 billion years ago) were bacteria which obtained there energy
by chemical reactions. Some bacteria developed the ability to photosynthesis and release
oxygen, which killed some anaerobic bacteria. Those that survived have resulted in life
forms evolving to respire aerobically.
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Single celled organisms- their gas exchange can be by diffusion as they have a large
surface area to volume ratio.
Multicellular organisms- as an organism has more cells (more volume) its surface
area to volume ratio decreases and so organisms cannot rely on diffusion for gas
exchange. However earthworms are long and thin so have a large surface area, and
together with a permeable skin, so gas exchange can occur by diffusion.
Amphibians- gas exchange across the skin, via simple lungs, and from the floor of
their mouth. Water loss prevent in frogs by them secreting mucus.
Fish- have a single circulatory system and gas exchange occurs in gills
Blood flows from heart to the gill filaments (large surface area), which have a good blood
supply. The fish gulps in water, raises the floor of its mouth, which forces water containing
oxygen over the gills, where gas exchange occurs. Oxygenated blood then flows from the
gills to the body.
Oxygen consumption of active fish greater than resting fish as more respiration
occurring in cells to provide energy. As temperature is warming, less gas is dissolved in
the water (fish have a need for a higher volume of water over their gills). Extrapolated
lines show that around 50 degrees Celsius the oxygen consumption of the fish would
exceed the ability of water at that temperature to supply sufficient oxygen.
The human respiratory system
Ventilation= breathing in and out of air
Lungs= gas exchange surface
Inspiration (breathing in)
Expiration (breathing out)
• Intercostal muscles contract and
• Intercostal muscles relax and the
pull the ribs up and out
rib cage moves down and in
• Diaphragm flattens
• Volume inside the chest decreases
• Volume inside chest and lungs
• Air pressure inside the lungs
increases
increases, the alveoli which are
• Air pressure decreases inside the
elastic recoil to normal size, and
lungs, air is at a higher pressure
these both forces air to the outside.
outside the body and so moves into
• Some air stays in the lungs to stop
the lungs
the alveoli closing. This air is called
residual air
Spirometer
Measures lung function
Tidal volume= volume breathed in and out at rest
Vital capacity= max you can breathe in + tidal volume+ max you can breathe out
Residual air= volume air left in lungs when you breathe out fully
Lung capacity= vital capacity + residual volume
Safety= sterile mouth piece each time, stop is patient feels unwell
This diagram shows a surface view of the left lung, nd a section through the right lung showing the
airways and air sacs inside.
The alveoli
Oxygen diffuses through alveolar walls into blood, and carbon diffuses from blood into
alveoli. Oxygen dissolves in a film of water that lines the alveoli and then moves through
the alveolar walls.
Adaptations of alveoli for diffusion•
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Thin walls
Permeable
Good blood supply
Large surface area
Diseases of the respiratory system
To prevent dirt and microbes causes lung infections
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Hairs up nose
Ciliated cells and mucus producing cells lining trachea and bronchi, to trap dust and
microbes and sweep to back of throat for swallowing (acid in stomach kills
microbes).
White blood cells called macrophages patrols lung tissue and ingests (eats) anything
foreign.
If pathogens not removed from lungs- could get lung infection
Disease
bronchitis
asbestosis
cause
Virus, bacteria, breathing in
smoke
Occupational diseasebreathing in asbestos fibres
Cystic fibrosis
Inherited disease
Lung cancer
Tar from cigarettes
symptoms
Cough, sore throat,
wheezing
Inflammation and scarring
of alveoli. Difficulty
breathing, could lead to
cancer
Mucus that is too thick is
produced, so cilia cannot
waft microbes to throat
chest infections lungs
eventually damaged
Cells lining bronchioles
keep dividing and form a
tumour  prolonged cough
, with blood
Asthma
Triggered by allergens e.g.
pollen, exercise
Wheezing, tight chest due
to muscles in bronchioles
contracting  build-up of
fluid
Digestion
We need to digest large insoluble substances into small, soluble ones that can travel
around the body in the blood
Physical digestion- breaking food up with teeth, and muscular churning of stomach
Chemical digestion- breaking food up with enzymes
Food
Type of enzyme
Carbohydrates
carbohydrases
Fats (lipids)
Proteins
lipases
proteases
Part of gut
where works
Mouth and small
intestine
Small intestine
Stomach and
small intestine
Products of digestion
Starchmaltoseglucose
Fatty acids and glycerol
Amino acids
Enzymes work best at a particular pH. Protease in stomach is adapted to low pH, and
acid needed in stomach to kills microbes.
Bile- made by liver, stored in gall bladder, and enters small intestine via bile duct.
Emulsifies fats into small droplets for easier digestion (larger surface area).
Villi in the stomach-
Finger-like projections that line the small intestine and it is through these digested food
is absorbed from the small intestine into the blood.
Adaptations
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Large surface area
Thin walls
Good blood supply
Large intestine- water and minerals are absorbed back into blood supply here. What is left
is faeces and is passed out of the body- egestion
Excretion
Main organs•
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Skin
Lungs
Liver
Kidneys
Skin-
Makes sweat that cools body down. Also gets rid of excess salts and water
Lungs- gets rid of excess carbon dioxide which would make blood too acidic and denature
enzymes. Increased carbon dioxide levels are detected by brain and it stimulates the
increase in breathing rate to get rid of the excess.
Liver – breaks down old red blood cells (makes bile and also passes out in faeces). Liver
breaks down hormones, medicines, ad alcohol. If you eat too much protein, the liver breaks
down excess amino acids into ammonia (harmful), and ammonia is reacted with carbon
dioxide to produce urea which is taken to kidneys for excretion.
Kidneys –
Kidneys filter out salts, water, urea, and glucose from blood. Glucose, some salts and
water are reabsorbed.
Nephron-
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Kidneys consist of millions of filtering units called nephrons. Blood enters kidneys
from the afferent arteriole, and this becomes a knot of capillaries (the glomerulus).
Blood goes through the glomerulus under high pressure, and small substances are
filtered through into the Bowman’s capsule. In the first part of the nephron, all the
useful substances such as glucose, hormones, vitamins etc. are reabsorbed (called
selective reabsorption).
The Loop of Henle is where water and salts are regulated.
ADH (anti-diuretic hormone) is released from the pituitary gland in the brain, into
the blood and travels to the kidney where is brings about the reabsorption of waterThe female repr
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from the Loop of Henle back into the blood.
When the blood is dilute, less ADH is released and so less water is absorbed resulting
in lots of dilute urine. When there is less water in the blood, more ADH is released,
more water is absorbed back into blood, and less urine is produced and it is
concentrated.
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Renal dialysis- for people who kidneys are not working properly and their blood is
filtered by a machine.
Growth and development
Primary sexual characteristics- external genitals which determine whether you are a girl or
a boy
Sex hormones cause secondary sexual characteristics
male
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Voice deepens
Hair grows on face and body
Body becomes more muscular
Genitals develop
Testes start making sperm
female
• Breasts develop
• Pubic hair and under arm hair grows
• Hips widen
• Periods start
Menstrual cycle
Several hormones coordinate menstrual cycle
Hormone
FSH
LH
Oestrogen
Progesterone
What it does
Produced by pituitary gland in brain, and causes an egg in ovaries to
mature. Also stimulates the ovaries to make oestrogen
Triggers the release of an egg (ovulation)
Stimulates the pituitary gland to produce LH. Inhibits further
production of FSH and repairs uterus lining (endometrium)
Maintains the lining of the uterus and inhibits LH
Fertility and fetal screening
Hormones can be used to reduce and decrease fertility
Reducing fertility- if women take a contraceptive pill containing the hormones oestrogen
and progesterone, ovulation is prevented as they mimic pregnancy. At high levels these
hormones inhibit FSH and LH from the pituitary gland and so eggs cannot develop and are
not released.
First contraceptive pill had high levels of oestrogen which prevented ovulation but had
high levels of side effects.
Increasing fertilityInfertility could be due to blocked fallopian tubes, testes not producing enough sperm, eggs
not developing or not being released from the ovaries.
Fertility treatment- IVF (in-vitro fertilisation)
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Women inject with FSH to produce eggs
Eggs collected and mixed in petri dish with sperm (or sperm are injected into eggs)
Fertilised eggs develop into embryos and two and inserted into uterus.
Treatment
Artificial insemination
Egg donation
Surrogacy
Ovary transplants
Description and reason for treatment
Where male sperm count low, or lesbian couple want a child,
donor sperm in inserted into a vagina
Eggs are donated to another woman who cannot make own eggs
Embryo produced by IVF is implanted into the uterus of another
woman (surrogate mother). When the baby is born, the baby is
given to the biological mother
Ovary transplanted is from identical twin to her sister. May need
an ovary transplant due to early menopause or ovaries having
been removed due to cancer treatment.
Checking fetal development
Ultrasounds – check fetal development but cannot detect all abnormalities.
Amniocentesis- small amount of amniotic fluid is removed from around the baby and
contains fetal cells and the baby can be checked for Down’s syndrome etc.
Growth
At birth and during first 6 months- growth is monitored by measuring head circumference,
body length, and mass. If baby grows too slowly the pituitary gland may not be producing
enough growth hormone, and child may be treated with injections with growth hormone.
Stages of human growth
Infancy
Childhood
Adolescence
Maturity
Old age
First 2 years and is when the highest rate of growth occurs
2-11 years
Growth is slower than infancy
11-15 years
Puberty begins
Growth spurts (girls 10-12 years), boys (12-15 years)
Males continue to grow up to 18-20 years
Females reach adult height 16 years
60-65 years
Physical abilities deteriorate
Final height is determined by genes, diet, amount of exercise, hormones, health and
disease.
Life expectancy has increased in developed countries due to less industrial disease,
healthier diets, better housing, vaccination, better treatments for cancer and heart disease.
More old people means that more medical treatment needed, will be less jobs for younger
people, pension age will need to be changed as people living too long after retiring.
New parts for old
External replacements (replace organ function outside the body- heart-lung machines
(used in heart surgery), kidney dialysis machines (clean blood of people with kidney failure),
mechanical ventilators (cause gas exchange).
Internal mechanical devices- heart pacemakers, artificial knee and hip joints, artificial
hearts, eye lenses.
Internal mechanical devices need to be designed so that they are small enough to fit in, last
a while before a battery needs replacing, body does not react with the materials it is made
from, and it is strong (e.g. titanium in joints).
Organ transplants
Blood transfusions
Cornea transplants
Heart transplant
Lung transplants
Kidney transplants
Bone marrow transplant
Blood is removed from live donors and stored in blood banks
until it is needed
Removed from the eye of a dead person and transplanted
into another person’s eye. No risk of rejection as no blood
vessel
Donors are dead unless someone receives a heart and lung
transplant at the same time, and their own healthy heart can
be donated to someone else.
From dead donor to e.g. someone with cystic fibrosis
Donor can be dead or alive as close relative can donate one
kidney
Used to treat leukaemia. Donors can donate their matched
bone marrow to someone who has leukaemia