SG BIOLOGY SUMMARY
SG BIOLOGY SUMMARY BODY IN ACTION
Sub topic a – Movement
1G Movement depends on the skeleton, muscles, energy and coordination from the brain.
2G The skeleton provides support, attachment of muscles for movement and protection
for heart, lungs and spinal cord.
3G A Ball and socket joint can move in 3 planes (e.g. shoulder or hip).
A hinge joint moves in 1 plane (e.g. elbow or knee).
At a joint ligaments hold bones together.
Cartilage on the ends of bones acts like a shock absorber to cushion and protect them.
3C Parts and Functions of a synovial joint.
Cartilage – acts as a shock absorber cushioning
and protecting the ends of bones .
Synovial membrane – produces synovial fluid (an oily sticky liquid).
Synovial fluid – acts as a lubricant
and reduces friction between bones.
Ligaments – are slightly elastic fibres that hold
bones together.
4G/C Bone tissue is made of living cells, which contain flexible fibres and hard minerals (calcium phosphate).
5G/C Muscles are attached to bones by inelastic fibres called tendons.
6G Movement of the skeleton happens when muscles contract (get shorter).
The muscle pulls on the bone to which it is attached and the bone moves.
6C To work properly joints need to have two sets of muscles to make them move.
As one set of muscles contract the opposing set of muscles relaxes and the joint moves in one direction.
To move the joint in the opposite direction the first set of muscles must relax and the second set must contract.
Muscles often work in antagonistic pairs.
Sub Topic b The Need for Energy
G1 Energy is needed by the body for growth, repair, movement and chemical reactions.
To maintain a healthy body there must be a balance between energy taken in and
energy used.
More energy taken in than used would mean a gain in weight, less energy taken in than is needed would mean a loss in weight.
G2 To gain energy efficiently from food oxygen is needed.
Oxygen is absorbed into the blood from the air breathed into the lungs and carbon
dioxide is removed from the blood and breathed out.
G3
Air is breathed in through the
nose and mouth. It travels down
the windpipe (trachea), branches in the bronchi to each lung and passes
down the smaller and smaller
tubes called bronchioles.
The bronchioles end in
air sacs (alveoli) where some of
the oxygen diffuses into the
blood and carbon dioxide from
the blood diffuses into the lungs.
The lungs are pink, spongy and have a large surface area created by the air sacs.
C1
Inhalation
To breathe in the ribs move up and out by contraction of the intercostals muscles and the diaphragm moves down. This draws air into the lungs because the pressure outside the chest is greater than that inside.
Exhalation to breathe out the rib cage moves down and in as the muscles relax and the diaphragm moves up. This pushes air out of the lungs as the pressure inside the chest is greater than that outside.
C2 The trachea and bronchi are lined with cells that produce mucus to trap dirt and microbes.
They also have cilia which push the mucus and trapped material up to the throat to be swallowed.
The cartilage in these tubes prevents them from collapsing.
C3
Air sacs in the lungs are surrounded by capillaries. As the blood flows through them
oxygen will diffuse into the blood to the red blood cells. Carbon dioxide will diffuse out
of the blood into the air sacs. These are both going from high to low concentrations.
C4 The lungs are efficient at gas exchange because they have a large surface area, have a
good blood supply and the air sacs and capillaries are both thin walled.
G4 The heart is a muscular pump with 4 chambers. The top 2 are small and called left atrium and right atrium. The bottom 2 are bigger and called left ventricle and right ventricle.
Study the diagram below with these notes.
G5 Blood flows into the heart from the body through the vena cava (vein). It then flows
through the right atrium and into the right ventricle, through a valve. It then flows out
of the heart (through a valve) in the pulmonary artery to the lungs. In the lungs it picks
up oxygen and gets rid of carbon dioxide. Blood flows back to the heart in the
pulmonary vein. It enters the left atrium and flows into the left ventricle, through a
valve. It leaves the heart (through a valve) in the aorta (artery) to the take blood to the body.
G6 The valves in the heart prevent blood flowing in the wrong direction. They are found
between atria and ventricles as well as in the blood vessels that take blood out of the ventricles.
G7 The muscular walls of the ventricles are different thicknesses because the right
ventricle pumps blood around the lungs but the left ventricles pumps blood around the
body so it is doing more work.
G8 The heart obtains its own blood supply from a branch of
the aorta called the Coronary arteries.
These supply the heart tissues with their oxygen and
other essential materials for survival.
G9 Blood leaves the heart in arteries,
flows through a series of capillaries and
returns to the heart in veins.
G10 The pulse is a measurement of the heart
beat. A pulse is usually felt in an artery
as blood flows through it.
G11 Blood is made up of a liquid plasma, red
blood cells, white blood cells and platelets.
The red cells contain haemoglobin which
carries oxygen. The plasma carries most
of the carbon dioxide, plasma also carries
dissolved food like sugars and amino acids.
C5 Haemoglobin in the red cells picks up the oxygen from the lungs to form oxyhaemoglobin
and transports it to cells and tissues. The oxygen is released in areas where there is a
low concentration.
G12 Near every cell are capillaries. Oxygen leaves the red blood cells and enters the tissues.
Carbon dioxide leaves the tissues and enters the blood.
C6 The capillary network is efficient for gas exchange because it is found throughout the
body and it provides a large surface area, a thin wall between cells and blood. All these features mean diffusion can happen effectively.
Sub Topic c Co-ordination
G1 Co-ordination is the working together of the senses with the central nervous system and
effectors to ensure the body is coordinated.
G2 Two eyes are better for judging distance than one
C1 Two eyes give humans binocular vision because two images are received by the brain, this gives much better judgment of distance as the brain can compare them.
G2
|Part |Function |
|Cornea |Transparent front layer that lets light in |
|Iris |Muscles that change size of the pupil |
|Pupil |Hole that allows light into back of eye |
|Lens |Bends light focusing it on the retina |
|Retina |Light sensitive cells that change the light|
| |into electric signals |
|Optic nerve |Nerve that take nerve impulses to the brain|
G3 Two ears give a better judgment of the direction a sound is coming from than one ear.
|Part |Function |
|Ear drum |Vibrates when sound waves hit it and |
| |passes them to ear bones |
|Middle ear bones |Amplifies vibrations and passes them to |
|(ossicles) |cochlea |
|cochlea |Changes vibrations into nerve impulses |
|Auditory nerve |Relays nerve impulses to the brain |
|Semi-circular canals|Sense movement of head and relays |
| |messages to the brain to maintain balance|
G4
C2 The semi-circular canals are three fluid filled tubes that are arranged in three different directions to each other. As the head is moved the liquid in the tube moves and this message is sent to the brain to keep us balanced.
G5 The nervous system is made up of the brain, spinal cord and the nerves.
The central nervous system (CNS) is made up the brain and spinal cord.
G6 Nerves carry impulses from the sense organs to the central nervous system and from the central nervous system to the muscles.
C4 The central nervous system sorts out information from the sense organs and sends impulses to muscles, which will make the appropriate response.
C3 Reflex actions are used by the body to react very quickly usually to protect the body
from harm.
A reflex arc
A stimulus usually painful
is detected by the senses. The sensory neurone (nerve) transmits
an impulse to the central nervous system in the spinal cord.
A relay neurone
passes the impulse to a motor neurone, which sends an impulse to a muscle. The muscle would cause the body part to move avoiding the danger.
|Part of brain |Function |
|Cerebrum |memory, reasoning, intelligence, |
| |conscious thought |
|Cerebellum |muscular control and balance |
|Medulla |Automatic control of breathing and |
| |heartbeat |
C5
Sub topic d Changing levels of performance
G1 Muscles can become fatigued (tired out) if the same ones are used continuously and
Rapidly.
G2 Muscle fatigue happens because the muscles are not getting enough oxygen and there is a ` build up of lactic acid
C1 Lactic acid is produced because the muscles begin to respire anaerobically as they are not receiving enough oxygen form the blood.
Glucose lactic acid + energy
G3 During exercise breathing rate and pulse rate increase. This is because the muscles
require more oxygen (and glucose) as they are doing more work. The heart pumps the
blood faster and the lungs take in more air to try and provide the necessary oxygen.
G4 Pulse and breathing rates are affected by levels of fitness.
The fitter a person is the lower their resting pulse and breathing rates.
When exercising the pulse rate, breathing rate and lactic acid levels will rise less in an athlete compared to an untrained person.
G5 Recovery time is the time taken for pulse rate, breathing rate and lactic acid levels to
return to normal once a person has stopped exercising.
G6 Recovery time for athletes will be faster than the recovery time for an untrained person.
C2 Training can improve the efficiency of the lungs and the circulation system.
This is because the muscles involved become bigger and more efficient.
C3 Training will also reduce the recovery time for an individual.
This is because the heart becomes more efficient at pumping the blood, the lungs are
more efficient at moving air into and out of the lungs and the lactic acid is broken down
more efficiently in the muscles
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Semi circular canals
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