Yr 9 Science - Biology
Introduction – topics
• How the body’s systems work together to
meet all the requirements of life
• The nervous and endocrine systems
• Microorganisms
• How diseases are transmitted
• The Immune System
From year 8 - Human Body
Organization
The Human Body
is composed of
Organ Systems
are composed of
Organs
are composed of
Tissues
are composed of
Cells
In your books
1. Write down all the
things necessary for life
2. List all the body
systems you can think of
Now draw lines to linking which body systems perform these functions
Revision of systems covered in
Year 8
Circulatory System
Major Structures
• heart, blood vessels,
blood,
Functions
• transports nutrients,
wastes, hormones,
and gases
Interesting Facts…
• The heart is a muscle about the size of a fist.
• Each blood cell takes around 20 seconds to make its
deliveries and travel back to the heart.
• The heart works by contracting and relaxing.
• The heart has flapping valves that allow blood to flow in one
direction. The flaps create a “lub-dup” sound.
• A heart attack is caused by a blood vessel blocked by a clot.
• The average person has about 5 liters of blood.
• The body can replace blood within a few weeks after loss.
• Platelets in the blood help it to clot, or stick together, to
make scabs.
• The four blood types are A, B, AB, and O.
Respiratory System
Major Structures
• lungs, nose, mouth,
trachea
Functions
• moves air into and out of
lungs; controls gas
exchange between blood
and lungs
Interesting Facts…
• The lungs fill up most of the chest cavity.
• The left lung is slightly smaller than the right lung,
because it must allow enough space for the heart.
• Inside each lung is a network of thousands of tunnels
called the bronchial tree which branch into bronchioles
containing six million tiny bags (air sacs) called alveoli.
• The lungs take millions of O2 molecules out of the air
and put them into the blood to be delivered to the cells.
• Simultaneously, the lungs also take waste gases out of
the blood.
• A smoker’s lungs are dark grey and full of dirt and tar.
Digestive System
Major Structures
• Mouth teeth, tongue,
salivary glands, throat,
esophagus, stomach,
liver, pancreas, small and
large intestines
Functions
• extracts and absorbs
nutrients from food;
removes wastes;
maintains water and
chemical balances
Interesting Facts…
• Food takes 3 days to complete its journey through the
digestive system.
• An adult digestive system is about 30 feet long.
• An average person takes in about 4.4 pounds of food and
drink every day, consuming over 110,000 pounds in a
lifetime.
• Gravity and bands of muscles help food travel down the
esophagus to the stomach, making it possible to eat lying
down or even upside down.
• The stomach is lined with a slimy mucus and releases an
acid called gastric juice to help dissolve food.
• Stomach noises are caused by food and air sloshing around.
• Water makes up about 70% of the body.
Reproductive System
Major Structures
• ovaries, uterus, and
breasts (in females);
testes and penis (in
males)
Functions
• produces gametes (eggs
and sperm) and offspring
Interesting Facts…
• A person grows over 5 million times bigger changing
from a single cell to a newborn human being.
• Humans grow for about 20 years, changing from a child
to an adult.
• Male reproductive cells are called sperm, and female
reproductive cells are called eggs.
• Sperm and eggs have only 23 chromosomes each.
• When joined together, sperm and egg make a whole cell
called a fertilized egg which can grow into a baby.
• All other body cells have 46 chromosomes
Overview of a few systems not
covered in Year 8
Skeletal System
Major Structures
• bones and joints
Functions
• protects and supports
the body and organs;
interacts with skeletal
muscles; produces red
blood cells, white blood
cells, and platelets (in
the bone marrow)
Interesting Facts…
• A baby is born with 270 bones while an adult body has
206 bones.
• The hands and feet contain half of the bones in the
human body.
• Bones are made of the hard mineral calcium, living cells,
blood vessels and nerves.
• Bones are made of several layers – periosteum,
compact bone, and spongy bone.
• A joint is where two bones meet.
• Joints can be cartilagenous (spine), ball-and-socket
(shoulders and hips), pivot (neck), gliding (wrists), and
hinged (fingers, elbows, and knees).
Muscular System
Major Structures
• skeletal, smooth, and
cardiac muscle tissues
Functions
• moves limbs and trunk;
moves substances
through body; provides
structure and support
Interesting Facts…
• There are nearly 600 skeletal muscles that make up
nearly half of the total body weight in the human.
• Muscles can only pull – they cannot push.
• Energy is stored in the muscles in a chemical called ATP.
• Lactic acid is released when the muscles are overworked
and lack O2, making the muscles hurt or ache.
• Muscles are attached to bones by tendons.
• The biggest muscles in the body are the gluteus maximus
muscles (buttocks), but the muscle that can exert the
most force is the masseter (jaw muscle).
Excretory System
Major Structures
• kidneys, urinary bladder,
ureters, urethra, skin,
lungs, rectum
Functions
• removes wastes from
blood; regulates
concentration of body
fluids
Interesting Facts…
• Leftover waste in the large intestine is called fibre. Fibre
sweeps the digestive system clean as it moves along.
• The large intestine contains millions of bacteria that feed
on the leftovers in the bowel.
• Kidneys are located in the middle of the back.
• Each kidney contains up to a million tiny units called
nephrons that filter all of the blood in the body.
• People with failing kidneys have their blood cleaned by a
dialysis machine or have a new kidney transplanted.
• Waste can be breathed out as gas, or sweated out
through the skin