Download Year 8 Body Systems DRA

Body Systems
YEAR 8
Contents:
This PowerPoint covers the following Body Systems:
 Circulatory (3-8)
 Respiratory (9-13)
 Digestive (14-22)
 Excretory (23-25)
 Nervous (26-30)
 Endocrine (31-33)
 Muscular (34)
 Skeletal (35)
The Circulatory System
The circulatory system consists of
the heart, blood vessels and blood.
It is responsible for transporting
oxygen and nutrients to your body
and wastes and carbon dioxide out
of your body.
Arteries (Red):
 Carry blood away from the heart,
for this reason they are tough
and elastic. This helps them deal
with the pressure caused by
blood.
 In some places (eg. neck and
wrists) the constant expansion
and contraction of arteries can
be felt, this is your pulse.
Arteries are high pressure.
The Circulatory System
Capillaries (Purple):
 Network-like vessels that join the arteries and veins together,
allowing blood to flow continuously.
 Their walls are very thin which allows dissolved material to
pass through them very easily.
 Oxygen and nutrients flow from the capillaries into the cells of
the body, and waste materials flow back from the cells into the
capillaries, which carry this back to the heart.
Veins (Blue):
 Carry blood back to the heart (they are low pressure).
 Veins contain valves which open and shut to ensure blood is
only flowing in one direction (upwards). Because they are
working against gravity, they need the help of muscle
contractions.
Right and Left
 The heart is essentially
broken up into two sides,
right (blue-oxygen poor)
and left (red-oxygen rich).
Recall that the “mixingzone”, capillaries, we think
of as purple.
 We use these colours as a
model. In reality, oxygenrich blood does appear a
bright red but oxygen-poor
blood is a less exciting, dark
red.
Circulation Cycle
Blood coming from the body flows through the
Superior (Upper Body) and Inferior (Low Body) vena
cava into the right Atrium. This blood has travelled
around the body and is hence oxygen poor.
2. The blood then passes from the right atrium to the
right ventricle. The right ventricle then pumps the
blood out of the heart through the pulmonary artery
which carries it to the lungs.
3. Blood coming back from the lungs is oxygen rich, it
flows through the pulmonary veins into the left
atrium.
4. Blood then passes from the left atrium into the left
ventricle. The left ventricle then pumps blood out of
the heart, through the aorta, which carries it to the
rest of the body.
1.
Summarised: Circulation Cycle
Body
Aorta
Vena Cava
Left
Ventricle
Right
Atrium
Left
Atrium
Right
Ventricle
Pulmonary
Vein
Pulmonary
Artery
Lungs
The Respiratory System
 Respiration is a series of chemical reactions that takes
place in cells to release energy.
 It takes place in our cells within the mitochondrion- you
will visit this as you explore cells!
 We get our energy from the food we eat which can be
broken down to carbohydrates, proteins and fats.
However we most often see this reaction involving
glucose (broken down carbohydrates).
 Glucose + Oxygen  Carbon Dioxide + Water + Energy
Human Respiratory System
How does oxygen reach the bloodstream?
 Breathing in: occurs through the mouth and nose, air is
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warmed, moistened and filtered and it passes the nasal cavity
and pharynx
The air then passes down the elastic windpipe (trachea),
which splits off into two tubes (bronchi). These tubes divide
into smaller tubes again (bronchioles) and end up at the
alveoli.
trachea -> bronchi -> bronchioles -> alveoli
The reason for this splitting into smaller and smaller parts is
for oxygen to be able to permeate (move into) the blood
stream.
Alveoli are microscopic (approximately 500 million in the
human lung). They have a very high surface area. The walls of
the alveoli are covered with tiny blood vessels (capillaries).
The oxygen diffuses from the alveoli into the capillaries to be
used around the body.
Alveoli and the Gas Exchange
Breathing in and out
Breathing in:
 As you inhale the muscles
between your ribs contract
 The rib cage pulls up and out
 The diaphragm contracts and
flattens
 This all helps the lungs expand
when air is sucks in through your
mouth and nose
Breathing out:
 The muscles between your ribs
relax
 The ribs move down and in
 The diaphragm arches upwards
 The lungs return to normal size,
forcing air out of the lungs
The Digestive System
 Animals are unable to make their own food as plants do.
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Instead they must eat other organisms to get the
nutrients they need to survive.
These nutrients need to be small enough to enter cellsremember, cells are where all the important body
functions happen!
Think about a Big Mac. You couldn't’t fit it inside of a
cell. It’s made up of proteins, carbohydrates and fats
which must be broken down to their simpler forms.
Carbohydrates  glucose
Proteins  amino acids
Fats  fatty acids and glycerol
Consider this model:
 A carbohydrate molecule is a long chain. Digestion
breaks it apart to its smaller parts which can pass
into a cell.
Two types of Digestion:
The body is involved in two kinds
of digestion: mechanical and
chemical.
Mechanical digestion occurs in the:
 Mouth
 Stomach
This allows food to be physically
broken down into smaller pieces.
Chemical digestion involves
chemicals known as digestive
enzymes.
 Amylase breaks down
carbohydrates
 Protease breaks down proteins
 Lipase breaks down fats/oils
Stop! What’s an enzyme?
Without enzymes our bodies wouldn't’t be able to function at a fast enough
rate for us to survive.
Digestion: 7 Key steps
1.
2.
3.
4.
5.
6.
7.
Mouth and Teeth
Oesophagus
Stomach
Liver
Pancreas
Small intestine
Large intestine
7 Key Steps of Digestion
In the mouth, teeth chew the food, whilst enzymes and
lubricants are released in the mouth to further digest.
These are released from the salivary glands found
under the tongue.
2. From here the food passes into the oesophagus, a long
muscular tube which squeezes food down by muscular
contractions called peristalsis.
3. At the end of this tube, the sphincter opens up allowing
food into the stomach. The stomach churns the food
into a liquid called chyme. Pepsin, and hydrochloric
acid is released.
4. The liver acts like a storage unit, releasing food into the
blood when needed. It also breaks down toxins and
makes bile. Bile is stored in the gall bladder.
1.
Continued.
The pancreas releases juices which help digestion in the
small intestine. It produces the important enzymes
lipase, protease and amylase.
6. Some digestion occurs here, but mostly the small
intestine is responsible for absorbing the digested food.
The small intestine is 7 m long, but it also has tiny
finger-like projections called villi which help food get
into the bloodstream.
7. Undigested food ends up in the large intestine. All
that’s left is to remove any water from the matter and
form a solid waste. As well as water, vitamins and
minerals are absorbed. Solid waste is stored in the
rectum until it leaves through the anus.
The end
5.
Peristalsis
Villi in the Small Intestine
The Excretory System
Often when we talk about excretion, people think
that only urination is involved. This isn’t the case.
The excretory system is responsible for removing
unwanted products and wastes from the body using
the:
 Lungs
 Liver
 Skin
 Kidneys
The Excretory System
Lungs
 Through respiration, the lungs produce carbon dioxide and water as
waste products. Recall that these are carried back to the lungs and
are breathed out.
Liver
 Our liver breaks down excess amino acids, poisonous substances
and old red blood cells.
Skin
 The skin excretes water and salts by sweating, which is also our
body’s way of maintain body temperature. Skin also contains a
small amount of urea!
Kidneys
 Kidneys filter about 50L of blood every hour. They control the water
and salt levels in the body. If you drink lots of water the kidneys
filter out the extra water, producing dilute urine (clear in colour).
For the opposite case, kidneys take out less water making the urine
concentrated (dark in colour).
Urinary System
The Nervous System
 The Nervous System is broken up into two parts: The Central
Nervous System and the Peripheral Nervous System.
Nerve Cells (Neurons)
 Specialised cells that
transmit and receive
messages through the
nervous system.
 Nerve cells send
messages in the form
of electrical impulses.
 Many neurons
bundled up together
form nerves.
Transmitting Signals
The Brain
 You can remember the
four lobes of the brain
by FPOT: frontal,
parietal, occipital and
temporal.
 Most of the brain is
the cerebrum,
however the brain
also contains the
cerebellum, brain
stem and spinal cord.
Stimulus-Response
The nervous system concerns itself with responding to our changing
environments. Right now you are being inundated by your senses, but
you’re only noticing what’s being changed…
1.
2.
3.
4.
Stimulus is produced from the surroundings
Receptor cells in the body detect the stimulus (they are sensitive
to change). Receptor cells are in your eyes, ears, tongue etc…
Effector (organ, gland or muscle) which receives the message
from the receptor, brain and spinal cord.
Finally, the response. This is the action or reaction caused by the
effector. Sometimes these require coordination from the brain.
 Actions that don’t involve the brain are called reflex actions. These
actions are done automatically (without thinking). Eg. Blinking,
sweating and coughing.
The Endocrine System
 The endocrine system uses
chemicals called hormones to
transfer information to our
bodies.
 Hormones regulate functions
such as growth, water balance,
sexual reproduction etc…
 We often only hear about
hormones when we’re talking
about puberty, but they have
many other functions across a
human’s life cycle.
 Hormones are made in different
glands throughout the body.
They are controlled in one
central location, the pituitary
gland.
How Hormones Work
 Hormones travel around the body but only act on
particular cells
 They act in a very similar manner to enzymes, which
we describe as the ‘lock and key’ model:
The Muscular System
There are two
main functions of
the muscular
system:
1. Produce heat
(eg. shivering)
2. Movement
(contraction
and relaxation).
The Skeletal System
1. Stature (holding the body
upright)
2. Movement: attached to
muscles and moves with
contraction.
3. Protection of the vital
organs (rib cage).
4. Production of blood cells
5. Stores minerals and fats
and releases them into the
body when required.