1. 1
Human Body Systems
Learning Objectives
Be able to :
1. Identify 5 body cavities and major
structures in each cavity.
2. Identify 8 body systems and major
structures in each system.
3. Describe the primary functions of body
systems.
4. Understand how body systems work
together.
2. 2
Cells & Tissues
Mitochondria: Power house
Centrioles: Spindle fibres that move
chromosomes around when cell is dividing.
Lysosomes: Membrane bags with digestive
enzymes.
Golgi Bodies: “Packaging & shipping”bodies –
they mend the cell membrane.
Vacuole: a storage bubble in the cytoplasm
Ribosomes: help make proteins;translate
genetic code.
Endoplasmic reticulum or ER : transport
proteins.
4. 4
5 major human body cavities
Body Cavity Organs
Cranial Cavity Brain
Protected by skull.
Spinal Cavity Spinal Cord
Protected by vertebrae.
Thoracic Cavity Lungs and heart
Protected by rib cage & spine
Abdominal
Cavity
Liver, pancreas, stomach, spleen, kidneys
and intestines.
Located between the diaphragm and the pelvis.
Pelvic Cavity Bladder, rectum and reproductive organs.
Partially protected by pelvic bones & lower portion of spine.
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Human Body Systems
Body is made up of billions of cells .
Each cell is the basic unit of all living tissue.
Different types of cells perform different functions.
Collections of similar cells form tissues, which
form organs.
A body system consists of a group of organs and
other structures that are specially adapted to
perform specific body functions.
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Type of tissue Function Where found?
1. Epithelial
tissue
Membranes lining organs •Outer layer of skin
• Tissue surrounding organs
• Inside of mouth & stomach
2. Connective
tissue
Its fibrous strands of proteins
of collagen add support and
structure to body
• Inner layers of skin
• Tendons, ligaments
• Cartilage, bone and fat tissue
3. Muscle tissue a specialized tissue that can
contract to effect movement
• Muscles of body
4. Nerve tissue Nerve tissue has the ability to
generate and conduct
electrical signals in the body.
These electrical messages are
managed by nerve tissue in the
brain and transmitted down the
spinal cord to the body.
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Human Body Systems
For our body to work properly, all the eight body
systems must work in harmony.
1. Respiratory system
2. Circulatory system
3. Nervous system
4. Musculoskeletal system
5. Endocrine system
6. Digestive system
7. Genitourinary system
8. Integumentary system
8. 8
1. Respiratory System
Our body’s need for continuous supply of oxygen to stay
alive is provided by the respiratory system through
breathing.
The respiratory system includes the lungs, pathways
(airways) connecting them to the outside environment, and
structures in the chest involved with moving air in and out of
the lungs.
An average adult breathes about 12 times per minute while
awake or asleep (inhaling in 500 ml of air per breath). The
purpose of moving so much air in and out of the body is to
enable the lungs to do 2 things –
To take in the oxygen needed to sustain life.
To rid the body of the carbon dioxide – the waste product of
internal chemical processes.
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Respiratory System
Air enters through the nose and mouth,
and travels down the pharynx (back of
throat) to enter the larynx (voice-box).
The entrance to the larynx is protected by
a muscular flap (epiglottis), which closes
during swallowing to prevent aspiration of
food.
1. As air enters the nose, larger airborne particulates are
trapped by the coarse hairs of the nostrils.
The air is then warmed & moistened by the mucous
membrane lining (all the way downto the alveoli) as it
passes through the nasal cavities into the pharnyx and
down to the larnyx.
2.Air breathed in through mouth is drier, colder and less
clean.
Air then enters the trachea (wind-
pipe). From here, it goes into the right
and left primary bronchi ,down into the
secondary bronchi, which branch into the
bronchioles.
Right lung has 3 lobes while the
left lung has 2 lobes.
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Respiratory System
Gas exchange takes place
between the alveoli and
the capillaries in the
lungs.
Bronchioles are repeatedly branched
into terminal bronchioles which carry
air to the exchange levels of the
lungs – the alveolar sacs (alveoli).
Alveoli are covered by a thin film of
moisture to protect their delicate
tissues.
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Respiratory Protection System
Physical Filtration
1. Large airborne particulates are trapped by the moist hairs
in the nose and nasal sinuses, and subsequently washed out.
2. As air travels through the twists and bends of the nasal cavity
airborne particulates collide with the sticky mucus lining and
become trapped. They are then washed down the pharynx,
where they are either swallowed or coughed out.
3. Sneezing occurs if airborne dust concentrations are high or
have irritant effects.
4. The repeatedly branching of airways from the lower end of
trachea down to bronchioles with gradual narrowing of their
lumen slows down the airflow allowing some particulates to
sediment on the mucus lining, and subsequently propelled
by the cilia in constant motion up the pharynx to be
swallowed or coughed out.
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Efficiency of the Filtration System
Depends of the sizes of the particulates. The smallest size of a
particulate that can be seen by our naked eyes is 25 μm
Nose & nasal
sinuses
Particulates 10 to
100 μm
(diameter) can be
removed
Particulates <10 μm can
pass through.
Trachea to terminal
bronchioles
Particulates up to 7 μm can be removed.
Alveoli Particulates
ranging from 7
μm to 0.5 μm may
be deposited.
Particulates < 0.5 μm
may be exhaled out to the
outside environment or
may be deposited in the
alveoli by diffusion.
Note: Particulates with size-range 7 μm to 0.5 μm is termed as
the respirable dust.
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Biochemical Clearance
When particulates become deposited in the
alveoli, it activates our defensive
mechanism. This involves the movement of
granulocytes (white cells) from the blood
into the alveoli.
These amoeba-like cells are called
phagocytes.
Phagocytes engulf foreign bodies and
neutralise their harmful action. If the
material is inert, phagocytes will move them
to a lymph gland or out of alveoli to be
cleared by the ciliary escalator.
Certain dusts that are not ‘inert’ kill the
phagocytes. When this occurs tissue cells
(alveoli) are damaged (inflammation &
scarring)
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Class Discussion Exercise
As an adult, how many times do we breath in air per
minute while at rest or asleep? How much air (in
millilitres, mls) do we breathe in per breath?
What is the main function of our lungs?
What is the function of epiglottis?
How do our respiratory system prevent airborne
particulates from entering into the lungs?
Particulates of sizes PM10 and PM2.5. Which one can
travel a longer distance in air, and which one is more
harmful to our human body?
