This document discusses the key body systems involved in the three vital functions of the human body: nutrition, interaction, and reproduction. It focuses on the digestive, respiratory, circulatory, and excretory systems that enable nutrition, and describes how the nervous, sensory, and musculoskeletal systems facilitate interaction by transmitting and responding to stimuli. It provides details on bones, joints, muscles, and the main parts of the brain and nervous system that allow for coordinated movement and responses.

2. The three vital functions
 There are three vital functions: nutrition (eating),
interaction (the relationships between us and with the
environment) and reproduction (having babies).

3. Human body and nutrition

4. Human body and nutrition
 There are four body systems that enable us to carry out
nutrition:
 Digestive system
 Respiratory system
 Circulatory system
 Excretory system

5. Digestive system
 Breaks down the food we
eat so our body can
absorb the nutrients.
 The stomach and
intestines are organs of
this system.

6. Respiratory system
 Absorbs oxygen into the
body and releases carbon
dioxide.
 The lungs and the
trachea are organs of this
system.

7. Circulatory system
 Transports blood all over
the body.
 The heart is an organ of
this system.

8. Excretory system
 Eliminates the waste our
body produces.
 The kidneys are organs
of the excretory system.

9. The interaction function
 We are able to control and coordinate our activities
through the interaction function.
 It help us to receive information either from the
environment or from own body through the sense
organs and respond to it.

10. The interaction function
 We follow three steps to
process information:
 Stimulus-sensation:
any action or change that
we can feel.
 For example: freezing
temperatures

11. The interaction function
 The body sends
information about the
sensation to the brain.
 The brain processes the
information and
decides the order to
send.

12. The interaction function
 The order becomes a
response to the stimuli
that makes us perform
an action.
 For example: wear
clothes that makes us
feel warmer.

13. Types of stimuli
 External stimuli
(sounds):
 Are changes that happen
in our environment
outside the body.
 The sense organs capture
these stimuli and send a
message to the brain.
 Internal stimuli
(hunger):
 Are changes that happen
inside our body.
 Receptor organs inside
our body receive this
stimuli. Then they send a
message to the brain.

14. Types of response
 Motor responses:
 Happen when our
muscles move.
 For example: stretc your
arms to catch a ball.
 Glandular responses:
 Happen when organs
called glands produce a
substance.
 For example: when the
body is very hot, the
body sweats.

15. The sensory system

16. Sight
 Eyes are the sense organ
of sight.
 Light enters the eye
through the pupil, the
lens and the retina.
 The retina sends stimuli
to the brain through the
optic nerve.

17. Touch
 The skin is the sense
organ of touch.
 Touch receptors can
detect temperature,
pressure, pain and
texture.

18. Hearing  The ears are the sense
organs of hearing.
 The outer ear collects
sounds. This passes
through the inner ear
canal, the middle ear and
the three small bones.
 Then, the sounds reach the
cochlea and the auditory
nerve and it sends it to the
brain.

19. Taste
 Taste receptors are on
the tongue. They are
small bumps called taste
buds.
 They help us taste the
different flavours: sour,
bitter, sweet and salty.

20. Smell
 Olfactory receptors are
in the nasal cavity next
to the pituitary area.
 The sense of smell needs
the sense of taste in
order to work properly.

21. The nervous system
 It controls our entire body sending, receiving and
interpreting information.
 These messages travel through the body as nerve
impulses in the following sequence:
 Sense organs: they respond to a stimulus and send
impulses along the sensory nerves.

22. The nervous system
 Sensory nerves: carry information from the sense organs
and internal organs to the central nervous system.
 Central nervous system (C.N.S.): receives and interprets
information and produces responses. It is made up of
spinal cord and brain.
 Spinal cord: produces fast and automatic responses.
 Brain: is inside the cranium, makes decisions and give
orders.

23. The nervous system
 Motor nerves: CNS coordinates the information
received and sends impulses along motor nerves.
These carry signals from the CNS to which can be
either voluntary or invol the muscles.
 Musculoskeletal system: it brings a response which
can be either voluntary or involuntary.

24. The nervous system
 Involuntary: are produced by the spinal cord action.
They are fast and automatic responses. For example:
our reflexes.
 Voluntary: are produced by brain activity. It receives
information from sense organs and produces a
response. They are slower than involuntary responses.

25. The brain
 It has three parts:
 Cerebrum: produces
voluntary responses.
Controls thinking, memory
and language.
 Brain stem: controls
organ functions.
 Cerebellum: controls
balance and coordination.

26. The musculoskeletal system
 Ligaments connect bones
to each other.
 Muscles can stretch and
contract. It helps bones to
move.
 Bones give shape to the
human body and protect
internal organs.
 Tendons attach muscles to
bones.

27. Joints

28. Joints

29. Joints
 A joint is the place where two bones meet. There are
different types of joints:
 Fixed: can’t move. For example: the cranium.
 Hinge: it moves or swings like a door. For example: the
elbow.
 Ball and socket: it can rotate. One piece is shaped like a
ball and it goes inside another piece which is shaped like a
round cup. For example: the shoulder.

30. Joints
 Pivot: it rotates around one point. For example: the
wrist.
 Gliding: it moves in a smooth and easy way. For
example: the clavicle.

31. Bones

32. Muscles