Chapter 4 : Human Body Systems

●The Digestive System
●Respiratory System
●Circulatory System
●Integumentary System
●Excretory System
●The Immune Systme
●The Endocrine System
●The Nervous System

Nutrition: Getting Food to Cells

We need food to provide energy for
moving about. Food also supplies the
raw materials needed for growth and
repair of body parts.
Body cells need food for energy,
growth and repair. However when food
is eaten, it is not in form that can be
used by cells in body. Food must be
broken down into a form that cells can
use. The body changes food into a
usable form by means of a group of
organs known as the Digestive
System

There are two groups of organs in
the digestive system. One group
makes up the gastrointestinal tract, a
food tube that is open at each end
and includes the mouth, esophagus,
stomach, and intestine.
The other group of organs makes
and stores the chemicals that
chemically break down the food.
These are liver, pancreas, gall
bladder, and salivary glands.

Learning about the digestive
system is a unique and exciting way
to discover the things your body goes
through on a daily basis. Let’s see
how it works.

The Digestive System breaks down
food in two ways: Mechanically and
Chemically.
Organs responsible for chewing,
tearing, churning, squeezing and
grinding food help in mechanical
digestion. On the other side, the
organs that make and use chemicals
to break apart the food and reduce to
liqud help in chemical digestion.

Parts of the Digestive System
Mouth
-This is the beginning of the
digestive tract. As a matter of
fact, the first time you chew
something, digestion starts
here. Chewing food breaks
down food molecules into
smaller food molecules so that
it can be easily more digested.
Saliva produced by the salivary
glands, mixes with food to
begin the process of digestion.

Esophagus
- It is a tube that connects the mouth to the
stomach. Muscles of the esophagus push and
transport foods and liquids to the stomach.
Stomach
- The stomach is a bag-like muscular organ. The
function of the stomach is to grind the food and mix
it with the digestive juices. It can hold about one
liter of liquid and food. The product of digestion in
the stomach is chyme. The stomach has special
cells in its walls that make gastric juice. Gastric
Juice begings the chemical breakdown of proteins.
After about four hours, the stomach pushes food
into the small intestines.

Small Intestine
- The small intestine is where most of the food is
chemically digested. The small intestine itself makes
several digestive juices. Some of these chemicals
digest proteins into amino acids. Other digest
carbohydrates into simple sugars.
Liver
- It is the largest organ in the body. It has a mass
of about two kilograms. The liver makes bile, a
green liquid that breaks up large fat droplets into
small fat droplets and stores it in the gall bladder.
When needed, bile enters the small intestine and
aids in the digestion of fat. If bile is not needed, it is
delivered to the gall bladder.

Pancreas
- The pancreas is a small organ that makes 3
different kinds of enzymes and is found below the
stomach. It makes about half of the liters of digestive
juices made each day.
Gall Bladder
- It is a small pear shape sac that can hold about
50ml of bile. It stores the bile until it is needed by the
small intestine to emulsify fats.
Large Intestine
- The job of this part is to remove the useful liquids
from the undigested food. This undigested food called
feces, is solidified and pushed out to the anus. If the
large intestine did not return two liters of liquid to the
body a day, a person could die from lack of water.

Gas Exchange with the Environment
“You can survive for several days without water and
survive for a month without food, but you cannot live
for more than five minutes without oxygen”

Oxygen is the part of the air that we breath. Air is a
mixture of different gases. The air you breath is
made
up of:
Oxygen 21.0%
Nitrogen 78.1%
Carbon Dioxide 0.03%
Other Gases 0.87%
Life depends on breathing because the cells of the
body need oxygen. You breath in to bring fresh air
into the lungs. The lungs must separate the oxygen
from the air. Then you breath out to get rid of the
carbon dioxide that the body does not need.

● Breathing is a mechanical process.
● The function of the respiratory system is to exchange
oxygen and carbon dioxide between the air and the cells
● The respiratory organs filter particles form incoming air.
They help control the temperature and water content of air.
● They also aid in producing the sounds used in speech.
LET US TAKE A TOUR TO OUR RESPIRATORY
SYSTEM.

Parts of the Respiratory System
Nose
- The function of the nose is to
filter and warm the entering air
with the help of the cilia.
Pharynx
-It is commonly called the
throat. It connect the nose with
the windpipe.
Trachea
-The trachea is commonly
called the windpipe.

Bronchus
- The trachea branches has a 2 tubes, the bronchi,
inside the lungs. Each bronchus continues to branch
and rebranch until it is very small. Each tube finally
ends in a tiny air sac called an alveolus.
Lungs
- The lungs are twi up-side-down, cone-shaped
organs inside the chest. The lungs are really two bags
full of thousands and thousands of alveoli.
Diaphram
- It is a large muscles that lies flat at the bottom of
the chest cavity. The diaphram aids in breathing by
moving up and down.

Rib Muscles
- The lungs are protected in the chest
cavity by a set of rib bones. The tissue
between the rib bones called the rib
muscle. These muscles are the meat you
eat on a sparerib. The rib muscles move
the rib bones and cause the chest cavity to
enlarge and contract. The rib muscle work
together with the diaphram to aid
breathing.

●Circulatory system- the life support system that
feeds the cell with food and oxygen. They also
remove the waste product.
●It has three main parts- heart, blood vessels
and blood.
●It has two divisions: Lymphatic; helps return
tissue fluid to the blood and Blood division; a
closed circuit.
●Its function is to carry materials to and from all
parts of the body.
●The power for the circulatory system comes
from the muscular action of the heart. By
contraction and relaxation of the heart.

●It is a closed system.
●It has two separate system; system pumps
blood to lungs and system pumps blood to the
body.
Fuctions of the Circulatory System

Parts of the Circulatory System
Human Heart
●A bundle of muscles
about the size of our
fist.
● It is located in the
center of our chest
between the lungs and
tilted to one side and
points downward left.

It is really two pumps at one; a pump on the
right and left. Each side is divided into two
chambers. The upper chamber is atrium and the
lower chamber is ventricle.
The valves are like one-way door that keep the
blood moving in only one direction and lie
between the atrium and ventricles.
How the Heart Works
When the top contracts, the bottom relaxes.
When a chamber contracts, it becomes smaller
and the blood inside gets squeezed or pumped
out.

The Four Valves in the Heart
When the atrium contract, the tricuspid(right) and
bicuspid(left) open. When the ventricle contract, the
pulmonary(right) and aortic(left) valves are open. When
it is repeated, one heartbeat cycle occur.
The two phases of heartbeat cycle can be heard as “Lub-
dub” and it is caused by the contraction of the muscles
and slamming shut of the valves.
In the “lub” phase, the ventricles contract and the
tricuspid and bicuspid close. In the “dub” phase , the
pulmonary and aortic valves are closed.
The Blood Vessels
Our blood moves through the body in tubes called
vessels. There are three kinds of it that made up the
circulatory system.

Arteries- have thick muscular walls and they are
elastic and expand when ventricles contract.
●It carries blood away from the heart.
●The blood in arteries is red because it contains
oxygen.
●The large artery is the aorta and is first artery
leaving the heart to the body..
Veins- have muscular walls but thinner than the walls
of artery.
●Veins carry blood to the heart.
●The blood in the veins is blue in color because it
lacks oxygen.
●The veins begin at the capillaries and join into
larger veins until it reaches the heart.

Capillaries- tiny vessels that connect arteries to the
veins
●The walls of it are only one-cell thick and so small
that the red blood cells must past through them in
single life.
●It is here that the exchange of materials between
the blood and cells takes place. At the capillaries,
food, oxygen, carbon dioxide and waste products
pass from the cells to the blood.

The Blood
The blood is a fluid that carries the most of materials
necessary for life. It has two different parts:
●Plasma- liquid part and yellowish fluid that makes up
55% of our blood
●Red blood cells, white blood cells and platelets is 45%
Plasma- It is composed of 92% water and 8% of
dissolved nutrients, mineral salts, antibodies and
hormones.
The proteins present in plasma are:
●Albumin- helps in keeping blood pressure normal and
regulates amount of water in plasma.
●Globulin- contains antibodies.

Chemical Substances- effective against specific disease.
Fibrinogen- works with platelets in clotting process.
Red Blood Cells (RBC)- also called erythrocytes and key
to life.
●Constantly traveling through the body, delivering
oxygen and removing waste.
● The most numerous cells in the body. Each liter of
blood contains 4.5 to 6 trillion red blood cells.
● Hemoglobin is the main component of RBC and it
binds and carries oxygen.
● As blood passes through the lungs, oxygen
molecules attach to the hemoglobin. As it passes
through body tissues it releases oxygen to the
cells.
● The average life cycle of RBC is only 120 days and
our bone continually producing it.

White Blood Cells (WBC)- larger and less numerous
than RBC. Also called as leukocytes.
●It contains nuclei and other types of organelles.
● It may circulate in the blood for weeks before
leaving the blood and entering other tissues.
● It helps defend the body against infections.
● They produce antibodies.

The Integumentary and Excretory Systems (Salt and
Water Balance and Waste Removal)

Integumentary System- organ system consisting of
the skin, hair, nails and exocrine glands
Take a look of this!

Parts of Integumentary System
Skin- forms the body’s
outer covering and forms a
barrier to protect the body
from chemicals, UV
physical damage.
●Largest and most visible
organ of the body.
● It has two layers; the
epidermis and dermis.

●It is composed of different types of membranes; the
serous, mucous, cutenous and synovial membrane.
●It is also called integument which means covering and
external covering.
●The skin functions are protective covering, synthesizes
various chemicals and excrete waste.
●It keeps water and precious molecules in the body from
drying out and keeps water out through perspiration.
The Parts of the Skin
Epidermis- the outer skin layer and protects body from
bacteria and foreign matter.
●Skin’s surface has many ridges and valleys which is
called papillae.
● The small openings in the skin surface is called pores.

● Pigment called melanin is made in the inner layer of
epidermis.
Dermis- thicker layer of cells and composed of nerve
endings, blood vessels and muscle fibers.
● Oil and sweat glands are found in dermis.
● The sebaceous gland are found almost
everywhere on the surface of the body except to our
palms of our hands and soles of our foot
●Sebaceous gland are found in the hair shafts and
produce oil known as sebum.
●Elastic fibers in the dermis allow foe extensibility
and elasticity of the skin.

Subcutaneous Layer- deepest of skin layer. It
supplies fat to our body. It insulates the body against
heat and cold. It acts as a cushion to protect the
body from injuries.
Hair- formed by epidermal cells that line in a pocket
called follicle, which lies deep in dermis. The outside
layer of hair and skin are both composed of keratin
cells. Cells overlap in hair shaft and if it lies flat, they
reflect light and give shines to our hair. Hair fullness
depends on the number of shafts and diameter and
melanin give hair colors as well.

Nails- The hard part of the nail is made up of skin
tissue, It grows from the epidermal cells below
it. The skin around the nail forms hardened
margin called the lunula.
Teeth- It is helpful for clear speech and also
important in grinding food into small pieces.

Wastes are either made by your body cells or are
taken into your body as part of your diet. Getting rid of
liquid waste is the job of the urinary system. A urinary
system is made up of those organs that rid the body of
liquid waste. Urea is a waste that results from the
breakdown of body protein. It is poisonous and must
be removed from the body. Urea is picked up by the
blood and carried to the kidneys.
●The Kidneys are the most important organs of the
urinary system. The kidneys lie in the small of the
back, one on each side of the vertebrate

●The kidneys clean the blood by removing wastes
chemicals. These waste chemicals are carried out of the
kidneys by the ureter and stored in the bladder as urine.
Thus, the function of the kidneys is to clean the blood.

The kidneys undertake the following procedures
during the cleansing of blood.
1. Blood carrying wastes moves through the
body’s arteries.
2. Small arteries carry the blood to be filtered
into each kidney.
3. The kidneys filter the blood.
4. Blood leaves the kidneys through a vein. The
blood is now free of wastes.
5. These veins connect to large veins in the body
bringing clean blood to all body parts.
6. Wastes leave the kidneys through the ureters.
7. The urinary bladder is a sac that stores wastes
removed from the kidneys.
8. The urethra is a tube that carries wastes from
the urinary bladder outside the body.

The urinary system shown in the figure is composed
of two kidneys, one urinary bladder, two tubes called
ureters, and another tube called the urethra .
There are couple of blood vessels attached directly
to each kidney. These blood vessels are the renal
artery and the renal vein.

Your kidneys clean all the blood in your body every
thirty minutes. In one day that totals 200 liters of
blood, from which 2 liters of urine are produced.
A large amount of the water your body needs comes
from the foods you eat and the liquids you drink.
Excretion Through the Lungs
Lungs also help in ridding the body of water and
excess heat. You lose water each time you breathe
out. If you exhale on a cold day, the “breath” you can
see is water from your lungs forming in the air.

Excretion Through the Large Intestine
Indigestible matter or wastes enter it from the small
intestine in a watery mixture and spends about 4 hours
here. Where the contents enter the rectum, they have
become nearly solid because of water absorption. The
feces in the rectum are held by sphincter muscle until
they are discharged through the anus.
Excretion and Homeostasis
The main function of the integumentary and
excretory system is to excrete waste. The
integumentary system does it by excreting sweat, and
the excretory system does it by excreting urine.
The integumentary and the excretory system also
help the body to maintain homeostasis. The word
homeostasis comes from the Greek word homoio, which
means “the same” or “constant”.

The immune system, is made up of specialized
cells, proteins, tissues, and organs, to protect and
defend us against germs and pathogenic
microorganisms every day. In most cases, the
immune system does a great job of keeping people
healthy and preventing infections.
The immune system is the body’s defense
against infectious organisms and other invaders
through a series of steps calld the immune
response. The immune system attacks and fights
organisms and substances that invade body systems
that cause diseases.

Our immune system is made up of a network of
cells, tissues, and organs that work together to
protect the body. The key primary lymphoid organs
of the immune system include the thymus and bone
marrow, as well as secondary lymphatic tissues
including spleen, tonsils, lymph, vessels, lymph
nodes, adenoids, skin, and liver.

Parts of the Immune System
Lymph Nodes
(also called “Lymph
Glands”)
- These small, bean-
shaped structures are part
of our lymphatic system.
Lymph nodes filter the
lymphatic fluid and store
special cells
that can trap cancer cells or
bacteria that are traveling
through your body in the
lymph fluid.

Thymus
-A small organ located just behind your
breastbone. This is where your T-cells mature (That’s
why they are called T-cells. The “T” is for Thymus)
Spleen
-The largest lymphatic organ in the body it’s about
the size of your fist. Your spleen is located in the
upper-left part of your abdomen. It contains white
blood cells that fight infection disease. Your spleen
also helps control the amount of blood in your body
and destroys old and damaged blood cells.

Bone Marrow
The yellow tissue in the center of your bones that is
responsible for making white blood cells that are
destined to become lymphocytes.
One of the important cells involved which is being
produced from the bone marrow, and also called
leukocytes, come in two basic types that combine to
seek out and destroy disease-causing organisms or
substances
Leukocytes
- are produced or stored in many locations in the
body, including the thymus, spleen, and bone marrow.
For this reason, they’re called the lymphoid organs.

The two basic types of leukocytes are:
1. Phagocytes, cells that chew up invading
organisms
2. Lymphocytes, cells that allow the body to
remember and recognize previous invaders and help
the body destroy them.
Lymphocytes
-A small white blood cell that plays a larger role
in defending the body against disease. There are two
main types of lymphocytes: B-cells and T-cells.
-B-cells make antibodies that attack bacteria and toxins. T-
cells help destroy infected or cancerous cells and attack boy cells
themselves when they have been taken over by viruses or have
become cancerous.

-It is also known as natural immunity, a type of
general protection. Most of the germs that affect
other species are not harmful to humans. For
example, the viruses that cause leukemia in cats or
distemper in dogs don’t affect humans. Innate
immunity works in both ways.
-Innate immunity also includes the external
barriers of the body, like the skin and mucous
membranes like the line of the nose, throat, and
gastrointestinal tract, which are the first line of
defense in preventing diseases from entering the
body.

Adaptive Immunity
- The second kind of protection is adaptive (or active)
immunity, which develops throughout our lives. Adaptive
immunity involves the lymphocytes and develops as
people are exposed to diseases or immunized against
diseases through vaccination.
Passive Immunity
- Passive immunity is “borrowed” from another source
and it lasts for a short time. For example, antibodies in a
mother’s breast milk give a baby temporary immunity to
diseases the mother has been exposed to. This can help
protect the baby against infection during the early years
of childhood.

HOW HORMONES GOVERN BODY ACTIVITY

The second system that allows different parts
of your body to keep in touch is called the
endocrine system.
●The endocrine system is made up of small glands
that make special chemicals for carrying messages
through the body. The glands are found
throughout the body.
●The chemicals made by endocrine glands are
called hormones.
●Hormones are found in the blood. Once in the
blood, hormones travel to different organs of the
body.

Any organ, tissue or group cells that make a
secretion is called a gland.
There are two types of glands : exocrine and
endocrine glands.
●An exocrine gland makes a secretion that travels
through a tiny tube called duct.
● The ducts carry the secretions to where they are to
go.
● An endocrine gland makes a secretion that does not
travel through a duct.
● Endocrine glands are not very large either.
Let’s see how endocrine system works.

HORMONES CONTROL BY REGULATION
The word hormone comes from the Greek word
that means “to excite”.
For example, body metabolism, growth and blood
pressure must be kept at constant states. These
and many other body activities are kept at their
constant state by hormones.
Remember:
●A hormone is a chemical substance
●Made by a gland
●Secreted irectly into the bloodstream
●Acts as a chemical messenger
●Excites a body activity
●Controls by regulation.

The Different Glands Of The Body
● The Thyroid Gland- The thyroid hormone regulates
metabolism, or the release of energy to the body.
● The Parathyroid Glands- The parathyroid hormone
regulates the body’s use of calcium. Normal use of
calcium is important for the growth of bones and the
contraction of muscles.
● The Adrenal Gland- Adrenalin causes the heart to
beat faster, the blood pressure to go up, and the extra
sugar to be burned for energy.
● The Pancreas Gland- The pancreas gland makes the
hormone insulin and glucagon. Insulin regulates the
burning of sugar and helps the liver to store excess
sugar.

● The Sex Glands- The sex glands are the
ovaries in the female and the testes in the
male. The ovaries secrete female sex
hormones and the testes secrete male sex
hormones.
-Female sex hormone(estrogen or
progesterone) cause girls at puberty to
develop female sex characteristics.
-Male sex hormones(androgen or
testosterone) cause a boy at puberty to
develop male sex characteristics

The Pituitary Gland
●Pituitary gland is a pea-sized organ tucked
away at the based of the brain.
● The pituitary gland secretes several
hormones, many of which regulate the
activities of the other glands.
● The pituitary gland stimulates another gland
with ahormone. The stimulated gland secretes
a hormone to do its own work.

There are two main system that your body uses
to stay in touch. These are nervous system and
endocrine system.
This system makes you feel, know, and do
anything. The nervous system uses special cells to
keep in touch. These cells help the body
communicate with other body parts.
Let us took a bit information about this

The Nerve Cell- The basic
unit of the nervous systemis
the nerve cell. Nerve cells are
called neuron. There are
billions of neurons in the body.
A human being has
approximately 100 billion
neurons. By far the largest
part of it is located in the
central nervous system
(brains and spinal cord).
A specific feature of nerve
cells is that they are irritable;
they can receive and transmit
signals without loss of signal
strength.

DIFFERENT TYPES OF NEURONS
There are different types of neurons. They all
carry electro- chemical nerve signals but differ in
structure (the number of processes, or axons,
emanating from the cell body) and are found in
different parts of the body.
●Sensory Neurons- (Bipolar neurons) carry
messages from the body’s sense receptors (eyes,
ears, etc) to the central nervous system(CNS).
●Motoneurons- (Multipolar neurons) carry signals
from the CNS to the muscles and glands. These
neurons have many processes originating from
the cell body.

●Interneurons- Pseudopolare (Spelling) Cells) from
all the neural wiring within the CNS. These have two
axons (instead of an axon and a dendrite).
●Life Span of Neurons- Unlike most other cells,
neurons cannot regrow after damage (except
neurons from the hippocampus). Fortunately, there
are about 100 billion neurons in the brain.
●Glial Cells- Glial cells make up 90 percent of the
brain’s cells. These are nerve cells that don’t carryr
nerve impulses. Types of Glial cells include
Schwann’s Cells, Satellite Cells, Microglia,
Oligodendrgoglia, and Astroglia.

A Stimulus Causes a Response
The Nervous system is assisted by five organs- the
eyes, ears, nose, tongue, and the skin.
●Stimulus- is any information received by the nervous
system about a condition in the environment.
●Response- is a reaction to a condition or stimulus. A
stimulus is received by the body and a response is
made.
The Nerve Impulse
Neurons are cells with the special ability to carry
signals or impulses. It may be difficult to believe, but
thoughts, emotions, learning and many body functions
are controlled by nerve impulses.

●A nerve impulse is a combination of an electrical
charge and a chemical reaction. A nerve impulse
is not a flow of electricity.
●A nerve impulse cannot jump from one neuron to
another. The space between neuron is called
synapse.
THE BRAIN
● The brain is the main control center of
coordination. It is about the size of a small head of
a cauliflower.
● The brain weighs about 1.4 kilograms and is
protected by the skull.
● The brain is made up of three areas. These are
the cerebrum, cerebellum, and medulla.

The brain is divided into:
●Cerebrum- the largest part of the brain. It is the
centre for thought and intelligence. It is divided into
right and left hemispheres. The right controls
movement and activities on the left side of the body.
The left controls the right side of the body.
●Cerebral Cortex- the outside of the cerebrum. Its
function is learning, reasoning, language, and
memory.
●Cerebellum- lies below the cerebrum at the back of
the skull, Its functions are to voluntary muscles,
balance and muscle tone.
● Medulla- controls heart rat, breathing, swallowing,
coughing, and vomiting. Together with the pons and
the midbrain, the medulla forms the brainstem that
connects the cerebrum to the spinal cord.

The Spinal Cord
●The spinal cord extends down from the medulla.
It is an organ made up of tightly packed neurons,
which are mostly connecting neurons.
●The spinal cord has two main functions. First, it
carries nerve impulses from all over the body to
and from the brain. Second, it controls many of
the body’s involuntary actions.
The brain and spinal cord make up the central
switchboard, or coordinating center of the nervous
system.

Peripheral Nervous System
-The peripheral nervous system of humans
has thirty-one pairs of spinal nerves , which
connect with the spinal cord. Some nerves of
peripheral system carry only sensory information
the diagram again.
The optic nerves, which carry visual signals
from the eyes are like this. Other nerves contain
both sensory and motor axons.
Somatic Autonomic Subdivisions
-The peripheral nervous system has two
subdivisions called somatic and autonomic. The
somatic is concerned with the movements of the
body’s head, trunk, and limbs.

The Sympathetic and Parasympathetic Nerves
-The autonomic nervous system is entirely
involuntary and automatic. It is composed of two
parts, one of which is called the sympathetic
system.
Sympathetic Nervous System- it helps to
regulate heart action, the secretion of ductless
glands, the blood supply in the arteries, the action
of smooth muscles of the stomach and the intestine,
and the activity of other internal organs.
Parasympathetic System- opposes the
sympathetic system and thus maintains a system of
checks and balances. The principal nerve of
parasympathetic system is the vagus nerve, and
abdomen.

GROUP 4
Grade 11 HUMSS(1)
-Dacanay, Chrizell Joy
-Digon, Rina Angeline
-David Abegail
-Edwin Ponseca
THANK YOU!! 

Chapter 4 : Human Body Systems

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Chapter 4 : Human Body Systems