Human Body
Systems Part 1
The levels of organization in the
human body:
Connective and Epithelial Tissue
•Connective Tissue
– Provides support for the body and
connects its parts
Example: blood, bone, cartilage, fat
•Epithelial Tissue
– Covers interior and exterior body surfaces;
protects, absorbs, filters, and secretes
Example: skin, blood vessels
Muscle and Nervous Tissue
•Muscle Tissue
-provides movement with help from the
skeleton (contracts)
 Example: heart, biceps, stomach
•Nervous Tissue
– Transmits and processes information in
the body
Example: brain, sciatic nerve
TissuesOrganOrgan Systems
Human body has 11 organ
systems:
–
–
–
–
–
–
–
–
–
–
–
Nervous
Integumentary
Respiratory
Digestive
Excretory
Skeletal
Muscular
Endocrine
Reproductive
Lymphatic
Immune
Homeostasis
• All 11 body systems interact to maintain homeostasis.
– The Nervous system coordinates the body functions to
maintain homeostasis.
• Feedback inhibition/Negative feedback: a stimulus
produces a response that opposes the original
stimulus.
– Ex: body temperature and home heating unit
Fun Facts about… the Nervous
System
• The number of neurons in our body is more
than the number of stars in the Milky Way.
• The speed of message transmission to the brain
can be as high as 180 miles per hour.
• The human brain alone consists of about a 100
billion neurons. If all these neurons were to be
lined up, it would form a 600 mile long line.
Nervous System
• Function: controls and • Nervous cells are called neurons.
coordinates functions
– 3 types:
throughout the body.
• Sensory (sends msgs TO brain)
Responds to external
• Motor (sends msgs FROM brain)
and internal stimuli.
• Interneurons (connects neurons)
• Neurotransmitters –
chemicals used by a
neuron to transmit an
impulse across a synapse
to another cell
Typical Neuron
Explaining Nerve impulses
Two Divisions of Nervous System
1) Central Nervous
System (CNS)
– Relays messages,
processes and analyzes
information
– Includes brain and
spinal cord
• Brain: Cerebrum
(voluntary activity,
thinking, learning,
judgement), cerebellum
(coordinates muscles),
brain stem (involuntary
activity i.e. breathing,
heart rate)
2) Peripheral Nervous
System (PNS)
– Receives information
from environment and
relays commands from
CNS to organs and
glands.
– Includes nerves and
associated cells not
part of CNS
How is the spinal cord like a
telephone line?
PNS is so BIG – It’s divided into 2
divisions
1) Sensory:
2) Motor: transmits impulses from
transmits
CNS to muscles or glands
impulses from
•Divided into 2 divisions:
sense organs
1)Somatic NS: regulates
to the CNS
activities under conscious
**Eyes, ears,
tongue, etc..
5 Senses: Touch,
Taste, Smell,
Hearing, Sight
control
Ex: moving skeletal muscles
2)Autonomic NS: regulates
activities that are automatic,
or involuntary
Ex: breathing
Nervous
System
Central
Nervous
System
Peripheral
Nervous
System
Sensory
Motor
Somatic
Autonomic
Drugs and the Nervous System
• Stimulants: Increase heart rate, blood
pressure and breathing rate. Increase
neurotransmitters
– Ex: amphetamines, cocaine, caffeine
• Depressants: slow down heart and
breathing rate, lower blood pressure, relax
muscles and relieve tension
– Ex: alcohol, heroin
Fun Facts about… the
Integumentary System
• It contains your body’s
largest organ… your
skin.
• An average adult's skin
spans 21 square feet,
weighs nine pounds, and
contains more than 11
miles of blood vessels.
• The skin releases as
much as three gallons of
sweat a day in hot
weather
• In a lifetime, the average
person sheds enough
skin cells to fill an entire
2 story house. In one
minute, you can lose
between 30,000 and
40,000 skin cells.
Integumentary System
• “To Cover”
• Includes skin, hair, nails, and glands
• HAIR AND NAILS:
– Made of keratin (protein)
– Hair: covers the body, gives warmth, protects
eyes and nose, develops from hair follicles
– Nails: develop at the nail root
Skin
• Function: barrier between infection and
injury; regulates body temperature; protects
from UV rays; removes waste
• 2 layers:
– Epidermis: outer layer (keratin/melanin)
•No blood vessels
•Made of flat dead cells
– Dermis: beneath epidermis
•Sweat glands: reduce heat
•Oil glands: keep skin flexible and waterproof
Fun facts about… the Muscular
System
• The busiest muscles in your body are the eye
muscles, which approximately move more than
100,000 times in a day
• Muscles cannot push, they can only pull.
• There are approximately 640 muscles in the
body.
– The largest is your gluteus maximus.
– The smallest are in your middle ear.
Muscular System
• ALL a muscle can do is
contract (get shorter)
– Ex: moving forearm
(uses muscle pairs)
• 3 Types:
– Skeletal
– Smooth
– Cardiac
Skeletal Muscle
•
•
•
•
Attached to bones
Voluntary movements
Striated
Controlled by the CNS
Smooth Muscle
•
•
•
•
Involuntary
Not striated
Controlled by the PNS
Found in walls of
stomach, blood
vessels, intestines, etc;
Cardiac Muscle
•
•
•
•
In heart
Striated (like
skeletal)
Involuntary (like
smooth)
Controlled by the
PNS
Muscular System Cont’d
** The more you use it the stronger it gets
** Tendons connect muscle to bone
** Muscles work in pairs – one contracts while
the other relaxes
Fun Facts about…the Skeletal
System
• A baby is born with 300 bones, but an adult
only has 206.
• 54 of those bones are in your hands.
• Humans and giraffes have the same number
of bones, but giraffes’ vertebras are much
longer.
Skeletal System
• Function: supports the
body, protects internal
organs, provides for
movement, stores
mineral reserves, and
provides a site for
blood cell formation as
well as a place for
muscles to attach
• FACT: There are 206
bones in the human
body.
Two parts of the skeletal system
1) Axial Skeleton:
skull, vertebral
column, rib cage
**Protects
organs**
2) Appendicular
skeleton: bones
of arms and
legs, pelvis, and
shoulder area
**Involved in
movement**
Bones
• Bones are made of living and nonliving tissue
• Red marrow- makes new red blood cells, white
blood cells, and some platelets
• Early bone starts as cartilage.
• Ossification – process of bone formation
– Osteoblasts: build up bone
– Osteoclasts: break down bone
• Why do we need both??
Joints
• Ligaments hold bones together at joints
• Joint-place where two bones meet
• 3 TYPES:
– Immovable: no movement (ex: skull)
– Slightly Movable: restricted movement (ex:
bones in lower leg, joints between vertebrae)
– Freely Movable: movement in one or more
direction
(ex: Ball-and-socket, hinge, pivot, and saddle joints)
Fun Facts about… the Digestive
System
• We eat about 500kg of
food per year. 1.7 liters
of saliva is produced
each day.
• The stomach must
create a new lining of
mucous every 2 weeks,
otherwise it would
digest itself.
• An adult stomach can
hold 1.5 liters of food.
• In an average person, it
takes 8 seconds for
food to move through
the esophagus, 1-3
hours in the stomach,
3-5 hours in the small
intestine, and 3-4 days
in the large intestine.
Why is it important?
The digestive system’s
function is to help
convert food into
simpler molecules
that can be
absorbed and used
by the cells of the
body.
Step 1. The Mouth
• Teeth
– Chewing begins the
process of
mechanical digestion
•The physical
breakdown of large
pieces of food into
smaller pieces called
a BOLUS
• Saliva
– Begins the process
of
chemical digestion
•The enzyme
AMYLASE breaks
down carbohydrates
Step 2. The Esophagus
• Food tube that connects
the mouth to the
stomach
• The bolus moves
through the esophagus
by PERISTALIS
– Muscles in the walls of the
esophagus contract in
waves, which pushes the
bolus until it reaches the
stomach
“Help Me”! My food went down
the wrong pipe!
Step 3. The Stomach
•Chemical Digestion:
– The stomach contains hydrochloric acid
– This acid activates an enzyme, PEPSIN
•Pepsin is responsible for breaking down
protein
– Chemical digestion of carbohydrates stops
while in the stomach
The Stomach
• Mechanical Digestion:
– Stomach muscles
contract to churn and
mix the stomach acid
and food to create
CHYME
– After about an hour of
churning, the chyme
begins to flow into the
small intestine
Step 4. The Small Intestine
• Most of chemical digestion and absorption
of food you eat occurs in the small intestine.
• As chyme enters the S.I., it mixes with
enzymes and digestive juices from the
pancreas and liver.
How does the Small Intestine Work?
• In the lining of the small
intestine, there are folds that are
covered in fingerlike projections
called VILLI and microvilli
• Carbohydrates and protein
products are absorbed into the
capillaries in the villi.
• After the small intestine, the only
things remaining are water,
cellulose, and other indigestible
substances
Step 5. The Large Intestine
• The large intestine’s main
role is to remove water
from the undigested
material that is left.
• The concentrated waste
material that remains after
the water has been
removed passes through
the rectum and is
eliminated from the body.
Accessory Structures:
The Pancreas
• Functions:
– Produces hormones
that regulate blood
sugar
– Produces enzymes that
break down
carbohydrates,
proteins, lipids, and
nucleic acids
– Neutralizes stomach
acid that allows the
enzymes to be effective
Accessory Structures:
The Liver
• Organ located just
above and to the right
of the stomach
• Function:
– Produces BILE
• Helps dissolved droplets
of fat found in the small
intestine
• Extra bile is stored in the
gall bladder
Digestive System