Body Organization
Levels of Organization
Section 7- 4
Muscle cells
Go to
Section:
muscle tissues
Organs
Organ systems
These Organ Systems function together
to maintain homeostasis – a stable
internal environment
Figure 35-2 Human Organ Systems Part I
Section 35-1
Nervous System
Integumentary System
Skeletal System
Muscular System
Circulatory System
Figure 35-2 Human Organ Systems Part 2
Section 35-1
Respiratory System
Endocrine System
Digestive System
Excretory System
Reproductive System
Lymphatic System
4 Main Types of Tissues
1. Epithelial Tissue –
cells pack tightly
together and cover
and protect
underlying tissue;
Lines our organs;
Ex: stomach lining
& skin
4 Main Types of Tissues
2. Connective Tissue
joins, supports,
protects, and
nourishes organs;
Ex: ligaments,
tendons, cartilage,
bone, blood
4 Main Types of Tissues
3. Muscle Tissue –
contracts and relaxes
for movement
–
–
–
Skeletal muscle- moves
bone; voluntary (works
when you want it to)
Cardiac Muscle-Only
found in the heart.
Involuntary (works all the
time)
Smooth Muscleinvoluntary (works all the
time)
4 Main Types of Tissues
4. Nervous Tissue –
sends electrical
signals throughout
the body. Ex: Brain,
Spinal Cord, Nerves
Integumentary System
Functions of the Skin
1. Covers and protects the
body
What does the skin protect us
from?
– Pathogens
– Injury
– Ultra-violet radiation
Body’s
Museum
in Atlanta
Functions
2. Regulate body
temperature/reduces
water loss
How does it regulate
temperature?
– Sweating
– Dilate/constrict of blood
vessels
– Goose bumps
Functions
3. Excretes Waste like Urea
How are
wastes
excreted?
In sweat
subcutaneous
Functions
4. Sensory receptors input information to the
brain about the outside environment
Chemo
Mechano
Chemo
Photo
Mechano
There are 2 main layers of skin
outer layer
deeper
layers
Epidermis
Stratum
corneum
Outer (surface) layers
of skin
Stratum
lucidum
Stratum
granulosum
10-30 cells thick
Two Parts:
Inner part
composed of living
cells
Lamellar granules
Keratinocyte
Langerhans cell
Stratum
spinosum
Outer part is of dead
cells
Dead
keratinocytes
Melanocyte
Stratum
basale
Dermis
Merkel cell
Tactile disc
Sensory neuron
Dermis
Deeper layers of skin
10-20 times thicker
than epidermis.
Top layer arranged
In ridges.
Dermis
Specialized Cells of the Epidermis
Melanocytes are cells that
produce melanin.
Melanin is a pigment that
helps to protect the skin
from harmful ultraviolet
solar radiation from the
sun.
Makes your skin darker or
lighter
Interesting Tidbit
Melanocytes
Do some people have
more melanocytes
than other people?
Interesting Tidbit
Skin pigmentation is due
to the type and amount
of melanin produced
Eumelanin produces
darker pigments
Phaeomelanin produces
lighter pigments and
freckles
These often occur
together in varying
amounts
Melanocyte
Interesting Tidbit
Ridges help the
epidermis bind to the
dermis.
The uneven ridges
create fingerprints
Dermis
Accessory Organs of the Dermis
1. Hair follicles – tube-like depression where
the hair develops
Accessory Organs of the Dermis
2. Sebaceous glands – secret oily sebum to
soften and waterproof skin
Accessory Organs of the Dermis
3. Nails – protective covers of ends of
fingers and toes.
Accessory Organs of the Dermis
4. Sweat glands:
– secrete waste
– regulate heat
Accessory Organs of the Dermis
5. Blood vessels – to nourish skin cells
Accessory Organs of the Dermis
6. Nerves – to send and receive messages
Subcutaneous
Accessory Organs of the Dermis
7. Erector pilli muscle
-smooth muscle
-causes
“goosebumps”
-causes
hair to
stand erect
subcutaneous
Subcutaneous layer
Anchors dermis to the body
Contains fat
cells to
protect
and cushion
Subcutaneous layer
Self
Quiz
What are the three
layers of skin?
Self Quiz
Self Quiz
Self Quiz
Self Quiz
Self Quiz
Self Quiz
Self Quiz
Self Quiz
Self Quiz
Self Quiz
Self Quiz
Interesting Tidbits
• A fingernail or toenail takes about 6
months to grow from base to tip
• Fingernails grow faster than toenails
• An average human scalp has 100,000
hairs
• We lose between 40 and 100 hairs per
day
• Blondes have more hair than brunettes
Interesting Tidbits
• Friction of the epidermis causes cell division to
increase.
• This outward thickening is called a callous.
• Sometimes growth is inward, creating a corn.
• Humans shed about 600,000 particles of skin
per hour – about 1.5 pounds per year.
• At age 70, you will have lost about 105 lbs of
skin.
Interesting Tidbits
• Fingerprints provide traction for grasping objects
• Even identical twins have different fingerprints
• Every square inch of dermis contains twenty feet
of blood vessels
• Skin on our hands and feet is thicker. When we
bathe, skin takes on water and swells slightly.
• In the thicker areas, increased surface area
creates crowding. The skin must wrinkle to
accommodate the changes
Interesting Tidbits
• Your body is composed of approximately 100
Trillion cells
• About 16% of your body weight is skin
• The skin is completely renewed every 27 days
• You will make almost 1000 new skins in a
lifetime
• If all the layers of your skin were laid out on the
ground, it would cover about 20 m2 or 2 parking
spaces
Disorders of the Skin
1. Acne – infection of sebaceous gland
Disorders of the Skin
2. Vascular Birthmarks – Blood vessel
abnormality affecting .5% of population –
darkens skin
Disorders of the Skin
3. Dermatitis – dry, sensitive skin
Disorders of the Skin
4. Fungal infections
Athlete’s Foot
Ring Worm
Disorders of the Skin
5. Impetigo – bacterial infection
Disorders of the Skin
6. Psoriasis – chronic inflammation
Disorders of the Skin
7. Cancer
Carcinoma
Melanoma
Disorders of the Skin
8. Warts- viral infection
Disorders of
the Skin
9. Burns
First degree
Second degree
Third degree
Concept Map
Section 36-3
Skin
functions
as a
Barrier to
infection
Regulator of
body
temperature
is made
up of the
Remover of
waste products
Protector
against UV
radiation
Epidermis
which
is the
Outer layer
Dermis
which
is the
Inner layer
Albanism: a defect of melanin production
that results in little or no color (pigment) in the skin,
hair, and eyes.
Albanism is a genetic disorder
that is carried on the recessive
allele.