LEARNING OBJECTIVES
- Read the Class Notes, using the Textbook
illustrations to help understand the concepts. Read the chapter using the
Class Notes as your guide. There are many questions included
to help tie the systems and concepts together into an integrated,
holistic understanding of anatomy and physiology.
- Take the
Ch.
5 self test in the online textbook.
DO NOT EMAIL THIS TEST TO YOUR INSTRUCTOR. It is a learning tool
only. These tests will also include
questions that are NOT covered in this course.
- Use any resources on the
Online Textbook,
to integrate your learning.
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Chapter 5:
Integumentary System
Use the diagrams in the book to
enhance comprehension of these concepts.
State the three functions of the integumentary system
The skin (integumentary system) is a BARRIER between the
environment inside the body and everything outside the body.
This function is much like that of the
CM – describe the similarities.
The most immediate function is to prevent the evaporational
loss of water.
Why is the most immediate function?
What are the other functions of the skin?
Protection - against anything external to the body: bacteria,
2X4's, gravel on the road, acid, dirt,
UV radiation,
Sensations - detect external conditions: air temperature, things
crawling on the skin, etc.
Thermoregulation - lose excess heat, retain heat when the external
environment is too cool.
Secretion - secrete substances to help the skin stay supple
Define abrasion.
Some common types of abrasion include 'rug burn', 'road rash', 'skinned
knee or elbow', etc
Protection: the layered construction of the
skin, especially the keratinized S. corneum.
Name the two layers of skin
The skin is also called the cutaneous membrane or
integumentary system.
The two layers are the:
Epidermis - the outer layer
Dermis - the inner layer
The Epidermis is composed of 5 distinct layers
on a basement membrane - it is an EPITHELIUM.
The stratum corneum is the outer most later
and is composed of MANY layers of cells.
State the location and function of the stratum corneum and
the stratum germinativum
What are the 5 layers of the epidermis?
List them.
Which layer is the 'growth' layer?
i.e. which layer produces new 'skin' cells?
Stratum Basale (aka S.
Germinativum)
The 'germ' cells are the cells that go through Cell Reproduction.
Stratum germinativum is named for its ability to undergo Cellular
Reproduction or Mitosis.
Stratum germinativum is the innermost
layer of the epidermis and sits directly on the basement membrane.
These cells are 'live' and able to under go mitosis.
Describe the stages of Mitosis (look back at Chapter 3,
Cells)
What is the functional unit of the integumentary system?
The stratum corneum and its cornified cells full of
keratin.
How does the stratum corneum resist abrasion?
Keratinization: the process by which a basal cell
undergoes mitosis producing cell that moves outward toward the surface
of the skin. As the cell continues from the inner most layer,
through the subsequent layers, a durable, tough, indigestible protein -
Keratin - is produced. The cell loses the nucleus and 'dies' -and
in the process fills with keratin.
The cells of the stratum corneum are flat and
scale-like, and filled with the hard, tough, durable, Keratin.
These scale-like cells form the tough, durable,
abrasion-resistant layer that is the functional unit of
the Integumentary system.
The skin is WATERPROOF because there are extracellular
lipids between the cells.
Drugs suspended in oil can cross cell membranes and penetrate the
skin.
How do 'dermal patch' type drugs work to deliver
drugs?
How does Alcohol or gasoline 'dry'
out the skin?
Remember from Chapter 3 - alcohol and
gasoline are 'nonpolar solvents' and 'like dissolves like'?
Nonpolar solvents dissolve the 'extracellular
lipids' in the skin and wash them away.
The skin is no longer 'water proof'
and therefore, water evaporates... leaving dry tissues
which then 'crack' and peel.
Bacteria - cannot easily pass through the epidermis
due to the dry, keratinized stratum corneum.
Two common bacteria that are easily found on the skin - opportunistic
(facultative) pathogens:
Staphylococcus aureus - (the villain in
MRSA: methycillin resistant S. aureus)
Staphylococcus epidermidis
When the skin is 'broken'
as in a cut or scrape (abrasion), these bacteria immediately enter
the wound and start to multiple
- INFECT the wound.
The DERMIS contains a layer of Irregular
Dense Connective Tissue - the Reticular Region.
What is the function of irregular dense CT?
It is STRONG in all directions and forms capsules and sheathes around
vessels and hollow organs.
Because we have a layer of irregular dense connective tissue in the
subcutaneous layer, we have a SHEATH or Capsule around the entire body!
How is irregular dense CT different from regular dense CT?
(see Chap. 4, Tissues)
MOST of the Sensory nerve endings (NE) are found in
the Dermis.
These NE's sense 'conditions of the
environment' and help us as 'living organisms' to respond to our
environment.
Remember from chapter 1 - the characteristics of life?
Describe the function of melanocytes and melanin
Melanocytes secrete Melanin.
Define pigment and melanin.
Melanin is the pigment that makes skin tan, brown, or black.
The less melanin - the lighter the color. The more melanin, the
darker the color. It does the same for HAIR.
Melanin causes the iris of the eyes to be red, blue, green, brown, or
black. NO melanin results in a RED iris - as in Albino. Blue is
a result of little melanin, while brown and black result from lots of
melanin.
Melanin absorbs UV light. UV light causes damage to
skin cells resulting in skin cancer. Therefore, melanin is an important
molecule.
When a word ends in 'oma' it usually indicates 'cancer'.
CARCINOMA
Describe these types of skin cancer:
Melanoma,
basal
cell carcinoma,
squamous cell carcinoma.
Which is most lethal?
Carcinogen - a chemical or condition that causes
cancer.
Approximately 75% of all cancers, skin or
otherwise are the result of Chemical exposure or other Environmental
factors, such as exposure to UV sunlight - sun tanning and sunburn.
Why does our body produce melanin?
What is the cause of 3/4 of all cancers?
Sensations: the sensory nerve endings of the
integumentary system
Name the cutaneous senses and explain their purpose
(NOTE: These are detailed in the NERVOUS SYSTEM)
Here are the SENSATIONS - i.e. Stimuli or Conditions that
must be 'sensed'
Touch – Free nerve endings, root hair plexus,
Meissner’s and Merkel’s,
Light and Deep pressure – Free nerve endings, root
hair plexus, Pacinnian, Meissner, Merkel, Ruffini.
Pain - Free nerve endings, root hair plexus
Heat – Free nerve endings, root hair plexus
Cold – Free nerve endings, root hair plexus
Here are the 'Sensory Nerve Endings'
aka Dendritic Nerve Endings - i.e. the structures in
the Cutaneous system
that 'detect' the stimulus.
Pacinian (lamellated) corpuscles – deep pressure,
pulsing or vibrations; skin of fingers, breasts, external genitalia, joint
capsules, mesenteries, pancreas and urinary bladder.
Meissners corpuscles – fine or light touch and
pressure; genitals, eyelids, lips, fingertips, nipples.
Ruffini corpuscle – pressure and distortion of skin;
deep - dermis.
Merkel’s disc – fine or light touch and pressure; in
the lower epidermis (S. germinativum)
Bare nerve ending (free nerve ending) - all
sensations; between epidermal cells.
Root hair plexus – hair root bulb and sheath; hair
distortion and movement.
now - HOW do you study/learn these
sensations and the structures that detect them?
MAKE YOURSELF A TABLE FOR COMPARISON!
2 columns. 1st is the name of the sensory nerve
ending, 2nd is the sensation detected
7 or 8 rows. You will add a couple of sensory nerve endings when you
get to the nervous system
Describe the function of hair and nails
Hair and nails are accessory organs of the integumentary
system.
Where is the 'growing point' for
hair?
Where is the 'growing point' for nails?
What are the arrector pili muscles?
What happens when they contract?
Hair and nails are both made up of dead, keratinized
cells. Therefore, we can 'cut' these without pain, loss of blood,
etc.
List the accessory organs of the
integumentary system.
Secretions:
Describe the functions of the secretions of sebaceous
glands, ceruminous glands and eccrine sweat glands
All the sweat glands are accessory organs of the cutaneous
membrane.
What are the two main types of glands in the body?
How are they different?
Which type of glands in the skin are the eccrine, apocrine
and holocrine glands? This is based on the characteristics of the
secretion.
Which is mostly water?
Which is mostly oil?
Eccrine glands are also called Merocrine sweat glands.
These are the glands that produce the stuff we know as 'sweat' -
99% water,
salty,
cools us off,
helps prevent bacteria from living on the skin.
Why is it 'salty'?
List some 'electrolytes' (see Chapter 2, Chemistry)
What is another name for Merocrine sweat glands?
Where on the body is the highest
concentration of Merocrine sweat glands?
Although found all over the body, the highest concentrations of
merocrine glands are on the palms of the hands and on the soles of the
feet.
Apocrine glands secrete part of the cell.
They are located all over the body, but in the highest concentration
circum nipple and circum anus.
Where on the body is the highest concentration of Apocrine sweat
glands?
Where is the axillary region?
What does circum nipple mean?
What does circum anus mean?
When first secreted, apocrine sweat has no odor. Bacteria
'eat' the contents of apocrine sweat - which then causes Body Odor.
What is it that the bacteria 'eat'?
Milk glands are Apocrine Glands. The 'sweat' produced by
apocrine glands contains parts of the cell which includes organic
molecules: fats, sugars and proteins.
Holocrine sweat glands produce an OILY substance.
Sebaceous glands are holocrine glands found in hair follicles.
What what condition is caused by 'clogged' sebaceous glands?
Acne
Where on the body do you find the highest concentration of Holocrine
sweat glands?
Thermoregulation
Describe the 4 ways that Heat is lost.
Review: Chapter 17, Metabolism
How does hair aid thermoregulation?
What is the role of the errector pili muscle in thermoregulation?
Describe how the arterioles in the dermis respond to heat,
cold, and stress
What is vasodilation and vasoconstriction?
What happens to the arterioles in the skin when you get
‘hot’?
Review heat loss in chapter 17.
Vasodilation means that MORE blood comes to that area - blood is carrying
heat from the muscles - that heat heats the skin surface and you sweat
(evaporate), radiate the heat, or transfer the heat to the air molecules
that touch your body.
What happens to the arterioles in the skin when you get
cold?
Again, vasodilation brings heat to the skin surface to keep the cells
warm.
How does this help the skin maintain its function?
With continued COLD (and extreme loss of heat energy
from the body), the blood vessels vasoconstrict, and blood is diverted
to the interior of the body so that heat can be retained. This
leads to 'frostbite' and loss of external tissues.
What happens to the arterioles in the skin when you get
stressed?
What is ‘flushing" or embarrassed?
How does vasodilation cause 'redness' of the skin?
The Integumentary system also plays a
part in synthesizing functional vitamin A and Vitamin D.
Vitamin D - fat soluble, cholesterol derived,
absorption of Ca from the food - antirachitic
Helps prevent
Rickets.
Vitamin A - fat soluble, needed for vision and skin
epithelium
Name the tissues that make up the subcutaneous tissue and
describe their functions
What is adipose tissue?
What is the function of adipocytes?
Why is areolar loose connective tissue called ‘loose’?
It contains a lot of water with fewer extracellular proteins and
specialized cells.
Describe the types of burns
A Burn is the most common extensive damage to the skin.
What are the functions of the
skin? Damage to the skin prevents it from
maintaining those functions.
Today, EMTs are using
Superficial to describe 1st degree burns – red
painful - sunburn.
This is damage to the outer layers of the epidermis: S.
corneum and S granulosum.Partial thickness to describe 2nd degree – red
painful – the epidermis is damaged, some
blisters form which indicates damage to the dermis. Full thickness to describe 3rd (and 4th)
degree burns – white or black.- NOT painful (why?)
-
The entire epidermis and dermis are totally destroyed and
perhaps some damage
to the
underlying tissues.
Where are the sensory nerve ending located?
How does the location of the sensory nerve endings affect the 'pain'
from a burn?
Which is painful - superficial, partial thickness, or full thickness?
Why?
What is the function of the integumentary system?
Folks who have been burned over an extensive part of their
body die first from loss of water – the water evaporates or drains from
the body – the skin is not there to hold the water inside the body and
prevent its loss.
Burn units first make sure that the patient will stay
hydrated. After water loss is stabilized – patients can die from secondary
infections – the skin is not there to protect against bacteria and other
pathogens.
Rule of Nines – describes the percentage of the total
surface area of a person’s body that has been damaged. Take the skin off
the body, spread it out on a flat surface and measure the total surface
area.
NOW:
The head is approximately 9% of the total body surface area. Left arm is approximately 9%. Right arm = 9 % The front of the torso = 9 x 2 = 18% The back of the torso = 9 x 2 = 18% Left leg = 9 x 2 = 18% Right leg = 9 x 2 = 18%This is 11 sections that are about 9% for a total of 99%
of the body surface area.
The groin area makes up the other 1%.
How does aging affect this system?
Age causes the skin to become thinner - and more prone to tearing and
abrasion.
There is decreased sweat gland activity.
The blood vessels do not vasodilate or vasoconstrict as
readily-
therefore body temperature and sensations of hot and cold are not well
controlled or regulated. Old folks may feel either hot or cold at
'odd' times.
The repair processes (mitosis) does not function well, and
old folks skin may not heal properly or may be prone to cancers.
The dendritic nerve endings become less sensitive to
environmental stimuli - therefore, there is slower response to
environmental conditions.
How does this system interact with the other systems?
Remember – all the systems have to work together to
maintain homeostasis.
-The function of the cardiovascular system is to move
nutrients (including O2) around the body. If the skin is not
there to prevent water loss – the blood will become too thick to be
effectively pumped around the body.
Now, how does the integumentary system interact with the
other systems?
Think of this in terms of the major functions of each
system
What does the function of each system do for the
integumentary system?
What does the function of the integumentary system do
for all the other systems?
I will ask this same set of questions for each system
throughout the course.
LAB
Epidermis
- Stratum Germinativum
- Stratum Spinosum
- Stratum Granulosm
- Stratum Lucidum
- Stratum Corneum
Dermis
- Papillary Layer
- Reticular Layer
Hypodermis / Subcutaneous
Accessory Structures
- Hair Follicles
- Sebaceous Glands
- Sweat Glands
- Apocrine Sweat Glands
- Merocrine Sweat Glands
- Nails
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