The Integumentary System

1
The Integumentary System
2
The Integumentary System

• Integument is skin
• Skin and its appendages make up the integumentary
  system
• A fatty layer (hypodermis) lies deep to it
• Two distinct regions
• Epidermis
• Dermis

3
Functions of skin

• Protection
• Cushions and insulates and is waterproof
• Protects from chemicals, heat, cold, bacteria
• Screens UV
• Synthesizes vitamin D with UV
• Regulates body heat
• Prevents unnecessary water loss
• Sensory reception (nerve endings)

4
Epidermis

• Four types of cells
• Keratinocytes deepest, produce keratin (tough
  fibrous protein)
• Melanocytes - make dark skin pigment melanin
• Merkel cells associated with sensory nerve
  endings
• Layers (from deep to superficial)
• Stratum basale or germinativum single row of
  cells attached to dermis youngest cells
• Stratum spinosum spinyness is artifactual
  tonofilaments (bundles of protein) resist tension
• Stratum granulosum layers of flattened
  keratinocytes producing keratin (hair and nails
  made of it also)
• Stratum corneum horny layer (cells dead, many
  layers thick)

(see figure on next slide)
5
Epithelium layers (on left) and cell types (on
right)
6
Remember

• Four basic types of tissue
• Epithelium epidermis just discussed
• Connective tissue - dermis
• Muscle tissue
• Nervous tissue

7
Dermis

• Strong, flexible connective tissue your hide
• Cells fibroblasts, macrophages, mast cells, WBCs
• Fiber types collagen, elastic, reticular
• Rich supply of nerves and vessels
• Critical role in temperature regulation (the
  vessels)
• Two layers (see next slides)
• Papillary areolar connective tissue includes
  dermal papillae
• Reticular reticulum (network) of collagen
  and reticular fibers

8
Dermal papillae
Dermis layers


9
Epidermis and dermis of (a) thick skin and (b)
thin skin (which one makes the difference?)
10
Hypodermis

• Hypodermis (Gk) below the skin
• Subcutaneous (Latin) below the skin
• Also called superficial fascia
• fascia (Latin) band in anatomy sheet of
  connective tissue
• Fatty tissue which stores fat and anchors skin
  (areolar tissue and adipose cells)
• Different patterns of accumulation
• (male/female)

11
Skin color

• Three skin pigments
• Melanin the most important
• Carotene from carrots and yellow vegies
• Hemoglobin the pink of light skin
• Melanin in granules passes from melanocytes (same
  number in all races) to keratinocytes in stratum
  basale
• Digested by lysosomes
• Variations in color
• Protection from UV light vs vitamin D?

12
Skin appendages

• Derived from epidermis but extend into dermis
• Include
• Hair and hair follicles
• Sebaceous (oil) glands
• Sweat (sudoiferous) glands
• Nails

13
(No Transcript)
14
Nails

• Of hard keratin
• Corresponds to hooves and claws
• Grows from nail matrix

15
Hair and hair follicles complexDerived from
epidermis and dermisEverywhere but palms, soles,
nipples, parts of genitalia
arrector pili is smooth muscle

Hair bulb epithelial cells surrounding papilla
Hair papilla is connective tissue________________
16

• Functions of hair
• Warmth less in man than other mammals
• Sense light touch of the skin
• Protection - scalp
• Parts
• Root imbedded in skin
• Shaft projecting above skin surface
• Make up of hair hard keratin
• Three concentric layers
• Medulla (core)
• Cortex (surrounds medulla)
• Cuticle (single layers, overlapping)

17
Sweat glands

• Entire skin surface except nipples and part of
  external genitalia
• Prevent overheating
• 500 cc to 12 l/day! (is mostly water)
• Humans most efficient (only mammals have)
• Produced in response to stress as well as heat

18
Review

• The role that the integumentary system plays?
• Order these skin layers superficial to deep
  dermis, hypodermis, epidermis. Where might you
  find keratin?

• What are the top and bottom layers of the
  epidermis
• What are the 4 cell types within the epidermis
• What structures reside in the dermis?

19
Dissecting the Fetal Pig

• Sus scrofa

20
Introduction to Mammals

• Of all the classes of animal life, mammals are
  considered to be the most advanced.
• Examples dogs, cats, squirrels, pigs, whales,
  horses, sheep, and HUMANS!
• Vary greatly in sizefrom 2 inches (the shrew) to
  100 feet long (the blue whale)

21
Mammalian Characteristics

• Vertebrates (have backbones)
• Presence of lungs (breathe air)
• Warm-blooded (endothermic)
• This means that the body temperature of a mammal
  stays the same, no matter what the outside
  temperature is
• 4 chambered heart

22
Mammalian Characteristics, contd

• Give birth to live young
• Monotremes mammals that lay eggs
• EX the platypus and the echidna (spiny
  anteater)
• Body Hair
• Produce milk (have mammary glands)

Platypus
Echidna
23
Mammalian Characteristics, cont

• Less Obvious Characteristics
• The diaphragm separates the heart and lungs from
  the stomach
• Lower jaw has one bone on each side
• Different types of teeth adapted to different
  uses (tearing, chewing)
• Brains are much more highly developed than any
  other animal

24
Comparative Anatomy

• Study of similarities and differences in the
  anatomy (structure) of organisms
• Many aspects of structure and function are
  identical between different species of mammals
• Homologous Structures same structure
  (embryologically speaking), different function
  (have a common evolutionary descent)
• EX wings of bats and arms of humans
• Analogous Structures different structure, same
  function (evolved in a similar environment)
• EX wings of bats and wings of insects

25
Comparative Anatomy
Fetal Pigs Humans
Kingdom Animalia Animalia
Phylum Chordata Chordata
Class Mammalia Mammalia
Order Artiodactyla Primates
Family Suidae Hominidae
Genus Sus Homo
Species Scrofa sapiens
26
Why Fetal Pigs?

• The fetal pig is a mammal, like humans. Nearly
  all the structures are the same or very similar
  in anatomy.
• Fetal pigs are NOT bred for the purpose of
  dissection. They are a by-product of the pork
  food industry.
• Fetal pigs are NOT killed for the purpose of
  dissection. Those that are not dissected are
  used for fertilizer or discarded.
• Fetal pigs are relatively inexpensive. Even in
  the extra large size, when the structures are
  well-developed, they can be obtained for about
  1/3 the cost of a similarly sized cat.
• Most people do not think of pigs as pets.

27
Advantages to Dissection

• Dissection is a hands-on, investigatory kind of
  activity for students. Dissection allows students
  to "test the truthfulness" of what they see in
  books.
• Dissection impresses on students the normal
  variation that is present in the natural world.
  No two fetal pigs, even though they are perfectly
  normal, will look exactly the same.
• In fact, to do well on practicals, students MUST
  looks at several examples of each structure in
  different animals. Occasionally, quite
  significant anatomical variations (anomalies)
  will be noticed.

28
Safety and Handling

• Sharps
• All Dissecting tools should be considered
  dangerous.
• Notify your teacher IMMEDIATELY if you are cut.
• Handle probes, dissection scissors, razor blades,
  etc. with extreme caution.
• Always cut away from you, never toward yourself
  or another person.
• Dissection specimens should be properly mounted
  in the dissection pan before cutting.

29
Safety and Handling, contd

• Do not place your hands near your mouth or eyes
  while handling preserved specimens.  Most of the
  preservatives in use today are non-toxic to the
  skin, but they may cause minor skin irritations. 
  If the preservative gets on your skin, wash with
  soap and warm water.
• If the preservative gets in your eyes, rinse them
  thoroughly with the safety eyewash.
• Wear lab gloves and goggles at all times!
• Lab gloves and paper towels go in
• the regular trash.  Skin and pieces
• of pig go into the separate plastic
• bag at the front of the room
• (NOT down the sink).

30
Dissection Helpful Points

• Actual cutting should be kept to a MINIMUM
• Tissue are picked and teased apart with needle
  probes, forceps, and blunt probes in order to
  trace the pathways of blood vessels, nerves,
  muscles, and other structures.
• NEVER CUT OR MOVE MORE THAN IS NECESSARY TO
  EXPOSE A GIVEN PART.
• Compare dissections with other students,
  especially students whose pig is of a different
  sex. You will be responsible for both sexes on
  the lab practical (test).

31
Determine the Sex of your Pig

• Female  Look for a single urogenital opening
  just ventral to the anus.  A prominent genital
  papilla projects from the urogenital opening. 
• Male  Look for the scrotum, a sac-like swelling
  containing the testes and located ventral to the
  anus.  The male urogenital opening is faintly
  visible just posterior to the umbilicus.  Note
  that males as well as females have multiple
  nipples teats mammary papillae.

32
Female Male