Integument Flashcards
what are the 6 major views for labelling drawings?
rostral: toward nose
caudal: toward tail
ventral: toward belly
dorsal: toward back
medial: toward middle
lateral: toward side
What are the 3 major axes for labelling drawings?
rostral-caudal
dorsal-ventral
medial-lateral
What are 3 major planes for labelling biological drawings?
horizontal plane (plane splitting horizontally in half)
coronal plane (plane splitting front from back)
sagittal plane (plane between eyes/down spine)
What are the 3 major layers of the skin?
epidermis
dermis
hypodermis
What are the major functions of the skin?
protection
barrier
regulator
sensory
What kind of secretory cells does the skin have?
mucoid
proteinaceous
What do mucoid cells do?
produce mucus
What do proteinaceous cells do?
produce slimes, poisons
Which of the 3 layers is the surface/outer layer?
epidermis
What are the 3 components of the epidermis?
stratum corneum: outermost layer
ketatins
stratum germinativum: innermost layer
Which is the outermost layer of the epidermis?
stratum corneum
What are keratins?
fibrous proteins found in the epidermis that can be alpha keratin or beta keratin types
Describe alpha keratin; where are they found?
relatively soft (can be hard)
component of hair, nails, horns
found in the epidermis
Describe beta keratin; where are they found?
hard
component of feathers, reptilian scales, claws, beaks
found in the epidermis
Where do keratinocytes mature?
in the stratum spinosum
What is the innermost layer of the epidermis? What is significant about it?
stratum germinativum
the main site of cell division
Where is the main site of cell division in the epidermis?
the stratum germinativum
Describe the basic make up of the dermis
it’s a meshwork of collagenous and elastic fibers
it has two layers:
stratum spongiosum
stratum compactum
also contains
- mechanoreceptors
- nerves
- blood vessels
- other structures such as hair follicles, sweat glands
What are the two layers of the dermis?
stratum spongiosum
stratum compactum
What two types of fibers are found in the dermis?
collagenous
elastic
Aside from fibers, what other
things are found in the dermis?
mechanoreceptors
blood vessels
nerves
depending on the groups, some have hair follicles, sweat glands
What is the hypodermis made of?
connective and adipose tissue
what is the scale bar formula?
drawing size/ actual size = X mm length of scale bar / mm represents scale bar
ex.
drawing size = 120 mm
actual size = 0.8 mm
represents scale bar = 0.1 mm
length of scale bar = (120 x 0.8) / 0.1 = 15 mm
What is the germ tissue origin of the epidermis?
ectoderm
What germ tissue did the dermis arise from?
mesoderm
What separates the epidermis and the dermis?
the basement membrane which is a non-cellular layer
T or F: the epidermis is generally thicker than the dermis
false
the dermis is usually thicker than the epidermis
Which contains more cell types: dermis or epidermis?
the epidermis
Briefly describe the epidermis of bony fish
non-keratinized
thin
glandular
coated with a non-cellular cuticle produced by mucus cells
many mucus cells present
glands are near the surface of the epithelium
multiple types of cells can be present: epithelial, mucus, club
Are bony fish integuments keratinized?
no
Describe the basic structure of bony fish integuments
thin, glandular, mucus coating, non-keratinized
What is the purpose of the mucus cuticle coating bony fish?
reduces drag in water (improves flow of water across the skin surface)
protection against infection
participates in osmoregulation
predator evasion = makes them slippery, and sometimes includes toxic chemicals
What are the 3 common types of cells in bony fish epidermis?
epithelial
mucus
club
Describe the dermis of fish
thin
composed of loose and dense connective tissues
features:
- chromatophores
- mast cells
- scale beds
- scales
Where do fish scales originate?
from the dermis
How does the origin of fish scales compare to scales in tetropods?
fish scales originate from the dermis, whereas tetrapod scales originate from the epidermis
How do scales in cartilaginous fishes (Chondrichthyes) differ to those in bony fish?
cartilaginous fish have placoid scales which are not flat like those in bony fish, but look like shark teeth
In what way does amphibian integument not represent the skin of fish?
lacks scales
surface skin cells are keratinized
The stratum corneum is best developed in what type of amphibians?
ones that spend more time on land
these cells are molted in sheets occasionally
What causes warts on toads?
local thickenings of cells
What is the major function of the integument for most amphibians?
major respiratory organ
How does the skin contribute to respiration in amphibians?
the dermis has many blood vessels and lymph spaces for gas exchange
How does amphibians prevent water loss when they’re on land?
mucus glands in their epidermis-dermis secrete a mucus cuticle to keep their skin moist
Where are poison glands located in amphibian skin?
the epidermis
How have reptiles ‘airproofed’ their skin?
use of keratin and lipids
How has the reptilian integument been modified for life on land?
the epidermis has been hardened to cover the reptile in horny scales
What do snakes and lizards molt?
their entire epidermis layer
What composes the reptilian epidermis?
first layer is characterized by beta-keratin - tough, thick, dead, and acellular layer
deeper layer is characterized by alpha-keratin
What is a major component of fish and amphibian skin which reptilian skin is lacking?
mucus glands - reptiles do not have mucus glands
What are scutes?
layers of overlapping keratinized scales of epidermal origin in some reptiles (crocodiles, tortoises) that are not shed, but instead layered over time
What is the major difference between bird skin and all other vertebrates?
the presence of feathers
Where do feathers originate from?
the epidermis
What is a second major difference between bird skin and other vertebrates? But common between non-bird reptiles?
non-glandular
just one single gland
How many glands are present in the bird integument? What is/are the function(s)?
1
secretes oil for preening and waterproofing
What type of keratin are feathers made of?
beta
How do the epidermis and dermis of mammals grow in relation to one another?
they are interwoven through epidermal and dermal ridges
How is mammal skin classified as thin or thick?
by the extent to which the outermost layer of the epidermis is keratinized
Where is thick mammalian skin typically found?
in areas of the body where there’s more abrasion (ex. bottom of feet, hands)
What are some examples of skin derivatives in mammals? where do they originate?
hair
sebaceous glands
sweat glands
nails
epidermal
Describe the connection between hair, hair follicles and sebaceous glands in mammals
a strand of hair is composed of a cornified shaft and a root with a hair follicle
sebaceous glands secrete sebum (oil) into the neck of a hair follicle
In mammals, what gland types develop in association with hair follicles and which do not?
do: sebaceous glands
do not: sweat glands
What are two other features of mammalian skin?
blood vessels
adipose tissue
What is the purpose of skin derivatives such as hair in mammals?
heat retention
