The integument provides protection, regulation of body temperature and moisture, sensory reception, and in some cases locomotion and skeletal support. In invertebrates it consists of epidermis and a secreted cuticle. Invertebrate integument includes a single layered epidermis in many multicellular invertebrates, and a cuticle in crustaceans, arachnids and insects which provides additional protection and may harden through calcification or sclerotization. Vertebrate integument includes a keratinized stratified epidermis and an underlying dermis with blood vessels, nerves and connective tissue. The dermis may contain bony structures and gives rise to hair, feathers,

1. Protection, Support
and Movement
General Biology Lecture

2. Integument
The integument is this the protective outer
covering of the animal body
It includes the skin and structures associated
with the skin (derivatives of the skin) such as
hair, nails, scales, feathers, and horns

3. Functions of the Integument
Protection from mechanical & chemical injury
Protection against invasion by microorganisms
Regulation of body temperature
Excretion of waste materials
Vitamin D production
Reception of environmental stimuli
Locomotion/movement
Controls movement of nutrient and gases

4. Invertebrate Integument
Some singled-celled protozoa have only a plasma membrane
for external covering (Amoeba)
Other protozoa have a thick protein coat called pellicle outside
the plasma membrane (Paramecium)
Most multicellular invertebrates have a single-layered epidermis
covering the body (nematodes, annelids)
Others have added a secreted non-cellular cuticle over the
epidermis (crustaceans, arachnids, insects)
Additional protection
Old cuticles need to be shed periodically in a process called
molting to permit growth

5. Invertebrate Integument

6. Invertebrate Integument

7. Invertebrate Integument
Molluscs have a delicate epidermis.
Protection is provided by the shell
Cephalopods have a more complex epidermis
with a cuticle, simple epidermis, layer of
connective tissue, & a layer of iridocytes - a
guanine-containing cell in the skin of fish and
some cephalopods, giving these animals their
iridescence

8. Invertebrate Integument
Arthropods have a complex
integument that provides
protection and skeletal support
Single layered epidermis
(hypodermis) which secretes
a complex cuticle
Procuticle – layers of
chitin and protein
Epicuticle – moisture
proofing barrier

9. Invertebrate Integument
The arthropod cuticle may remain tough, but
flexible as in many small crustaceans and insect
larvae, or it may become hardened
Decapod crustaceans have a cuticle stiffened
by calcification (deposition of calcium
carbonate in the procuticle)
In insects, hardening occurs by sclerotization
where protein molecules bond together
producing the insoluble protein sclerotin

10. Other Examples of
Invertebrate Integument
Rotifers – cuticles are thin and elastic
Arthropods – cuticles are thick and rigid
Cnidarians – epidermis is only a few cell layers thick (Hydra),
contains mucous glands that secrete calcium carbonate shells
(corals)
Platyhelminthes – covering is a tegument (functions for nutrient
ingestion and for protection)
Nematodes and annelids – have an epidermis that is one cell thick
and secretes a multilayered cuticle
Echinoderms – integument consists of a thin, ciliated epidermis & an
underlying connective tissue dermis that contains calcium carbonate

11. Other Examples of
Invertebrate Integument
Rotifers
Cnidarians

12. Other Examples of
Invertebrate Integument
Nematodes
Platyhelmintes

13. Other Examples of
Invertebrate Integument
Echinoderms
Annelids

14. Vertebrate Integument
Vertebrate Integument
includes:
Epidermis – thin outer
stratified epithelial
layer, derived from
ectoderm
Dermis – thick inner
layer, derived from
mesoderm

15. Epidermis
The epidermis gives rise to hair, feathers, and hooves (epidermal
derivatives)
Epidermis is stratified squamous epithelium
Cells in the basal part undergo frequent mitosis
As cells are displaced upward, cytoplasm is replaced by keratin

16. Epidermis
Keratin is a tough protein that is also light and
flexible
Reptile scales are composed of keratin
Birds have keratin in feathers, beaks, and claws
Mammals use keratin in hair, hooves, claws, and
nails

17. Dermis
The dermis is a dense
connective tissue
layer containing blood
vessels, collagenous
fibers, nerves,
pigment cells, fat
cells, and fibroblasts
Dermis serves to
support, nourish, and
cushion the epidermis

18. Dermis
The dermis may contain bony structures of dermal
origin
Ostracoderms and placoderms had heavy bony
plates
Living sturgeons

19. Dermis
Scales of fishes are
bony dermal
structures that
evolved from the
armor of Paleozoic
fishes

20. Dermis
In reptiles, dermal bone contributes to the armor
of crocodilians, the beaded skin of some lizards,
and portions of a turtle’s shell (carapace &
plastron)
Dermal bone is found in the antlers of mammals.

21. Dermis
Claws, beaks, nails, and horns are composed of a
combination of epidermal (keratinized) and
dermal components.

22. Examples of Vertebrate Integument
Agnathans (jawless fishes) – several types of glandular cells
may be present; multicellular slime glands produce large
amounts of slime that covers the body
Chondrichthyes (cartilaginous fishes) – skin is multilayered
and with mucous and sensory cells; dermis has bones in
the form of denticles

23. Examples of Vertebrate Integument
Osteichthyes (bony fishes) – skin has scales; skin
is permeable and functions in gaseous exchange;
epidermis may also contain mucous cells; dermis
is richly supplied with capillary beds to facilitate
its use in respiration
Functions of Mucus:
Prevents bacterial and fungal infections
Reduces friction as the fish swims

24. Examples of Vertebrate Integument
Amphibians – stratified epidermis and a dermis
containing mucous, serous glands and with
pigmentation
Keratin: protects the skin against UV and physical
abrasions
Mucus: helps prevent desiccation and facilitates
gaseous exchange
Poison glands: produce an unpleasant-tasting or
toxic fluid that acts as a predator deterrent

25. Examples of Vertebrate Integument

26. Examples of Vertebrate Integument
Reptiles – stratum corneum is very thick and
modified into keratinized scales
Functions:
Resist abrasion
Inhibit dehydration
Acts as a “suit of armor” for protection

27. Examples of Vertebrate Integument
Birds – show many reptilian features
Epidermis: over most of the body is thin and only 2 or 3 cell layers
thick
Outer keratinized layer is soft
Feathers are the most prominent parts of the epidermis
Dermis: with blood, lymphatic vessels, nerves, sensory bodies
Arrector plumose: dermal smooth muscle associated with feathers
(control the position of the feathers)
Aquatic birds – may also have fat deposits in the hypodermal layer
that store energy & help insulate the body

28. Examples of Vertebrate Integument

29. Mammalain Skin (Human Skin)
Notable features of mammalian skin are:
a highly stratified, cornified epidermis
a dermis with blood and lymphatic vessels, nerve
endings, small muscles, glands, hair follicles
a hypodermis composed of loose connective
tissue, adipose tissue and skeletal muscles – the
hypodermis attaches the skin to the underlying
muscles

30. Skin (Integument)

31. Sweat Glands
Different types prevent overheating of the body; secrete sweat,
cerumen and milk
Eccrine sweat glands – found in palms, soles of the feet, and
forehead
Apocrine sweat glands – found in axillary and anogenital
areas
Ceruminous glands – modified apocrine glands in external
ear canal that secrete cerumen
Mammary glands – specialized sweat glands that secrete
milk

32. Sebaceous Glands
Simple alveolar glands found all over the body
Soften skin when stimulated by hormones
Secrete an oily secretion called sebum

33. Skin Receptors
Meissner’s corpuscles – touch receptors
Pacinian corpuscles – pain receptors
Ruffini’s corpuscle – heat receptors
End Bulbs of Krause – cold receptors
Merkel’s disk – texture and touch receptors

34. Structures associated with Skin
Hair
Composed of keratin-filled dead cells that
developed from epidermis
Nails
Modification of epidermis
Flat, horny plates on dorsal surface of distal
segments of the digits

37. Skeletal Systems
Skeleton is the hardened part of the animal body
Functions:
Supports the body
Framework of the body
Protects vital organs of the body
Blood cell formation/hematopoiesis
Site for the attachment of muscles
Accessory to movement
Storage of minerals

38. Hydrostatic Skeletons
In the hydrostatic skeleton of an earthworm,
muscles in the body wall develop force by
contracting against incompressible coelomic fluids
Alternate contractions of circular and longitudinal
muscles of the body wall enable a worm to move
forward

39. Hydrostatic Skeletons

40. Hydrostatic Skeletons

41. Rigid Skeletons
Rigid skeletons contain some kind of rigid elements
Provide anchor points for pairs of opposing
muscles
Provides protection & support
Exoskeleton – found in molluscs, arthropods, some
invertebrates & vertebrates
Endoskeleton – found in echinoderms, sponges,
and chordates

42. Exoskeletons

43. Exoskeletons

44. Endoskeletons

45. Endoskeletons

46. Vertebrate Endoskeleton
The vertebrate endoskeleton
is composed of bone and
cartilage (types of
connective tissue)
Bone provides support,
protection, and serves as a
reservoir for calcium and
phosphorous

47. Cartilage
Jawless fishes (eels, hagfishes) and elasmobranchs
(sharks, sting rays) have cartilaginous skeletons
Most vertebrates have bony skeletons, with some
cartilaginous parts

48. Cartilage
Cartilage is a soft,
pliable tissue that resists
compression and is
variable in form
Hyaline cartilage has a
clear, glassy appearance
with chondrocytes
surrounded by a matrix
No blood vessels

49. Cartilage
Cartilage is often found at articulating surfaces of
many bone joints, larynx, trachea, vertebral
column, nose, pinnae, and Eustachian tube

50. Bone
Bone is highly vascular living tissue that contains
significant deposits of inorganic calcium salts
Endochondral (replacement) bone develops
from another form of connective tissue –
usually cartilage
Intramembranous bone develops directly from
sheets of embryonic cells
Face, cranium, clavicle

51. Structure of the Bone

52. Bone
Bone can vary in density.
Spongy bone consists of
open, interlacing
framework of bony tissue,
oriented to give strength
Compact bone is dense –
the open framework of
spongy bone has been
filled in by additional
calcium salts.

53. Bone
Compact bone is
composed of a calcified
bone matrix arranged in
sets of concentric rings
- osteons
Bones consist of
bundles of osteons
interconnected with
blood vessels and
nerves.

54. Bone
Between the rings are lacunae (cavities) filled with
osteocytes (bone cells) connected by tiny
passageways that distribute nutrients (canaliculi)

55. Bone - Dynamic Tissue
Bone is a dynamic tissue
Osteoclasts are bone destroying/resorbing cells
Osteoblasts are bone forming/building cells.
Both processes occur together so that new osteons
are formed as old ones are resorbed.

56. Bone - Dynamic Tissue
Hormones (parathyroid hormone for resorption
and calcitonin for deposition) are responsible for
maintaining a constant calcium level in the blood.

57. Vertebrate Skeleton
The vertebral column serves as the main stiffening
axis
In fishes it provides points for muscle
attachment, provides stiffness, and preserves
body shape during muscle contraction

59. Vertebrate Skeleton
Most vertebrates have paired appendages
Pectoral and pelvic fins in fishes supported by the
pectoral and pelvic girdles
Tetrapods have two pairs of pentadactyl limbs
(although they may be highly modified through
bone loss or fusion)
The pelvic girdle is generally firmly attached to the
axial skeleton, while the pectoral girdle is more
loosely attached

60. Vertebrate Skeleton
Axial skeleton includes the
skull, vertebral column,
ribs, and sternum
Appendicular skeleton
includes the limbs and
pectoral and pelvic girdles
Human skeleton is
composed of 206 bones

61. Bones of the Skeleton
The adult skeleton contains 206 bones

62. Divisions of Skeleton
Axial and
Appendicular
Skeletons

63. Axial Skeleton
THE AXIAL SKELETON - CONSIST OF THE SKULL,
VERTEBRAL COLUMN, AND THE RIB CAGE
Skull
Vertebral column
Rib cage (ribs + sternum)

64. Appendicular Skeleton
THE APPENDICULAR
SKELETON – consists of
bones of the:
ARMS (upper limbs)
LEGS (lower limbs)
SHOULDER GIRDLE
(pectoral girdle)
HIP GIRDLE (pelvic girdle)

65. Bone Classification by Shape
5 Types
Long
Short
Flat
Irregular
Sesamoid

66. Shapes of Bones
Long bones are longer than they are wide and
work as levers. The bones of the upper and lower
extremities (ex. humerus, tibia, femur, ulna,
metacarpals, etc.) are of this type.
Short bones are short, cube-shaped, and found in
the wrists and ankles.

67. Shapes of Bones
Flat bones have broad surfaces for protection of organs and
attachment of muscles (ex. cranial bones, ribs, and bones of
hip and shoulder girdles).
Irregular bones are all others that do not fall into the previous
categories. They have varied shapes, sizes, and surface features
and include the bones of the vertebrae and a few in the skull.

68. Animal Movement
Most animal movement depends on contractile
proteins which can change their shape to relax or
contract
These fibrils will contract when powered by ATP
Actin and myosin form a contractile system
found in most animals
Cilia and flagella utilize different proteins called
tubulin.

69. Amoeboid Movement
Ameboid movement is
found in ameobas, white
blood cells, and
embryonic cells
Movement using
pseudopods (false feet)
depends on actin and
myosin

70. Cilia are found throughout the
animal kingdom (except in
nematodes, rare in arthropods)
Uniform in diameter (0.2-0.5
µm) and structure
Basal body similar to a centriole
– 9 triplets of microtubules
composed of the protein tubulin
Cilium has 9 pairs surrounding
two individual microtubules

71. Ciliary and Flagellar Movement
A flagellum is a whiplike
structure longer than a
cilium and usually
present singly
Structure is the same
Different beating pattern

72. Muscular Movement
Muscle cells (fibers) can only do work by contraction
They can’t actively lengthen
They are often arranged in opposing (antagonistic) pairs
Three types of muscle tissue
Skeletal
Smooth
Cardiac

73. Skeletal Muscle
Skeletal, (striated)
muscle appears to be
striped
Multinucleate fibers
Attached to skeleton
Voluntary
Fast acting, but fatigues
quickly.

74. Smooth Muscle
Smooth muscle lacks striations
Fusiform cells with a single, oval nucleus
Involuntary
Slow acting, but can maintain prolonged contractions
Muscles of the stomach, intestines, uterus are smooth muscle

75. Cardiac Muscle
Cardiac muscle, found only in the heart, is striated and fast acting
like skeletal muscle
Involuntary, with one or two nucleus per fiber
Fibers are joined by junctional complexes called intercalated discs

76. Muscles
A skeletal muscle
consists of a bundle of
long fibers running
parallel to the length of
the muscle
A muscle fiber is itself a
bundle of smaller
myofibrils arranged
longitudinally

77. Muscles
The myofibrils are composed of two kinds of filaments:
Thin filaments, consisting of two strands of actin and one strand of
regulatory protein
Thick filaments, staggered arrays of myosin molecules
The functional unit of the myofibril is a sarcomere

79. Muscles
Actin and myosin are contractile proteins

80. Muscle Contraction
Striated muscle contraction is explained by the sliding filament hypothesis
Actin & myosin filaments become linked together by cross bridges (myosin
heads), which act as levers to pull the filaments past each other
Z-lines pulled closer together, sarcomere shortens.

81. Muscle Contraction
Muscles contract in response to nerve stimulation
Skeletal muscles are innervated by motor neurons
whose cell bodies are in the spinal cord

82. Muscle Contraction
One motor neuron has many terminal branches
that may innervate many muscle fibers
A motor unit includes the motor neuron and all
the fibers it innervates

84. The Neuromuscular Junction
The place where a motor axon terminates on a
muscle fiber is called the neuromuscular junction
The synaptic cleft is a small gap that separates the
nerve fiber & muscle fiber
Acetylcholine is stored in synaptic vesicles in
the neuron

85. The Neuromuscular Junction
When a nerve impulse arrives, acetylcholine is
released into the cleft starting a wave of
depolarization in the muscle fiber

86. Excitation-Contraction Coupling
In the resting state, muscle shortening does not
occur because thin tropomyosin strands on the
actin myofilaments lie in a position that prevents
the myosin heads from attaching to actin

87. Excitation-Contraction Coupling
When the muscle is
stimulated, calcium ions
are released that bind to
troponin
This causes a change
in shape that causes
the tropomyosin to
move out of the way
exposing binding sites
on the actin molecule

88. Energy for Contraction
Energy for muscle contraction comes from ATP
ATP is synthesized during aerobic metabolism

89. Energy for Contraction
During prolonged exercise, blood flow can’t
supply oxygen fast enough for aerobic
metabolism to continue
Anaerobic glycolysis is not as efficient, but still
produces some ATP
An oxygen debt builds up because the
accumulated lactic acid must be oxidized

90. Fast and Slow Fibers
Skeletal muscles consist of different types of fibers
Slow oxidative fibers (red muscles) specialized for slow,
sustained contractions
Maintaining posture
Fast glycolytic fibers (white muscles) lack an efficient blood
supply and function anaerobically
Running muscles in cats
Fast oxidative fibers have an efficient blood supply and
function aerobically for fast, sustained activities
Wing muscles in migratory birds.