Skeletal, Muscular,
Nervous, and
Integumentary
Systems
By: Christina,
Sunny, & Ann
The Skeletal
System
Animal skeletons function in
support, protection, and
movement
 Most land animals would sag from
their own weight if they had no
skeleton to support them. Even an
animal that lives in water would
become a formless mass with no
framework/skeleton to support and
maintain its shape.
 In many animals, a hard skeleton
provides protection for soft tissues.
For example, the vertebrate skull
protects the brain, and the ribs of
terrestrial vertebrates form a cage
around the heart, lungs, and other
internal organs.
 Skeletons also aid in the
movement by giving muscles
something firm to work against.
Skeletons
There are three main types of
skeletons:
 Hydrostatic skeletons
 Exoskeletons
 Endoskeletons
Hydrostatic Skeletons
S
A Hydrostatic skeleton consists of fluid
held under pressure in a closed body
compartment.
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This is the main type of skeleton in most cnidarians , flatworms,
nematodes, and annelids. These animals control their form and
movement by using muscles to change the shape of fluid filled
compartments.
Among cnidarians, a hydra can elongate by closing its mouth and using
contractile cells in the body wall to constrict the central gastrovascular
cavity.
In planarians, the interstitial fluid is kept under pressure and functions as
the main hydrostatic skeleton. The planarian movement results mainly
from muscles in the body wall exerting localized forces against the
hydrostatic skeleton.
Nematodes hold fluid in their body cavity, which is a pseudocoelom.
In annelids and earthworms, the coelomic fluid functions as a hydrostatic
skeleton. The coelomic cavity is divided by septa between the segments
in many annelids, allowing the animal to change the shape of each
segment individually, using both circular and longitudinal muscles. These
annelids use their hydrostatic skeleton for peristalsis.
Exoskeletons
E
An exoskeleton is a hard encasement deposited
on the surface of an animal
 As an animal grows, it enlarges the shell by adding to its outer
edge.
 Clams close their hinged shell using muscles attached to the
inside of this exoskeleton.
 The jointed exoskeleton of arthropods is a cuticle, a non-living
coat secreted by the epidermis. Muscles are attached to knobs
and plates of the cuticle that extend into the interior of the body.
 About thirty to fifty percent of the cuticle consist of chitin, a
polysaccharide similar to cellulose. Fibrils of chitin are embedded
in a protein matrix, forming a composite material that combines
strength and flexibility. Where protection is the most important, the
cuticle is hardened with organic compounds that cross link the
proteins of the exoskeleton.
 Some crustaceans, such as lobsters, harden portions of their
exoskeleton even more by adding calcium salts.
Endoskeleton
An endoskeleton consists of hard
supporting elements, such as bones, buried
within the soft tissue of the animal.
 Endoskeletons of various complexity are found: chordates,
and echinoderms.
 An endoskeleton allows the body to move and gives the
body structure and shape.
 A true endoskeleton is derived from mesodermal tissue.
Such a skeleton is present in echinoderms and chordates.
 Echinoderms have an endoskeleton of hard plates called
ossicles beneath the skin.
 Chordates have an endoskeleton consisting of cartilage,
bone, or some combination of these materials.
 The mammalian skeleton is built from more than 200
bones, some fused together and others connected at
jointsby liagments that allow freedom of movement.
 Vertebrates have a distinctive endoskeleton made up of an
axial and appendicular skeleton.
Joints
 Joints provide flexibility for body
movements.
 Some examples of joints are:
- Ball and socket joints
- Hinge joints
- Pivot joints
Label the
skeleton
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
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Some Helpful Sites on the
Skeletal System
 http://www.mnsu.edu/emuseum/biology/h
umananatomy/skeletal/skeletalsystem.ht
ml
 http://yucky.discovery.com/flash/body/pg0
00124.html
 http://hes.ucfsd.org/gclaypo/skelweb/skel
01.html
The Integumentary
System
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Definition
 Integumentary system is the
outer covering of a mammal;s
body, including the skin, hair,
and nails
Functions
 Protects the body's internal living tissues
and organs
 Protects against invasion by infectious
organisms
 Protects the body from dehydration
 Protects the body against abrupt
changes in temperature
Functions (continued)
 Helps dispose of waste materials
 Acts as a receptor for touch, pressure,
pain, heat and cold
 Stores water, fat, and vitamin D.
Epidermis
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The outermost layer of skin and is composed mostly of dead
epithelial cells that continually flake and fall off. New cells pushing
up from lower layers replace the cells that are lost.
Dermis
Supports the
epidermis and
contains hair
follicles, oil
and sweat
glands,
muscles,
nerves, and
blood vessels
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Activity: True or False
 1. Skin is the largest organ.
 2. The integumentary system only consist
of skin.
 3. Part of the integumentary system job is
to protect the body from dehyrdration.
 4. The skin consists of five layers of skin.
Answer to Activity
1. True
2. False, the Integumentary system consists of the
outer covering of a mammal’s body, including the
skin, hair, and nails
3. True
4. False, the skin consist of two layers, the
epidermis and dermis
To learn more about the
integumentary system you can
look under:
 AP Biology Textbook by Campbell & Reece
 Websites such as
http://www.cancerindex.org/medterm/medtm5.ht
m
 And even videos:
ttp://video.google.com/videoplay?docid=5613693526435958138
Muscular System
Overview
 The main job of the muscular system is to
provide movement for the body.
 There are just over 650 skeletal muscles
in the whole human body.
 The muscular system consist of three
different types of muscle tissues : skeletal,
cardiac, smooth, all of which have the
ability to contract, allowing the body
movements and functions.
Major muscles of the body
Cardiac Muscle
 Cardiac muscle, called the myocardium, is found
only in the heart.
 It is involuntary, controlled by the autonomic
nervous system.
 The myocardium is composed of thick bundles
of muscle, forming the walls of the chambers of
the heart and contracts to pump blood
throughout the body.
 Its cells are joined by intercalated disks that
relay each heartbeat.
Smooth Muscle
• Smooth muscles are involuntary muscles
found in the stomach and intestinal walls,
in artery and vein walls, and in various
hollow organs.
• In a vessel or organ, smooth muscles are
arranged in sheets or layers.
Skeletal Muscle
 Stabilize joints, help maintain posture,
and give the body its general shape.
 In men, they make up about 40 percent
of the body's mass or weight and in
women, about 23 percent.
 Are generally responsible for the
voluntary movements of the body.
Structure of Muscle Cells
•Within the cells are myofibrils; myofibrils contain
sarcomeres, which are composed of actin and
myosin.
•Individual muscle fibers are surrounded by
endomysium.
•Muscle fibers are bound together by perimysium
into bundles called fascicles; the bundles are then
grouped together to form muscle, which is
enclosed in a sheath of epimysium.
•Muscle spindles are distributed throughout the
muscles and provide sensory feedback
information to the central nervous system.
Muscle Cell in Detail
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Movement and muscle
arrangement
•In skeletal muscle, contraction is stimulated by electrical impulses
transmitted by the nerves, the motor nerves and motorneurons in
particular.
•Cardiac and smooth muscle contractions are stimulated by internal
pacemaker cells which regularly contract, and propagate contractions to
other muscle cells they are in contact with.
•Muscular activity accounts for much of the body's energy consumption. All
muscle cells produce adenosine triphosphate (ATP) molecules which are
used to power the movement of the myosin heads.
•Muscles also conserve energy in the form of creatine phosphate which is
generated from ATP and can regenerate ATP when needed with creatine
kinase.
•They keep a storage form of glucose in the form of glycogen. Glycogen
can be rapidly converted to glucose when energy is required for sustained,
powerful contractions.
Activity
1. What are muscles made of?
2. What are the 3 types of muscles?
3. What are smooth muscles and what do they do and
where are they found?
4. What are cardiac muscles, where are they and what
do they do?
5. What are skeletal muscles what do they do?
6. What’s the difference between voluntary and
involuntary muscles?
7. Where do facial muscles attach?
8. What do facial muscles do?
9. Name the muscle that’s attached only at one end?
10.List the 6 major types of muscles
Nervous System
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Overview
 All animals except the sponges have some
type of nervous system.
 Nervous systems consist of circuits of
neurons and supporting cells.
 The human brain contains an estimated 100
billion nerve cells or neurons.
 Invertebrate nervous systems range in
complexity from simple nerve nets to highly
centralized nervous systems having
complicated brains and ventral nerve cords.
The Brain
 The brain is composed of three parts: the cerebrum, the
cerebellum, and the medulla oblongata.
 The medulla oblongata is closest to the spinal cord, and is
involved with the regulation of heartbeat, breathing,
vasoconstriction (blood pressure), and reflex centers for
vomiting, coughing, sneezing, swallowing, and hiccuping.
 The hypothalamus regulates homeostasis. It has regulatory
areas for thirst, hunger, body temperature, water balance, and
blood pressure, and links the Nervous System to the Endocrine
System.
 The midbrain and pons are also part of the unconscious brain.
The thalamus serves as a central relay point for incoming
nervous messages.
 The cerebellum is the second largest part of the brain, after the
cerebrum. It functions for muscle coordination and maintains
normal muscle tone and posture. The cerebellum coordinates
balance.
Central nervous system consists
of the brain and the spinal cord
 In invertebrates, the central nervous system consists of the
brain and the spinal cord, which is located dorsally.
 Nervous systems process information in three stages:
sensory input, integration, and motor output to effector
cells.
 The three stages are illustrated by the knee jerk reflex.
 The CNS integrates information, while the nerves of the
peripheral nervous system transmit sensory and motor
signals between the CNS and the rest of the body.
 Sensory neurons transmit information from sensors that
detect external stimuli and internal conditions.
 Most neurons have highly branched dendrites that receive
signals from other neurons.
 They also typically have a single axon that transmits
signals to other cells at synapses.
Nerve Cell
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A basic nerve cell consists of a cell body, an axon, and many dendrites.
Dendrites are thread-like branches that increase the surface area of a cell
making it possible for the receiving many connections with other nerve
cells.
Signals picked up by the dendrites travel through the cell and continue
along the axon where they are transmitted to the next cell.
Synaptic bulbs on the ends of the axons make connections with other
nerve cells, via synapses.
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All cells have an electrical potential difference
across their plasma membrane called the
membrane potential
•Ions pumps and ion channels maintain the resting potential of a neuron.
•In neurons, the membrane potential is typically between -60 and -80 mV when the
cell is not transmitting signals.
•The inside of the cell is negative related to the outside.
•The membrane potential depends on ionic gradients across its plasma membrane:
the concentration of Na + is higher in the extracellular fluid than in the cytosol, while
the reverse is true for K+.
•A neuron that is not transmitting signals contains many open K+ channels and fewer
open Na + channels in its plasma membrane.
•The diffusion of K + and Na+ through these channels leads to separation of charges
across the membrane, producing the resting potential.
•Gated ion channels open or close in response to membrane stretch, the binding of a
specific ligand, or a change in the membrane potential.
•Stretch gated ion channels are found in cells that sense stretch and open when the
membrane is mechanically deformed.
Somatic Nervous System
•Includes all nerves controlling the muscular system and
external sensory receptors.
• External sense organs are the receptors.
•Muscle fibers and gland cells are effectors. The reflex arc is an
automatic, involuntary reaction to a stimulus.
•A reaction to the stimulus is involuntary, with the CNS being
informed but not consciously controlling the response.
•Sensory input from the PNS is processed by the CNS and
responses are sent by the PNS from the CNS to the organs of
the body.
•Motor neurons of the somatic system are distinct from those of
the autonomic system.
•Inhibitory signals, cannot be sent through the motor neurons of
the somatic system.
Autonomic Nervous System
 Part of PNS consisting of motor neurons that control internal
organs. It has two subsystems.
 The autonomic system controls muscles in the heart, the smooth
muscle in internal organs such as the intestine, bladder, and
uterus. The Sympathetic Nervous System is involved in the fight or
flight response.
 The Parasympathetic Nervous System is involved in relaxation.
 Each of these subsystems operates in the reverse of the other
(antagonism). Motor neurons in this system do not reach their
targets directly (as do those in the somatic system) but instead
they just connect to a secondary motor neuron which innervates
the target organ.
Crossword Activity
1. System of the nervous system that contains the
brain and spinal cord
2. The sensory and motor neurons that connect to
the central nervous system
3. Receive and communicate information from the
sensory environment
4. Makes synaptic connections with other neurons
a. one of many short, branched processes of a
neuron that help bring the nerve impulses toward
the cell body
b. A system of the nervous system that can be
broken down into a sensory and a motor division
c. Takes the command of the CNS and put them
into action as motor outputs
d. one of three divisions of the autonomic nervous
system; generally enhances body activities that
gain and conserve energy, such as digestion and
reduced heart rate
e. one of three divisions of the autonomic nervous
system; generally increases energy expenditure
and prepares the body for action
f. Longer extensions that leave from a neuron and
carry impulse away from the cell body to toward
target cells
g. main body of the neuron
Answer to Activity