Download Musculoskeletal notes (Human Body I)

THE HUMAN BODY PLAN
Recall the levels of organization:
Cell-tissueorganorgan systemorganismpopulationcommunity
ecosystembiomebiosphere
Terms of reference for human biology: Master these words, as they will be used throughout the unit!
Coelom: body cavity
Thoracic: refers to the chest cavity containing the heart and lungs (aka, “trunk” or “torso”)
Abdominal: refers to the lower body cavity; separated from the thoracic cavity by the diaphragm
Pelvic: refers to the lowest cavity containing the reproductive organs
Viscera: a general reference to the abdominal organs (“guts”)
Focus concept: As you read your text about bones, muscles and skin, note how their structures are
related to their functions in the human body, and how they relate to those all-important life
characteristics we learned about the first week of class.
I.
Body Tissues
A.
Muscle tissue
1.
composed of cells that can contract in a coordinated fashion
2.
there are 3 types of muscle in the human body
a.
Skeletal muscle—moves bones in the trunk, limbs and face
b.
Smooth muscle—handles body functions that you cannot control
consciously, such as the movement of food through the digestive system
c.
cardiac muscle—found only in the heart; pumps blood throughout the
body
B.
Nervous tissue
1.
contains cells that receive and transmit messages in the form of electrical
impulses
2.
cells are called neurons
3.
makes up the brain, spinal cord, and nerves
4.
found in parts of sensory organs, such as the eye
5.
provides sensation and response to the internal and external environment
6.
coordinates both voluntary and involuntary activities
C.
Epithelial tissue
1.
layers of cells that cover all internal and external body surfaces
2.
“guards” of the body and protects from dehydration or physical damage
3.
cells exist in a variety of arrangements
a.
simple epithelial is one cell layer thick, and lines the respiratory tract,
lungs, and major cavities
b.
stratified epithelial is several cell layers thick, and is most abundant in the
skin
c.
glandular epithelial is also stratified, but produces a substance like milk,
sweat, enzymes, hormones, etc.; cells tend to be cuboidal
D.
Connective tissue
1.
binds, supports, and protects structures in the body
2.
most abundant and diverse of the tissues and includes bone, cartilage, tendons, fat,
blood and lymph
3.
characterized by cells that are embedded in large amounts of an intercellular
substance called matrix
a.
matrix may be solid (bone), semisolid (cartilage, tendon, fat) or liquid
(blood, lymph)
II.
Organs and organ systems
A.
Skeletal system
1.
axial skeleton
a.
contains bones of the skull, ribs, spine and sternum (breastbone)
2.
appendicular skeleton
a.
contains the bones of arms, legs, scapula, clavicle (pectoral girdle) and
the pelvic bones (pelvic girdle)
3.
study the bones on your skeleton—there will be a quiz! Note the following bones
that are not labeled in the diagrams. You do not need to memorize how many
vertebrae are in each section of the spinal column
a.
illium (pl. –ia): the “flared” bones of the pelvis (what we think of as
“hips)
b.
ischium: (pl. –ia) the “butt bones”
c.
the sacrum is labeled “sacral vertebrae” in your text
4.
bones have many functions
a.
provide a rigid framework for muscles to pull against
b.
give shape and structure to the body
c.
protect delicate internal organs
d.
store minerals such as calcium and phosphorus
i.
bones are actually dynamic—they store calcium until it is needed
for metabolic function, then release it into the blood stream
e.
some produce red and some white blood cells
B.
Bone structure
1.
bones make up 20% of the body’s mass
2.
are not the dry, rigid structures that we see in museum exhibits
3.
are moist, living tissues
4.
come in many shapes and sizes: long, short, flat, irregular
5.
long bones
a.
consist of a porous central canal surrounded by dense material
b.
covered in a tough membrane called the periosteum
i.
contains a network of blood vessels which supply nutrients and
nerves to signal pain
c.
compact bones lies directly beneath the periosteum and surrounds the
central canal
i.
is composed of cylinders of mineral crystals and protein fibers
(lamellae)
ii.
in the center of each cylinder is a narrow channel called a
Haversian canal
iii.
blood vessels run through the interconnected Haversian canal to
carry nourishment to the bone tissue
iv.
bone cells (osteocytes) are embedded within the gaps between
protein fibers
6.
spongy bone
a.
a network of connective tissue that lies inside the compact bone
i.
is not soft, despite what its name implies
ii.
makes bones both light and strong
7.
marrow
a.
can be either red or yellow
b.
red marrow
C.
D.
E.
F.
i.
found in the ends of long bones and inside flat bones
ii.
produces red blood cells and certain white blood cells
c.
yellow marrow
i.
fills the shaft of long bones
ii.
composed mostly of fat cells and serves as a reserve energy source
iii.
can also be converted to red marrow and produce blood cells when
severe blood loss occurs
Injury and repair
1.
bones will crack or break from extreme loads, sudden impacts, or stress from
unusual directions (fracture)
2.
greenstick fractures are common in young people (bone does not completely
separate at the site of the break)
3.
simple fractures do not break the skin and must be diagnosed by xray
4.
compound fractures break through the tissues and skin and are more severe
Bone Development
1.
ossification: process by which cartilage slowly hardens into bone as a result of
mineral deposits
a..
most fetal cartilage is eventually replaced by bone as growth occurs
i.
some cartilage remains to lend flexibility to the areas between
bones, at the end of nose, outer ear, and inside the trachea
2.
bone elongation
a.
bones continue to develop after a person’s birth
b.
occurs between early childhood and late adolescence
c.
bone cells gradually replace the cartilage in long bones of limbs
(epiphyseal plate)
d.
continues until a person is considered to have reached “full height”
Joints: the place where two bones meet (3 kinds)
1.
joint function
a.
fixed joints prevent movement
i.
sutures are fixed joints that join the various skull bones together
b.
semimovable joints permit limited movement
i.
vertebrae are semimovable
ii.
allows movement only in certain directions
iii.
also found in the ribcage and sternum
c.
movable joints: 5 types
i.
hinge: elbows and knees
ii.
ball-and-socket: shoulder and hips
iii.
pivot: top 2 vertebrae of the spine that allows you to turn your
head side to side
iv.
saddle: base of each thumb
v.
gliding: between the small bones of the foot
joint structure
1.
all movable joints are covered with cartilage where they come into contact with
each other
a.
protects bones from grinding against each other
2.
ligaments hold bones together
a.
lined with a tissue that secretes a lubricant called synovial fluid
3.
susceptible to injury and disease
a.
tendonitis occurs when joints are irritated by injury or overuse


Tennis elbow
Golfer's elbow



Pitcher's shoulder
Swimmer's shoulder
Jumper's knee
i. over production of synovial fluid, meant to protect, actually increase
pain and inflammation
b.
c.
d.
III.
rheumatoid arthritis occurs when a flaw in the immune system attacks
joints, causing them to be swollen and painful
i.
may have a genetic component
osteoarthritis is a degenerative joint disease that occurs when the
cartilage between bones becomes thin and rough
i.
occurs in most people as they age
ii.
more common in extremely active people
osteoporosis—bone gets thin and brittle because it doesn’t take up
calcium sufficiently
i.
common in women after menopause
ii.
estrogen is not produced after menopause, and is necessary for
storing calcium
Muscular system: approx. 600 in the human body and makes up about 40% of total body mass
A.
Muscle types
1.
skeletal (striated) muscle
a.
responsible for moving parts of the body, such as the limbs, trunk and face
b.
composed of elongated cells called muscle fibers (think of a string from a
beef roast), about 0.1-8 cm long (3.3 inches)
c.
each fiber contains many nuclei and is crossed by light and dark stripes
called striations
d.
are grouped into dense bundles called fascicles
e.
are bound together with connective tissue to form a “muscle”
f.
are voluntary because we can control them (mostly)
g.
can have very rapid contractions
2.
smooth muscle
a.
found in the walls of the stomach, intestines, blood vessels and other
internal organs
b.
cells are spindle-shaped and have a single nucleus
c.
interlace to form sheets of smooth muscle tissue
d.
lacks the striations seen in skeletal muscle
e.
are surrounded by connective tissue
f.
most cannot be consciously controlled so are involuntary
g.
generally have slow, smooth contractions
h.
response to chemical signals (enzymes or hormones)
3.
cardiac muscle
a.
makes up the walls of the heart
b.
shares characteristics of both smooth and striated muscle
i.
is involuntary (fortunately!)
ii.
provides the rapid contractions associated with striated muscle
iii.
a specialized bundle of cells in the upper part of the heart sends
electrical signals to other heart cells
B.
Muscle structure and contraction
1.
a muscle fiber multinucleated muscle cell (again, think beef roast “string”)
a.
C.
may be made up of hundreds or even thousands of muscle fibers,
depending on muscle size
b.
fibers make up most of a muscle, but connective tissue, blood vessels and
nerves are also abundant
c.
are soft and easy to injure
d.
health of a muscle depend on sufficient nerve and blood supply
i.
each has a nerve ending that controls activity
ii.
requires a continuous supply of oxygen and nutrients which are
supplied by arteries
iii.
produce a large supply of metabolic waste that must be removed
by veins
e.
muscle fiber structure consists of bundles of threadlike structures called
myofibrils (bundles of two protein filaments—long chains)
i.
myosin fibers are thicker (about 15 nm in diameter)
ii.
actin filaments are thinner (about 7 nm in diameter)
iii.
filaments are arranged to form an overlapping pattern, which gives
it the striated (striped) appearance
iv.
thin actin filaments are anchored at their endpoints to a structure
called a z line
v.
the region from one z line to the next is called a sarcomere
f.
the sliding filament theory describes how the fibers slide over each other
to shorten during a contraction
g.
requires the presence of nerve fibers to stimulate them to shorten
(contract)
i.
weak muscles involve very fibers
ii.
strong muscles involve many fibers
iii.
muscle fibers + nerve fibers = a motor unit
Muscular movement of bones
1.
tendons link muscles to bones (attached to periosteum of bone)
a.
the origin of the muscle is attached to the stationary bone (doesn’t move
and acts like an anchor)
b.
the insertion is attached to the bone that moves
2.
use ATP molecules to apply a force to the bones by shortening their length
(contraction)
a.
acts as a lever system (review your physical science!)
b.
muscles can only pull a bone, never push
i.
flexor muscles pull a bone in one direction; decreases the angle of
a joint (e.g., the biceps)
ii.
extensors pull the bone in the other direction; increases the angle
of a joint (e.g., the triceps)
iii.
muscles must work in pairs (antagonistic pairs)
3.
exercise increase the size and efficiency of a muscle
a.
oxygen needed to burn the “fuel” (glycogen), which is stored in muscle
cells as a source of energy (converted to glucose when needed)
i.
when reserves are burned during prolonged activity, fat reserves
are accessed for energy (weight loss occurs)
ii.
when all energy is used, ATP can’t recycle and muscle fatigue
occurs (inability to contract)
b.
does not increase the number of muscle fibers, only size and strength
c.
muscle soreness results when oxygen debt occurs and lactic acid builds up
d.
“working out” injures (tears) muscle fibers, causing the body to try to
“repair” it by increasing the size of the myofibrils
4.
IV.
A.
B.
C.
D.
anabolic steroids
a.
“anabolic” refers to the building up of molecules in the body (catabolic
refers to the break down)
b.
are produced naturally by the body, but when taken as a supplement, tricks
the body into producing muscle growth by simulating male hormones
c.
has severe side effects in both genders
i.
severe acne, cancer, heart disease, altered sexual development
1)
may cause breast enlargement, reduced size of genitalia in
males
2)
may cause enlargement of external female genitalia
5.
Muscle injury
a.
strain—“pulled muscle”—overstretching and tearing of muscle fibers
b.
sprain—torn muscle, tendon or ligament
c.
tendonitis—previously discussed
d.
disuse atrophy—weakness or “flabby muscles”
Integumentary system (skin, external covering): 1 sq. inch of skin contains ~200 nerve
endings, 10 hairs & muscles, 100 sweat glands, 15 oil glands, 3 blood vessels, 12 heat
sensors, 3 cold sensors, and 25 pressure sensors (don’t memorize! Info only)
Skin is the largest of the human body’s organs; very complex
1.
Epidermis (outer layer) is 10 to 30 cells thick (stratified epithelial)
a.
composed of many sheets of flattened, scaly epithelial cells (mostly dead)
b.
shed continuously and replaced by rapidly dividing lower layers
c.
filled with a protein called keratin
d.
gives skin its rough, leathery, waterproof qualities
e.
is colored by a brown pigment called melanin
i.
produced by lower layers of the epidermis
ii.
absorbs harmful UV radiation and is designed to protect DNA
from mutation (cancer)
iii.
amount varies (determined by DNA) which is why different races
have a different skin “color”
2.
outermost layer (corneal) prevents dehydration is a layer of dead cells
3.
the basal layer (under corneal) replaces corneal layer cells (these are the ones that
produce melanin)
Dermis is the inner layer and composed of living cells and the structures listed in IV
1.
is the chief layer, 30-40 times thicker than the epidermis
2.
has tiny muscles attached to each hair
3.
provides insulation and nourishment to living cells
4.
helps regulate body temperature
Subcutaneous layer (not mentioned in text book)
1.
very fatty
2.
provides for shock absorption, insulation, protection in cooperation with dermis
Nails and hair
1.
nails protect the ends of fingers and toes
2.
form from nail roots under skin folds at their bases and sides
3.
as new cells form, nails grow longer (become keratinized)
a.
grows approx.. 1 mm per week
b.
rest on a bed of tissues filled with blood vessels, giving them a pinkish
color
c.
color may be an indicator of disease somewhere in the body
i.
may turn yellow in people with chronic respiratory disorders, or
just a fungal infection
ii.
may turn concave in persons with certain blood disorders
4.
F.
G.
hair insulates and protects the body
a.
produced by a cluster of cells at the base of dermal pits called hair
follicles
b.
the “shaft” extends beyond the skin and is composed of dead, keratinfilled (keratinized) cells that overlap like roof shingles
c.
glands associated with the hair follicles secrete oils to prevent hair from
drying out and breaking off
d.
hair length is genetically determined; each hair has a programmed life
span, after which it falls out and is replaced by new hairs
e.
color is determined by the presence of the pigment melanin, just like skin
Glands
1.
skin contains exocrine glands (exporters) which release secretions through ducts
2.
sweat and oil glands are the main exocrine glands of the skin
a.
“sweat” is mostly water (about 99%), but contains salts and urea (a
component of urine), so it has an excretory function
b.
is the first line of defense for the immune system
c.
helps in thermoregulation (body temperature); sweat increases evaporation
when overheated
3.
oil glands are found in large numbers on the face and scalp
a.
secrete a fatty substance known as sebum
b.
are usually connected by tiny ducts to hahir follicles and coats the surface
of the skin and shafts of hair, preventing excess water loss, and
lubricating/softening skin and hair
c.
only mildly toxic to bacteria; many use it for a food source and incubation
area
d.
neither sebum or sweat actually cause body odor; it is the bacteria that
survive and colonize certain areas that produce the smell
e.
production of sebum is controlled by hormones, which is why teens often
suffer acne
i.
acne is actually very complex, and is an advanced bio topic
ii.
blackheads, pimples, cysts, etc., are rooted in inflamed, clogged or
irritated follicles
iii.
may be somewhat controlled through diet (processed carbs),
meticulous skin care, and sometimes, medication
Other skin disorders
1.
carcinoma is the most common type of skin cancer, originating in the nonpigment producing cells
a.
very high cure rate, if detected early
2.
malignant melanoma (about 1% of skin cancers)
a.
occurs in pigment-producing cells called melanocytes
b.
grows fast and spreads easily to other body parts (metastisis)
c.
low survival rate (usually because of metastasis)
d.
research shows that tanning beds increase the likelihood of skin cancer in
young people by 75%
e.
turns skin into “shoe leather” that you will regret when you are 50, and
still wish you were “beautiful”! You can’t undo it. Sorry! But hey, you
looked great at prom!
3.
Psoriasis
a.
genetic skin disorder that causes cells to reproduce at an extremely high
rate, causing cells to build up in scaly patches (but not in a cancerous way)
b.
may be controlled by new medications in some situations; genetics does
play some part in the tendency for acne, but not the acne itself