Bones, Muscles, Blood
• Skeletal System is
made up of bones,
the ligaments that
bind bones together,
and cartilage
• Bones are the hard
elements of the
skeleton whose
function is to:
1. Support the muscles
& soft organs
2. Interact with muscles
3. Protect delicate
internal organs
4. Contain bloodproducing cells
5. Store minerals like
calcium & phosphate
• Parts of a long bone are the shaft (diaphysis) and ends (epiphyses)
• Compact bone makes up the periphery, spongy bone internally, and the
cavity is filled with yellow bone marrow (fat), except for a few places of red
marrow- the hip, sternum, ribs, skull, and epiphyses of the humerus &
fumur (produces RBC’s & WBC’s & platelets)
• Spongy bone (trabecular) is in the epiphyses & extends from compact bone
into marrow
• Bone is covered with a periosteum membrane, epiphyses covered with
cartilage
• Bone is hard because of extracellular calcium phosphate,
which surrounds osteocyte cells
• The cells are in spaces called lacunae that are arranged in
osteons (Haversian system) surrounding a central canal that
carries blood vessels, canaliculi connect them
• Ligaments attach bone to bone, and are made of
dense fibrous connective tissue with collagen
• Cartilage has strands
of collagen, and is
smooth & flexible
• Fibrocartilage has
bundles of collagen,
and make up the
intervertebral disks &
menisci of knee
• Hyaline cartilage has
a glassy appearance,
is found at
articulations, & forms
the embryonic
models of bone
• Elastic cartilage is
most flexible and
found in the ear &
epiglottis
• Embryos have hyaline cartilage with chondroblasts surrounded by
perichondrium, instead of bone, for most of their skeleton
• The perichondrium eventually forms a bony collar
• The cartilage inside the bony collar dies - nutrients can’t diffuse
through bone – and then becomes calcified
• Blood vessels invade the calcified cartilage, osteoblasts enter &
secrete osteoid proteins and enzymes that help with the
crystallization of extracellular calcium phosphate salts - forming
hydroxyapatite
• Grow in
length occurs
at the growth
plate, which is
stimulated by
growth
hormone
• Growth stops
when sex
hormone
levels rise
• Ages 18 –
females and
21 – males
• Osteoclasts remodel bone by dissolving hydroxyapatite
& digesting osteoid, releasing calcium & phosphate ions
into the blood
• Shapes of bone change in response to mechanical
forces – weight bearing exercises increase overall bone
mass & strength
• Osteoporosis –
bones lose mass
to release
calcium to
maintain body
levels of calcium
• If there is low
body calcium
levels,
parathyroid
hormone
stimulates
osteoclasts to
digest bone, with
high levels,
calcitonin
stimulates
osteoblasts to
make bone
• 10 million
Americans
have
osteoporosis
• 1.5 million
fractures/year
• Contributing
factors include
low calcium
levels,
estrogen
decline,
smoking,
sedentary
lifestyle,
underweight
• Steps in healing a
fracture –
• A hematoma
(blood clot) forms
within hours, then
a fibrocartilage
callus fills in the
space within days,
and is replaced by
a bony callus
within months,
remodeled bone
resembles prefracture status
after a year
• Bone
classification
is by shape:
• Long bones
• Short bones
• Flat bones
• Irregular
bones
• 206 bones in
human body
are divided
into the axial
&
appendicular
skeletons
• Skull has 2
categories:
• Cranial bones
surround the
brain: frontal,
parietal,
temporal,
sphenoid,
ethmoid,
occipital bone
• Facial bones:
maxilla,
palatine,
vomer,
zygomatic,
nasal, lacrimal
bones
• Mandible – the
chin, hyoid bone
– at top of neck
• Sinuses make
the skull lighter,
and develop
shortly before
and after birth
as invaginations
from the nasal
cavities
• The vertebral
column supports
the head, protects
the spinal cord,
attaches limbs
• 33 vertebrae bones
with spinous
processes
• 7 cervical
• 12 thoracic
• 5 lumbar
• 5 fused sacrum
• 4 fused coccyx
• Intervertebral disks
• 12 pair ribs
• sternum
• The pectoral
girdle (scapula
and clavicle)
attaches the
upper
extremity to
the axial
skeleton
• Humerus arm
• Radius, Ulna forearm
• 8 Carpals wrist
• Hand has 5
Metacarpals &
14 Phalanges
• The pelvic girdle
attaches the lower
extremity to the axial
skeleton, made up of
the coxal bones:
• Iliac crest
• Ischial tuberosity
• Pubic symphysis
• Femur – thigh bone
• Tibia & Fibula are the
leg bones
• 7 tarsals at the ankle
• Foot has 5
metatarsals & 14
phalanges
• Joints connect
bones to each
other and are
tabilized by
ligaments &
tendons
• Fibrous joints –
immovable (skull
sutures)
• Cartilagenous
joints – slightly
movable –
intervertebral
disks
• Synovial joints –
freely movable
and lined with a
synovial
membrane
• Examples of hinge joints
are the knee & elbow
• Knee: fibrocartilage
menisci deepen the joint
on the tibia, cruciate
ligaments cross inside the
joint between the tibia
and fibula, and collateral
ligaments hold it together
on the sides
• Examples of ball
and socket joints
are hip, shoulder
• Tendons are what
attach muscles to
bones
• A sprain is a partial
tear to a ligament or
tendon
• Bursitis is
inflammation of a
bursa that protects a
tendon
• Tendinitis is
inflammation of a
tendon
• Arthritis is
inflammation of a
joint – osteoarthritis
is loss of cartilage at
the joint
• Muscles make
up:
• 40% of body
weight males
• 32% of body
weight in
females
• Includes
skeletal,
cardiac, and
smooth muscle
cells
• Muscles
produce or
resist
movement,
maintain
blood
pressure,
generate
heat
• Muscles
cells are
excitable
and can
contract &
relax
• Skeletal muscles interact
with skeleton & cause
bones to move
• >600 skeletal muscles
• Work together as
synergistic & antagonist
groups – one side
contracts while the
opposite side relaxes
• Attach to bones by
tendons
• Muscles consist of groups of multinucleated muscle cells (fibers)
and bundles of fibers are called fascicles, enclosed in fascia sheath
• Fibers contain sarcomeres – segments between Z lines that attach
actin microfilaments
• Myosin & actin microfilaments – made of protein – interact to
cause muscle contraction
• Motor neurons stimulate muscle contraction by releasing
acetylcholine (ACh) at the neuromuscular junction
• ACh causes the membrane (sarcolemma), including indents
called t-tubules, to depolarize, allowing an influx of sodium
ions, which causes the release of calcium ions from the
sarcoplasmic reticulum terminal cisternae
• Calcium ions allow myosin to contact the myosin binding site on
actin, form crossbridges, split ATP, and swing, grab the next
binding site, repeat; like pulling a rope - the ‘sliding filament’
mechanism
• Troponin is attached to tropomyosin that wraps
around the actin & hides the myosin binding site
• Binding splits ATP bound on
myosin into ADP & P, which
then falls off the myosin so
another can take its place
• Muscles store enough ATP for
10 seconds of activity
• Creatine phosphate is a
molecule that attaches
phosphate to ADP for 30 - 40
more seconds of activity
• Muscles need stored glycogen
for a quick source of glucose
(anaerobic – 2 ATP, forming
lactic acid)
• Aerobic respiration takes place
in mitochondria, requires
oxygen, and oxygen debt
occurs from build-up of lactic
acid before aerobic kicks in
• Muscles will store more
glycogen, develop more
mitochondria and capillaries to
bring oxygen, if they are active
all the time
• Fatigue - from lack of ATP
• Isotonic contractions – muscle shortens while
maintaining a constant force
• Isometric contraction – force is generated & muscle
tension increases but bones do not move
• Motor neurons
stimulate muscles by
releasing ACh
• A motor unit consists of
all the muscle cells that
a neuron stimulates - an
all or none situation
• One action potential
cause a muscle twitch
• Muscle tone is produced
by an intermediate level
of force, causing some
fibers to contract
• Increasing force recruits
more motor units
• After stimulation and contraction there is a latent
period where the membrane repolarizes and calcium
transports back
• Additional stimuli cause greater force
• An increase of force by an increase of rate of
stimulation is called summation
• Too much summation with no relaxation is tetanus –
sustained contraction – that leads to fatigue
• Rigor mortis – myosin can not unlock from actin
• Slow twitch muscles contract slowly, use aerobic
metabolism – have many mitochondria & blood vessels,
little glycogen, store oxygen in myoglobin – body
posture
• Fast twitch muscles contract more quickly, have fewer
mitochondria, store glycogen, need creatine phosphate
& anaerobic metabolism, are unable to sustain long
contractions (but can use aerobic mechanism too) –
used for quick movements
• Strength
training builds
more
myofibrils,
glycogen and
creatine
phosphate
storage
capacity
• Aerobic
training increase
capillaries,
mitochondria,
myoglobin
• Involuntary muscle types:
• Cardiac – connected by intercalated discs, rhythm
set by pacemaker cells – make up the heart
• Smooth muscles – joined by gap junctions – make
up walls of the guts and blood vessels
• Myasthenia gravis –
destroys
acetylcholine
receptors on skeletal
muscle cells
• Muscular dystrophy –
abnormal dystrophin
protein allows
calcium to leak into
muscle cells
• Tetanus – bacterial
toxin overstimulates
the nerves controlling
muscle activity,
especially jaw & neck
muscles, causing
sustained contraction
• Muscles of the
Body
• Facial expression:
frontalis,
zygomaticus
major, orbicularis
oris, orbicularis
oculi, depressor
anguli oris
• Back: trapezius,
latissimus dorsi,
erector spinae
• Chest and
abdomen:
pectoralis major,
serratus anterior,
external oblique,
rectus abdominus
• Upper extremity:
deltoid, biceps
brachii, triceps
brachii,
brachioradialis
• Lower extremity: gluteus maximus, sartorius,
quadriceps, tibialis anterior, hamstrings,
gastrocnemius
• The circulatory
system is made up of
the heart, blood
vessels & blood
• Supplies cells with
nutrients from
digestive system and
removes wastes with
urinary system
• Exchange of gases
with interaction with
the respiratory
system
• Blood is classified as a connective tissue with cells in a watery
extracellular matrix, functions include:
• Transportation of all substances needed by the body –
oxygen, nutrients, hormones, wastes
• Regulation of body temperature, volume, and pH
• Has defense cells to protect against infection & the ability to
clot to prevent blood loss
• Humans have 4-6
liters of blood –
approximately a
gallon
• Blood has red blood
cells, white blood
cells & platelets
• Plasma makes up 55%
of the volume of
blood and contains
water, ions, proteins,
hormones, gases,
nutrients, wastes
• Plasma proteins
include albumin,
globulins, clotting
proteins
• Electrolytes (ions) are
sodium, potassium,
chloride, bicarbonate,
calcium, hydrogen,
magnesium
• Hormones, nutrients
are transported in
blood
• Wastes include
carbon dioxide, urea,
lactic acid
• Red blood cells have
no nuclei, a biconcave
disc shape, and
transport oxygen
• One cubic millimeter
of blood has ~ 5
million RBC’s and each
cells had ~ 300 million
hemoglobin
molecules/cell
• Globulins have heme
groups with iron
atoms that bind
oxygen, 4/molecule
• RBC’s have no
mitochondria, rely on
glycolysis for energy,
and make carbonic
anhydrase to
transport most of the
carbon dioxide
• A hematocrit
measures the
amount of cells
• Stem cells in red
bone marrow
produce RBC’s, and
are called
normoblasts (or
erythroblasts)
• RBC’s live only 120
days and old ones
get removed by
liver & spleen cells
called
macrophages
• Bilirubin pigment
from hemoglobin
gets secreted into
bile and is taken up
in urine, causing
dark brown or
yellow coloration
• A hormone called erythropoietin which is secreted
by the kidney stimulates RBC production
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There are far fewer white blood cells – 7,000/cubic millimeter – which are classified as
granular or agranular types, also made in red bone marrow
Neutrophils – 60% - function in infection
Eosinopils – 2% - fight parasites, engulf immune complexes, moderate allergic reactions
Basophils – 1%, granules initiate inflammatory response
Monocytes – 5% - become macrophages in tissue
Lymphocytes – 30% - function in immune response
• Platelets are known as
‘formed elements’,
break off of large bone
marrow cells called
megakaryocytes –
250,000/cubic
millimeter of blood
• Function in hemostasis
• Steps in blood clotting
after initial injury:
vascular spasm,
formation of platelet
plug, coagulation
• Vascular spasm happens within ½ hour – a platelet plug forms
when platelets adhere to exposed vessel wall collagen & von
Willebrand factor, damaged cells cause release of
prothrombin activator, a reaction that requires calcium
• Formation of thrombin from plasma proteins converts
fibrinogen into fibrin that weaves around and secures the
platelet plug
• Hemophilia is
caused by a
deficiency of
clotting factors
• Hemophilia A
is X-linked, so
boys are more
prone to
inheriting it –
lack of factor
VIII
• Blood types - blood antigens are inherited equally
from parents & antibodies are produced to protect
against wrong blood types – include A, B, O & Rh
factor
• Anemia is
defined as a
reduction in
blood’s oxygencarrying ability,
there are many
diffferent types:
iron deficiency,
hemorrhagic,
pernicious,
hemolytic, and
sickle cell anemia
• Leukemia is a
cancerous
overproduction of
one type of blood
cell
• Multiple myeloma is
the cancerous
overproduction of an
activated B
lymphocyte
• Mononucelosis –
infection of
lymphocytes with
Epstein-Barr virus
• Thrombocytopenia –
reduction in amount
of platelets
• The immune system protects the body from
pathogens like bacteria, viruses, fungi, protozoans,
prions, parasites, and involves white blood cells
• Bacteria are single celled prokaryotes (have no
nucleus) that decompose, make products like drugs,
hormones, vaccines, food, produce energy and
make vitamins in our digestive tract, live on our skin
& mucous membranes, but can cause infections
• VIRUSES – TINY INFECTIOUS AGENTS, THAT CONSIST OF A SMALL
PIECE OF RNA OR DNA SURROUNDED BY A PROTEIN COAT
• ENTER CELLS AND INSERT GENETIC MATERIAL TO REPRODUCE
• Prions – infectious proteins like bovine spongiform
encephalopathy Creutzfeldt Jakob disease
• Prions convert normal brain cell protein
• Transmission and virulence determines disease
• The lymphatic
system defends
the body, returns
excess tissue fluid,
transports fats
• Lymph nodes
filter lymph
vessels and lymph
eventually enters
circulation at the
subclavian vein
• The spleen cleans
blood in its red
pulp and fights
infection with its
white pulp
• Thymus gland
produced T
lymphocytes
• Tonsils are
patches of lymph
tissue in the
throat
• The skin is a good barrier to infection and sweat has an antibiotic
& low pH
• Tears, saliva, cerumen also have lysozyme
• Vomiting, urination, defecation rid body of harmful wastes
• Resident bacteria on the skin and mucus membranes prevent
bacterial infections from other bacteria
• Inflammation can be
caused by infection or
damage and signs are
rubor, dolore, calore,
tumor, stupor, discharge
• Injured cells release
chemicals that cause
mast cell histamine
release that causes
vasodilation and attracts
neutrophils, monocytes &
macrophages,
lymphocytes & natural
killer cells
• Activation of
complement, fever,
interferons to protect
neighboring cells
• Phagocytosis by neutrophils and macrophages
begins the cellular part of inflammation,
macrophages process what they engulf and split it
into different antigens
• The body’s
immune
response relies
on the major
histocompatibility complex,
which is a marker
on every cell
membrane
(except RBC’s)
that is unique for
each person
• Antigenpresenting cells
like macrophages
activate B & T
lymphocytes
designated for
that specific
antigen
• Antibodies
made by plasma
cells
(transformed B
lymphocytes)
are specific for
antigens
• IgG, IgM, igA,
IgD, IgE bind to
antigens
• After 1st
exposure –
measurable
after 14 days,
2nd exposure
causes
immediate
response
• Antigen
presenting
cells also
stimulate T
cell response
• Cytokine
proteins
activate cells
• Cytotoxic T
cells destroy
cells
• Immune memory - Primary response in 2 weeks
• Second response in a few hours - immunization – active & passive
• Monoclonal antibodies are used as drugs
• Type I allergic response – antibody known as IgE causes
histamine release from basophils and mast cells
• Type II & III
allergic
responses are
antibodymediated as
well
• Type IV – tissue
rejection,
poison ivy
response,
comes from T
cells
• Autoimmune
disorders
include
rheumatoid
arthritis,
lupus
erythematosus,
multiple
sclerosis,
grave’s
disease,
diabetes
mellitis type I
• HIV virus is specific for CD4 receptors- disables the T
helper lymphocytes - T helper count < 200/cubic
millimeter, allows an opportunistic infection or
cancer to take over the body