Download Protection, Support, and Movement

Protection, Support, and
Movement
Integumentary
• Function
A. outer covering of body
B. protects against injury, dehydration,
UV radiation and some pathogens
C. helps regulate body temperature
D. excretes certain wastes
E. receives external stimuli
F. Produces vitamin D
Evolutionary trends in integument with move to
land
A. keratinization of outer layer for protection
-keritinocytes –produce water resistant
protein keratin
-melanocytes – produce pigment, melanin,
as a barrier to UV radiation
B. recession of glands with ducts to surface
Human Skin
i. largest organ of your body
ii. see figure 37.3, p646
iii. stretches, conserves water, fixes small cuts and
bruises, helps regulate body temp and protects
against pathogens
Vertebrate Skin
• Two layers
– Upper epidermis
– Lower dermis
• Lies atop a layer
of hypodermis
Figure 37.3
Page 646
Layers
A. epidermis – stratified epithelial cells with an abundance
of cell junctions with no extracellular matrix
-continual mitosis pushes cells from deep layer to
surface
-outer layers are dead flattened cell that continuously
flake away
B. dermis – dense connective tissue
-stretch resistant elastin fibers
-supportive collagen fibers
-blood and lymph vessels, and sensory receptors thread
throughout it
C. hypodermis – below the skin
-anchors the skin
-loose connective tissue and adipose tissue to insulate
and cushion the skin
Skin coloration – combination of several pigments
i. melanocytes – brownish black
ii. hemoglobin – pink, found in red blood cells
(sometimes shows through the skin)
iii. carotene – yellow orange
Exocrine Glands – their ducts extend through the skin
i. types
a. mammary glands – produce milk
b. sweat glands
-sweat = 99% water with dissolved salts,
ammonia and vitamin C
-controlled by sympathetic nerves
-located on palms, soles, forehead and armpits
-decrease body temperature
c. oil glands
-not on palms or soles
-called sebaceous glands
-lubricates and softens hair and skin
-secretions kill many surface bacteria
-clogged and infected = acne
Hair
A. flexible, mostly keratinized (made of keratin protein) cells
B. cells divide near root, push upwards, flatten
and die
C. influenced by genes, nutrition and hormones
(growth and density)
D. root embedded in skin, shaft above its surface
Nails, Claws, Scales, Horns, Hooves and Beaks
A. made of keratin
-a fibrous protein
Langerhans Cells
• White blood cells that arise in bone
marrow, migrate to epidermis
• Engulf pathogens and alert immune
system
• UV radiation can damage these cells
and weaken body’s first line of defense
Granstein Cells
• Also occur in epidermis
• Interact with cells that carry out immune
response
• Issue suppressor signals that keep
immune response under control
• Less vulnerable to UV damage than
Langerhans cells
Skeletal System
• Function – human bone function table on page 652
A. Protects and supports the body and organs
B. interacts with skeletal muscles for movement
C. Produces red blood cells, white blood cells, and
platelets
D. provides muscle attachment sites
E. stores minerals (calcium and phosphorus)
• muscles require the presence of some structural
element to cause movement
• 3 types of animal skeletons
i. hydrostatic – muscles work against internal
body fluid and redistribute it: soft-bodied
invert’s such as annelids and sea anemones
ii. exoskeleton – rigid, external, receives the
applied muscle contraction: arthropods
iii. endoskeleton – internal, receives the
applied muscle contraction: vertebrates
SKULL
PECTORAL GIRDLES
AND UPPER EXTREMITIES
cranial bones
facial bones
RIB CAGE
sternum
ribs
clavicle
Human Skeletonscapula
VERTEBRAL COLUMN
vertebrae
intervertebral disks
humerus
ulna
radius
phalanges
carpals
metacarpals
PELVIC GIRDLE AND
LOWER EXTREMITIES
pelvic girdle
femur
patella
tibia
fibula
tarsals
metatarsals
phalanges
• organs consisting of connective tissue and epithelia
i. bone tissue consists of mature bone cells
(osteocytes) and collagen fibers in a calcium
hardened substance
• Long bone structure
i. compact bone – resists mechanical shock
ii. Haversian system – within compact bone, thin
cylindrical dense layers around canals for
blood vessels and nerves
iii. spongy bone – imparts strength but doesn’t
weigh much
iv. red marrow –blood cell formation, in some
bones
v. yellow marrow – fatty region, converts to red
marrow in times of severe blood loss
Long Bone
Structure
• Compact bone
• Spongy bone
• Central cavity
contains yellow
marrow
nutrient canal
contains yellow
marrow
compact bone tissue
spongy bone
tissue
Fig. 37.12 (1)
Page 652
Compact Bone Structure
• Mature compact bone consists of many
cylindrical Haversian systems
Haversian system
blood vessel
spongy bone tissue
compact bone tissue
outer layer of
dense connective
tissue
Fig. 37.12 (2)
Page 652
Bone Marrow
• Yellow marrow
– Fills the cavities of adult long bones
– Is largely fat
• Red marrow
– Occurs in spongy bone of some bones
– Produces blood cells
Joints
• Areas of contact or near contact between bones
• Fibrous joints
– Short connecting fibers join bones
– Ex. newborn skull
• Synovial joints
– Move freely; ligaments connect bones
– pivot, saddle, hinge, ball and socket
– See packet
• Cartilaginous joints
– Straps of cartilage allow slight movement
– Ex. Breastbone, ribs, vertebrae
Bone formation
i. bone forms around cartilage in embryos
a. osteoblasts (bone forming cells) secrete
organic substance that becomes mineralized
forming osteocytes and the cartilage then breaks
down leaving the marrow cavity
ii. bone remodeling
a. mineral ions and osteocytes are constantly
being removed and replaced
b. this adjusts bone strength and helps maintain
blood levels of calcium and phosphorus
c. osteoblasts deposit new bone, osteoclasts
digest (chemically breakdown) bone with
enzymes
d. free ions can then enter the interstitial fluid
and get absorbed by the bloodstream
Bone, Blood, and Calcium
i. bone and teeth store all but 1% of the bodies
calcium
ii. negative feedback of calcitonin and PTH help
regulate blood calcium levels
iii. calcitonin suppresses osteoclast activity (lowers
blood calcium levels)
iv. PTH enhances osteoclast activity (increases blood
calcium levels)
Common Disorders
• Osteoporosis is a decrease in bone
density
– May occur when the action of osteoclasts
outpaces that of osteoblasts
– May also occur as a result of inability to
absorb calcium
• Arthritis
– Inflammation of joints
Muscular System
I. Function
a. Movement
i. Limbs and trunk
ii. Substances through the body
- blood and food
b. maintains posture
c. structure and support
d. generates heat
I.
Structure
a.
3 types of muscle – see packet picture
i. skeletal –we will concentrate on this type
functional partners of bone
striated (striped)
voluntary
opposing groups (antagonistic,
against) or in pairs (helping)
muscle cells contract or lengthen
humans have over 600, we will
learn 10 (see packet diagram)
ii.
Smooth – internal organs
iii. Cardiac - heart
Skeletal Muscle
• Bundles of striped
muscle cells
• Attaches to bone
biceps
triceps
• Often works in
opposition
Figure 37.17
Page 654
triceps brachii
biceps brachii
Major Human Muscles
pectoralis major
deltoid
serratus anterior
external oblique
trapezius
latissimus dorsi
rectus abdominus
gluteus maximus
adductor longus
sartorius
biceps femoris
quadriceps femoris
gastrocnemius
tibialis anterior
Figure 37.18
Skeletal Muscle Structure
• A muscle is made
up of muscle cells
• A muscle fiber is a
single muscle cell
myofibril
• Each fiber contains
many myofibrils
Figure 37.19a
Page 656
Muscle Structure
• A muscle fiber is a single, multinucleated muscle cell
• A muscle could be made up of hundreds or even
thousands of muscle fibers
– Muscle fibers make up most of a muscle but connective
tissue, blood vessels, and nerves are also present
– Nerves stimulate the muscle
– Arteries supply oxygen and nutrients while veins carry away
metabolic wastes
– Connective tissue covers and supports each fiber as well as
the whole muscle
Muscle Fibers
• Fibers consist of bundles of threadlike structures
called myofibrils – made up of two protein filaments
– Myosin – thick filaments
– Actin – thin filaments
• Myosin and actin are arranged in overlapping
patterns that give the appearance of light and dark
bands (striations)
• Actin filaments are anchored at their midpoints to a
structure called a Z-line
• The region from one z-line to another is called a
sarcomere – functional unit of muscle contraction
Sarcomere
A myofibril is made up of thick and
thin filaments arranged in sarcomeres
sarcomere
sarcomere
Z line
sarcomere
sarcomere
Z line
Z line
Figure 37.19b
Page 656
Muscle Microfilaments
Actin - Thin filaments
• Like two strands of
pearls twisted
together
• Pearls are actin
• Other proteins in
grooves in filament
Myosin -Thick
filaments
• Composed of myosin
• Each myosin
molecule has tail and
a double head
Figure 37.19c
Page 656
a. each muscle cell has many myofibrils (looked striped when
stained) containing Z bands and sarcomeres
i. cardiac muscle also has these, that is why they are
called striated muscle
b. many sarcomeres contract simultaneously causing the
muscle to contract and move a bone
i. remember, this is the main purpose of skeletal muscle
sliding filament model – see page 657
i. actin fibers are attached to the Z –bands
ii. myosin fibers run parallel but between actin fibers
iii. myosin heads attach to nearby actin filaments creating a
cross bridge
iv. myosin heads tilt toward sarcomeres center causing the
actin filaments to slide with them and shorten the sarcomere
myosin head releases moves back and regrips the actin filament to
move again
Sliding-Filament Model
• Myosin heads
attach to actin
filaments
• Myosin heads tilt
toward sarcomere
center, pulling
actin with them
Fig. 37.20c-g
Page 657
Sliding-Filament Model
Sarcomere shortens because the actin
filaments are pulled inward, toward the
sarcomere center
Fig. 37.20a,b
Page 657
Muscle Contraction
• Sliding filament theory
– Myosin and Actin filaments interact to shorten the sarcomere
– Knob like projections on myosin form cross-bridges with actin
filaments
– When the muscle is stimulated, the filaments move across each
other
Contraction Cont.
• When the cross-bridge has moved as far as it can, it
is released and the actin filament returns to its
original position; the cross-bridge attaches at another
point and the cycle is repeated
• The synchronized shortening of sarcomeres causes
the entire fiber to contract and thus the muscle
shortens
• ATP is required to attach and detach myosin heads
from actin
• Without ATP, the filaments would not be able to
contract or relax – rigor mortis
Control of Muscle Contraction
•
Motor neurons connect to muscles at points called
neuromuscular junctions
1.
2.
3.
4.
When an action potential reaches the axon terminal, the
neurotransmitter acetylcholine diffuse across the synapse
and initiate an impulse in the muscle cell
Impulse causes the release of calcium ions in the cell
Calcium ions affect proteins that regulate the interaction of
Actin and Myosin filaments
An enzyme, acetylcholinesterase, destroys acetylcholine
to stop the impulse
Nervous System
Controls Contraction
• Signals from nervous
system travel along
spinal cord, down a
motor neuron
• Endings of motor
neuron synapse on a
muscle cell at a
neuromuscular junction
-Motor neurons stimulate or inhibit contractions
with an action potential
-Muscle cells have a specialized structure
called the sarcoplasmic reticulum that stores and
releases calcium
-When an action potential reaches a muscle cell it
travels down the membrane (sarcolemma) and
into a T-tubule that carries the action potential
inside. This triggers the release of calcium ions
from the sarcoplasmic reticulum to the actin
filaments
-The calcium clears the binding site for the cross
bridge so sarcomere contraction can occur
i.
2 proteins are involved in this action
- tropomyosin, blocks the binding site
-
tropomyosin is bound to the troponin
- troponin binds the free calcium and
changes its shape, this causes the
tropomyosin to move - the binding site is
therefore unblocked
ii. After the contraction, the calcium is
transported back into the sarcoplasmic reticulum
for storage
Contraction Requires Energy
• Muscle cells require huge amounts of
ATP energy to power contraction
• The cells have only a very small store of
ATP
• Three pathways supply ATP to power
muscle contraction
i.
Phosphorylation
- quick reaction that transfers phosphate from creatine phosphate to
ADP, creating ATP
- this gives the cell time to perform cellular respiration (aerobic) to
further supply ATP
ii.
Cellular respiration
- aerobic
- produces lots of ATP but takes time
- phosphorylation gives the cell time to do this
iii.
Glycolysis
- anaerobic respiration
- may kick in if needed (when not enough oxygen for aerobic respiration)
- produces less ATP, but allows processes to continue
ATP for Contraction
ADP + Pi
Pathway 1
relaxation
Dephosphorylation
Creatine Phosphate
contraction
creatine
Pathway 2
Aerobic
Respiration
oxygen
Pathway 3
Glycolysis
Alone
glucose from bloodstream and
from glycogen break down in
cells
Figure 37.23
Page 659
Motor Unit
• One neuron and all the muscle cells that
form junctions with its endings
• When a motor neuron is stimulated, all
the muscle cells it supplies are activated
to contract simultaneously
• Each muscle consists of many motor
units
- tetanus is a sustained contraction resulting from repeated
stimulation
i.
also the name of a disease that disrupts muscle
relaxation
- muscle fatigue
i.
decline in a muscles capacity to generate force
ii.
decline in tension
iii.
after a time of rest, fatigues muscles can contract
again
a. the time depends on the amount of fatigue
iv. the molecular mechanism of fatigue is not known
-- cramps
i.
involuntary, large, often painful contractions
ii.
can persist for up to 15 minutes or more
iii.
can be caused by fatigue
- muscular dystrophies
i. genetic disorders where muscles progressively weaken
and degenerate
- muscles, exercise, and aging
i.
with regular use, muscle cells increase in size and
metabolic activity
a.
ii.
become more resistant to fatigue
muscle tension declines in adults (after age 30 or 40)
a.
regular exercise may help