Integumentary Systems

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Integumentary Systems

• Structure Functions of Integumentary System
• Integumentary system consists of layers of the
  four types of body tissues
• 1) epithelial tissue - outer layer of skin
• 2) connective tissue - tough flexible protein
  fibers that act to hold body together
• 3) muscle tissue - interact w/ hairs on skin
  respond to stimuli like cold and fright
• 4) nervous tissue - detects external stimuli like
  pain and pressure (Chapter 19)

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Skin The Bodys Protection

• Main organ in integumentary system is the skin,
  which makes it the largest organ in the body
  since it is 12-15 of body weight!
• Made of two layers
• Epidermis outer layer of skin
• Dermis inner layer of skin

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Layers of Skin
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Epidermis

• Outermost layer of skin made of 2 parts
  exterior and interior portions
• Exterior 25-30 layers of dead, flattened cells
  that are continually being shed
• Even though dead, are important since contain
  keratin which helps protect living cells
  underneath

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Epidermis

• Interior living cells that continually divide to
  replace dead cells
• Contain pigment melanin that colors skin and
  protects it from damage by solar radiation
• Melanin is not sole protector for sun damage
  can get skin cancer if are dark pigmented!
• process of shedding takes 28 days (4 weeks)

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Dermis

• Inner, thicker portion of skin
• Contains many structures
• Blood vessels (arteries veins)
• Nerves nerve endings
• Hair follicles
• Sweat glands
• Sebaceous (oil) glands
• Muscles (to make hair stand up)

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Subcutaneous Layer

• Beneath dermis is subcutaneous layer
• Made of fat and connective tissue
• Help body absorb impacts, retain heat, store food

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Functions of Skin

• 1. Maintains homeostasis
• Regulates internal body temperature
• When temperature rises, small blood vessels in
  dermis dilate (increase in circumference),
  allowing blood flow to increase, so blood loses
  heat
• When temperature lowers, blood vessels constrict
  (decrease in circumference), decreasing blood
  flow, so blood keeps in heat

Feedback loop Backward/forward
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Feedback (Homeostasis) Loop
Internal Body Temperature Changes
Blood vessels dilate
Blood vessels constrict
Blood flow increases
Blood flow decreases
Blood loses heat
Blood keeps in heat
Internal Body Temperature Normalizes
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• 2. sensory organ
• Nerve cells get information from external
  environment about pain, pressure, and temperature
  and send message to brain
• 3. produces Vitamin D
• When exposed to UV light, skin makes Vitamin D,
  which is essential to help body absorb calcium
• Most calcium supplements contain Vitamin D for
  that same reason
• 4. protective layer
• Shields underlying tissues from physical and
  chemical damage and from invading pathogens
  (viruses and bacteria)

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Skin injury and Healing

• Injuries to skin can occur due to scrapes, cuts,
  or burns, but how skin heals depends on severity
• Mild scrape (no blood, epidermis only)
• Deepest layer of affected epidermal cells start
  to divide to fill in gap left by abrasion
• Cut (blood, epidermis and dermis)
• Blood flows out of wound until clot forms
• Scab develops, creating barrier between bacteria
  on skin and underlying tissues

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Skin injury and Healing

• Bacteria already present in wound gets killed by
  white blood cells that migrate to site
• New skin cells begin repairing wound from beneath
• Scab falls off when new skin is formed
• Large wound needs high amount of connective
  tissue which may form a scar

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Healing of a Cut
Before
Cut in skin
Blood pools, creating scab
Skin cells regenerate from bottom up
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Skin Burns

• Burn (Sun, chemicals, hot objects)
• First degree (mild sunburn)
• Death of epidermal cells
• Redness and mild pain
• Heal in 1 week w/out scar
• Second degree
• Damage of both epidermal and dermal cells
• Blistering and scaring may occur

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Skin Burns

• Burn (sun, chemicals, hot objects)
• Third degree
• Destruction of both epidermal and dermal cells
• Skin function is lost, so skin grafts are
  required
• Fourth degree
• Destruction through skin and into muscles,
  tendons, ligaments, and bone

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Bones The Bodys Support

• Skeletal System Structure
• Adult human skeleton contains 206 bones! Made of
  two main parts
• Axial skeleton skull and bones that support it
  like vertebral column, ribs, sternum
• Appendicular skeleton bones of arms and legs
  (appendages), and all structures associated with
  them (shoulder, hips, wrists, ankles, fingers,
  toes)

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Axial vs. Appendicular Skeleton
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Skeletal joints

• Bones meet other bones at areas called joints
• Joints facilitate movement of bones in relation
  to one another
• Joints can be fixed (non-moveable) or non-fixed
  (moveable)
• Fixed joints skull

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Skeletal joints

• Non-fixed joints knee, wrist, etc.
• - 4 types of moveable joints
• Ball-and-socket hips, shoulders
• Pivot twisting arm at elbow
• Hinge elbows, knees, fingers, toes
• Gliding wrists, ankles

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Types of Joints Found in Human
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Types of Joints Found in Human
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Ligaments

• Joints are held together by ligaments
• Ligament tough band of connective tissue that
  attaches one bone to another
• Joints with a large range of motion (knee) have
  many ligaments

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Cartilage

• Ends of bones are covered in cartilage
• Allows for smooth movement between bone ends
• Cushions joints

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Bursae

• Certain joints have fluid-filled sacs called
  bursae (bursa is singular)
• Outside of joint between tendon and bone to
  reduce friction

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Tendons

• Muscles are attached to bones with tendons
• Tendons are thick bands of connective tissue

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JOINTS
TENDON
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Types of Bone

• Two types of bone tissue
• Compact bone and spongy bone
• Compact bone hardened bone that contains tubular
  structures called osteons (or Haversian systems)
• Surrounds spongy bone to protect it
• Spongy (cancellous) bone less dense bone with
  many holes and spaces
• Living bone cells are called osteocytes, which
  receive oxygen and nutrients from small blood
  vessels

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Types of Bone
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Formation of Bone

• Skeleton of human embryo is actually made of
  cartilage, not bone (same as what nose is made
  of)
• Not until embryo is 9 weeks does cartilage get
  replaced by bone
• When blood vessels penetrate cartilage membrane,
  stimulate it to become osteoblasts (precursors to
  osteocytes)

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Bone
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Human skeleton growth

• Human skeleton is almost 100 bone, with
  cartilage found only in places where flexibility
  is needed nose, ears, vertebral disks, and
  joint linings
• Bone grows in length and diameter as result of
  sex hormones released during growth
• Length from cartilage plates at ends of bones
• Diameter from outer surface of bone
• After growth stops, bone-forming cells are
  involved in repair and maintenance

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Skeletal System Functions

• Function of skeleton is five-fold
• 1. Provide framework for tissues of body
• Allows muscles to attach to bones so they can
  provide movement to body
• 2. Protects internal organs
• 3. Produce blood cells
• Red marrow where red blood cells, white blood
  cells, blood clotting factors are produced
• found in humerus, femur, sternum, ribs,
  vertebrae, pelvis

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Skeletal System Functions

• Function of skeleton is five-fold
• 4. Store fat
• Yellow marrow many other bones store fat in here
• 5. Mineral storage
• Bodys supply of calcium and phosphorous is
  stored in bone

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Skeletal injury disease

• Skeleton is vulnerable to injury and disease
• Broken bones
• Too much force against bone can cause it to break
  or fracture
• Physician must set bone back in place so new
  osteocytes may form in broken area and put two
  ends back together

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Skeletal injury disease

• Skeleton is vulnerable to injury and disease
• Osteoporosis
• Loss of bone volume and mineral content which
  leads to bones becoming more porous and brittle
  and more susceptible for breakage
• More common in older women since they produce
  lower amounts or estrogen which aids in bone
  formation

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Bone Fracture Types
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Bone Fracture Types
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Osteoarthritis

• Joints can become diseased
• Arthritis inflammation of the joints
• Bone spurs are outgrowths of bone inside the
  joints so it limits mobility

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Muscle

• Muscles
• Nearly half of body mass is muscle!
• Muscle groups of fibers, or cells, bound
  together. Almost all muscle fibers have been
  present since birth
• 3 main types of muscle
• Smooth muscle walls of internal organs and blood
  vessels
• Cardiac muscle heart muscle
• Skeletal muscle muscles attached to bones

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Muscle Types
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Muscle Types
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Smooth Muscle

• Made up of sheets of cells that form a lining for
  organs
• Most common function is to squeeze via
  contractions, exerting pressure on space inside
  tube or organ to move material inside it
• Ex food bolus gets squeezed through digestive
  system until it comes out semen gets squeezed
  through vas deferens, then urethra

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Movement of Smooth Muscle
Smooth muscle of vessel or organ
Contractions are involuntary (cant be controlled
by human) so smooth muscle is considered to be an
involuntary muscle
Direction of movement
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Cardiac Muscle

• Found in heart and is adapted to generate and
  conduct electrical impulses!
• Considered an involuntary muscle

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Skeletal Muscle

• Muscle that is attached to and moves bones
• Makes up majority of muscles in body which work
  in opposing pairs
• Muscle X on one side of bone, Muscle Y on other
  side of bone
• If Muscle X is contracted, Muscle Y is relaxed,
  and vice versa
• Considered a voluntary muscle since contractions
  can be controlled
• How do we contract our muscles?

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Opposing Muscle Pairs
Muscle Contracted
Muscle Relaxed
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Muscle Names
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Skeletal Muscle Contraction

• All muscle tissue is made of muscle fibers, which
  are very long, fused muscle cells
• Each fiber is made of smaller units called
  myofibrils
• Myofibrils made of thick and thin filaments
• Thick filaments myosin
• Thin filaments actin
• Myofibril can be divided into segments called
  sarcomeres

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Muscle Contraction
Relaxed Sarcomere
Z Disc
Actin
Myosin

• How do muscles contract? How do they know that
  you want to make a muscle?
• Sliding Filament Theory

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Sliding Filament Theory

• Sliding filament theory when signaled, actin
  filaments within each sarcomeres slide toward one
  another, shortening sarcomeres in a fiber and
  causing muscle to contract
• Myosin fibers do NOT move
• When skeletal muscle receives a signal (via
  brain), calcium is released inside muscle fibers,
  causing two sides of sarcomere to slide toward
  each other contraction
• When signal is gone, calcium gets absorbed,
  sarcomeres relax and slide away back into place

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Sliding Filament Theory
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Black Z disk
Yellow actin (thin)
Pink myosin (thick)
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Muscle Strength and Exercise

• Muscle strength does not depend on amount of
  fibers but does depend on thickness of fibers
• You are born with the number of fibers you will
  always have, but exercise can increase thickness
  of each fiber making entire muscle bigger
• Exercise stresses muscle fibers slightly, so to
  compensate for workload, fibers increase in
  diameter by adding myofibrils

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Muscle Strength and Exercise

• Energy that muscles need to contract comes from
  ATP produced by cellular respiration (aerobic and
  anaerobic processes)
• Most energy comes from aerobic respiration when
  oxygen (from breathing) is delivered to muscle
  cells during rest or MODERATE activity

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Muscle Strength and Exercise

• During VIGOROUS activity (when we have tendency
  to hold our breaths delivery of oxygen is not
  as fast as it needs to be), anaerobic respiration
  kicks in and in addition to ATP being made,
  lactic acid fermentation makes lactic acid which
  makes muscles cramp up
• Lactic acid build up gets sent into bloodstream,
  where triggers rapid breathing (panting!)
• Inhalation of oxygen again breaks down lactic
  acid cramps go away