Introduction to Body Structure:

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CHAPTER 37

• Introduction to Body Structure
• OVERVIEW, SKELETAL, MUSCULAR AND INTEGUMENTARY
  SYSTEMS

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Anatomy and Physiology

• Anatomy structure of an organism and its parts
• Physiology the study of what structures do and
  how they do it - function
• Levels of body structure
• Cell
• Tissue
• Organ
• Organ system

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Levels of Structural Organization

• Cells in the body are organized into four kinds
  of tissue
• Epithelial - line ,cover
• protect (from dehydration, physical damage)
• constantly being replaced as cells die
• ex. found in skin, linings and coverings of
  internal organs
• Connective binds, supports, protects
• few cells, widely spaced
• embedded in nonliving matrix
• ex. found in bone, fat, blood.

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Levels of Structural Organization

• Four kinds of tissue continued
• Nervous specialized cells (neurons) that
  receive and transmit messages throughout the body
  in the form of electrical impulses
• Muscle enable the movement of body structures
  by muscle contraction.
• Three types cardiac, skeletal, smooth

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There are 12 organ systems
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Body Cavities

• Many organs of the body are housed in
  compartments called body cavities.
• Cavities
• protect delicate organs from injuries
• permit organs to expand and contract while
  remaining securely supported
• .

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• Four Main Cavities
• Cranial encases the brain
• Spinal surrounds the spinal cord
• Thoracic upper in main trunk houses heart,
  esophagus, organs of respiratory system
• Abdominal lower in main trunk contains organs
  of digestive, excretory, reproductive systems

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Endothermy

• Like all mammals (and birds), human are
  endothermic.
• Endotherms maintain a constant internal body
  temperature.
• Much of the energy that is lost during the
  process of cellular respiration is given off as
  heat.
• Hypothermia and hyperthermia are dangerous to
  your survival.

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Skeletal System

• The Skeleton
• The axial skeleton (80 bones) is made up of the
  skull, spine and rib cage.
• The appendicular skeleton (126 bones) consists of
  the bones of the arms and legs and of the
  pectoral and pelvic girdles.

Pelvis
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Bone Structure

• Bones
• Provide a rigid framework against which muscles
  can pull
• Give shape and structure to body
• Support and protect internal organs
• About 18 of body weight

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Bone Structure

• Compact bone consists of concentric rings
  deposited around a Haversian canal.
• Spongy bone is porous and is partially filled
  with red bone marrow where blood cells are
  produced. Spongy bone - lightweight support

• Bones are made up of 4 major sections

• Yellow marrow - stores fat
• The outer membrane surrounding bones is called
  the periosteum which is filled with blood vessels

(Periosteum)
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Bones...

• Osteoblasts are young bone cells that produce
  collagen fibers on which calcium phosphate is
  deposited
• Osteoblasts are located around Haversian Canals
  which are hollow tubes running the length of the
  bone containing blood vessels
• Osteocytes are the mature osteoblasts that are
  now trapped within the bone.

Haversian Canal
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Bones

• The process in which cartilage slowly hardens
  into bone as a result of the deposition of
  minerals is called ossification.

Bone Cross-section

• During growth bones elongate in areas known as
  the epiphyseal plate.

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Osteoporosis

• Loss of bone density that causes bones to become
  brittle and break easily.
• Can be caused by lack of calcium.

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Joints

• Joints occur where bones meet three types
• Immovable joints - permit little or no movement
  ex. skull
• Slightly movable joints - permit limited movement
  ex. between vertebrae

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Joints

• 3. Freely movable joints - permit greatest
  degree of movement several types
• hinge - movement in 1 direction(plane) ex. knee,
  elbow, knuckles
• saddle - movement in 2 planes ex. thumb to hand
• gliding allow bones to slide over each other
  ex. wrist, ankles
• ball and socket - movement in many directions
  ex. shoulder
• pivot allows turning motion - head on vertebrae

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Joints (another look)
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Joints

• Ligaments hold the bones of a joint together.
• Synovial fluid helps lubricate the joint.
• Arthritis is a painful degeneration of movable
  joints caused by age (osteoarthritis) or
  auto-immune disease(rheumatoid arthritis).

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Muscular System

• A muscle is a tissue that can contract in a
  coordinated fashion.
• Muscles make up about 40 of body weight.

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Types of muscles

• Smooth - involuntary found in gut, circulatory,
  respiratory systems
• Skeletal - voluntary found attached to bones
• Cardiac - involuntary found only in heart

Smooth
Cardiac
Skeletal/striated
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Muscular Structure

• Skeletal muscles consist of bundles of individual
  fibers (cells) that contain bundles of smaller
  fibers called myofibrils.

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Muscular Contraction

• Muscles contract when myosin and actin filaments
  arranged in repeating units called sarcomeres
  slide together and shorten the sarcomeres along a
  myofibril.
• This is called the sliding filament theory.

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Muscular Contraction

• The contraction of individual muscle fibers is an
  all or none response. Different responses are
  the result of how often a muscle fiber is
  stimulated and how many fibers are involved.
• Exercise can increase the efficiency of muscles
  by increasing the bodys ability to supply oxygen
  to its muscle cells. It can also increase the
  size and strength of muscles.

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Muscular Movement of Bone

• Because muscles can only pull not push, skeletal
  muscles work together in antagonistic pairs to
  produce movement in two directions - extensor
  flexor.
• The point where a muscle attaches to a stationary
  bone is the origin the point attached to the
  moving bone is the insertion.

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Miscellaneous Muscle Info

• Tendons attach muscle to bone.
• Muscle fatigue is the inability of the muscle to
  contract it is caused by depletion of ATP.
• Oxygen debt caused by strenuous exercise can
  result in muscle fatigue.
• A sprain is a torn or overly stretched muscle,
  ligament or tendon.
• A muscle strain is caused by overusing a muscle.
• Anabolic steroids resemble male sex hormones and
  can increase the size and strength of muscles.

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Integumentary System

• Human skin, the largest organ of the body,
  consists of three layers
• epidermis - 10 -30 cells thick outer layer
• contains melanin (pigment) causes tanning
• produces hair and nails (keratin)
• dermis - 25-40x thicker than epidermis
• contains nerves, blood vessels, etc.
• exocrine glands- release secretions through ducts
  (ex. sweat and oil glands)
• subcutaneous layer - layer of fat-rich cells
• acts as shock absorber
• provides insulation
• stores energy and fat-soluble vitamins
• varies in thickness - none on eyelids thick on
  feet

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The Skin
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The Skin

• The skin and its specialized structures
• Help protect the body from disease
• unbroken skin is your best line of defense
  against infection.
• Help maintain the bodys temperature (sweat and
  redness) homeostasis
• goose bumps caused by contraction of
• dermis muscle
• Synthesize vitamin D (with small amounts of UV
  radiation).
• Contain sensory receptors (touch, pressure, etc.)

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The Skin

• Melanin pigmented protein
• Produced in bottom layer of epidermis
• Protects against UV radiation (tan)
• Too much UV radiation can lead to
• Premature aging of the skin
• Carcinomas and melanomas are skin cancers, which
  result from mutations in skin cells.
• Carcinomas are common and have a high cure rate.
• Melanomas are fast-growing and spread easily to
  other parts of body.
• Acne is a common skin condition that results from
  clogged oil ducts.

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Hair and Nails

• Hair
• Mainly on head in humans
• Insulates and helps protect against UV rays
• Eyebrows and lashes keep particles out of the
  eye
• Composed of keratin
• Formed in follicles deep in dermis layer where
  the keratin is deposited making hair grow
• Hollow shaft filled with pigment

Hair Shaft - l.s.
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Hair and Nails

• Nails
• Protects the ends of fingers toes
• Composed primarily of keratin
• Grow ( about 1 mm /wk) because they are pushed
  outward by living cells in the nail bed

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Thick Skin
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Thin skin with melanin