Unifying Concepts of Animal Structure and Function

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Chapter 20

• Unifying Concepts of Animal Structure and Function

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Structure and Function in Animal Tissues

• Structure fits function at all levels of
  organization in the animal body
• Anatomy is the study of structure.
• Physiology is the study of function.
• Animals consist of a hierarchy of levels or
  organization.
• Tissues are an integrated group of similar cells
  that perform a common function.
• Organs perform a specific task and consist of two
  or more tissues.
• Organ Systems consist of multiple organs that
  together perform a vital body function.

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TISSUES

• Tissues are groups of cells with a common
  structure and function-They are an integrated
  group of similar cells that perform a common
  function and combine to form organs.
• Animals have four main categories of tissues
• epithelial tissue,
• connective tissue,
• muscle tissue, and
• nervous tissue.

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Epithelial Tissue

• Epithelial tissue covers the body and lines its
  organs and cavities
• are sheets of closely packed cells that
• cover body surfaces and
• line internal organs and cavities.
• Epithelial cells come in three shapes
• squamouslike a fried egg,
• cuboidalas tall as they are wide, and
• columnartaller than they are wide.
• Epithelial tissues are named according to the
• number of cell layers they have and
• shape of the cells on their apical surface

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Connective Tissues

• Connective tissue can be grouped into six major
  types.
• Loose connective tissue
• is the most widespread,
• consists of ropelike collagen and elastic fibers
  that are strong and resilient, and
• helps to join skin to underlying tissues.
• Fibrous connective tissue
• has densely packed collagen fibers and
• forms tendons that attach muscle to bone.
• Adipose tissue stores fat in large, closely
  packed cells held in a matrix of fibers.

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Connective Tissues continued

• Cartilage is a strong and flexible skeletal
  material and commonly surrounds the ends of
  bones.
• Bone has a matrix of collagen fibers embedded in
  a hard mineral substance containing calcium,
  magnesium, and phosphate.
• Blood transports substances throughout the body.

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Muscle Tissue

• Muscle tissue functions in movement, it is the
  most abundant tissue in most animals.
• There are three types of vertebrate muscle
  tissue
• Skeletal muscle causes voluntary movements.
• Cardiac muscle pumps blood.
• Smooth muscle moves walls of internal organs,
  such as the intestines

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Nervous Tissue

• Nervous tissue forms a communication network
• senses stimuli and
• rapidly transmits information.
• Neurons carry signals by conducting electrical
  impulses. Other cells in nervous tissue
• insulate axons, nourish neurons, and regulate the
  fluid around neurons.

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Organs and Organ Systems

• Organs are made up of tissues. Each tissue
  performs specific functions.
• The heart has extensive muscle that generate
  contractions, epithelial tissues that line the
  heart chambers, connective tissues that make the
  heart elastic, and neurons which regulate
  contractions.
• The small intestine
• is lined by a columnar epithelium,
• includes connective tissues that contain blood
  vessels, and
• has two layers of smooth muscle that help propel
  food.
• The inner surface of the small intestine has many
  fingerlike projections that increase the surface
  area for absorption.
• The skin is the largest organ.

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Organ Systems

• Organ systems work together to perform lifes
  functions
• Each organ system typically consists of many
  organs,
• has one or more functions, and works with other
  organ systems to create a functional organism.
• The skeletal and muscular systems support and
  move the body.
• The digestive and respiratory systems obtain food
  and oxygen.
• The circulatory system transports these
  materials.
• The urinary system disposes of wastes.
• The integumentary system covers the body.
• The lymphatic and immune systems protect the body
  from infection.
• The nervous and endocrine systems control and
  coordinate body functions.
• The reproductive system produces offspring.

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New Imaging Technologies

• New imaging technology reveals the inner body
• New technologies are used in medical diagnosis
  and research and
• allow physicians to examine organ systems without
  surgery.
• X-rays help create images of hard structures such
  as bones and teeth.
• Magnetic resonance imaging (MRI)
• takes advantage of the behavior of the hydrogen
  atoms in water molecules and
• provides three-dimensional images of very small
  structures.
• A newer X-ray technology called computed
  tomography (CT)
• produces high-resolution images of cross sections
  of the body and
• can detect small differences between normal and
  abnormal tissues in many organs.
• Positron-emission tomography (PET) helps identify
  metabolic processes at specific body locations.
• CT and PET images can be combined for an even
  more informative image.

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Integumentary System

• The integumentary system protects the body
• The skin consists of two layers
• The epidermis
• is a stratified squamous epithelium and
• forms the surface of the skin.
• The dermis
• forms a deeper skin layer and
• is composed of dense connective tissue with many
  resilient elastic fibers and strong collagen
  fibers.
• The dermis contains hair follicles, oil and sweat
  glands, muscle cells, nerves, sensory receptors,
  and blood vessels.

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Skin

• Skin has many functions.
• The epidermis resists
• physical damage,
• decreases water loss, and
• prevents penetration by microbes.
• The dermis
• collects sensory information,
• synthesizes vitamin D, and
• helps regulate body temperature.
• Exposure of the skin to ultraviolet light
• causes skin cells to release melanin, which
  contributes to a visible tan, and
• damages DNA of skin cells and can lead to
• premature aging of the skin,
• cataracts, and skin cancers.

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Hair

• Hair is an important component of the
  integumentary system of mammals,
• helps to insulate their bodies, and consists of a
  shaft of keratin-filled dead cells.
• Oil glands release oils that are associated with
  hair follicles, lubricate hair,
• condition surrounding skin, and inhibit the
  growth of bacteria.
• Homeostasis is the active maintenance of a steady
  state within the body.
• External environmental conditions may fluctuate
  wildly.
• Homeostatic mechanisms regulate internal
  conditions.
• Control systems
• detect change and
• direct responses.
• Negative-feedback mechanisms
• keep internal variables steady and
• permit only small fluctuations around set points