Animal Tissues and Organ Systems

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Animal Tissues and Organ Systems

• Chapter 28

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Epithelial Tissue

• Lines the bodys surface, cavities, ducts, and
  tubes
• One free surface faces a body fluid or the
  environment

simple squamous epithelium
basement membrane
connective tissue
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Simple Epithelium

• Consists of a single layer of cells
• Lines body ducts, cavities, and tubes
• Cell shapes

Squamous
Cuboidal
Columnar
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Stratified Epithelium

• Two or more layers thick
• Functions in protection, as in skin
• Cells in the layers may be squamous, columnar, or
  cuboidal

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Glands

• Secretory organs that are derived from epithelium
• Exocrine glands secrete products onto free
  epithelial surface via ducts or tubes
• Endocrine glands are ductless and release
  hormones into the fluid that surrounds the gland

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Frog Epithelium
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Cell Junctions

• Tight junctions prevent leaks
• Gap junctions connect abutting cytoplasms
• Adhering junctions cement cells together

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Connective Tissue

• Most abundant tissue in the body
• Cells are scattered in an extracellular matrix
• Matrix is collagen and/or elastin fibers in a
  polysaccharide ground substance

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Soft Connective Tissues
Loose connective tissue
Dense, regular connective tissue
Dense, irregular connective tissue
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Specialized Connective Tissues
Cartilage
Bone
Adipose tissue
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Cartilage and Bone Tissue
cartilage on knobby end of a long bone

• Cartilage is a solid but pliable intercellular
  material
• Bone is a hardened connective tissue with living
  cells imprisoned in their mineralized secretions

compact bone tissue
spaces in spongy bone tissue
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Blood

• Classified as a connective tissue because blood
  cells arise in bone
• Serves as the bodys transport medium
• Red cells, white cells, and platelets are
  dispersed in a fluid medium called plasma

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Muscle Tissue

• Composed of cells that contract when stimulated
• Helps move the body and specific body parts

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Three Types of Muscle

• Skeletal muscle
• Cardiac muscle
• Smooth muscle

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Skeletal Muscle

• Located in muscles that attach to bones
• Long cylindrical cells are striated
• Cells are bundled closely together in parallel
  arrays

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Cardiac Muscle

• Present only in the heart
• Cells are striated and branching
• Ends of cells are joined by communication
  junctions that allow the cells to contract as a
  unit

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Smooth Muscle

• In walls of many internal organs and some blood
  vessels
• Cells are not striped and taper at the ends

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Nervous Tissue

• Detects stimuli, integrates information, and
  relays commands for response
• Consists of excitable neurons and supporting
  neuroglial cells

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Neurons

• Excitable cells
• When stimulated, an electrical impulse travels
  along the plasma membrane
• Arrival of the impulse at the neuron endings
  triggers events that stimulate or inhibit
  adjacent neurons or other cells

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Neuroglia

• Constitute more than half of the nervous tissue
• Protect and support the neurons, both
  structurally and metabolically

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Tissue Engineering

• Lab-grown epidermis for treating skin ulcers is
  one success
• In the works
• lab-grown bladder
• designer organs each type containing cells that
  synthesize hormones, enzymes, growth factors, or
  other substances patients cant make themselves

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Organs

• An organ is a group of tissues organized to
  perform a task or tasks
• Heart is an organ that pumps blood through body
• Heart consists of muscle tissue, nervous tissue,
  connective tissue, and epithelial tissue

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Tissue and Organ Forerunners

• Ectoderm
• Gives rise to the skins outer layer and to the
  nervous systems tissues
• Mesoderm
• Source of muscles, bones, and most of the
  circulatory, reproductive, and urinary systems
• Endoderm
• Gives rise to linings of the digestive tract and
  organs derived from it

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Organ Systems

• Organs interact physically, chemically, or both
  to perform a common task
• Circulatory system includes the heart, the
  arteries, and other vessels that transport blood
  through the body

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What Do Organ Systems Do?

• Maintain stable internal conditions
• Acquire nutrients and raw materials dispose of
  wastes
• Protect the body against injury and attack
• Allow reproduction and nourishment of young

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Major Organ Systems

• Circulatory
• Lymphatic
• Respiratory
• Urinary
• Reproductive
• Digestive

• Integumentary
• Muscular
• Skeletal
• Nervous
• Endocrine

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Major Body Cavities
cranial cavity
spinal cavity
thoracic cavity
abdominal cavity
pelvic cavity
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Planes of Symmetry 1
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Planes of Symmetry 2
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Organ System Human Skin

• Bodys largest organ
• Two layers
• Upper epidermis
• Lower dermis
• Lies atop a layer of hypodermis

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Epidermis

• Stratified epithelium
• Grows from bottom upward
• Most abundant cells are keratin-producing
  keratinocytes
• Melanocytes produce the brown pigment melanin

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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
  bodys first line of defense

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Dermis

• Dense connective tissue with many elastin and
  collagen fibers
• Includes blood vessels, lymph vessels, and
  receptor endings of sensory nerves

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Oil Glands

• Also called sebaceous glands
• Derived from epidermal cells
• Secretions lubricate and soften hair and skin
  also kill many surface bacteria
• Acne occurs when bacteria infect oil gland ducts

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Sweat Glands

• Arise from epidermal cells
• Composition of sweat
• 99 water, with dissolved salts, trace of ammonia
  (waste product)
• Controlled by sympathetic nerves

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Hair

• Root is embedded in skin
• Cells near the base of the root divide and push
  cells above them upward
• Hair follicles are nourished by the dermis
• As cells move upward away from the dermis they
  die
• Shaft of dead cells extends above the skin surface

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Hair Structure
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Keratin Reaction to Chemicals
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Functions of Human Skin

• Protects the body from injury, dehydration, UV
  radiation, and some pathogens
• Helps control temperature
• Receives some external stimuli
• Produces vitamin D

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Vitamin D

• Steroid-like compounds that help the body absorb
  calcium from food
• Produced in the skin from a precursor molecule
• Reaction requires sunlight
• In cooler climates, dietary vitamin D is required
  to supplement that produced by skin

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Sunlight Damages Skin

• UV light stimulates melanin production in skin
  produces a tan
• Tan is the bodys way of protecting itself
  against UV
• Prolonged sun exposure causes elastin fibers to
  clump, skin to age prematurely