Animal Cells and Tissues

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Animal Cells and Tissues

• AP Biology

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Animal Cells and Tissues

• Four tissue types
• Epithelial
• Connective
• Muscle
• Nervous

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Cells, Tissues and Organs
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Epithelial Tissue

• Covers body surfaces and lines body cavities
• Three types
• Squamous epithelium comprised of flattened cells
• Cuboidal epithelium is made up of cube-shaped
  cells
• Columnar epithelium consists of elongated cells

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Squamous Epithelial Cells

• Squamous cells have the appearance of thin, flat
  plates
• Have horizontally flattened, elliptical nuclei
  because of the thin flattened form of the cell
• Form the lining of cavities such as the mouth,
  blood vessels, heart and lungs and make up the
  outer layers of the skin

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Squamous Epithelial Cells
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Squamous Epithelial Cells
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Cuboidal Epithelial Cells

• Cuboidal cells are roughly square or cuboidal in
  shape
• Each cell has a spherical nucleus in the center
• Found in glands and in the lining of the kidney
  tubules

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Cuboidal Epithelial Cells
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Cuboidal Epithelial Cells
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Columnar Epithelial Cells

• Cells are elongated and column-shaped
• Nuclei are elongated and are usually located near
  the base of the cells
• Columnar epithelium forms the lining of the
  stomach and intestines
• Some columnar cells are specialized for sensory
  reception such as in the nose, ears and the taste
  buds of the tongue

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Columnar Epithelial Cells
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Columnar Epithelial Cells
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Epithelial Tissue

• Simple epithelium made up of only one cell layer

• Stratified epithelium has more than a single
  layer of cells

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Simple (Squamous)
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Simple (Squamous)
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Stratified (Squamous)
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Functions of Epithelial Tissue

• Movement of materials into, out of, or around the
  body
• Protection of the internal environment against
  the external environment
• Secretion of a product

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Examples of Epithelial Tissues

• Glands
• Intestinal goblet cells (single epithelial cells)
• Endocrine glands (multicellular)
• Many animals have skin that is composed of
  epithelium
• Vertebrates have keratin in their epithelial
  cells to reduce water loss
• Many invertebrates secrete mucus or other
  materials from their skin (earthworms)

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Connective Tissue

• Serve many purposes in the body including
• Support
• Protection
• Binding
• Blood formation
• Fat storage
• Fill space

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Connective Tissue

• Cells are separated from one another by a
  non-cellular matrix
• This matrix may be
• Solid as in bone
• Soft as in loose connective tissue
• Liquid as in blood

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Types of Connective Tissue

• There are 3 main types of connective tissue
• Loose Connective Tissue
• Fibrous Connective Tissue
• Specialized Connective Tissues
• Adipose Tissue (Fat)
• Cartilage
• Bone
• Blood

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Loose Connective Tissue (LCT)

• Fibroblasts are separated by a collagen
  fiber-containing matrix
• Collagen provides elasticity and flexibility
• Occurs beneath epithelium in skin and many
  internal organs
• Forms a protective layer over muscle, nerves and
  blood vessels

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Fibrous Connective Tissue (FCT)

• Consists of many collagen fibers closely packed
  together
• Occurs in tendons, connecting muscle to bone
• Make up ligaments, connecting bone-to-bone at a
  joint

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Specialized Connective Tissue Fat
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Cartilage

• Soft
• Structural proteins deposited in the matrix
  between cells
• Forms embryonic skeletons
• Occurs in mature human adults in ears, joints and
  tip of nose

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Cartilage
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Bone

• Hard
• Calcium salts deposited in matrix
• Serve as a sink for calcium
• Proteins provide elasticity while minerals
  provide strength
• Dense bone has osteocytes located in lacunae
  (Haversian canals)
• Spongy bone occurs at the end of bones and absorb
  stress

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Bone
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Blood

• Connective tissue separated by a liquid matrix
  called plasma
• Red blood cells (erythrocytes) carry oxygen
• White blood cells (leukocytes) function in the
  immune system
• Platelets are cell fragments important in blood
  clotting
• Plasma transports glucose, wastes, CO2, hormones
  and regulate water balance for the blood

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Blood
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Blood
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Muscle Tissue

• Facilitates movement by contraction of individual
  muscle cells referred to as muscle fibers
• Found only in members of the animal kingdom
• Three types
• Skeletal (Striated)
• Smooth
• Cardiac

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Muscle Fibers

• Multinucleated with nuclei just beneath the
  plasma membrane
• Prominent striated, thread-like myofibrils
• The fundamental unit of the muscle is the
  sarcomere
• Each sarcomere consists of
• Thick filaments made of myosin at the center
• Thin filaments made of actin attached to the Z
  line

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Muscle
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Skeletal Muscle

• Function in conjunction with the skeletal system
  in voluntary muscle movement
• Striated with alternating bands at right angles
  to the long axis of the cell
• The bands are areas of actin and myosin deposition

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Skeletal Muscle
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Smooth Muscle

• Lack banding
• Spindle shaped cells that form masses
• Function in involuntary movements and/or
  autonomic responses like breathing, secretion,
  etc.
• Make up structures in the digestive system,
  reproductive tract and blood vessels

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Smooth Muscle
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Cardiac Muscle

• Striated
• Limited to the heart
• Cells are forked, with nucleus near the center
• Cells are connected together by disks
• Intercalated disks

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Cardiac Muscle
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Nervous Tissue

• Important in the integration of stimulus and
  control of the response to that stimulus
• Made of nerve cells called neurons and glial
  cells (helper cells)
• Neurons transmit nerve messages
• Glial cells are in direct contact with neurons
  and often surround them

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Nervous Tissue

• The neuron is the functional unit of the nervous
  system
• Variable in size and shape
• Humans have about 100,000,000,000 (100 billion)
  neurons in their brain! Wow!

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Neuron
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Nervous Tissue

• Each neuron has a cell body, an axon and many
  dendrites
• The cell body contains the nucleus, mitochondria
  and other organelles
• The axon conducts messages away from the cell
  body
• Dendrites receive information from other cells
  and direct them to the cell body

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Neuron Structure