Biol 121 Chapter 4 – 09-22-2020
Tissues! – 4 Major Types
** The term “tissue” refers to a group of cells that work together to carry out a common – often
specialized function. Frequently the cells of the tissue share a common embryonic origin.
Types:
1. epithelial
(a) covers a body surface – either inside or outside
Examples: the lining of hollow organs (think urinary bladder); lining of body cavities
(such as the thoracic cavity); ducts (looks like a tube or channel – think about the pancreatic duct that
delivers enzymes into the small intestine to support digestion; skin (example of outer epithelium)
(b) forms the secretory portions of glands
Examples: sweat glands, salivary glands; many organs like the heart contain glandular
tissue which is made of epithelium
2. connective – “elmer’s glue”
(a) generally serves to protect, support and bind body structures together
Examples: cartilage; adipose cells contain fat which is energy rich; the white blood cells of the
bloodstream are part of your body defense and blood itself is a connective tissue
3. muscle
(a) made of cells that contract and generate force to move body structures
Example: skeletal muscles that tug on bones (via tendons – connective tissue); heart
contracts to force blood through the blood vessels of your cardiovascular system
(b) the energy consumed to generate contraction produces a lot of waste heat which his used to
maintain body temperature
4. Nervous
(a) made of cells that allow an organism to detect and respond to information in the
environment
(b) communication of information within the nervous is both electrical (nerve impulse) and
biochemical (neurotransmitter)
Cell Junctions
** The phrase “cell junction” refers to points of contact between the plasma membrane of adjacent cells
Types: (Fig 4.2 – p108)
Tissues! – 4 Major Types
** The term “tissue” refers to a group of cells that work together to carry out a common – often
specialized function. Frequently the cells of the tissue share a common embryonic origin.
Types:
1. epithelial
(a) covers a body surface – either inside or outside
Examples: the lining of hollow organs (think urinary bladder); lining of body cavities
(such as the thoracic cavity); ducts (looks like a tube or channel – think about the pancreatic duct that
delivers enzymes into the small intestine to support digestion; skin (example of outer epithelium)
(b) forms the secretory portions of glands
Examples: sweat glands, salivary glands; many organs like the heart contain glandular
tissue which is made of epithelium
2. connective – “elmer’s glue”
(a) generally serves to protect, support and bind body structures together
Examples: cartilage; adipose cells contain fat which is energy rich; the white blood cells of the
bloodstream are part of your body defense and blood itself is a connective tissue
3. muscle
(a) made of cells that contract and generate force to move body structures
Example: skeletal muscles that tug on bones (via tendons – connective tissue); heart
contracts to force blood through the blood vessels of your cardiovascular system
(b) the energy consumed to generate contraction produces a lot of waste heat which his used to
maintain body temperature
4. Nervous
(a) made of cells that allow an organism to detect and respond to information in the
environment
(b) communication of information within the nervous is both electrical (nerve impulse) and
biochemical (neurotransmitter)
Cell Junctions
** The phrase “cell junction” refers to points of contact between the plasma membrane of adjacent cells
Types: (Fig 4.2 – p108)
