Histology summary
(Cell Biology - Histology exam 1)
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,Tissues (4-1) 3
Epithelial tissue (4-2 - 4-3) 3
Connective tissue (4-4 - 4-7 & 6-3 - 6-6) 7
Muscle tissue (4-9 & 10-1 - 10-4 & 10-9 - 10-10) 12
Nervous tissue (4-10 & 12-1 - 12-3) 16
Digestive system (4-8 & p935+936 & p945) 20
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, Tissues (4-1)
- Tissues: collections of specialized cells and cell products that carry out a limited number of
functions
- Histology: study of tissues
- 4 basic types of tissue:
- Epithelial tissue — covers exposed surfaces, lines internal passageways and
chambers, and forms glands
- Connective tissue — lls internal spaces, provides structural support for other tissues,
transports materials within the body, and stores energy
- Muscle tissue — specialized for contraction and includes skeletal muscles of the body,
the muscle of the heart, and the muscular walls of hollow organs
- Nervous tissue — carries information from one part of the body to another in the form
of electrical impulses
- Cell types that are part of the same basic tissue type can look much di erent; these cells share
the same embryonic origin
- Embryology & germ layers:
- Ectoderm — nervous tissue, skin
- Endoderm — digestive tissue, lung
- Mesoderm — muscle, connective tissue (from mesenchyme)
Epithelial tissue (4-2 - 4-3)
- Epithelium: tissue existing of cells that are tightly connected to each other
- 2 types: covering epithelia (e.g. skin) & glands
- Epithelia: layers of cells that cover external or line internal surfaces
- Glands: structures that produce uid secretions; attached or derived from epithelia
- 4 functions:
- Provide physical protection
- Control permeability
> Some are relatively impermeable, others are not
> Many epithelia contain molecular ‘machinery’ to absorb/secrete speci c
substances
> Epithelial barrier can be regulated+modi ed in response to stimuli (e.g. hormones
& physical stress)
- Provide sensation
> Most epithelia have large sensory nerve supply that continually provides info
about external+internal environments
> Neuroepithelium is specialized to perform particular sensory function
(smell+taste+sight+equilibrium+hearing)
- Produce specialized secretions
> Gland cells: epithelial cells that produce secretions; ranging from scattered
among other cell types to complex glandular organs
> In glandular epithelium, most/all epithelial cells produce secretions
> Cells discharge secretions onto epithelium surface (for physical protection
/ temperature regulation) or release them into surrounding interstitial
uid+blood (as chemical messengers)
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