ANP 1105 Lecture Notes - Lecture 2: Basal Lamina, Reticular Connective Tissue, Epithelial Polarity
29 Aug 2016
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1.3 Describe the different tissues of the human body (Chapter 4)
Unicellular: one cell that alone carries out all activities necessary to
keep itself alive.
Multicellular: cells do not operate independently but instead form tight
cell communities that live and work together.
The human body is multicellular.
Individual body cells are specialized to perform specific functions to
maintain homeostasis.
Tissues: groups of cells that are similar in structure and perform a
common or related function.
There are four tissue types that interweave to form the “fabric” of the
body:
1. Epithelial: covers
2. Connective: supports
3. Muscle tissue: produces movement
4. Nervous tissue: controls
Tissues are organized into organs. Most organs have all 4 types of
tissue.
Histology: the study of tissues
We can study tissues using microscopy.
•specimen must be fixed (preserved) and
cut into sections.
•sections must be thin enough to transmit
light or electrons.
•specimen must be stained to add
contrast.
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Epithelial Tissue (epithe = laid on, covering)
Also called an epithelium, this is a sheet of cells that covers a body
surface or lines a body cavity. Tends to create boundaries.
Two forms of epithelial tissue that occur in the body:
1. covering and lining epithelium:
•forms the outer layer of the skin
•dips into and lines the open cavities of the urogenital (urinary and
genital organs), digestive and respiratory systems
•covers the walls and organs of the closed ventral body cavity.
•Ex:
2. Glandular epithelium: fashions the glands of the body, secretes
something, found in organs where secretion is important.
Ex: stomach
Epithelia forms boundaries between environments and acts as a filter
for the body because nearly all substances given or received by the
body must pass through an epithelium.
6 Functions of epithelium
1. Protection-skin
2. Absorption-GI tract
3. Filtration-kidney
4. excretion-
5. Secretion-glands
6. Sensory Reception-taste buds
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Special Characteristics of Epithelium
!
Polarity (direction):
•Epithelia exhibits apical-basal polarity. This means that all
epithelia have an apical surface and a basal surface.
•An apical surface is an upper free surface exposed to the body
exterior or the cavity of an internal organ. Contains cilia and
microvilli.
•A basal surface is a surface near the base or interior of a structure;
nearest the lower side or bottom of a structure. Connected to
connective tissue below.
•adhesive sheet
•The two surfaces differ in both structure and function which
therefore creates polarity.
Specialized contacts:
•(excluding glandular epithelia), epithelial cells fit closely together to
form continuous sheets.
•Desmosomes and tight junctions (which are lateral contacts), bind
adjacent cells together at many points.
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
1. 3 describe the different tissues of the human body (chapter 4) Unicellular: one cell that alone carries out all activities necessary to keep itself alive. Multicellular: cells do not operate independently but instead form tight cell communities that live and work together. Individual body cells are specialized to perform speci c functions to maintain homeostasis. Tissues: groups of cells that are similar in structure and perform a common or related function. There are four tissue types that interweave to form the fabric of the body: epithelial: covers, connective: supports, muscle tissue: produces movement, nervous tissue: controls. Most organs have all 4 types of tissue. We can study tissues using microscopy: specimen must be xed (preserved) and cut into sections, sections must be thin enough to transmit light or electrons, specimen must be stained to add contrast. Also called an epithelium, this is a sheet of cells that covers a body surface or lines a body cavity.
