Chapter 4- Tissues Flashcards
Histology is:
The study of tissues.
Histos= tissue Logos= study
The 4 basic types of tissues:
- Epithelial tissue
- Connective tissue
- Muscle tissue
- Nervous tissue
Ocular lenses:
Magnify 10x
The 4 objective lenses on the compound microscope:
1st objective - magnifies 5x (red ring)
2nd objective - magnifies 10x (yellow ring)
3rd objective - magnifies 40x (blue ring)
4th objective - magnifies 63x (silver)
Human are made of:
Eukaryotic cells; all other cells are called Prokaryotic cells (bacteria).
Epithelium:
A sheet of cells that covers a body surface or lines a body cavity.
Epi= upon Theleo= to grow
The functions of epithelium include:
- Protection (of underlying tissues)
- Secretion (release of molecules from cells)
- Absorption (bringing small molecules into cells)
- Diffusion (movement of molecules down their concentration gradient)
- Filtration (passage of small molecules through a sieve-like membrane)
- Sensory reception
Classification of epithelial tissue is based on 2 basic criteria:
- The number of layers
- The morphology (shape) of cells
Simple epithelia:
Contains a single layer of cells, with each cell attached to the basement membrane.
Stratified epithelia:
Contains more than one layer of cells. The cells on the basal surface are attached to the basement membrane; those on the apical surface border an open space.
Types of cell morphology:
Squamous = flat, scale-like
Cuboidal = look like square from the side. Width and height are similar
Columnar = like a column from the side. Cells are tall and thin
Squamous cells:
Flat cells with flat, disc-shaped nuclei
Cuboidal cells:
Cube-shaped cells with spherical, centrally located nuclei
Columnar cells:
Taller than they are wide. The nuclei are located near the basal surface and are commonly oval shaped.
Simple squamous epithelium:
Single layer of flat cells
Very thin usually quite porous
Functions: diffusion, filtration, make smooth surface
Location: lines sacs of lungs (alveoli), lines blood vessels, lining of body cavities, lines renal capsules, lining of heart, lining of lymphatic vessels. Serous membrane (plus connective tissue)
Simple cuboidal epithelium:
Simple layer of cuboidal cells
Function: diffusion, filtration, make smooth surface
Location: Forms the secretory cells of many glands, and the walls of the smallest ducts of glands, and the walls of many tubules in the kidney.
Simple columnar epithelium:
Single layer of columnar cells.
Taller than they are wide.
Function: propels what is on top of the cilia
Location: lines oviduct (ciliated), respiratory tract (ciliated), digestive tract (microvilli)
Cilia:
Hair-like, motile structures that extend from the free surfaces.
Made up of microtubules.
Important for removing products outside the cell.
E.g., mucus + anything trapped in the respiratory tract; the egg in the oviduct of the female.
Microvilli:
Finger-like, non-motile extensions of the cells free surfaces (surface exposed to lumen or an organ)
Increase the surface area of a cell, more common in areas that are involved in absorption
(E.g., digestive tract and proximal convoluted tubules of kidney)
Non-ciliated Simple Columnar:
Single layer of columnar cells.
Function: absorption
Location: stomach- large and small intestine, gall bladder, some glands
2 types of stratified squamous epithelium:
Non-keratinized (less keratin)
Keratinized (a lot of keratin)
Both gives protection, but keratinized gives more.
Keratin:
A protein that forms a scaffolding inside the cell giving lots of structural strength to the cell.
Dead cells, no nucleus.
Located: skin
Non-keratinized:
Live cells, nuclei and mucous present.
Located: in mouth, esophagus, vagina, anal canal
Pseudostratified columnar epithelium:
A single layer of cells that appear to be multilayered.
Nuclei are located at different heights, but all cells touch the basement membrane.
Functions: secretion and absorption
Located in trachea.
Identified by the presence of cilia and Goblet cells.