Histology Flashcards
Histology
Study of tissues
Tissue
a group of cells with similar structure and function
4 major tissue types
- Epithelial Tissue
- Connective Tissue
- Muscle Tissue
- Nervous Tissue
Membrane junctions
points of contact between adjacent cells - seen in epithelial tissue, some nervous and muscle cells
3 types of membrane junctions
- tight
- Desmosomes
- gap
Tight junctions
Protein molecules in the cell membrane fuse together. Serve to prevent substances from passing in between cell
Desmosomes junctions
Loose attachments, Use linker proteins to join adjacent cells
Gap junctions
- Protein channels that connect adjacent cells
- Allow direct communication between cells
- Allow substances to pass from the inside of one cell to the inside of another
- Extremely important in smooth muscle and cardiac muscle cells
Epithelial tissue
Found on all of the body surfaces and lines all of the body cavities
Connective tissue
connecting tissue
Muscle tissue
contractile tissue
Nervous tissue
signalling tissue
Characteristics of epithelial
- one free membrane that sits on top of a basement membrane
- held together by tight junctions
- avascular (lacks blood vessels
- reproduce via mitotic division
basement membrane
extracellular layer, attaches epithelium to underlying CT layer
Number of cell layers of epithelial
- simple
- stratified
- pseudo stratified
Simple epithelial
A single cell layer with one free surface, that sits atop a basement membrane
Stratified epithelium
Several cell layers with one free surface.
the basal/bottom-most layer sits atop a basement membrane
Pseudostratified epithelium:
Appears as more than one layer but all cells really do sit on top of the same basement membrane –> a single cell layer
Squamous
Irregularly shaped, scale-like cells
Found on the outer surfaces of the skin –> resist abrasion
Cuboidal
Cube-shaped cells
Specialized for secretion and absorption
Columnar
Column-shaped cells
Specialized for secretion and absorption
Cell shape of epithelial
- squamous
- cuboidal
- columnar
- transitional
Transitional
Stratified cell layer but the appearance varies with stretching (bladder)
Epithelial tissue classification
Layer and shape are classified together
Example: stratified squamous epithelium, simple cuboidal
Glandular epithelial
Epithelial tissue of the glandular subtype
-Adapted for secretion
Glandular epithelial subtypes
- exocrine gland
- endocrine gland
exocrine gland
secrete products onto surface or cavity
exocrine glands can be..
- single celled (goblet cells) (Secrete mucous into a cavity)
- multicellular (secretory and duct cells) (ex: Sudoriferous glands, Sebaceous glands, and salivary glands)
endocrine glands
no ducts
Secretions are called hormones
Release hormones directly into blood
Example: thyroid gland secretes thyroid hormone
Functions of epithelial
- protection (stratified squamous)
- secretion (glandular epithelium )
- control of permeability (exchange of material, simple epithelia)
Connective tissue consist of cells..
that are separated from one another by a matrix
Extracellular matrix (ECM) of CT
surrounds the cells of the connective tissue
provides the connective tissue with its characteristics
CT cell types
cell name ending in:
- Blast: form and secrete the matrix
- Cyte: maintain the matrix
- Clast: break down the matrix
Matrix composition
proteins fibers, ground substance, and water
Protein fibers are..
- collagen (strength)
- elastic (elastin, allow stretch and recoil)
Ground substance
unstructured material located between the cells
contains fibers
Example: chondroitin sulfate and hyaluronic acid
Three primary characteristics of connective tissue include:
1: Highly vascular with some exceptions (Cartilage is an avascular connective tissue)
2: A lot of extracellular matrix (Keeps the cells far apart from one another)
3: Primary function is to support and connect the tissues in the body
Types of connective tissue
- Connective Tissue Proper
- Cartilage
- Bone
- Blood
types of CT proper cells
loose and dense
2 type of Loose CT
areolar and adipose
Areolar CT
loosely arranged collagen and elastin fibres, surrounded by ground substance. highly vascular
Adipose CT
very little matrix,
large calls (adipocytes/store fat triglyceride),
look like chicken wire,
highly vascular
Functions in shock absorption, insulation and energy storage
2 types of dense CT
dense regular and dense irregular
Dense irregular
composed of fibroblast cells
very little matrix
composed of bundles of collagen fibers
Fibers are larger and run in more than one direction
Found in areas of the body where there is pull in more than one direction
Example: the dermis of the skin
Dense regular
Cells are fibroblasts Very little ground substance Bundles of collagen fibers packed very close together All run in the same direction Poor vasculature Forms tendons Serve to attach muscle to bone
Cartilage cells
are called chondrocytes and found inside of compartments called lacunae, avascular
Cartilage matrix formed of..
- tightly bound collagen fibers
- ground substance (chondroitin sulfate and hyaluronic acid
- water (80%)
Bone cells are called
osteocytes and located in organized structures called lacunae and highly vascular
Bone matrix formed of..
- Densely packed collagen fibers
- Inorganic calcium and phosphate salts —>collectively called hydroxyapetite crystals
- Water
Blood cells are..
red blood cells and white blood cells
Blood matrix formed of..
plasma
Muscle tissue
contractile (can shorten and lengthen)
3 subtypes of muscle tissue
- skeletal
- cardiac
- smooth
Nervous tissues cell types
- neurone: conduct electrical impulses.
- glial cells: support and protect neurons
2 types of bone
spongey and compact
Skeletal muscle
Striated
Used for voluntary movemen
Cardiac muscle
Striated
Found in the heart
Involuntary movement
Smooth muscle
Non-striated
Found in areas that are required to stretch (esophagus, bladder, uterus)
Involuntary movement
Membranes
Composed of two or more tissues therefore membranes are very simple organs
Form continuous multi-cellular sheets
3 types of membranes
- Mucous membranes: mucosa
- Serous membranes: serosa
- Cutaneous membranes: skin
Mucous membrane
line cavities that open to the outside of the body (Example: reproductive tract, respiratory tract, digestive tract)
Whats present in mucous membrane
- epithelial layer (Can be simple squamous or pseudostratified)
- connective tissue layer (Always areolar and Called the lamina proper when part of the mucous membrane)
Serous membranes
line cavities that do not open to the outside of the body (Example: thoracic cavity (chest cavity), abdominal cavity) Covers the organs that are located within these cavities
Serous double membrane composed of
of epithelial and connective tissues
- The visceral layer covers the organs
- The parietal layer is against the wall of the thoracic and abdominal cavitiy
The pericardium surrounds the.. and what layers touch what surfaces
heart
Visceral layer contacts the heart surface
parietal layer contacts the mediastinum
The pleura surrounds the.. and what layers touch what surfaces
lungs
Visceral layer contacts the lung surface
parietal layer contact the thoracic cavity wall
The peritoneum surrounds the.. and what layers touch what surfaces
the abdominal cavity and the viscera
Visceral layer contacts the viscera
parietal layer contacts the abdominal cavity wall
