Introduction to Cellular Pathology Flashcards
What are the four types of tissues that we look at?
- EPITHELIAL tissue
- CONNECTIVE tissue
- MUSCLE tissue
- NERVE tissue
Describe the structure of epithelial tissue.
Epithelial tissue is made up of cells arranged in a continuous sheet, with one or more layers. It has apical and basal layers.
A basement membrane separates the epithelial layer from the underlying connective tissue.
There are two types of epithelial tissue:
- covering and lining epithelia
- glandular epithelium (endocrine and exocrine)
Describe how epithelial tissue is classified.
The number of cell layers and the shape of the cells in the top layer are used to classify epithelium.
CLASSIFICATION:
- SIMPLE EPITHELIUM: one cell layer
- STRATIFIED EPITHELIUM: two or more cell layers
- PSEUDOSTRATIFIED EPITHELIUM: cells are anchored to the basement membrane (ie. one cell layer) but not all cells reach the apical surface (nuclei do not align, so it doesn’t look like one cell layer)
The shape of the top layer cells can be:
- cuboidal
- columnar
- squamous
Describe the structure of connective tissue.
There are two main groups of connective tissue:
- PROPER connective tissue
- SPECIALISED connective tissue
Connective tissue contains many different cell types, including fibroblasts, macrophages, mast cells and adipocytes.
The connective tissue matrix is made up of two materials:
1) GROUND SUBSTANCE such as proteins and polysaccharides
2) FIBRES: reticular, collagen and elastic
How is connective tissue classified?
LOOSE CONNECTIVE:
- fibres and many cell types in a gelatinous matrix
- found in the skin and the surrounding blood vessels, nerves and organs
DENSE CONNECTIVE:
- bundles of parallel collagen fibres and fibroblasts
- found in tendons and ligaments
Describe the structure of cartilage.
Cartilage is made up of two main components:
- collagen and elastin fibres embedded in a matrix of glycoproteins
- cells called chondrocytes
List the three types of cartilage and describe them.
HYALINE CARTILAGE:
- the weakest, most abundant type
- found at the end of long bones, and structures like the ear and nose
ELASTIC CARTILAGE:
- maintains shape
- the branching elastic fibers distinguish it from hyaline
FIBROUS CARTILAGE:
- the strongest type
- has dense collagen and a little matrix
- found in the pelvis, skull and vertebral discs
Describe the structure of the bone.
The bone is composed of bone cells - osteoprogenitor cells, osteoblasts, osteocytes and osteoclasts - suspended in a matrix consisting of collagen fibres and minerals.
Bone development can be:
- MEMBRANOUS: as in flat bones, the clavicle (collarbone) or mandible (lower jawbone)
- ENDOCHONDRAL: as in the limbs and vertebral column bones
How is mature bone classified?
Mature bone may be:
- COMPACT: concentric circular layers (lamellae) organised in lacunae and a central canal (Haversian system)
- TRABECULAR: slender, interlacing parallel lamellae with marrow within the spaces
What are the units of muscle fibres?
The principal functional unit is the muscle fibre.
There are also some satellite cells (stem cells) with the capacity to develop into new muscle fibres.
Name and describe the three types of muscle tissue.
SKELETAL MUSCLE:
- voluntary, striated striations perpendicular to the muscle fibres
- mainly found attached to bones
- organised in myofibres with nuclei peripherally located
- forms a lined-up banding pattern from one cell to another when observed longitudinally
CARDIAC MUSCLE:
- involuntary, striated and branched
- has intercalated discs
- the cells are smaller than in skeletal muscle
- nuclei are centrally located
SMOOTH MUSCLE:
- involuntary, non-striated and spindle-shaped
- found in blood vessels and the GI tract
- cells may vary in size and have a fusiform shape
- nuclei are observed in different positions
Describe the constituents of nerve tissue.
It constitutes the Central Nervous System (CNS) and the Peripheral Nervous System. It consists of two main functional cell types:
- NEURONS: cells that convert stimuli into electrical impulses to the brain
- NEUROGLIAL: collection of different cell types with supportive roles
Describe what neurons and neuroglial cells are made out of.
NEURONS:
They’re made up of a cell body, an axon and dendrites. There are three types of neurons:
- MOTOR NEURONS: carry impulses from the CNS to muscles and glands
- INTERNEURON: interpret input from the sensory neurons and responses to the motor neurons
- SENSORY NEURON: receive information from the environment and transmit it to the CNS
NEUROGLIA: It's made up of: (IN THE CNS) - astrocytes - oligodendrocytes - ependymal cells - microglia
(IN THE PNS)
- Schwann cells
- satellite cells
List the three primary cell layers that form the embryo.
All tissues of the body develop from the three primary cell layers that form the embryo:
- ECTODERM: develops into the nervous tissue and epithelial tissue
- MESODERM: develops into epithelial tissue, connective tissue and muscle tissue
- ENDODERM: develops into epithelial tissue
