Introduction to Histology Flashcards
Define tissue
- Complex structures formed due to the organisation of particular cells in a specific pattern.
- Consists of interwoven masses of cells and extracellular material
Define histology
The study of these tissues and the way in which they are organised and structured
What does the ‘structure’ of tissues consist of?
- Tissue structure - how the cells interact with the extracellular material and one another to form the tissue
- Cellular structure - how the cell is shaped and how its components are organised to support the cell’s specific function
- Subcellular (organelle) structure - analysis of the cell’s organelles
- Histochemical structure - molecular analysis of cell structure
What is the importance of histology in pathology?
HISTOPATHOLOGY
- Studying tissues affected by disease to determine its severity and progression
What are the four basic tissues in the human body and what do they have in common?
- Epithelial
- Connective
- Muscle
- Nervous
How is epithelial tissue usually structured?
- Made up of cells arranged in a continuous sheet with one or more layers - with apical and basal surfaces
- Basement membrane separates epithelial tissue from underlying connective tissue
- 2 types - covering/lining and glandular(involved in endocrine/exocrine secretion)
- Classified based on number of cell layers, distribution of cells within the layers and shape of cells on top layer
Define cell
Living, self-sufficient entities that form ‘complex’ structures - i.e tissues
- Membrane-bound
Outline the different classifications of epithelial tissue
Classification can be based on number of layers of cells and the way that the cells are distributed
- Simple epithelium - single cell layer
- Stratified epithelium - two or more cell layers
- Pseudostratified epithelium - cells are anchored to the basement membrane (one cell layer) but not all reach the apical surface (nuclei do not align so does not look like a single layer). Cells are different sizes
Classification also based on shape of upper cells
- Columnar
- Cuboidal
- Squamous
EXAMPLES
- Simple Cuboidal- renal collecting ducts
- Stratified Cuboidal – lining of ducts of mammary gland
- Pseudostratified columnar- lining of the epithelium of the trachea
What are the two types of connective tissue?
In general, what does connective tissue contain?
PROPER and SPECIALISED connective tissue
- Contains many cell types e.g adipocytes, macrophages, fibroblasts and mast cells
- Consists of a matrix made up of a ground substance - made up of proteins and polysaccharides, as well as fibres - usually reticular, collagen and elastic fibres
What can connective tissue be classified into?
Loose Connective – fibres & many cell types in gelatinous matrix, found in skin & surrounding blood vessels, nerves and organs
Dense Connective – bundles of parallel collagen fibres & fibroblasts, found in tendons and ligaments
What is cartilage made up of?
Briefly outline the 3 types of cartilage
Made of two main components: 1) collagen & elastin fibres embedded in a matrix of glycoproteins; 2) chondrocytes.
3 TYPES
- HYALINE - weakest, most abundant type - found at end of long bones, and in structures such as the ear and nose
- ELASTIC - maintains shape, has branching elastic fibres(which is the distinguishing feature from hyaline)
- FIBROUS - strongest type, little matrix and dense collagen, found in pelvis, skull & vertebral discs
What is bone made up of?
Outline the two types of bone development
Composed of bone cells - osteoprogenitor cells, osteoblasts, osteocytes and osteoclasts – Suspended in a matrix consisting of collagen fibres and minerals
- Membranous – as in flat bones, clavicle(collarbone) or mandible (jawbone)
- Endochondral – as in limb and vertebral column bones
How can mature bone be classified?
- Compact – concentric circular layers (lamellae) organised in lacunae and a central canal (Harvesian system)
- Trabecular – slender interlacing parallel lamellae with marrow within the spaces
Outline the general structure of
- skeletal muscle
- smooth muscle
- cardiac muscle
SKELETAL MUSCLE
- Striations are voluntary and striated, and striations found perpendicular to muscle fibres and found attached to the bone
- Organised as myofibres - nucleus located peripherally
- When observed longitudinally, forms a lined up banding pattern from one cell to the next
SMOOTH MUSCLE
- Involuntary, non- striated and spindle shaped
- Found in blood vessels
- Cells vary in size and have a fusiform shape
- Position of nuclei varies
CARDIAC MUSCLE
- Involuntary, striated and branched
- Contains intercalated discs
- Cells in cardiac muscle are smaller than those found in skeletal muscle
- Nuclei centrally located
What are the following layers and what do they develop into?
- Ectoderm
- Mesoderm
- Endoderm
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
